The incidence of pelvic fractures and related surgery in the Finnish adult population: a nationwide study of 33,469 patients between 1997 and 2014

Background and purpose — Information on the epidemiological trends of pelvic fractures and fracture surgery in the general population is limited. We therefore determined the incidence of pelvic fractures in the Finnish adult population between 1997 and 2014 and assessed the incidence and trends of fracture surgery.Patients and methods — We used data from the Finnish National Discharge Register (NHDR) to calculate the incidence of pelvic fractures and fracture surgery. All patients 18 years of age or older were included in the study. The NHDR covers the whole Finnish population and gives information on health care services and the surgical procedures performed.Results and interpretation — We found that in Finnish adults the overall incidence of hospitalization for a pelvic fracture increased from 34 to 56/100,000 person-years between 1997 and 2014. This increase was most apparent for the low-energy fragility fractures of the elderly female population. The ageing of the population is likely therefore to partly explain this increase. The annual number and incidence of pelvic fracture surgery also rose between 1997 and 2014, from 118 (number) and 3.0 (incidence) in 1997 to 187 and 4.3 in 2014, respectively. The increasing number and incidence of pelvic fractures in the elderly population will increase the need for social and healthcare services. The main focus should be on fracture prevention.

Pelvic fractures range from minor to major trauma and constitute about 3% to 8% of all fractures treated in hospitals (Court-Brown and Caesar 2006). The incidence of pelvic fractures has varied from 17 to 364/100,000 person-years (Melton et al. 1981, Ragnarsson and Jacobsson 1992, Lüthje et al. 1995, Kannus et al. 2000, Balogh et al. 2007, Andrich et al. 2015, Kannus et al. 2015, Verbeek et al. 2017). This wide range in incidence rates can be explained by different study populations with varying age, and by variations in study designs and follow-up periods. In previous studies, the incidence (n/100,000 person-years) of pelvic fractures was in the United States 37 between 1968 and 1977 (Melton et al. 1981), in Sweden 20 between 1976 and 1985 (Ragnarsson and Jacobsson 1992), in Finland 24 in 1988 (Lüthje et al. 1995), in the Finnish population aged 60 years or older 20 in 1970 and 92 in 1997 (Kannus et al. 2000), in Australia 23 between 2005 and 2006 (Balogh et al. 2007), in the German population aged 60 years or older 22 between 2008 and 2011 (Andrich et al. 2015), in the Finnish population aged 80 years or older 73 in 1971 and 364 in 2013 (Kannus et al. 2015) and in the Netherlands 14 between 2008 and 2012 (Verbeek et al. 2017).In the 80 years and older population, the incidence of low-energy pelvic fractures seems to be increasing (Kannus et al. 2015). Indeed, between 1997 and 2014, the incidence of acetabular fractures, especially low-energy acetabular fractures, rose in Finland (Rinne et al. 2017), whereas the incidence of high-energy acetabular fractures remained at the same level. Notably, since 1997, the incidence of many other fall-related low-energy fractures, such as hip fractures, has decreased in Finland (Korhonen et al. 2013, Kannus et al. 2018).Most pelvic fracture studies concentrate on surgical treatment, even though the majority of these fractures can be treated nonoperatively (Osterhoff et al. 2019, Tornetta et al. 2019). Unstable and dislocated pelvic fractures often need surgery, while stable, non-displaced, or minimally displaced fractures, mostly occurring in elderly people after a simple fall, can usually be treated nonsurgically. At present, however, there is only limited information available regarding the incidence and trends of pelvic fracture surgery in the general population.We assessed the incidence of pelvic fractures in the Finnish adult population between 1997 and 2014 and the incidence and trends of pelvic fracture surgery.     

Tibial lengthening using a retrograde magnetically driven intramedullary lengthening device in 10 patients with preexisting ankle and hindfoot fusion

Background and purpose — Motorized intramedullary lengthening nails (ILNs) have been developed as an alternative to external fixators for long bone lengthening. The antegrade approach represents the standard method for tibial ILN insertion. In patients with preexisting ankle and hindfoot fusion a retrograde approach provides an alternative technique that has not been evaluated so far. We report the outcome of this method in 10 patients.Patients and methods — This retrospective study included 10 patients (mean age 18 years [13–25]) with preexisting ankle and hindfoot fusion who underwent tibial lengthening with a retrograde ILN (PRECICE). The mean leg length discrepancy (LLD) was 58 mm (36–80). The underlying conditions were congenital (n = 9) and post tumor resection (n = 1). The main outcome measures were: ILN reliability, distraction achieved, distraction index (DIX), time to bone healing, consolidation index (CIX), complications, and functional results.Results — All patients achieved the goal of lengthening (mean 48 mm [26–80]). Average DIX was 0.6 mm/day (0.5–0.7) and mean CIX was 44 days/cm (26–60). Delayed consolidation occurred in 2 patients and healed after ILN dynamization or nail exchange with grafting. Toe contractures in 2 other patients were resolved with physiotherapy or tenotomy. Until last follow-up (mean 18 months [12–30]) no true complications were encountered, knee motion remained unaffected, and full osseous consolidation occurred in all patients.Interpretation — In patients with LLD and preexisting ankle and hindfoot fusion distal tibial lengthening using a retrograde ILN is a reliable alternative to the standard approach with equivalent bone healing potential and low complication rates leaving the knee unaffected.

Fully implantable intramedullary lengthening nails (ILNs) with mechanical (Guichet and Casar 1997, Cole et al. 2001) and motorized (Baumgart et al. 1997, Schiedel et al. 2014) drive systems have been developed as an alternative to external fixators for bone lengthening (Mahboubian et al. 2012, Black et al. 2015, Laubscher et al. 2016). Recently, magnetically driven ILNs in particular have become increasingly popular (Kirane et al. 2014, Wagner et al. 2017) and in contrast to external fixation provide an equally safe and more comfortable option for limb lengthening and deformity correction (Szymczuk et al. 2019, Horn et al. 2019). Antegrade or retrograde femoral and antegrade tibial lengthening with the PRECICE limb lengthening system (NuVasive, San Diego, CA, USA) has been assessed by several studies (Kirane et al. 2014, Schiedel et al. 2014, Shabtai et al. 2014, Tiefenboeck et al. 2016, Wiebking et al. 2016, Fragomen and Rozbruch 2017, Wagner et al. 2017, Iobst et al. 2018, Cosic and Edwards 2020, Nasto et al. 2020).In tibial lengthening the antegrade approach represents the standard method for ILN implantation (Fragomen and Rozbruch 2017). In patients with preexisting ankle and hindfoot fusion a retrograde approach provides an alternative technique for tibial nail insertion. Approach-associated affections of the knee joint like anterior knee pain (Rothberg et al. 2019) and—in immature patients—damage to the proximal tibial growth plate (Wagner et al. 2017, Frommer et al. 2018) can be avoided. Despite these potential advantages, the use of a retrograde tibial nailing approach and distal tibial osteotomy in patients with preexisting ankle and hindfoot fusion has not been evaluated so far.     

Reduced incidence and economic cost of hardware removal after ankle fracture surgery: a 20-year nationwide registry study

Background and purpose — Open reduction and internal fixation (ORIF) is a treatment method for unstable ankle fractures. During recent years, scientific evidence has shed light on surgical indications as well as on hardware removal. We assessed the incidence and trends of hardware removal procedures following ORIF of ankle fractures.Patients and methods — The study covered all patients 18 years of age and older who had an ankle fracture treated with ORIF in Finland between the years 1997 and 2016. Patient data were obtained from the Finnish National Hospital Discharge Register.Results — 68,865 patients had an ankle fracture treated with ORIF in Finland during the 20-year study period between 1997 and 2016. A hardware removal procedure was performed on 27% of patients (n = 18,648). The incidence of hardware removal procedures after ankle fracture decreased from 31 (95% CI 29–32) per 100,000 person-years in the highest year 2001 (n = 1,247) to 13 (CI 12–14) per 100,000 person-years in 2016 (n = 593). Moreover, the proportion and number of removal operations performed within the first 3 months also decreased. The costs of removal procedures decreased from approximately €994,000 in 2001 to €472,600 in 2016.Interpretation — Removal of hardware after ankle surgery (ORIF) is a common operation with substantial costs. However, the incidence and cost of removals decreased during the study period, with a particular decrease in hardware removal operations within 3 months.

It is estimated that approximately 40% of all ankle fractures require surgical management, most commonly open reduction and internal fixation (ORIF) (Jensen et al. 1998). According to Kannus et al. (2016), an earlier increasing trend in the incidence of ankle fractures in Finland has steadied.Ankle fractures are associated with high costs related not only to the operation and subsequent hospitalization, but also to the duration of occupational disability (Stull et al. 2017). To reduce the costs of occupational disability, an early return to previous activities and the avoidance of secondary operations is crucial. In a recent study, Fenelon et al. (2019) found that 13% of patients who had had ankle fracture surgery in Ireland underwent hardware removal. The most common reason was planned removal (6%) followed by symptomatic hardware (6%), and infection (0.5%). The reasons for hardware removal include pain and soft tissue irritation, deep late infection, metal allergy or toxicity, hardware migration, metal failure, and secondary fracture (Bostman and Pihlajamaki 1996). The hardware removal rates reported by previous studies have varied between 12% and 80% (Richards et al. 1992, Sanderson et al. 1992, Bostman and Pihlajamaki 1996).While the removal of hardware after ankle fracture surgery is often a straightforward procedure, complication rates are still as high as 10–20% (Sanderson et al. 1992, Kasai et al. 2019). Patient satisfaction and symptomatic relief following ankle fracture surgery is also controversial (Jamil et al. 2008, Williams et al. 2012). Postoperative complications include infections, impaired wound healing, refractures, tissue and nerve damage, postoperative bleeding, and incomplete removal (Sanderson et al. 1992).We determined the incidence and trends in Finland of ankle fracture surgery and hardware removal after ORIF of ankle fractures on a national level. Additionally, we estimated the costs and economic burden of the removal and surgery itself.     

Mortality and revision rate of cemented and uncemented hemiarthroplasty after hip fracture: an analysis of the Dutch Arthroplasty Register (LROI)

Background and purpose — Femoral neck fractures are commonly treated with cemented or uncemented hemiarthroplasties (HA). We evaluated differences in mortality and revision rates in this fragile patient group.Patients and methods — From January 1, 2007 until December 31, 2016, 22,356 HA procedures from the Dutch Arthroplasty Register (LROI) were included. For each HA, follow-up until death, revision, or end of follow-up (December 31, 2016) was determined. The crude revision rate was determined by competing risk analysis. Multivariable Cox regression analyses were performed to evaluate the effect of fixation method (cemented vs. uncemented) on death or revision. Age, sex, BMI, Orthopaedic Data Evaluation Panel (ODEP) rating, ASA grade, surgical approach, and previous surgery were included as potential confounders.Results — 1-year mortality rates did not differ between cemented and uncemented HA. 9-year mortality rates were 53% (95% CI 52–54) in cemented HA compared to 56% (CI 54–58) in uncemented HA. Multivariable Cox regression analysis showed similar mortality between cemented and uncemented HA (HR 1.0, CI 0.96–1.1). A statistically significantly lower 9-year revision rate of 3.1% (CI 2.7–3.6) in cemented HA compared with 5.1% (CI 4.2–6.2) in the uncemented HA was found with a lower hazard ratio for revision in cemented compared with uncemented HA (HR 0.56, CI 0.47–0.67).Interpretation — Long-term mortality rates did not differ between patients with a cemented or uncemented HA after an acute femoral neck fracture. Revision rates were lower in cemented compared with uncemented HA.

The number of hemiarthroplasties (HA) after displaced femoral neck fracture increases as a result of global aging, and inferior results and high risk of reoperation after internal fixation. Although the literature on the decision to use cemented or uncemented HA may favor a cemented implant, both techniques are currently used. The use of bone cement is associated with bone cement implantation syndrome (BCIS) characterized by hypoxia, hypotension, loss of consciousness around the time of bone cementation, and intraoperative death (Olsen et al. 2014, Rutter et al. 2014). More intraoperative complications including intraoperative death were found in cemented HA in the Norwegian register (Gjertsen et al. 2012, Talsnes et al. 2013). However, no differences in mortality were found after 1 week (Costain et al. 2011, Yli-Kyyny et al. 2014). More studies including randomized controlled trials (Deangelis et al. 2012, Taylor et al. 2012) and registry studies (Costa et al. 2011, Ekman et al. 2019) did not show differences in mortality between cemented and uncemented HA. Randomized controlled trials (Taylor et al. 2012, Langslet et al. 2014, Inngul et al. 2015) and register studies (Gjertsen et al. 2012, Yli-Kyyny et al. 2014) have shown that the use of uncemented implants could result in a higher risk of periprosthetic fractures. A meta-analysis by Li et al. (2013) concluded that differences in several outcome parameters indicated cemented hemiarthroplasty to be superior to the uncemented counterpart. However, a serious flaw in this analysis is that several studies were included using an outdated stem like the Austin Moore (Sonne-Holm et al. 1982, Emery et al. 1991, Parker et al. 2010) and the experimental uncemented Thomson stem (Sadr and Arden 1977). The use of a prosthesis without Orthopaedic Data Evaluation Panel (ODEP) rating > 3A could influence outcome and is therefore discouraged (Grammatopoulos et al. 2015). A recent review by Rogmark and Leonardsson (2016) included 5 randomized studies comparing modern uncemented and cemented hemiarthroplasties. They found no differences in mortality, but more periprosthetic fractures in uncemented cases. We compared cemented and uncemented HA after an acute hip fracture with primary outcome mortality and revision rate. Data from the Dutch Arthroplasty Register (LROI) were used and the cohort of cemented HAs was compared with uncemented HAs, accounting for the ODEP rating and other confounders.     

Why are patients still in hospital after fast-track,unilateral unicompartmental knee arthroplasty

Background and purpose — Previous studies have investigated risk factors related to prolonged length of stay following total knee arthroplasty (TKA), but little is known about specific factors resulting in continued hospitalization within the 1st postoperative days after unicompartmental knee arthroplasty (UKA). We investigated what specific factors prevent patients from being discharged on the day of surgery (DOS) and the first postoperative day (POD-1) following primary UKA in a fast-track setting.Patients and methods — We prospectively collected data on 100 consecutive and unselected medial UKA patients operated from December 2017 to May 2019. All patients were operated in a standardized fast-track setup with functional discharge criteria continuously evaluated from DOS and until discharge.Results — Median length of stay for the entire cohort was 1 day. 22% and 78% of all patients were discharged on DOS and POD-1, respectively. Lack of mobilization and pain separately delayed discharge in respectively 78% and 24% of patients on DOS. The main reasons for lack of mobilization were motor blockade (37%) and logistical factors (26%). For patients placed 1st or 2nd on the operating list, we estimate that the same-day discharge rate would increase to 55% and 40% respectively, assuming that pain and mobilization were successfully managed.Interpretation — One-fifth of unselected UKA patients operated in a standardized fast-track setup were discharged on DOS. Pain and lack of mobilization were the major reasons for continued hospitalization within the initial postoperative 24–48 hours. Strategies aimed at decreasing length of stay after UKA should strive to improve analgesia and postoperative mobilization.

The number of unicompartmental knee arthroplasties (UKAs) performed in patients suffering from osteoarthritis has steadily increased. UKA has the potential benefit of not only improving patient-reported outcomes, but also to reduce morbidity, complications, and cost (Liddle et al. 2014, Beard et al. 2019). In the United Kingdom, 9% of all primary knee arthroplasties performed in 2018 were UKAs while this number is as high as 20% in Denmark (Danish Knee Arthroplasty Register 2019, National Joint Registry for England 2019).UKA is effective and safe when performed in a fast-track setting and outpatient UKA in selected patients has been shown to be feasible and safe (Munk et al. 2012, Cross and Berger 2014, Bovonratwet et al. 2017, Kort et al. 2017). However, the number of patients actually being discharged on DOS that were scheduled for outpatient surgery differs between studies and ranges from 37% to 100% (Gondusky et al. 2014, Bradley et al. 2017, Jenkins et al. 2019, Rytter et al. 2019).Studies have shown an association between increased length of stay (LOS) and an increase in both complication and readmission rates (Otero et al. 2016). In order to reduce LOS and increase patient satisfaction, a focus on successfully managing well-defined discharge criteria in a multimodal approach is imperative (Husted et al. 2008, Cross and Berger 2014). In addition, decreased LOS and outpatient procedures are associated with financial benefits, which have further fueled interest in decreasing LOS and ensuring DOS discharged following UKA (Bradley et al. 2017). Finally, decreased LOS is also shown to increase patient satisfaction levels (Reilly et al. 2005, Richter and Diduch 2017).A study has been conducted to explore reasons for prolonged hospitalization in a fast-track setting following TKA (Husted et al. 2011). However, in spite of a growing number of UKAs performed each year, no study explicitly exploring reasons for prolonged hospitalization beyond DOS following UKA in a fast-track setting has been published at present.Therefore, we investigated reasons for continued hospitalization beyond DOS following UKA in a fast-track setting.     

No association between blood count levels and whole-blood cobalt and chromium levels in 1,900 patients with metal-on-metal hip arthroplasty

Background and purpose — The accelerated wear of poorly functioning metal-on-metal (MoM) hip implants may cause elevated whole-blood cobalt (Co) and chromium (Cr) levels. Hematological and endocrinological changes have been described as the most sensitive adverse effects due to Co exposure. We studied whether there is an association between whole-blood Co/Cr levels and leukocyte, hemoglobin, or platelet levels.Patients and methods — We analyzed whole-blood Co and Cr values and complete blood counts (including leukocytes, hemoglobin, platelets) from 1,900 patients with MoM hips. The mean age at the time of whole-blood metal ion measurements was 67 years (SD 10). The mean time from primary surgery to whole-blood metal ion measurement was 8.2 years (SD 3.0). The mean interval between postoperative blood counts and metal ion measurements was 0.2 months (SD 2.7).Results — The median Co value was 1.9 µg/L (0.2–225), Cr 1.6 µg/L (0.2–125), mean leukocyte count 6.7 × 10⁹/L (SD 1.9), hemoglobin value 143 g/L (SD 13), and platelet count 277 × 10⁹/L (SD 70). We did not observe clinically significant correlations between whole-blood Co/Cr and leukocyte, hemoglobin, or platelet counts.Interpretation — Elevated whole-blood Co and Cr values are unlikely to explain abnormal blood counts in patients with MoM hips and the reason for possible abnormal blood counts should be sought elsewhere.

The abnormal wear of poorly functioning MoM implants may cause elevated whole-blood cobalt (Co) and chromium (Cr) levels (Brodner et al. 2003, Cheung et al. 2016). Soft-tissue reactions termed “pseudotumors” related to poorly functioning MoM hip replacements have been widely described (Boardman et al. 2006, Gruber et al. 2007, Pandit et al. 2008). The use of MoM implants has dramatically decreased but due to their previous popularity there are still a large number of patients with MoM hip replacements under follow-up (Silverman et al. 2016).Even though local reactions have been the most discussed, systemic reactions in patients with high-wearing hip implants have been described. Cardiomyopathy, polyneuropathy, hypothyreosis, and polycythemia have been described in some patients with MoM hip implants and in patients with fractured ceramic-on-ceramic implant revised to metal-on-polyethylene, resulting in abrasive wear of the CoCr head by ceramic fragments (Cheung et al. 2016). Systemic adverse events have been linked mostly to Co, and hematological and thyroid effects have been described as the most sensitive responses to Co in humans (Tvermoes et al. 2014). A case report described polycythemia with hemoglobin 190 g/L due to massive abrasive CoCr head wear when a ceramic-on-ceramic implant had been revised to metal-on-polyethylene after fracture of the ceramic liner (Gilbert et al. 2013). Several studies have suggested that blood lymphocyte counts may be affected by implant metals from MoM hip replacements (Hart et al. 2009, Hailer et al. 2011, Penny et al. 2013, Chen et al. 2014, Briggs et al. 2015, Markel et al. 2018). Although thrombocytopenia has not been linked to implant metals, it has been reported that platelets adhere to and are activated by CoCr (Ollivier et al. 2017).Complete blood count including leukocyte count, hemoglobin, and platelets is among the most used blood tests in the world (Horton et al. 2019) and 10–20% of the measurements include abnormal values (Tefferi et al. 2005). Due to wide media attention to MoM hip replacements, patients with MoM hips are sometimes worried whether their abnormal laboratory findings are related to their hip replacement. We sought to find out whether whole-blood metal ion levels are associated with blood count. Our hypothesis was that if Co or Cr affected leukocytes, hemoglobin, or platelets at concentrations noted in our study group, we would observe an upward or downward trend (depending on variable) when blood Co or Cr concentrations are approaching the highest values.     

14-year hip survivorship after periacetabular osteotomy: a follow-up study on 1,385 hips

Background and purpose — Few studies have evaluated the long- and mid-term outcomes after minimally invasive periacetabular osteotomy (PAO). We investigated: (1) the long-term hip survival rate after PAO; (2) the risk of complications and additional surgery after PAO; and (3) the hip function at different follow-up points.Patients and methods — We reviewed 1,385 hips (1,126 patients) who underwent PAO between January 2004 and December 2017. Through inquiry to the Danish National Patient Registry we identified conversions to total hip arthroplasty (THA) and complications after PAO. We evaluated the Hip disability and Osteoarthritis Outcome Score (HOOS) obtained preoperatively, and at 6 months, 2-, 5-, and 10-years’ follow-up.Results — 73 of the 1,385 hips were converted to THA. The overall Kaplan–Meier hip survival rate was 80% (95% CI 68–88) at 14 years with a mean follow-up of 5 years (0.03–14). 1.1% of the hips had a complication requiring surgical intervention. The most common additional surgery was removal of screws (13%) and 11% received a hip arthroscopy. At the 2-year follow-up, HOOS pain improved by a mean of 26 points (CI 24–28) and a HOOS pain score > 50 was observed in 86%.Interpretation — PAO preserved 4 of 5 hips at 14 years, with higher age leading to lower survivorship. The PAO technique was shown to be safe; 1.1% of patients had a complication that demanded surgical intervention. The majority of the patients with preserved hips have no or low pain. The operation is effective with a good clinical outcome.

Periacetabular osteotomy (PAO) is the most common surgical procedure to treat symptomatic hip dysplasia (Ganz et al. 1988, Clohisy et al. 2009). Previous studies have reported a 10-year hip survivorship of 78–95% in patients undergoing PAO. These studies, however, only include a small number of hips and surgical procedures performed during the surgical learning curve (Steppacher et al. 2008, Matheney et al. 2009, Hartig-Andreasen et al. 2012, Albers et al. 2013, Lerch et al. 2017, Ziran et al. 2018).In addition to hip survivorship, several studies have investigated the risk of complications following PAO. It has been estimated that early serious complications occurred in 6–37% of patients (Clohisy et al. 2009). Delayed complication rates suggested that 9% of patients had major complications requiring surgical or arthroscopic intervention, including nonunion, hematoma/deep infection, revision PAO, heterotopic ossification, intraoperative fractures, osteotomy, or sciatic nerve damage (Wells et al. 2018b). To our knowledge, only a few studies have evaluated the long-term complications after PAO (Wells et al. 2018b).Moreover, conversion to total hip arthroplasty (THA) may not be sufficient to describe the outcome after PAO, since patients may not want a THA or surgeons may not recommend it. Patient-reported outcomes (PRO) can therefore supplement the evaluation of the outcome after PAO. Previous studies have used different PROs to identify a failure after PAO, including the Merle d’Aubigné–Postel score < 15 or the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) ≥ 10 (Matheney et al. 2009, Hartig-Andreasen et al. 2012, Albers et al. 2013, Lerch et al. 2017, Wells et al. 2018a). In this study, we used the Hip disability and Osteoarthritis Outcome Score (HOOS).This study determines (1) long-term hip survival rate after PAO; (2) risk of complications after PAO; (3) hip function using HOOS at different follow-up points.     

Increases in the rates of primary and revision knee replacement are reducing: a 15-year registry study across 3 continents

Background and purpose — Rates of knee replacement (KR) are increasing worldwide. Based on population and practice changes, there are forecasts of a further exponential increase in primary knee replacement through to 2030, and a corresponding increase in revision knee replacement. We used registry data to document changes in KR over the past 15 years, comparing practice changes across Sweden, Australia, and the United States. This may improve accuracy of future predictions.Patients and methods — Aggregated data from the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) were used to compare surgical volume of primary and revision KR from 2003 to 2017. Incidence was calculated using population census statistics from Statistics Sweden and the Australian Bureau of Statistics, as well as the yearly active membership numbers from Kaiser Permanente. Further analysis of KR by age < 65 and ≥ 65 years was carried out.Results — All registries recorded an increase in primary and revision KR, with a greater increase seen in the KPJRR. The rate of increase slowed during the study period. In Sweden and Australia, there was a smaller increase in revision surgery compared with primary procedures. There was consistency in the mean age at surgery, with a steady small decrease in the proportion of women having primary KR. The incidence of KR in the younger age group remained low in all 3 registries, but the proportional increases were greater than those seen in the ≥ 65 years of age group.Interpretation — There has been a generalized deceleration in the rate of increase of primary and revision KR. While there are regional differences in KR incidence, and rates of change, the rate of increase does not seem to be as great as previously predicted.

Knee replacement (KR) has a favorable survival rate with cumulative revision as low as 3% at 10 years (AOANJRR 2018, SKAR 2018) and this result appears to be improving with time as wear-related revisions become less common (Sharkey et al. 2014, Koh et al. 2017, Postler et al. 2018).Throughout the last decade, national joint replacement registries have recorded increasing yearly volumes of KR (AOANJRR 2018, NJR 2018, SKAR 2018). The reasons for this increase in procedure numbers are proposed to be increased surgeon and patient acceptance of KR (Hamilton et al. 2015), improved longevity (Patel et al. 2015), increasing incidence of osteoarthritis (OA), and use of KR in younger patients (Weinstein et al. 2013, Leyland et al. 2016, Karas et al. 2019).With increasing primary KR use it is predicted that the numbers of revision procedures will also rise (Kumar et al. 2015, Patel et al. 2015). Not only are more people receiving a KR, but some of the factors driving increased primary usage of KR also contribute to increased failure. These include longer life-expectancy, whereby patients with a KR have more time to be revised, and use in young and obese patients who place higher demands on their KR (Hamilton et al. 2015). Counter-balancing this trend, to a small extent, is improved prosthesis performance (Pitta et al. 2018).There is international variation in the use of KR (Kurtz et al. 2011). In a comparative study of 18 countries in 2008, Kurtz et al. (2011) found a range of 8.6 to 213 primary procedures/100,000 population, and a range of 0.2 to 28 revision procedures/100,000 population, but they could not determine if the observed variation related to healthcare systems, access to care, number and distribution of orthopedic surgeons, or the prevalence of joint disease. There are expectations of exponential increases for both primary and revision KR. However, predictions of revision KR in the year 2030 compared with 2005 levels vary widely, from a 75% increase in Taiwan to a 600% increase in the USA and a similar increase in the UK (Kurtz et al. 2007, Kumar et al. 2015, NJR 2018). A further study comparing 24 OECD countries’ KR utilization predicted a 400% increase by 2030 (Pabinger et al. 2015). There are other predictive models with a more conservative forecast for the United States (Inacio et al. 2017).We performed a multi-country comparison of KR, comparing the changing procedure volume and incidence of primary and revision KR using data from the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) over a 15 year period (2003–2017).     

Non-surgical treatment before hip and knee arthroplasty remains underutilized with low satisfaction regarding performance of work,sports, and leisure activities

Background and purpose — Guidelines for managing hip and knee osteoarthritis (OA) advise extensive non-surgical treatment prior to surgery. We evaluated what percentage of hip and knee OA patients received non-surgical treatment prior to arthroplasty, and assessed patient satisfaction regarding alleviation of symptoms and performance of activities.Patients and methods — A multi-center cross-sectional study was performed in 2018 among 186 patients who were listed for hip or knee arthroplasty or had undergone surgery within the previous 6 months in the Netherlands. Questions concerned non-surgical treatments received according to the Stepped Care Strategy and were compared with utilization in 2013. Additionally, satisfaction with treatment effects for pain, swelling, stiffness, and activities of daily life, work, and sports/leisure was questioned.Results — The questionnaire was completed by 175 patients, age 66 years (range 38–84), 57% female, BMI 29 (IQR 25–33). Step 1 treatments, such as acetaminophen and lifestyle advice, were received by 79% and 60% of patients. Step 2 treatments, like exercise-based therapy and diet therapy, were received by 66% and 19%. Step 3—intra-articular injection—was received by 47%. Non-surgical treatment utilization was lower than in 2013. Nearly all treatments showed more satisfied patients regarding pain relief and fewer regarding activities of work/sports/leisure. Hip and knee OA patients were mostly satisfied with NSAIDs for all outcomes, while exercise-based therapy was rated second best.Interpretation — Despite international guideline recommendations, non-surgical treatment for hip and knee OA remains underutilized in the Netherlands. Of the patients referred for arthroplasty, more were satisfied with the effect of non-surgical treatment on pain than on work/sports/leisure participation.

Worldwide guidelines for managing osteoarthritis (OA) of the hip and knee advise extensive non-surgical treatment prior to surgery (Zhang et al. 2010, Smink et al. 2011, McAlindon et al. 2014). Non-surgical treatment is cost-effective and may lower the rapidly increasing OA-related healthcare expenditure by delaying or even replacing surgery (Berwick and Hackbarth 2012).The global Choosing Wisely initiative aims to optimize healthcare usage and costs by advocating the use of proven but underused healthcare modalities, including preventive care (Berwick and Hackbarth 2012, Bernstein 2015). Regarding hip and knee OA, studies have found underuse of non-surgical treatments (Snijders et al. 2011, Hofstede et al. 2015). For example, 1 study showed that 81% of hip and knee OA patients did not receive all recommended non-surgical treatments (Snijders et al. 2011). In the Netherlands, a Stepped Care Strategy (SCS) was developed to stimulate the use of non-surgical treatment before hip and knee replacement (Smink et al. 2011). Moreover, providing adequate non-surgical treatment before hip and knee replacement was recommended by the Dutch Orthopedic Association for their Choosing Wisely Campaign (NOV 2015). Yet, the actual utilization of non-surgical treatment in hip and knee OA patients prior to arthroplasty in the Netherlands is described only by a cohort study from 2013 (Hofstede et al. 2015). Furthermore, no previous study has simultaneously assessed patient satisfaction with non-surgical treatments regarding their effect on symptoms like pain and swelling, and participation as in daily life and work. This is of importance given the increasing number of hip and knee OA patients who want to eliminate their pain and also wish to remain active in daily life, work, and sport/leisure (Kurtz et al. 2009, Otten et al. 2010, Culliford et al. 2015, Witjes et al. 2017). Given the impact of surgery on work participation, the effect of non-surgical treatment on work participation is also of interest (Kuijer et al. 2016, Stigmar et al. 2017).Therefore, the main aim was to assess preoperative non-surgical treatment by hip and knee OA patients referred for arthroplasty in 2018, as well as compared with 2013, and their satisfaction regarding alleviation of symptoms and performing activities of daily living (ADL), work, and sports/leisure activities.     

Influence of fast-track programs on patient-reported outcomes in total hip and knee replacement (THR/TKR) at Swedish hospitals 2011–2015: an observational study including 51,169 THR and 8,393 TKR operations

Background and purpose — Fast-track care programs have been broadly introduced at Swedish hospitals in elective total hip and knee replacement (THR/TKR). We studied the influence of fast-track programs on patient-reported outcomes (PROs) 1 year after surgery, by exploring outcome measures registered in the Swedish arthroplasty registers.Patients and methods — Data were obtained from the Swedish Knee and Hip Arthroplasty Registers and included TKR and THR operations 2011–2015 on patients with osteoarthritis. Based on questionnaires concerning the clinical pathway and care programs at Swedish hospitals, the patients were divided in 2 groups depending on whether they had been operated in a fast-track program or not. PROs of the fast-track group were compared with not fast-track using regression analysis. EQ-5D, EQ VAS, Pain VAS, and Satisfaction VAS were analyzed for both THR and TKR operations. The PROMs for TKR also included KOOS.Results — The differences of EQ-5D, EQ VAS, Pain VAS, and Satisfaction VAS 1 year after surgery were small but all in favor of fast-track for both THR and TKR, also in subscales of KOOS for TKR except KOOS QoL. However, the effect sizes as measured by Cohens’ d formula were < 0.2 for all PROs, in both THR and TKR.Interpretation — Our results indicate that the fast-track programs may be at least as good as conventional care from the perspective of PROs 1-year postoperatively.

Fast-track care programs in elective total hip and knee replacement (THR and TKR) were introduced in Europe at the beginning of the 2000s (Husted et al. 2006, Pilot et al. 2006). Using evidence-based methods in preparation and perioperative care aims to reduce surgical and psychological stress and accelerate recovery after surgery (Kehlet et al. 2008). The care concept has been spread worldwide (Antrobus and Bryson 2011, Christelis et al. 2015, Stowers et al. 2016), resulting in short perioperative hospital stay, and is considered to be safe and well tolerated by patients (Machin et al. 2013, Zhu et al. 2017, Deng et al. 2019, Wainwright and Kehlet 2019). During the last few years an increasing number of ambulatory arthroplasties have been performed as outpatients with maintained safety and short-term outcome (Goyal et al. 2017), Gromov et al. 2019, Coenders et al. 2020). The patients’ experiences and degree of satisfaction have been explored in qualitative studies (Specht et al. 2016, Strickland et al. 2018) and by self-made questionnaires concerning satisfaction rating of the care (Husted and Holm 2006, Specht et al. 2015, Winther et al. 2015).Patient reported outcomes (PROs) after THR and TKR with fast-track programs have been reported using both generic and disease-specific questionnaires (Larsen et al. 2010, 2012, Winther et al. 2015). The follow-up periods have been of different length and only a few of them had a control group with standard care (Larsen et al. 2008, Machin et al. 2013). The PROs with fast-track programs have been compared with PROs from an age- and sex-matched population (Larsen et al. 2010, 2012), and the THR patients but not TKR patients reached the population level after 12 months. In a study from Norway the PROs after 12 months were lower than the matched population level but similar to register-based average gain in general health (EQ-5D) in THR patients (Winther et al. 2015). Brock et al. (2017) studied the length of stay and its impact on WOMAC and SF-36 1 year after surgery. They found a slight improvement of SF-36 associated with shorter LOS but no significant influence on WOMAC. The question remains whether PROs 1 year after THR and TKR are better with fast-track or not compared with conventional care programs.In Sweden, fast-track programs have been broadly implemented for hip and knee replacements during 2011–2015. We studied the influence of the fast-track programs on PROs in elective THR and TKR 1 year after surgery by exploring the PROs registered in the Swedish hip and knee arthroplasty registers (SHAR and SKAR).     

Does cup position differ between trabecular metal and titanium cups? A radiographic propensity score matched study of 300 hips

Background and purpose — The use of trabecular metal cups in primary total hip arthroplasty (THA) is increasing, despite the survival of Continuum cups being slightly inferior compared with other uncemented cups in registries. This difference is mainly explained by a higher rate of dislocation revisions. Cup malpositioning is a risk factor for dislocation and, being made of a highly porous material, Continuum cups might be more difficult to position. We evaluated whether Continuum cups had worse cup positioning compared with other uncemented cups.Patients and methods — Based on power calculation, 150 Continuum cups from 1 center were propensity score matched with 150 other uncemented cups from 4 centers. All patients had an uncemented stem, femoral head size of 32 mm or 36 mm, and BMI between 19 and 35. All operations were done for primary osteoarthrosis through a posterior approach. Patients were matched using age, sex, and BMI. Cup positioning was measured from anteroposterior pelvic radiograph using the Martell Hip Analysis Suite software.Results — There was no clinically relevant difference in mean inclination angle between the study group and the control group (43° [95% CI 41–44] and 43° [CI 42–45], respectively). The study group had a larger mean anteversion angle compared with the control group, 19° (CI 18–20) and 17° (CI 15–18) respectively.Interpretation — Continuum cups had a greater anteversion compared with the other uncemented cups. However, the median anteversion was acceptable in both groups and this difference does not explain the larger dislocation rate in the Continuum cups observed in earlier studies.

Trabecular metal (TM) has become an increasingly popular implant material in both primary and revision total hip arthroplasty (THA) (Laaksonen et al. 2017, 2018). Its highly porous surface provides good initial stability and improves bone ingrowth (Bobyn et al. 1999, Beckmann et al. 2014). Continuum cups (Zimmer Biomet, Warsaw, IN, USA) with TM surface have showed higher revision rates than other uncemented cups after primary THA in some register studies mainly due to a higher dislocation rate (Laaksonen et al. 2018, Hemmilä et al. 2019).Dislocation is one of the most common postoperative complications leading to revision surgery (AOANJRR 2017, Finnish Arthroplasty Register [FAR] 2017). Risk for recurrent dislocation and periprosthetic joint infection increases after revision surgery and therefore prevention of the first dislocation is vital (Ezquerra et al. 2017). Potential risk factors for dislocation are posterior approach, small femoral head size, fracture as the indication for surgery, female sex, and suboptimal acetabular cup positioning (Hailer et al. 2012, Zijlstra et al. 2017). Optimal cup positioning to avoid dislocation is traditionally defined by Lewinnek safe zones. According to this definition optimal cup inclination angle is 40° ± 10° and optimal anteversion angle is 15° ± 10° (Lewinnek et al. 1978. Slight modifications to optimize the stability have also been presented (Danoff et al. 2016). In particular, lower anteversion has been associated with increased dislocation rate (Seagrave et al. 2017a). We theorized that the higher dislocation rate for Continuum cups compared with other uncemented cups may be caused by suboptimal cup positioning due to difficulties in optimizing the acetabular cup position with this highly porous material.In this observational multicenter cohort study, we analyzed whether there is a difference in acetabular implant positioning while using Continuum acetabular cups compared with other uncemented acetabular cups in primary total hip arthroplasty.     

Epidemiology and mortality of pelvic and femur fractures—a nationwide register study of 417,840 fractures in Sweden across 16 years: diverging trends for potentially lethal fractures

Background and purpose — Fractures of the pelvis and femur are serious and potentially lethal injuries affecting primarily older, but also younger individuals. Long-term trends on incidence rates and mortality might diverge for these fractures, and few studies compare trends within a complete adult population. We investigated and compared incidence and mortality rates of pelvic, hip, femur shaft, and distal femur fractures in the Swedish adult population.Patients and methods — We analyzed data on all adult patients ≥ 18 years in Sweden with a pelvic, hip, femur shaft, or distal femur fracture, through the Swedish National Patient Register. The studied variables were fracture type, age, sex, and 1-year mortality.Results — While incidence rates for hip fracture decreased by 18% (from 280 to 229 per 10⁵ person-years) from 2001 to 2016, incidence rates for pelvic fracture increased by 25% (from 64 to 80 per 10⁵ person-years). Incidence rates for femur shaft and distal femur fracture remained stable at rates of 15 and 13 per 10⁵ person-years respectively. 1-year mortality after hip fracture was 25%, i.e., higher than for pelvic, femur shaft, and distal femur fracture where mortality rates were 20–21%. Females had an almost 30% lower risk of death within 1 year after hip fracture compared with males.Interpretation — Trends on fracture incidence for pelvic and femur fractures diverged considerably in Sweden between 2001 and 2016. While incidence rates for femur fractures (hip, femur shaft, and distal femur) decreased or remained constant during the studied years, pelvic fracture incidence increased. Mortality rates were different between the fractures, with the highest mortality among patients with hip fracture.

Pelvic and femur fractures are potentially lethal to both young and elderly patients (Deakin et al. 2007). The younger multi-traumatized patient risks fatal bleeding or other simultaneous mortal injuries after high-energy trauma (Enninghorst et al. 2013). Frail elderly patients exhibit high mortality during the first months after simple falls (Reito et al. 2019). While proximal femur (hip) fractures among the elderly are well studied with respect to incidence and mortality, pelvic and non-hip femur fractures are less well described, and comparisons within a complete population are lacking.Hip fracture incidence has after many years of steady increase actually stabilized in several Western populations, and even decreased during the last decades, as especially evident in Scandinavia (Cooper et al. 2011, Rosengren et al. 2017, Kannus et al. 2018). Pelvic fractures seem instead to maintain an increasing incidence (Kannus et al. 2015, Melhem et al. 2020). While less frequent than hip and pelvic fractures, it has been suggested that shaft and distal femur fractures are increasing (Ng et al. 2012).1-year mortality after hip fracture has globally been described to be between 18% and 27%, trending downwards (Downey et al. 2019). Mortality data on pelvic and distal femur fractures points at similar or higher levels, while data on femur shaft fractures is scarce (Streubel et al. 2011, Moloney et al. 2016, Reito et al. 2019). Little has been published regarding mortality for pelvic and femur fractures within whole populations, and to our knowledge no study has compared the incidence and mortality rates within a complete national population.We investigated and compared the incidence and mortality rates of pelvic, hip, femur shaft, and distal femur fractures in the Swedish adult population over time, including age and sex distribution.     

Systematic review of complications with externally controlled motorized intramedullary bone lengthening nails (FITBONE and PRECICE) in 983 segments

Background and purpose — In recent years motorized intramedullary lengthening nails have become increasingly popular. Complications are heterogeneously reported in small case series and therefore we made a systematic review of complications occurring in lower limb lengthening with externally controlled motorized intramedullary bone lengthening nails.Methods — We performed a systematic search in PubMed, EMBASE, and the Cochrane Library with medical subject headings: Bone Nails, Bone Lengthening, and PRECICE and FITBONE nails. Complications were graded on severity and origin.Results — The search identified 952 articles; 116 were full text screened, and 41 were included in the final analysis. 983 segments were lengthened in 782 patients (age 8–74 years). The distribution of nails was: 214 FITBONE, 747 PRECICE, 22 either FITBONE or PRECICE. Indications for lengthening were: 208 congenital shortening, 305 acquired limb shortening, 111 short stature, 158 with unidentified etiology. We identified 332 complications (34% of segments): Type I (minimal intervention) in 11% of segments; Type II (substantial change in treatment plan) in 15% of segments; Type IIIA (failure to achieve goal) in 5% of segments; and Type IIIB (new pathology or permanent sequelae) in 3% of segments. Device and bone complications were the most frequent.Interpretation — The overall risk of complications was 1 complication for every 3 segments lengthened. In 1 of every 4 segments, complications had a major impact leading to substantial change in treatment, failure to achieve lengthening goal, introduction of a new pathology, or permanent sequelae. However, as no standardized reporting method for complications exists, the true complication rates might be different.

Distraction osteogenesis through an externally applied fixator is a well-established treatment for lower limb lengthening (De Bastiani et al. 1987, Paley 1988, Ilizarov 1990). However, complication rates of this treatment are high, amounting to 1–3.2 complications per patient (Tjernström et al. 1994, Noonan et al. 1998). The wires or pins penetrating soft tissues result in complications such as pin site infection, pain, scarring, muscle transfixation, reduced joint movement, and immobility (Paley 1990, Mazeau et al. 2012, Landge et al. 2015). When the external fixator is removed, there is a risk of further complications such as fracture or malalignment (Noonan et al. 1998, Simpson and Kenwright 2000). To reduce complications and improve patient comfort, limb lengthening by fully implantable bone lengthening nails has been introduced (Guichet 1999, Cole et al. 2001). Problems with purely mechanically driven lengthening nails were resolved by the introduction of motorized (FITBONE) or magnetically driven (PRECICE) bone lengthening nails (Baumgart et al. 1997, Kirane et al. 2014, Paley et al. 2014, Shabtai et al. 2014). A few case-control studies have compared these nails with external fixation (13–15 patients), and the largest case series on intramedullary bone lengthening reports on 92 patients (Black et al. 2015, Horn et al. 2015, Calder et al. 2019). However, the majority of reports of complications of the FITBONE and PRECICE lengthening nails are small case series (Krieg et al. 2008, Dinçyürek et al. 2012, Birkholtz and De-Lange 2016, Hammouda et al. 2017). In recent years motorized intramedullary lengthening nails have become increasingly popular, and we thus hypothesized that standardized data on complications could now be extracted from the literature. We performed a systematic literature review of complications using PRECICE and FITBONE bone lengthening nails in lower limb bone lengthening. The primary outcome was risk of complications imposing a new pathology or permanent sequelae in the patient.     

Combined massive allograft and intramedullary vascularized fibula transfer: the Capanna technique for treatment of congenital pseudarthrosis of the tibia

Background and purpose — Congenital pseudarthrosis of the tibia (CPT) is caused by local periosteal disease that can lead to bowing, fracturing, and pseudarthrosis. Current most successful treatment methods are segmental bone transport and vascularized and non-vascularized bone grafting. These methods are commonly hampered by discomfort, reoperations, and long-term complications. We report a combination of a vascularized fibula graft and large bone segment allograft, to improve patient comfort with similar outcomes.Patients and methods — 7 limbs that were operated on in 6 patients between November 2007 and July 2018 with resection of the CPT and reconstruction with a vascularized fibula graft in combination with a bone allograft were retrospectively studied. The mean follow-up time was 5.4 years (0.9–9.6). Postoperative endpoints: time to discharge, time to unrestricted weight bearing, complications within 30 days, consolidation, number of fractures, and secondary deformities.Results — The average time to unrestricted weight bearing with removable orthosis was 3.5 months (1.2–7.8). All proximal anastomoses consolidated within 10 months (2–10). 4 of the 7 grafts fractured at the distal anastomosis between 6 and 14 months postoperatively. After reoperation, consolidation of the distal anastomosis was seen after 2.8 months (2–4). 1 patient required a below-knee amputation.Interpretation — This case series showed favorable results of the treatment of CPT through a combination of a vascularized fibula graft and large bone segment allograft, avoiding the higher reintervention rate and discomfort with ring frame bone transport, and the prolonged non-weight bearing with vascularized fibula transfer without reinforcement with a massive large bone segment allograft.

Congenital pseudarthrosis of the tibia (CPT) is a rare disease affecting the development of the diaphysis of the tibia with a reported incidence ranging between 1 in 140,000 to 250,000 newborns (Ruggieri and Huson 2001, Horn et al. 2013). CPT is characterized by local periosteal disease, often leading to bowing and fracturing of the tibia and/or fibula, followed by the development of a pseudarthrosis (Stevenson et al. 1999). The etiology behind CPT remains largely unelucidated. Many theories regarding the influence of vascular, genetic, and mechanical factors have been proposed over the years, but none provides an entirely satisfactory explanation for the pathological features or its typical location (Hefti et al. 2000, Hermanns-Sachweh et al. 2005). However, there is a clear association with type 1 neurofibromatosis (NF1), as the prevalence of NF1 in CPT patients exceeds 50% (Van Royen et al. 2016).The challenge in cases of pseudarthrosis in CPT is obtaining solid union of the tibia with minimal limb length discrepancy and angular deformity (Grill et al. 2000). The most used treatments today are resection of the CPT part of the bone and vertical bone transport or the use of a pedicled or free vascularized fibula graft (Kesireddy et al. 2018). A multinational study from Japan, which included both the Ilizarov technique combined with diaphyseal transfer and vascularized fibula grafting, found high rates of union among both treatment groups and concluded that both approaches should be considered (Ohnishi et al. 2005).For the Ilizarov technique with diaphyseal transfer through proximal metaphyseal corticotomy and distraction at a distance from the dystrophic area, success rates between 50% and 90% have been reported (Paley et al. 1992, Ghanem et al. 1997, Romanus et al. 2000, Choi et al. 2011). Drawbacks of this technique are multiple interventions and prolonged discomfort of the patient due to many months of wearing a ring frame around the lower leg with pins and K-wires moving through muscle compartments. Also, pin tract infections and surgery to induce healing at the docking side of the bone transport lead to restrictions in social and psychological functioning (Ramaker et al. 2000, Patterson 2006).Studies on vascularized fibula grafts report union rates up to over 90% (Weiland et al. 1990, Erni et al. 2010). Drawbacks of this method include the prolonged period of non-weight bearing due to the lack of primary mechanical strength, resulting in graft fractures requiring reoperations prior to consolidation and hypertrophy of the graft (Weiland et al. 1990, Bos et al. 1993, Romanus et al. 2000, Ohnishi et al. 2005).In 1993, Capanna et al. reported on his “Capanna technique” in the resection of bone tumors in which the use of a vascularized autograft is combined with the use of a solid bone segment allograft in order to achieve instant stability with solid bone during consolidation and subsequent hypertrophy of the vascularized fibula during growth (Capanna et al. 1993).In order to avoid the drawbacks and discomfort of bone transport or vascularized fibula transfer without adding initial additional stability, we introduced this technique for the treatment of pseudarthrosis in CPT. Paley (2019) recently published the outcomes of his cross-union concept, reporting union in all 17 treated patients without refracturing with his latest technique, with follow-up to 11 years. If these outcomes prove to be reproducible, this will probably make the cross-union technique the gold standard for treating CPT. We report a retrospective case series on the Capanna technique in patients with CPT as reference for future strategies in this disease.     

Is there a reduction in risk of revision when 36-mm heads instead of 32 mm are used in total hip arthroplasty for patients with proximal femur fractures?: A matched analysis of 5,030 patients with a median of 2.5 years’ follow-up between 2006 and 2016 in the Nordic Arthroplasty Register Association

Background and purpose — 32-mm heads are widely used in total hip arthroplasty (THA) in Scandinavia, while the proportion of 36-mm heads is increasing as they are expected to increase THA stability. We investigated whether the use of 36-mm heads in THA after proximal femur fracture (PFF) is associated with a lower risk of revision compared with 32-mm heads.Patients and methods — We included 5,030 patients operated with THA due to PFF with 32- or 36-mm heads from the Nordic Arthroplasty Register Association database. Each patient with a 36-mm head was matched with a patient with a 32-mm head, using propensity score. The patients were operated between 2006 and 2016, with a metal or ceramic head on a polyethylene bearing. Cox proportional hazards models were fitted to estimate the unadjusted and adjusted hazard ratio (HR) with 95% confidence intervals (CI) for revision for any reason and revision due to dislocation for 36-mm heads compared with 32-mm heads.Results — 36-mm heads had an HR of 0.9 (CI 0.7–1.2) for revision for any reason and 0.8 (CI 0.5–1.3) for revision due to dislocation compared with 32-mm heads at a median follow-up of 2.5 years (interquartile range 1–4.4).Interpretation — We were not able to demonstrate any clinically relevant reduction of the risk of THA revision for any reason or due to dislocation when 36-mm heads were used versus 32-mm. Residual confounding due to lack of data on patient comorbidities and body mass index could bias our results.

During the past years total hip arthroplasty (THA) has become the preferred treatment option for displaced femoral neck fractures in even younger (55–64 years) patients (Rogmark et al. 2017). Previous studies have shown an increased risk of revision, especially due to dislocation, in patients receiving THA after proximal femur fracture (PFF) compared with patients operated due to primary osteoarthritis (OA) (Conroy et al. 2008, Hailer et al. 2012). The risk of THA dislocation in fracture patients varies widely from as low as 5% (Tabori-Jensen et al. 2019), especially when dual mobility cups (DMCs) are used, up to 6–18% (Burgers et al. 2012, Johansson 2014, Noticewala et al. 2018) with conventional cups. The risk of THA revision due to dislocation has been reported as even lower, ranging from 0.5 to 0.7% in national register studies (Conroy et al. 2008, Hailer et al. 2012), as not all unstable THAs are revised. According to the above-mentioned studies, increased age, male sex, the use of a posterior approach, and smaller head sizes are associated with increased risk of revision due to dislocation. To counteract the risk of dislocation, bigger head sizes have been used as they increase the impingement-free range of motion (Burroughs et al. 2005, Tsuda et al. 2016) and jumping distance of THA (Sariali et al. 2009). During the past years, the use of larger heads in THA has increased with 28-mm continuously declining and 32- and 36-mm increasing (Tsikandylakis et al. 2018b). However, register studies performed on patients with displaced femoral neck fracture (Jameson et al. 2012, Cebatorius et al. 2015) have not demonstrated any superiority of larger heads over smaller ones regarding risk of revision, especially due to dislocation. This effect has only been demonstrated in studies performed on a case mix of hip diagnoses that have reported an increased risk of revision due to dislocation when 28-mm or smaller heads are used compared with 32-mm or larger heads (Hailer et al. 2012, Kostensalo et al. 2013).Most of the above-mentioned register studies have used 28-mm heads as reference, which are rarely used nowadays (Tsikandylakis et al. 2018b). Patients receiving THA after PFF have a higher risk for revision than patients with OA and should preferably be studied separately, setting 32 mm as contemporary standard of reference. We therefore investigated if increasing head size from 32 to 36 mm is associated with a decreased risk of revision, especially due to dislocation, in patients with PFF in the Nordic Arthroplasty Register Association (NARA) database. We hypothesized that the risk is lower when 36-mm heads are used.     

Variation and trends in reasons for knee replacement revision: a multi-registry study of revision burden

Background and purpose — Studies describing time-related change in reasons for knee replacement revision have been limited to single regions or institutions, commonly analyze only 1st revisions, and may not reflect true caseloads or findings from other areas. We used revision procedure data from 3 arthroplasty registries to determine trends and differences in knee replacement revision diagnoses.Patients and methods — We obtained aggregated data for 78,151 revision knee replacement procedures recorded by the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) for the period 2003–2017. Equivalent diagnosis groups were created. We calculated the annual proportions of the most common reasons for revision.Results — Infection, loosening, and instability were among the 5 most common reasons for revision but magnitude and ranking varied between registries. Over time there were increases in proportions of revisions for infection and decreases in revisions for wear. There were inconsistent proportions and trends for the other reasons for revision. The incidence of revision for infection showed a uniform increase.Interpretation — Despite some differences in terminology, comparison of registry-recorded revision diagnoses is possible, but defining a single reason for revision is not always clear-cut. There were common increases in revision for infection and decreases in revision for wear, but variable changes in other categories. This may reflect regional practice differences and therefore generalizability of studies regarding reasons for revision is unwise.

Although the survivorship of knee arthroplasty has improved over the last 15 years, the increased volume of primary knee replacement has led to growing numbers of revision procedures (Kumar et al. 2015, Patel et al. 2015). A prior study we undertook outlined changes in the volume and incidence of revision rates in Sweden, Australia, and the Kaiser Permanente registry from the USA (Lewis et al. 2020b).Factors influencing revision change with time. Patient factors may affect the rate of primary procedures, such as rising patient and surgeon acceptance of knee replacement (Hamilton et al. 2015), increasing rates of osteoarthritis (Hunter and Bierma-Zeinstra 2019), growing use in younger patients (Leyland et al. 2016, Karas et al. 2019), and also survivorship, such as longer life expectancy, increasing obesity, and higher physical activity of those receiving a replacement (Hamilton et al. 2015). In addition, prosthesis designs change to improve perceived shortcomings such as wear, instability, and patellofemoral pain and tracking (Lewis et al. 2020a). Methods to improve surgical precision, such as computer navigation (Jones and Jerabek 2018), image-derived instrumentation (Kizaki et al. 2019), and robotic assistance (Jacofsky et al. 2016) may decrease revision requirements (Price et al. 2018)These changing factors alter the reasons for revision. Previous studies observed a decrease in revisions for wear and loosening (Sharkey et al. 2014, Thiele et al. 2015), and related this to improved prosthesis design and materials. Other studies note infection is now the most common reason for revision (Koh et al. 2017, Postler et al. 2018). Studies of changing knee replacement failure modes are limited by being derived from single institutions or regions and may not accurately reflect what is occurring elsewhere (Sharkey et al. 2014, Thiele et al. 2015, Dyrhovden et al. 2017, Koh et al. 2017, Lum et al. 2018, Postler et al. 2018). Additionally, these studies do not show the true revision burden as they are restricted to 1st revision procedures, or only revisions of previous total knee replacements (TKR), and do not include revisions of partial knee replacement procedures.Combining registry data can be difficult due to inconsistency in the definition of revision (Liebs et al. 2015), and lack of consensus in defining modes of failure, with different terminologies used (Niinimaki 2015, Siqueira et al. 2015). Some have attempted to overcome this by defining equivalent diagnoses (Havelin et al. 2011, Paxton et al. 2011, Rasmussen et al. 2016).We determined variations and trends in reasons for knee replacement revision using data on all knee arthroplasty revision procedures from the national registries of Sweden and Australia and the institutional registry of Kaiser Permanente in the USA by using equivalent diagnosis groups (Table 1, see Supplementary data).     

Cognitive training for the prevention of skill decay in temporarily non-performing orthopedic surgeons

Surgical tasks are prone to skill decay. During unprecedented circumstances, such as an epidemic, personal illness, or injury, orthopedic surgeons may not be performing surgical procedures for an uncertain period of time. While not being able to execute regular surgical tasks or use surgical simulators, skill decay can be prevented with regular mental practice, using a scientifically proven skill acquisition and retaining tool. This paper describes different theories on cognitive training answering the question on how it works and offers a brief review of its application in surgery. Additionally, practical recommendations are proposed for performing mental training while not performing surgical procedures.

This paper has previously been shared with the Slovenian Orthopedic Association as a blog post.Surgical tasks combine many gross and fine motor actions in a strict time frame, demanding a high degree of accuracy. As such, surgical skills usually present with a flat learning curve, especially in the case of minimally invasive operations. However, once acquired, surgical skills are prone to decay, especially after a period of not practicing (Sonnadara et al. 2012, Routt et al. 2015). Other important risk factors affecting decay are time pressure and the quality of the job performed (Wisher et al. 1999), both being vital components of surgical performance.During special circumstances, such as an epidemic (e.g., COVID-19), surgeons may be relocated to working environments away from their field of expertise, thereby not performing surgical procedures for a period of time. Similarly, an interval of not practicing is inevitable in the case of a surgeon’s illness or injury. While not being able to perform regular surgical tasks or use surgical simulators, the prevention of skill decay can be achieved through regular mental practice, using a scientifically proven skill acquisition and retaining tool.Mental practice or imagery, a form of cognitive training, is a symbolic rehearsal of a physical activity in the absence of any gross muscular movements (Richardson 1967). It is widely implemented in sports where it has long been used with success in enhancing the performance of elite athletes (Martin et al. 1999) and in certain other areas, such as aviation (Fornette et al. 2012), professional music (Bernardi et al. 2013), and surgery (Wallace et al. 2017). All these fields share crucial similarities, such as the importance of technical skills, performance under stressful conditions, and aiming for perfection without making mistakes. Mental practice improves a variety of different motor skills in sports, as well as acquisition, physical strength (Sevdalis et al. 2013), and technique performance (Surburg 1968), hence its application in surgery is not only scientifically justified but also common sense.It is believed that experienced subjects may benefit more from mental practice on physical tasks because of the requisite schematic knowledge to imagine an accurate and a precise outcome associated with the imagined performance (Posner 1989). For example, experienced athletes have better visualizing abilities and employ more structured mental practice sessions in comparison with novices (Feltz and Landers 2007). However, mental practice has also recently gained in popularity with novice surgeons, surgical trainees, and medical students learning new surgical techniques (Hall 2002, Sanders et al. 2004). Cognition, integration, and automation are typical steps in learning new surgical skills (Hamdorf and Hall 2000), the first two being most decay-susceptible and therefore a subject of interest for mental practice as a retaining tool.This article provides a brief theoretical background on cognitive training, followed by its application in surgery and surgical education. Finally, recommendations are provided for novice and expert surgeons for performing cognitive training while not performing surgery for a long or uncertain period of time.Theoretical basis for cognitive trainingThe motor system has been hypothesized to be part of a cognitive network including a variety of psychological activities. During cognitive training and real-life motor tasks, similar neural paths are being activated. In musicians, a close relationship between motor imagery and motor action has been described, for example changes in corticospinal activity with the same muscles involved in both circumstances (Fadiga et al. 1999).There are different theories on why mental practice improves motor skills (Vealey and Walter 1993). The psychoneuromuscular theory proposes that mental training causes activation pattern of muscles similar to actual movements (Jacobson 1931). The symbolic learning theory postulates that symbols are coding the sequence of movements (Sackett 1934). The repetition of symbolic components of the movement pattern facilitates execution of an actual motor pattern (Frank et al. 2014). A more recent theory suggests that motor imagery and motor performance are functionally equivalent, thereby suggesting that in both the same underlying neural structures and mechanisms are involved (Jeannerod 1994).Cognitive training in surgerySurgery as a medical specialty containing complex psychomotor and cognitive tasks is without any doubt subject to skill decay when tasks are not being performed for a certain period (Arthur et al. 1998). It is not only a question of one’s interest but is also a surgeon’s duty to master the skills and retain them. Novice surgeons and surgical trainees usually find themselves in cognitive and integrational phases of learning, thus being especially vulnerable to the decay of their skills, which can happen after a short retention interval (Sugihara et al. 2018). On such occasions, cognitive training can be of critical importance as it has been proven to enhance knowledge of a procedure, flow of an operation, and preparedness for the task (Komesu et al. 2009).There are numerous cognitive training techniques. At a novice level, cognitive task analysis (CTA) training has been shown to be the most effective, a method by which experts are used to construct a teaching program for novices through intuitive knowledge and thought processes (Tofel-Grehl and Feldon 2013, Wingfield et al. 2015). CTA has recently been proven to be an effective technique in hip arthroplasty, where its use resulted in shorter procedure time, decrease in the number of errors, and increase in accuracy of acetabular cup orientation (Logishetty et al. 2020). However, CTA requires a mentor to be present, which is potentially an inaccessible option in some specific situations. In this case, other techniques of cognitive training, such as external observative and subvocal training, are also potentially useful. In the former, a surgeon is an observer of a skill that is to be learned whereas in the latter a visual image is being called up by a surgeon through external or self-talk (Immenroth et al. 2007).Cognitive training is not beneficial for novice surgeons only. The most experienced surgeons report going over the procedures in “their mind’s eye” and consider mental readiness the most important type of preparation, followed by technical and physical readiness (Sanders et al. 2004). It has been shown that in experts not only are the same regions of the brain being engaged during visual imagery as in novices, but also additional regions are recruited suggesting that the pattern of activation moves from frontal parts at the beginning of the process to posterior parts responsible for retrieval of domain-specific knowledge around the final expertise stage (Bilalić et al. 2012). While cognitive specific skills tend to be the focus of novice subjects who are learning specific movements, cognitive general skills are usually used more by experts who link the skills together. Additionally, experts often use motivational and arousal techniques to enhance overall performance by setting specific goals and managing stress and relaxation (Mace et al. 1986, MacIntyre et al. 2002).In a review by Wallace et al. (2017) limitations of some studies evaluating cognitive training in surgical education have been identified, like small sample sizes, being focused only on short-term effectiveness and lacking psychological mechanisms that underlie their efficacy. However, they concluded that cognitive training is to be integrated as a training tool for surgeons.Recommendations for surgeonsCognitive training in combination with physical training impacts performance to a greater extent than physical training only. In the absence of specific elective surgical procedures, cognitive training is the only skill acquisition and retaining tool that can and should be used constantly. The literature suggests that mental practice should be brief and focused and should optimally be carried out for 20 minutes in a single session, since extended mental practice may lead to loss of concentration (Corbin 1972, Driskell et al. 1994).     

The role of bone cement for the development of intraoperative hypotension and hypoxia and its impact on mortality in hemiarthroplasty for femoral neck fractures

Background and purpose — The bone cement implantation syndrome characterized by hypotension and/or hypoxia is a well-known complication in cemented arthroplasty. We studied the incidence of hypotension and/or hypoxia in patients undergoing cemented or uncemented hemiarthroplasty for femoral neck fractures and evaluated whether bone cement was an independent risk factor for postoperative mortality.Patients and methods — In this retrospective cohort study, 1,095 patients from 2 hospitals undergoing hemiarthroplasty with (n = 986) and without (n = 109) bone cementation were included. Pre-, intra-, and postoperative data were obtained from electronic medical records. Each patient was classified for grade of hypotension and hypoxia during and after prosthesis insertion according to Donaldson’s criteria (Grade 1, 2, 3). After adjustments for confounders, the hazard ratio (HR) for the use of bone cement on 1-year mortality was assessed.Results — The incidence of hypoxia and/or hypotension was higher in the cemented (28%) compared with the uncemented group (17%) (p = 0.003). The incidence of severe hypotension/hypoxia (grade 2 or 3) was 6.9% in the cemented, but not observed in the uncemented group. The use of bone cement was an independent risk factor for 1-year mortality (HR 1.9, 95% CI 1.3–2.7), when adjusted for confounders.Interpretation — The use of bone cement in hemiarthroplasty for femoral neck fractures increases the incidence of intraoperative hypoxia and/or hypotension and is an independent risk factor for postoperative 1-year mortality. Efforts should be made to identify patients at risk for BCIS and alternative strategies for the management of these patients should be considered.

The bone cement implantation syndrome (BCIS) is a well-recognized and potentially fatal complication of orthopedic surgery involving pressurized bone cement (Donaldson et al. 2009). The syndrome is mostly noted in cemented hemiarthroplasty after displaced femoral neck fractures, but is also found in total hip and knee replacement surgery (Byrick et al. 1986, Clark et al. 2001). This syndrome is characterized by hypoxia, systemic hypotension, pulmonary hypertension, arrhythmias, loss of consciousness, and cardiac arrest (Clark et al. 2001, Kotyra et al. 2010).The pathophysiology of BCIS is unclear, but anaphylaxis, inflammatory, thermic and complement activation (Dahl et al. 1988) have all been implicated to induce BCIS (Donaldson et al. 2009). Studies employing invasive hemodynamic monitoring and perioperative ultrasound imaging have revealed subclinical pulmonary embolisms and hemodynamic changes, not detected in standard intra- and postoperative monitoring (Orsini et al. 1987, Bisignani et al. 2008, Kotyra et al. 2010).Until recently, the incidence of BCIS in cemented hemiarthroplasty for hip fractures has been unknown, mainly because a consensual definition of the BCIS syndrome has been lacking. Donaldson et al. (2009) defined a severity classification of BCIS (Grade 1, 2, and 3). In a previous study on patients undergoing cemented hemiarthroplasty for hip fractures, we found that the incidence for all grades of BCIS was 28%, with a huge impact on early and late mortality (Olsen et al. 2014).In this study, we evaluated the role of the cementation, per se, for the development of hypotension and hypoxia and its impact on mortality in patients undergoing hemiarthroplasty for femoral neck fractures. To enable this, a multitude of risk factors influencing mortality were collected in order to isolate the cementation effect. Our hypothesis was that the use of bone cement is an independent risk factor for postoperative mortality.     

Study protocol: Effectiveness of dual-mobility cups compared with uni-polar cups for preventing dislocation after primary total hip arthroplasty in elderly patients — design of a randomized controlled trial nested in the Dutch Arthroplasty Registry

Background and purpose — Dislocation is the leading reason for early revision surgery after total hip arthroplasty (THA). The dual-mobility (DM) cup was developed to provide more stability and mechanically reduce the risk of dislocation. Despite the increased use of DM cups, high-quality evidence of their (cost-)effectiveness is lacking. The primary objective of this randomized controlled trial (RCT) is to investigate whether there is a difference in the number of hip dislocations following primary THA, using the posterolateral approach, with a DM cup compared with a unipolar (UP) cup in elderly patients 1 year after surgery. Secondary outcomes include the number of revision surgeries, patient-reported outcome measures (PROMs), and cost-effectiveness.Methods and analysis — This is a prospective multicenter nationwide, single-blinded RCT nested in the Dutch Arthroplasty Registry. Patients ≥ 70 years old, undergoing elective primary THA using the posterolateral approach, will be eligible. After written informed consent, 1,100 participants will be randomly allocated to the intervention or control group. The intervention group receives a THA with a DM cup and the control group a THA with a UP cup. PROMs are collected preoperatively, and 3 months, 1 and 2 years postoperatively. Primary outcome is the difference in number of dislocations between the UP and DM cup within 1 year, reported in the registry (revisions), or by the patients (closed or open reduction). Data will be analyzed using multilevel models as appropriate for each outcome (linear/logistic/survival). An economic evaluation will be performed from the healthcare and societal perspective, for dislocation and quality adjusted life years (QALYs).Trial registration — This RCT is registered at www.clinicaltrials.gov with identification number {"type":"clinical-trial","attrs":{"text":"NCT04031820","term_id":"NCT04031820"}}NCT04031820.

Dislocation after total hip arthroplasty (THA) is the leading reason for early revision surgery (Bozic et al. 2009, Gwam et al. 2017). Most dislocations occur during the first year after surgery, of which approximately half within the first 3 months (Woo and Morrey 1982, Phillips et al. 2003, Meek et al. 2006, Hailer et al. 2012). Especially in patients with recurrent dislocation and the need for revision surgery, this leads to reduced physical functioning and quality of life (Enocson et al. 2009). Dislocations also increase healthcare costs (Sanchez-Sotelo et al. 2006, Abdel et al. 2015). A single dislocation adds 19% to the hospital costs of an uncomplicated THA, and of a revision surgery up to 148% (Sanchez-Sotelo et al. 2006).Despite the increased and, in some countries, broad use of DM cups, high-quality evidence of their effectiveness is lacking (Darrith et al. 2018). Recent reviews did not identify any randomized controlled trials (RCT) comparing DM cups with UP cups (De Martino et al. 2017a, 2017b, Darrith et al. 2018, Jonker et al. 2020) and the existing studies are of low methodological quality and at high risk of bias due to the lack of experimental design. So far only one—non randomized—cost-effectiveness study has been performed, suggesting that the DM cup may result in cost savings compared with a UP cup (Epinette et al. 2016). Although promising, the results of this cost-effectiveness database study are not transferrable outside France.Therefore we initiated an RCT to establish the effectiveness of DM cups for primary THA. The primary objective is to investigate whether there is a difference in the number of hip dislocations following primary total hip arthroplasty (THA), using the posterolateral approach, for a DM cup compared with a UP cup in elderly patients within 1 year after surgery. Several secondary outcomes will be specified in the methods section. The registry-nested design will facilitate long-term follow-up for all study participants.     

Repeated cobalt and chromium ion measurements in patients with bilateral large-diameter head metal-on-metal ReCap-M2A-Magnum total hip replacement

Background and purpose — Whole-blood (WB) chromium (Cr) and cobalt (Co) measurements are vital in the follow-up of metal-on-metal total hip replacement (MoM THR) patients. We examined whether there is a substantial change in repeated WB, Co, and Cr levels in patients with bilateral ReCap-M2A-Magnum THR. We also specified the number of patients exceeding the safe upper limit (SUL) of WB Co and Cr in the repeated measurement.Patients and methods — We identified 141 patients with bilateral ReCap-M2A-Magnum THR operated in our institution. 61 patients had repeated WB metal ion measurements with bilateral MoM implants still in situ in the second measurement. The mean time elapsing from the first measurement (initial measurement) to the second (control measurement) was 1.9 years (SD = 0.6, range 0.2–3.5). We used earlier established SUL levels for bilateral implants by Van Der Straeten et al. (2013).Results — The median (range) Co and Cr values decreased in the repeated measurement from 2.7 (0.6–25) to 2.1 (0.5–21) and 2.6 (0.8–14) to 2.1 (0.5–18) respectively. In 13% of the patients Co levels exceeded the SUL in the initial measurement and the proportion remained constant, at 13%, in the repeated measurement. In 5% of the patients, Cr levels were above SUL in the initial measurement and an equal 5% in the control measurement.Interpretation — Repeated WB metal ion levels did not increase in patients with bilateral ReCap-M2A-Magnum THR with a mean 1.9-year measurement interval. Long-term development of WB metal ion levels is still unclear in these patients.

More than 20,000 metal-on-metal (MoM) hip replacements were performed in Finland during 2000–2015 (Finnish Arthroplasty Register). Currently, there are still thousands of patients with a MoM THR in situ. Whole-blood (WB) metal ion measurements are an essential part of the follow-up of MoM patients, even though they do not solely identify failing implants alone (De Smet et al. 2008, Hart et al. 2014, Reito et al. 2016).While there is no agreed universal WB metal ion level that indicates revision surgery or predicts the outcome, different health authorities have suggested diverse follow-up protocols for the monitoring of MoM patients (Hannemann et al. 2013, MHRA 2017, US Food and Drug Administration (FDA) 2019). Furthermore, some MoM implants have better survival rates than others, which makes risk evaluation even more difficult (Matharu et al. 2016, MHRA 2017, Kasparek et al. 2018, Donahue et al. 2019).The evaluation of patients with bilateral MoM THR is even more challenging. Patients with bilateral MoM implants often present higher levels of Co and Cr than patients with a unilateral device (Van Der Straeten et al. 2013, Reito et al. 2014, 2016). Only a few studies have assessed blood metal ion levels in patients with bilateral MoM THR. Reito et al. (2016) evaluated ion level changes in bilateral ASR THR, and ASR (DePuy, Warsaw, IN, USA) hip resurfacing arthroplasty (HRA) patients. Both WB Co and Cr were substantially higher in the ASR THR cohort in the repeated measurement (Reito et al. 2016). However, metal ion levels were not able to distinguish failing MoM components from well-functioning hips in patients with bilateral ASR THR (Reito et al. 2016, Donahue et al. 2019).ReCap-M2A-Magnum was the most common MoM THR in Finland (Finnish Arthroplasty Register). We have previously reported that repeated metal ion measurements in unilateral ReCap-M2A-Magnum patients at a mean 2-year time interval did not show any increase (Mäntymäki et al. 2019).We performed a retrospective comparative study to further investigate the role of repeated WB metal ion measurements in patients with bilateral M2A-ReCap-Magnum THR. Our main objectives were to investigate:

1. Is there a substantial change in the WB Co and Cr level during a follow-up period?
2. How large proportion of patients’ measurements exceed the safe upper limits (SUL) of WB Co and Cr levels in the repeated measurement (thresholds WB Co 5.0 µg/L and Cr 7.4 µg/L) (Van Der Straeten et al. 2013).