Dislocation of hemiarthroplasty after hip fracture is common and the risk is increased with posterior approach: result from a national cohort of 25,678 individuals in the Swedish Hip Arthroplasty Register

Background and purpose — Reported revision rates due to dislocation after hemiarthroplasty span a wide range. Dislocations treated with closed reduction are rarely reported despite the fact that they can be expected to constitute most of the dislocations that occur. We aimed to describe the total dislocation rate on the national level, and to identify risk factors for dislocation.Patients and methods — We co-processed a national cohort of 25,678 patients in the Swedish Hip Arthroplasty Register, with the National Patient Register (NPR) and Statistics Sweden. Dislocation was defined as the occurrence of any ICD-10 or procedural code related to hip dislocation recorded in the NPR, with a minimum of 1-year-follow-up. In theory, all early dislocations should thereby be traced, including those treated with closed reduction only.Results — 366/13,769 (2.7%) patients operated on with direct lateral approach dislocated, compared with 850/11,834 (7.2%) of those with posterior approach. Posterior approach was the strongest risk factor for dislocation (OR = 2.7; 95% CI 2.3–3.1), followed by dementia (OR = 1.3; CI 1.1–1.5). The older the patients, the lower the risk of dislocation (OR = 0.98 per year of age; CI 0.98–1.0). Neither bipolar design nor cementless stems influenced the risk.Interpretation — The choice of posterior approach and dementia was associated with an increased dislocation risk. When hips treated with closed reduction were identified, the frequency of dislocation with use of direct lateral and posterior approach more than doubled and tripled, respectively, compared with when only revisions due to dislocation are measured.

Displaced femoral neck fractures in elderly patients have traditionally been treated with hemiarthroplasty (HA). Dislocation of the prosthesis is a major complication, affecting 1.5–15% of patients (Enocson et al. 2008, Figved et al. 2009, Leonardsson et al. 2012, Bensen et al. 2014, Parker 2015, Svenoy et al. 2017). The varying rate may be explained by different surgical approach, follow-up time, age, and frailty of the patients. In addition, dislocation may be defined and reported in various ways, for example closed reduction, revision surgery, or both. A systematic review of 7 randomized trials, with a mix of approaches and 1–5 years’ follow-up time, reported a risk of revision due to dislocation of 3% (Burgers et al. 2012). Only open surgery due to dislocation (i.e., open reduction or revision) is reported in the Swedish Hip Arthroplasty (SHAR). By including closed reduction with a linkage to the National Patient Register (NPR) the under-reporting of dislocation can be highlighted.Risk factors for dislocation can be divided into surgically related, implant-related, and patient-related factors. Posterior approach is a known surgically related risk factor (Varley and Parker 2004, Enocson et al. 2008, Leonardsson et al. 2012, Abram and Murray 2015, Svenoy et al. 2017). The risk is even higher if complete posterior repair is not performed (Enocson et al. 2008, Kim et al. 2016, Svenoy et al. 2017). Others are discrepancy of offset (Madanat et al. 2012, Mukka et al. 2015, Li et al. 2016) and, for elective THA, faulty positioning of the stem (McCollum and Gray 1990). Gjertsen et al. (2012) showed increased risk of revision because of dislocation if an uncemented technique was used compared with cementation, while other studies concluded no such association (Varley and Parker 2004, Figved et al. 2009, Abram and Murray 2015). The influence of the prosthetic design, uni- or bipolar head, on the risk of reoperation or dislocation in hip fracture patients is unclear. Several studies found no difference (Varley and Parker 2004, Enocson et al. 2008, 2012), while Leonardsson et al. (2012) showed increased risk of reoperation caused by dislocation with bipolar HA. For fracture patients, 2 studies (Li et al. 2016, Kristoffersen et al. 2020) reported dementia to increase the risk of dislocation while others (Ninh et al. 2009, Madanat et al. 2012, Abram and Murray 2015, Svenoy et al. 2017) did not. Neurological disease (Li et al. 2016) and dysplasia (Madanat et al. 2012, Mukka et al. 2015) are reported patient-related risk factors, whereas age, sex, and comorbidity do not seem to be associated with risk of dislocation (Enocson et al. 2008, 2012, Madanat et al. 2012, Abram and Murray 2015, Kim et al. 2016, Mukka et al. 2015, Svenoy et al. 2017). The influence of other possible confounders such as socioeconomic factors on the risk of dislocation have not, to our knowledge, been studied earlier.We aimed to describe the total dislocation rate on a national level and to explore risk factors with possible influence on the dislocation rate.     

Intramedullary leg lengthening with a motorized nail

Background and purpose

In the last decade, intramedullary limb lengthening has become a viable alternative to traditional external systems. We retrospectively analyzed the use of an intramedullary motorized nail (Fitbone) in a consecutive series of 32 patients.

Patients and methods

During the period September 2006 to December 2008, 32 consecutive patients with a median age of 17 (IQR: 15–19) years were treated with a fully implantable, motorized intramedullary lengthening device (Fitbone). The median leg length discrepancy was 35 (IQR: 30–44) mm at the femur (n = 21) and 28 (IQR: 25–30) mm at the tibia (n = 11).

Results

Leg lengthening was successful in 30 of 32 cases, with no residual relevant discrepancy (± 5 mm). No intraoperative complications were observed. The consolidation index was significantly different (p = 0.04) between femoral lengthening (mean 35 days/cm) and tibial lengthening (mean 48 days/cm) but did not depend on age older/younger than 16 or previous operations at the affected site. 3 problems, 3 obstacles, and 4 complications (3 minor, 1 major) were encountered in 8 patients, 5 of which were implant-associated.

Interpretation

This technique even allows correction in patients with multiplanar deformities. Compared to external devices, intramedullary systems provide comfort and reduce complication rates, give improved cosmetic results, and lead to fast rehabilitation since percutaneous, transmuscular fixation is prevented. This results in reasonable overall treatment costs despite the relatively high costs of implants.Operative leg length equalization includes techniques such as contralateral epiphysiodesis during growth, or shortening and lengthening procedures. In the last decade, lower complication rates and greater patient comfort (Baumgart et al. 1997, Guichet 1999, Cole et al. 2001) have made intramedullary limb lengthening a valuable alternative to traditional external fixation distractor systems (Guichet et al. 2003, Hankemeier et al. 2005, Leidinger et al. 2006, Krieg et al. 2008). Two mechanical devices, namely the Albizzia nail and the ISKD (intramedullary skeletal kinetic distractor) nail, and one motorized nail (Fitbone) have been reported (Betz et al. 1990, Cole et al. 2001, Guichet et al. 2003).Here we present the indications and limitations, and the results and complications of the Fitbone nail. We identified possible factors that may influence the clinical outcome. In addition, we did a comparative cost analysis of different treatment methods.     

Prior hip arthroscopy does not affect 1-year patient-reported outcomes following total hip arthroplasty: a register-based matched case-control study of 675 patients

Background and purpose — Femoroacetabular impingement syndrome (FAIS) is a common cause of hip pain and may contribute to the development of osteoarthritis. We investigated whether a prior hip arthroscopy affects the patient-reported outcomes (PROMs) of a later total hip arthroplasty (THA).Patients and methods — Patients undergoing hip arthroscopy between 2011 and 2018 were identified from a hip arthroscopy register and linked to the Swedish Hip Arthroplasty Register (SHAR). A propensity-score matched control group without a prior hip arthroscopy, based on demographic data and preoperative score from the EuroQoL visual analogue scale (EQ VAS) and hip pain score, was identified from SHAR. The group with a hip arthroscopy (treated group) consisted of 135 patients and the matched control group comprised 540 patients. The included PROMs were EQ-5D and EQ VAS of the EuroQoL group, and a questionnaire regarding hip pain and another addressing satisfaction. Rate of reoperation was collected from the SHAR. The follow-up period was 1 year.Results — The mean interval from arthroscopy to THA was 27 months (SD 19). The EQ-5D was 0.81 and 0.82, and EQ VAS was 78 and 79 in the treated group and the matched control group respectively. There were no differences in hip pain, and reported satisfaction was similar with 87% in the treated group and 86% in the matched control group.Interpretation — These results offer reassurance that a prior hip arthroscopy for FAIS does not appear to affect the short-term patient-reported outcomes of a future THA and indicate that patients undergoing an intervention are not at risk of inferior results due to their prior hip arthroscopy.

Femoroacetabular impingement syndrome (FAIS) implies abnormal morphology on the femoral or acetabular side of the hip joint and is a common cause of hip pain and dysfunction in the young population (Matar et al. 2019, Zhou et al. 2020). It reportedly increases the risk of developing osteoarthritis (OA), presumably due to damage to the chondrolabral structures (Ganz et al. 2003, Beck et al. 2005).Arthroscopic treatment of FAIS has been proven successful with 1- and 5-years’ follow-up (Griffin et al. 2018, Ohlin et al. 2020). However, one of the most common reoperations is conversion to a total hip arthroplasty (THA) (Harris et al. 2013). Depending on the follow-up period and severity of chondrolabral damages, 3–50% of patients with a previous hip arthroscopy for FAIS are reported to undergo THA later in life (Harris et al. 2013).Whether a prior hip arthroscopy affects the result of a subsequent THA (Haughom et al. 2016, Charles et al. 2017, Perets et al. 2017, Hoeltzermann et al. 2019, Vovos et al. 2019) has previously been discussed. However, many of these studies have been underpowered and the results have been incongruent. Most studies suggested no differences in outcomes in THA for patients with a prior hip arthroscopy (Haughom et al. 2016, Charles et al. 2017, Hoeltzermann et al. 2019). Yet inferior patient satisfaction and higher complication rates were reported in some studies (Perets et al. 2017, Vovos et al. 2019).To optimize the results for patients undergoing THA surgery, it is important to understand factors that could affect the outcomes. The possible effect of hip arthroscopy on future THA should also be considered during patient selection.We investigated the influence of a prior hip arthroscopy on a subsequent THA with patient-reported outcome measures (PROMs) 1 year after THA.Open in a separate windowFlow chart of included patients. Excluded diagnoses: tumors, fractures, or trauma. Excluded missing data due to missing preoperatively patient-reported outcomes or demographic data. Abbreviations: SHAR: Swedish Hip Arthroplasty Register, THA: total hip arthroplasty.     

Rapid decline of yearly number of hip arthroscopies in Sweden: a retrospective time series of 6,105 hip arthroscopies based on a national patient data register

Background and purpose — Hip arthroscopies (HAs) have increased exponentially worldwide and are expected to continue rising. We describe time trends in HA procedures in Sweden (10 million inhabitants) between 2006 and 2018 with a focus on procedure rates, surgical procedures, and patient demographics such as age and sex distribution.Patients and methods — We retrospectively collected data from the Swedish National Patient Register (NPR) for all surgeries including surgical treatment codes considered relevant for HA from 2006 to 2018. Surgical codes were validated through a multiple-step procedure and classified into femoroacetabular impingement syndrome (FAIS) related or non-FAIS related procedure. Frequencies, sex differences, and time trends of surgical procedures and patient demographics are presented.Results — After validation of HA codes, 6,105 individual procedures, performed in 4,924 patients (mean age 34 years [SD 12]) were confirmed HAs and included in the analysis. Yearly HA procedure rates increased from 15 in 2006 to 884 in 2014, after which a steady decline was observed with 469 procedures in 2018. The majority (65%) of HAs was performed in males. Male patients were younger, and surgeries on males more frequently included an FAIS-related procedure.Interpretation — Similar to previous studies in other parts of the world, we found dramatic increases in HA procedures in Sweden between 2006 and 2014. Contrary to existing predictions, HA rates declined steadily after 2014, which may be explained by more restrictive patient selection based on refined surgical indications, increasing evidence, and clinical experience with the procedure.

Hip arthroscopy was long deemed impossible due to anatomic constraints. Easier arthroscopic access to knee and shoulder joints led to an increasing arthroscopy rate in these joints during the 1990s and 2000s (Kim et al. 2011, Colvin et al. 2012a). During the 1990s, improved surgical equipment and techniques enabled surgeons to gain easier access to the hip joint for diagnosis and treatment of a variety of pathologies (Griffiths and Khanduja 2012), including femoroacetabular impingement syndrome (FAIS), acetabular labrum tears, and chondral lesions (Bedi et al. 2013). Arthroscopic hip surgery has been one of the fastest emerging fields within orthopedics and might be at a tipping point for even wider use (Khan et al. 2016a).An exponential worldwide increase in performed HAs has been documented between 2000 and 2013, based on data from private insurance databases (Sing et al. 2015, Maradit Kremers et al. 2017, Bonazza et al. 2018), performance data from surgical trainees (Colvin et al. 2012b, Bozic et al. 2013) and data from national health services (Palmer et al. 2016). While exponentially more patients received HA, evidence for its effectiveness has been questioned (Reiman and Thorborg 2015). In recent years, RCTs have indicated that hip arthroscopy may be more effective than structured rehabilitation in the treatment of FAIS (Griffin et al. 2018, Palmer et al. 2019). The clinical relevance of the statistical superiority for HA found in these trials is debated (Ferreira et al. 2021); however, a continued rise in HA rates has been predicted worldwide (Khan et al. 2016a, Palmer et al. 2016). The only study assessing HA rates beyond 2013 reports declining rates in Finland after 2014 (Karelson et al. 2020). In Sweden, time trends regarding HA have not been investigated. It is therefore unknown whether the rise in HA has continued, or if surgical practice has changed over the years.Therefore, we describe frequency and time trends in performance of hip arthroscopies, with regards to performance rates, surgical procedures, and patient demographics (age and gender distribution) in Sweden.     

Role of preoperative pain,muscle function,and activity level in discharge readiness after fast-track hip and knee arthroplasty

Methods Before surgery, hip pain (THA) or knee pain (TKA), lower-extremity muscle power, functional performance, and physical activity were assessed in a sample of 150 patients and used as independent variables to predict the outcome (dependent variable)—readiness for hospital discharge —for each type of surgery. Discharge readiness was assessed twice daily by blinded assessors.Results Median discharge readiness and actual length of stay until discharge were both 2 days. Univariate linear regression followed by multiple linear regression revealed that age was the only independent predictor of discharge readiness in THA and TKA, but the standardized coefficients were small (≤ 0.03).Interpretation These results support the idea that fast-track THA and TKA with a length of stay of about 2–4 days can be achieved for most patients independently of preoperative functional characteristics.Over the last decade, length of stay (LOS) with discharge to home after primary THA and TKA has declined from about 5–10 days to about 2–4 days in selected series and larger nationwide series (Malviya et al. 2011, Raphael et al. 2011, Husted et al. 2012, Kehlet 2013, Hartog et al. 2013, Jørgensen and Kehlet 2013). However, there is a continuing debate about whether selected patients only or all patients should be scheduled for “fast-track” THA and TKA in relation to psychosocial factors and preoperative pain and functional status (Schneider et al. 2009, Hollowell et al. 2010, Macdonald et al. 2010, Antrobus and Bryson 2011, Jørgensen and Kehlet 2013), or whether organizational or pathophysiological factors in relation to the surgical trauma may determine the length of stay (Husted et al. 2011, Husted 2012).We studied the role of THA and TKA patients’ preoperative pain and functional characteristics in discharge from 2 orthopedic departments with well-established fast-track recovery regimens (Husted et al. 2010).     

Uncemented femoral revision arthroplasty using a modular tapered,fluted titanium stem: 5- to 16-year results of 163 cases

Background and purpose —

Due to the relative lack of reports on the medium- to long-term clinical and radiographic results of modular femoral cementless revision, we conducted this study to evaluate the medium- to long-term results of uncemented femoral stem revisions using the modular MRP-TITAN stem with distal diaphyseal fixation in a consecutive patient series.

Patients and methods —

We retrospectively analyzed 163 femoral stem revisions performed between 1993 and 2001 with a mean follow-up of 10 (5–16) years. Clinical assessment included the Harris hip score (HHS) with reference to comorbidities and femoral defect sizes classified by Charnley and Paprosky. Intraoperative and postoperative complications were analyzed and the failure rate of the MRP stem for any reason was examined.

Results —

Mean HHS improved up to the last follow-up (37 (SD 24) vs. 79 (SD 19); p < 0.001). 99 cases (61%) had extensive bone defects (Paprosky IIB–III). Radiographic evaluation showed stable stem anchorage in 151 cases (93%) at the last follow-up. 10 implants (6%) failed for various reasons. Neither a breakage of a stem nor loosening of the morse taper junction was recorded. Kaplan-Meier survival analysis revealed a 10-year survival probability of 97% (95% CI: 95–100).

Interpretation —

This is one of the largest medium- to long-term analyses of cementless modular revision stems with distal diaphyseal anchorage. The modular MRP-TITAN was reliable, with a Kaplan-Meier survival probability of 97% at 10 years.Long-term outcome of femoral revision arthroplasty depends on proper restoration of joint mechanics by reconstructing the anatomic center of rotation in combination with fixation that provides long-term stability (Gravius et al. 2011).The published medium- to long-term survival rates of cemented revision THA are between 35% and 91% (Kavanagh and Fitzgerald 1985, Retpen et al. 1989, Stromberg and Herberts 1996, Weber et al. 1996). One stage cemented stem revision leads to increased bone loss (Rader and Eulert 2005) and is associated with a much higher rate of re-revision than cementless femoral stem revision (Dohmae et al. 1988). Cemented revision stems only appear to be advisable for less active patients with an average life expectancy of less than 10 years (Weiss et al. 2011). In comparison, uncemented revision hip arthroplasty gives medium- to long-term survival rates of 60–97% (Head et al. 2001, Engh et al. 2002, Kwong et al. 2003).Over the years, uncemented modular revision stems have become increasingly popular (Fink et al. 2009). In complex revision surgery, modular uncemented femoral implants may overcome the limitations of non-modular and mostly straight stems—for example, the difficulty in establishing femoral leg length, femoral anteversion, and soft tissue tension (Berry 2002, Mumme et al. 2004, Gutierrez et al. 2007). Modular cementless implant systems with a distal diaphyseal press-fit concept provide greater variability in difficult anatomical situations than non-modular revision stems (Berry 2002). The modular-designed components offer the opportunity to customize the prosthesis intraoperatively to the individual anatomical situation, allowing nearly physiological joint reconstruction (Gravius et al. 2011).Based on published studies, the modular cementless MRP-TITAN revision stem with its distal diaphyseal fixation concept has well-proven short-term effectiveness in femoral revision, especially for large femoral defects (types IIC and III, as described by Paprosky et al. (1990)). Previous studies have shown low mechanical failure rates of 2–5% after 4–5 years of follow-up (Wirtz et al. 2000, Mumme et al. 2004, 2007).Due to the relative lack of medium- to long-term results of femoral modular cementless revision surgery in the literature, we investigated the clinical and radiographic medium- to long-term outcome of femoral revision arthroplasty with the MRP-TITAN stem in a consecutive patient series.     

Embalmed and fresh frozen human bones in orthopedic cadaveric studies: which bone is authentic and feasible?: A mechanical study

Background and purpose

The most frequently used bones for mechanical testing of orthopedic and trauma devices are fresh frozen cadaveric bones, embalmed cadaveric bones, and artificial composite bones. Even today, the comparability of these different bone types has not been established.

Methods

We tested fresh frozen and embalmed cadaveric femora that were similar concerning age, sex, bone mineral density, and stiffness. Artificial composite femora were used as a reference group. Testing parameters were pullout forces of cortex and cancellous screws, maximum load until failure, and type of fracture generated.

Results

Stiffness and type of fracture generated (Pauwels III) were similar for all 3 bone types (fresh frozen: 969 N/mm, 95% confidence interval (CI): 897–1,039; embalmed: 999 N/mm, CI: 875–1,121; composite: 946 N/mm, CI: 852–1,040). Furthermore, no significant differences were found between fresh frozen and embalmed femora concerning pullout forces of cancellous screws (fresh frozen: 654 N, CI: 471–836; embalmed: 595 N, CI: 365–823) and cortex screws (fresh frozen: 1,152 N, CI: 894–1,408; embalmed: 1,461 N, CI: 880–2,042), and axial load until failure (fresh frozen: 3,427 N, CI: 2,564–4290; embalmed: 3,603 N, CI: 2,898–4,306). The reference group showed statistically significantly different results for pullout forces of cancellous screws (2,344 N, CI: 2,068–2,620) and cortex screws (5,536 N, CI: 5,203–5,867) and for the axial load until failure (> 7,952 N).

Interpretation

Embalmed femur bones and fresh frozen bones had similar characteristics by mechanical testing. Thus, we suggest that embalmed human cadaveric bone is a good and safe option for mechanical testing of orthopedic and trauma devices. Human cadaveric specimens are widely used in studies analyzing the mechanical properties and efficacy of orthopedic and trauadevices (Park et al. 2010). Storage of fresh human cadaveric bones at a temperature of –20°C is a commonly used and accepted method for preservation of bone. Many studies have shown that freezing does not alter the mechanical properties of human bone (Pelker et al. 1983, Goh et al. 1989, Linde and Sorensen 1993, Matter et al. 2001, van Haaren et al. 2008), although some changes have been shown compared to fresh bone (Sonstegard and Matthews 1977, Pelker et al. 1983).In Europe, there is some difficulty in obtaining a sufficient number of fresh frozen bones. Furthermore, they are expensive and need excessive storage space—and there is also the risk of transmitting pathogens to investigators (Sterling et al. 2000, van Haaren et al. 2008).Human cadaveric specimens are often obtained from anatomical institutes. The cadavers have usually been embalmed with a formaldehyde solution for at least 1 year before usage. Some studies have investigated the effects of embalming cadaveric bones regarding their mechanical properties (McElhaney et al. 1964, Pelker et al. 1983, Roe et al. 1988, Goh et al. 1989, Linde and Sorensen 1993, Currey et al. 1995).Most of the above studies used animal bones for mechanical testing, and had a maximum storage period of ≤ 100 days (McElhaney et al. 1964, Pelker et al. 1983, Roe et al. 1988, Goh et al. 1989, Currey et al. 1995). There have been few studies on long-term effects (van Haaren et al. 2008), and most of the studies using human bones have concentrated on small bone segments (Linde and Sorensen 1993, Currey et al. 1995, Burkhart et al. 2010).Another bone type that is commonly used is the artificial composite bone (Cristofolini et al. 1996, Zdero et al. 2008). Concerning the handling and mechanical properties, cadaveric specimens simulate reality best (Burkhart et al. 2010). In comparison, composite bones differ in some of their mechanical characteristics (Cristofolini et al. 1996).We compared fresh frozen human femora and long-period embalmed femora concerning stiffness, maximum axial load until fracture, type of fracture generated, and pullout strength of cortical and cancellous bone screws. Artificial femora were used as a non-osteoporotic reference group.     

Effects of metal-on-metal wear on the host immune system and infection in hip arthroplasty

Background and purpose

Joint replacement with metal-on-metal (MOM) bearings have gained popularity in the last decades in young and active patients. However, the possible effects of MOM wear debris and its corrosion products are still the subject of debate. Alongside the potential disadvantages such as toxicity, the influences of metal particles and metal ions on infection risk are unclear.

Methods

We reviewed the available literature on the influence of degradation products of MOM bearings in total hip arthroplasties on infection risk.

Results

Wear products were found to influence the risk of infection by hampering the immune system, by inhibiting or accelerating bacterial growth, and by a possible antibiotic resistance and heavy metal co-selection mechanism.

Interpretation

Whether or not the combined effects of MOM wear products make MOM bearings less or more prone to infection requires investigation in the near future.Many young patients with painful coxarthrosis want to return to a high level of activity and require an implant that provides durability. The low wear rates of metal-on-metal (MOM) bearings have led to a resurgence in the use of MOM bearings (Wagner and Wagner 2000, Silva et al. 2005, Pollard et al. 2006, Vendittoli et al. 2007, Delaunay et al. 2008). 35% of all prostheses in the United States in 2006 (Bozic et al. 2009) and 16% of all prostheses implanted in Australia from 1999 through 2007 had MOM bearings (Graves et al. 2008).Metal alloys used in MOM bearings degrade through wear, from corrosion, or by a combination of the two (Yan et al. 2006, Jacobs et al. 2008). Consequently, MOM bearings produce nanometer- to submicrometer-sized metal particles (Campbell et al. 1996, Doorn et al. 1998). The high number of these very small particles presents a large cumulative surface area for corrosion. The biological effects of these particles and their corrosion products in the human body are for the most part unclear. Since the renewed interest in MOM bearings, extensive research has been done to determine the consequences of local and systemic exposure to wear particles and accompanying biologically active corrosion products (Amstutz and Grigoris 1996). It is well known that metal debris can induce pathological changes such as the release of inflammatory cytokines from macrophages, histiocytosis, fibrosis, and necrosis (Basle et al. 1996, Granchi et al. 1998, Caicedo et al. 2008, 2009). Metal debris is also thought to be associated with hypersensitivity and osteolysis (Hallab et al. 2000, 2010, Goodman 2007b, Carr and DeSteiger 2008, Huber et al. 2009). However, there is very little literature on the bacteriological effects of these degradation products (Anwar et al. 2007, Hosman et al. 2009). It is therefore unclear whether they can influence the risk of infection.The Australian and New Zealand joint registries have shown that between 9% and 15% of all total hip arthroplasty (THA) revisions are carried out because of infections related to the primary prosthesis (Rothwell et al. 2007, Graves et al. 2008). In cases of infection, bacteria adopt a biofilm mode of growth on the surface of the prosthesis, thus increasing the antibiotic resistance and resulting in major difficulties in treatment (Trampuz and Widmer 2006). Removal and replacement of an infected implant is usually required to eliminate the infection (Bozic and Ries 2005, Vincent et al. 2006). Recent research has suggested that particulate debris of any composition promotes bacterial growth by providing a scaffold for bacterial adhesion and biofilm growth (Anwar et al. 2007). On the other hand, high concentrations of metal ions have been shown to have bacteriostatic properties (Hosman et al. 2009).Considering the paucity of publications on the effects of MOM particles on infection, we performed a review of the literature on the influence of MOM wear particles and their corrosion products on the risk of infection.     

1–year follow–up of 920 hip and knee arthroplasty patients after implementing fast–track: Good outcomes in a Norwegian university hospital

BackgroundFast–track has become a well–known concept resulting in improved patient satisfaction and postoperative results. Concerns have been raised about whether increased efficiency could compromise safety, and whether early hospital discharge might result in an increased number of complications. We present 1–year follow–up results after implementing fast–track in a Norwegian university hospital.MethodsThis was a register–based study of 1,069 consecutive fast–track hip and knee arthroplasty patients who were operated on between September 2010 and December 2012. Patients were followed up until 1 year after surgery.Results987 primary and 82 revision hip or knee arthroplasty patients were included. 869 primary and 51 revision hip or knee patients attended 1–year follow–up. Mean patient satisfaction was 9.3 out of a maximum of 10. Mean length of stay was 3.1 days for primary patients. It was 4.2 days in the revision hip patients and 3.9 in the revision knee patients. Revision rates until 1–year follow–up were 2.9% and 3.3% for primary hip and knee patients, and 3.7% and 7.1% for revision hip and knee patients. Function scores and patient–reported outcome scores were improved in all groups.InterpretationWe found reduced length of stay, a high level of patient satisfaction, and low revision rates, together with improved health–related quality of life and functionality, when we introduced fast–track into an orthopedic department in a Norwegian university hospital.The health service in Norway has been reorganized in the last decade. The number of available beds and the length of stay (LOS) in somatic hospitals have been reduced. Patients are increasingly being treated as outpatients rather than being admitted to hospital (SSB 2011). Changes in treatment modalities have contributed to this reorganization. Within elective surgery, the “fast–track” principles are increasingly being adopted, although there is still potential for improvement regarding both treatment and clinical results (Rostlund and Kehlet 2007, Kehlet and Soballe 2010). Fast–track originated in Denmark—in gastrointestinal surgery—and has been further developed and documented in joint replacement surgery in hospitals in Denmark over the last decade (Rasmussen et al. 2001, Husted et al. 2010a,d, 2012, Leonhardt et al. 2010). The fast–track concept is an evidence–based multimodality treatment that reduces convalescence time and improves clinical results, including reduction in morbidity and mortality (Kehlet and Wilmore 2008, Schneider et al. 2009). The particularly important elements are: anesthesia, fluid therapy, pain therapy, and early postoperative mobilization (Husted and Holm 2006, Husted et al. 2010a, 2011a, 2012, Khan et al. 2014) as well as preoperative information and supervision (Kehlet 1997, Andersen et al. 2007, 2009, Holm et al. 2010).It has been said that fast–track may result in increased complication rates and re–admissions (Mauerhan et al. 2003). However, several studies have found that reduced length of stay does not compromise patient safety (Pilot et al. 2006, Mahomed et al. 2008, Schneider et al. 2009) or increase complication rates compared to conventional treatment methods (Husted et al. 2010b). Also, it has been shown that fast–track surgery with early mobilization and short deep–vein thrombosis prophylaxis results in low rates of deep–vein thrombosis and pulmonary embolism (Husted et al. 2010c, Jorgensen et al. 2013).A reorganization in the orthopedic department at Trondheim University Hospital in 2010 led to an increased number of knee and hip arthroplasty patients, from 7 to 17 a week (Egeberg et al. 2010). Based on the successful implementation of fast–track in several hospitals in Denmark (Husted et al. 2008, Kehlet and Wilmore 2008), this model was adopted in our department. To be able to continually monitor treatment quality and process data, we established an internal quality register (Bjorgen et al. 2012). We now present the 1–year follow–up results after implementation of this fast–track procedure.     

Cross-sectional imaging of metal-on-metal hip arthroplasties: Can we substitute MARS MRI with CT?

Background and purpose —

Metal artifact reduction sequence (MARS) MRI is widely advocated for surveillance of metal-on-metal hip arthroplasties (MOM-HAs). However, its use is limited by susceptibility artifact at the prosthesis-bone interface, local availability, patient compliance, and cost (Hayter et al. 2011a). We wanted to determine whether CT is a suitable substitute for MARS MRI in evaluation of the painful MOM-HA.

Patients and methods —

50 MOM-HA patients (30 female) with unexplained painful prostheses underwent MARS MRI and CT imaging. 2 observers who were blind regarding the clinical data objectively reported the following outcomes: soft tissue lesions (pseudotumors), muscle atrophy, and acetabular and femoral osteolysis. Diagnostic test characteristics were calculated.

Results —

Pseudotumor was diagnosed in 25 of 50 hips by MARS MRI and in 11 of 50 by CT. Pseudotumors were classified as type 1 (n = 2), type 2A (n = 17), type 2B (n = 4), and type 3 (n = 2) by MARS MRI. CT did not permit pseudotumor classification. The sensitivity of CT for diagnosis of pseudotumor was 44% (95% CI: 25–65). CT had “slight” agreement with MARS MRI for quantification of muscle atrophy (κ = 0.23, CI: 0.16–0.29; p < 0.01). Osteolysis was identified in 15 of 50 patients by CT. 4 of these lesions were identified by MARS MRI.

Interpretation —

CT was found to be superior to MRI for detection of osteolysis adjacent to MOM-HA, and should be incorporated into diagnostic algorithms. CT was unable to classify and failed to detect many pseudotumors, and it was unreliable for assessment of muscle atrophy. Where MARS MRI is contraindicated or unavailable, CT would be an unsuitable substitute and other modalities such as ultrasound should be consideredIt is estimated that over 500,000 metal-on-metal (MOM) hip arthroplasties, including both hip resurfacing and total hip replacements (THRs), have been carried out worldwide in the last 15 years (Skinner et al. 2010). There are increasing reports of progressive soft tissue changes in response to metal debris including: solid or cystic, non-malignant masses around the prostheses (termed pseudotumors) (Pandit et al. 2008), perivascular lymphocytic infiltration (Davies et al. 2005), musculotendinous pathology (in particular, wasting of the hip abductors) (Sabah et al. 2011), and periprosthetic osteolysis (Park et al. 2005, Milosev et al. 2006, Korovessis et al. 2006).There is international agreement that the high failure rate of MOM hip arthroplasties (MOM-HAs) has created the need for surveillance of these devices with cross-sectional imaging (MHRA. 2012). Both pseudotumors and muscle atrophy have been associated with high rates of major complications and poorer outcomes after revision surgery (Grammatopolous et al. 2009). To this end, sensitive detection of periprosthetic changes is vital in order to provide the best outcome for MOM-HA patients with early detection and revision.Cross-sectional imaging has been shown to be useful for providing a diagnosis in cases of unexplained pain and in planning of revision surgery (Hayter et al. 2011b). A recent European multidisciplinary consensus statement recommended the use of cross-sectional imaging using any of US, MARS MRI, or CT (Hannemann et al. 2013). The gold standard modality is not clear, which has resulted in a variety of diagnostic algorithms being used in different referral centers.Both CT and MARS MRI similarly offer multi-planar and complete cross-sectional images from which the extent of disease and relationship of the abnormality to normal anatomy can readily be appreciated. MARS MRI has been reliably and extensively used to investigate MOM hip complications (Sabah et al. 2011, Hayter et al. 2012a, Thomas et al. 2013, Nawabi et al. 2013) and has been shown to permit early diagnosis of pseudotumor and other soft tissue pathologies (Toms et al. 2008) associated with pain, loss of function, and higher revision rates. However, the use of MARS MRI is limited by susceptibility artifact at the prosthesis-bone interface, local availability, patient compliance, and cost.CT is more widely available than MARS MRI (Anderson et al. 2011) and has been used routinely at some centers for the screening of periarticular masses (Bosker et al. 2012). It has been proposed as an alternative to it, for example in cases of claustrophobia, pacemaker, and where there are loose metal implants. CT has been shown to be useful in cases of suspected impingement, acetabular osteolysis (Cahir et al. 2007, Roth et al. 2012), and in identification of prostheses at risk of elevated wear (Hart et al. 2009). The notable success in detecting common complications of hip arthroplasty coupled with widespread accessibility has meant that some centers rely entirely on CT (McMinn. 2012) to follow up patients with suspected MOM-associated bony and soft tissue changes, but to date there have been no published studies comparing CT with MRI.We investigated whether CT is a suitable substitute for MARS MRI in the evaluation of the painful MOM-HA. We wanted to provide measures of diagnostic accuracy of CT compared to the current gold standard (MARS MRI) for the detection of common periprosthetic complications. The primary outcome measure focused on the detection of pseudotumors, owing to their high prevalence and strong association with adverse outcomes (Hart et al. 2009), with secondary outcome measures for the detection of muscle atrophy and osteolysis.     

Metal release and metal allergy after total hip replacement with resurfacing versus conventional hybrid prosthesis: 5-year follow-up of 52 patients

Background

Metal-on-metal (MOM) total hip arthroplasties were reintroduced because of the problems with osteolysis and aseptic loosening related to polyethylene wear of early metal-on-polyethylene (MOP) arthroplasties. The volumetric wear rate has been greatly reduced with MOM arthroplasties; however, because of nano-size wear particles, the absolute number has been greatly increased. Thus, a source of metal ion exposure with the potential to sensitize patients is present. We hypothesized that higher amounts of wear particles result in increased release of metal ions and ultimately lead to an increased incidence of metal allergy.

Methods

52 hips in 52 patients (median age 60 (51–64) years, 30 women) were randomized to either a MOM hip resurfacing system (ReCap) or a standard MOP total hip arthoplasty (Mallory Head/Exeter). Spot urine samples were collected preoperatively, postoperatively, after 3 months, and after 1, 2, and 5 years and tested with inductively coupled plasma-sector field mass spectrometry. After 5 years, hypersensitivity to metals was evaluated by patch testing and lymphocyte transformation assay. In addition, the patients answered a questionnaire about hypersensitivity.

Results

A statistically significant 10- to 20-fold increase in urinary levels of cobalt and chromium was observed throughout the entire follow-up in the MOM group. The prevalence of metal allergy was similar between groups.

Interpretation

While we observed significantly increased levels of metal ions in the urine during the entire follow-up period, no difference in prevalence of metal allergy was observed in the MOM group. However, the effect of long-term metal exposure remains uncertain.In the 1960s and 1970s, the articulations of hip implants were mainly metal-on-metal (MOM). The implants released cobalt, chromium, and nickel, which could be found in high levels in the blood, hair, and urine (Coleman et al. 1973, Benson et al. 1975, Elves et al. 1975, Gawkrodger 2003). Furthermore, the patients became sensitized to the metals released and an association with early loosening was observed (Coleman et al. 1973, Benson et al. 1975, Elves et al. 1975, Gawkrodger 2003, Jacobs et al. 2009). Gradually, MOM implants were abandoned and the work by Sir John Charley with the metal-on-polyethylene (MOP) bearing advanced hip replacement substantially. However, the MOM articulation was reintroduced in the 1990s, as it became clear that polyethylene debris caused osteolysis, which was a significant clinical issue—especially in young and active patients (Marshall et al. 2008). The MOM Hip Resurfacing System has been proposed to have advantages such as enhanced longevity (Chan et al. 1999, Sieber et al. 1999, Firkins et al. 2001), enhanced implant fixation (Grigoris et al. 2006), lower dislocation rate (Scifert et al. 1998), better reproduction of hip mechanics, and more native femoral shaft bone stock left for revision surgery (Shimmin et al. 2008).MOM articulations have greatly reduced the volumetric wear rate of hip prostheses; however, because of nano-sized metal wear particles, the absolute number of wear particles has greatly increased (Doorn et al. 1998, Chan et al. 1999, Sieber et al. 1999, Firkins et al. 2001, Rieker and Kottig. 2002). Also, Hallab et al. (2004) suggested that the prevalence of metal allergy could be higher in patients with implant failure. In both cases, a source of metal ion exposure with the potential to sensitize patients is present, but the long-term biological effect of the metal wear debris remains unknown.Metal hypersensitivity is a well-established phenomenon and is common, affecting about 10–15% of the general population (Thyssen and Menne 2010). Metal allergy can develop after prolonged or repeated cutaneous exposure to metal, usually from consumer products. Affected individuals typically suffer from allergic contact dermatitis and react with cutaneous erythema, papules, and vesicles after skin contact. This reaction is categorized as a type-4 T-cell-mediated hypersensitivity reaction. Also, metal hypersensitivity may develop following internal exposure to metal-releasing implants. Theoretically, metal hypersensitivity could lead to a powerful reaction to prosthesis implantation (Pandit et al. 2008).We hypothesized that an increased number of wear particles from MOM hip resurfacing arthroplasty (HRA) would lead to increased blood levels and urinary excretion of metal ions, and ultimately to an increased prevalence of metal allergy.     

No increase in postoperative contacts with the healthcare system following outpatient total hip and knee arthroplasty

Background and purpose — Discharge on the day of surgery (DDOS) after total hip arthroplasty (THA) and total knee arthroplasty (TKA) has been shown to be safe in selected patients. Concerns have been raised that discharging patients on the day of surgery (DOS) could lead to an increased burden on other parts of the healthcare system when compared with patients not discharged on the DOS (nDDOS). Therefore, we investigated whether discharging patients on the day of surgery (DOS) after THA and TKA leads to increased contacts with the primary care sector or other departments within the secondary care sector.Patients and methods — Prospective data on 261 consecutive patients scheduled for outpatient THA (n = 135) and TKA (n = 126) were collected as part of a previous cohort study. 33% of THA patients and 37% of TKA patients were discharged on the DOS. Readmissions within 3 months after surgery were recorded. Contacts with the discharging department, other departments, and primary care physicians within 3 weeks were registered.Results — No statistically significant differences were found when comparing DDOS patients and patients not discharged on the DOS (nDDOS) with regard to readmissions, physical contacts with the discharging department, and contacts with other departments as well as general practitioners. THA DDOS patients had significantly fewer contacts with the discharging department by telephone than THA nDDOS patients. TKA DDOS patients had significantly more contacts with the discharging department by telephone than TKA nDDOS patients.Interpretation — Patients discharged on the DOS following THA or TKA generally have similar postoperative contacts with the healthcare system when compared with patients not discharged on the DOS.

Total hip arthroplasty (THA) and total knee arthroplasty (TKA) are surgical procedures that have improved continuously perioperatively for many years as a result of implementation of fast-track principles (Husted 2012, Petersen et al. 2019). These changes have led to a reduced length of stay in hospital following THA and TKA while also limiting cost, morbidity, and mortality (Khan et al. 2014, Andreasen et al. 2017, Jørgensen et al. 2017, Burn et al. 2018, Petersen et al. 2020).The epitome of fast-track surgery is outpatient surgery, where patients are discharged from the hospital on the day of surgery (DOS) to their own homes. This has proven to be beneficial in several ways for selected patients, as these patients spend less time in the hospital while still having similar outcomes when compared with patients not discharged on the DOS with regard to both patient-reported outcome measurements (Husted et al. 2021) and safety (Goyal et al. 2017, Vehmeijer et al. 2018, Gromov et al. 2019). Finally, outpatient THA and TKA come with additional financial benefits (Lovald et al. 2014, Husted et al. 2018, Gibon et al. 2020).Although an early small study indicated that the reduction in number of hospital days from fast-track did not increase the number of patient contacts with the primary healthcare sector (Andersen et al. 2009), concerns exist that the reduced time patients discharged on the DOS spend in hospital has led to an increased potential burden on other parts of the healthcare system—specifically the primary healthcare system, an increase in readmissions, and/or more contacts with the discharging department as well as other departments (Shah et al. 2019). Therefore, we aimed to investigate whether discharging patients on the DOS after THA and TKA leads to an increased burden on other parts of the healthcare system when compared with patients not discharged on the DOS. This was achieved by comparing readmissions within 3 months, contacts with the discharging department, the surgeon, or other departments—both physical turnouts and by phone, as well as contacts with primary care physicians within 3 weeks.     

Body mass index and risk of perioperative cardiovascular adverse events and mortality in 34,744 Danish patients undergoing hip or knee replacement

Background and purpose

Obesity is a risk factor for osteoarthritis in the lower limb, yet the cardiovascular risks associated with obesity in hip or knee replacement surgery are unknown. We examined associations between body mass index (BMI) and the risk of a major adverse cardiovascular event (MACE: ischemic stroke, acute myocardial infarction, or cardiovascular death) or the risk of all-cause mortality in a nationwide Danish cohort of patients who underwent primary hip or knee replacement surgery.

Methods

Using Danish nationwide registries, we identified 34,744 patients aged ≥ 20 years who underwent elective primary hip or knee replacement surgery between 2005 and 2011. We used multivariable Cox regression models to calculate the 30-day risks of MACE and mortality associated with 5 BMI groups (underweight (BMI < 18.5 kg/m²), normal weight (18.5–24 kg/m²), overweight (25–29 kg/m²), obese 1 (30–34 kg/m²), and obese 2 (≥ 35 kg/m²)).

Results

In total, 232 patients (0.7%) had a MACE and 111 (0.3%) died. Compared with overweight, adjusted hazard ratios (HRs) were 1.2 (95% CI: 0.4–3.3), 1.3 (0.95–1.8), 1.6 (1.1–2.2), and 1.0 (0.6–1.9) for underweight, normal weight, obese 1, and obese 2 regarding MACE. Regarding mortality, the corresponding HRs were 7.0 (2.8–15), 2.0 (1.2–3.2), 1.5 (0.9–2.7), and 1.9 (0.9–4.2). Cubic splines suggested a significant U-shaped relationship between BMI and risks with nadir around 27–28.

Interpretation

In an unselected cohort of patients undergoing elective primary hip or knee replacement surgery, U-shaped risks of perioperative MACE and mortality were found in relation to BMI. Patients within the extreme ranges of BMI may warrant further attention.Obesity is one of the most prominent risk factors for the development and progression of osteoarthritis in the lower limb, especially in the knee (Felson et al. 1988, Sturmer et al. 2000). As a result, overweight people are overrepresented among patients undergoing joint replacement surgery (Bostman 1994, Cooper et al. 1998, Karlson et al. 2003, Jain et al. 2005). With an increasing proportion of elderly people and the high prevalence of overweight/obesity in the general population, the demand for joint replacement surgery is expected to rise (Kurtz et al. 2007). Considerable risks of peroperative and postoperative complications have been reported for obese patients undergoing hip or knee replacement surgery (Winiarsky et al. 1998, Foran et al. 2004a, Schwarzkopf et al. 2012), although with conflicting results (Pritchett and Bortel 1991, Griffin et al. 1998, Hawker et al. 1998, Winiarsky et al. 1998, Spicer et al. 2001, Foran et al. 2004a, b, Flegal et al. 2005, Davis et al. 2011). The majority of previous studies have focused on orthopedic-related outcomes, e.g. risks of infection and prosthesis dislocation (Smith et al. 1992, Griffin et al. 1998, Deshmukh et al. 2002, Amin et al. 2006, Hamoui et al. 2006). Major surgical procedures, including joint replacement surgery, also carry a significant risk of adverse cardiovascular events and mortality. Previous research has suggested that obesity may increase perioperative cardiovascular and mortality risks, but it has not concentrated specifically on elective hip and knee replacement surgery (Bamgbade et al. 2007). We therefore evaluated the relationship between body mass index (BMI) and perioperative cardiovascular events and mortality, as well as 1-year mortality, in patients undergoing elective total hip or knee replacement in a nationwide setting. We hypothesized that obese patients would have higher risk of adverse cardiovascular events than patients who were not obese.     

No change in reoperation rates despite shifting treatment trends: a population-based study of 4,070 proximal humeral fractures

Background and purpose — Clear and acknowledged treatment algorithms for proximal humeral fractures (PHFs) are lacking. Nevertheless, a change in treatment trends, including a change towards more reversed shoulder arthroplasties (RSA), has been observed during recent years. We examined the effect of these changes on reoperation rates.Patients and methods — Between 2011 and 2017, 4,070 PHFs treated at Sahlgrenska University Hospital were registered prospectively in the Swedish Fracture Register (SFR) and followed up until 2019 (mean follow-up of 4.5 years). Data on all reoperations were gathered from the SFR and from medical records.Results — The majority of PHFs were treated non-surgically and the proportion increased slightly, but not statistically significantly, during the study period (from 76% to 79%). Of the surgically treated fractures, the proportion fixed with a plate decreased from 47% to 25%, while the use of RSA increased 9-fold (from 2.0% to 19%). 221 patients underwent 302 reoperations. For those primarily treated surgically, the reoperation rate was 17%. Among treatment modalities, plate fixation was associated with the highest reoperation rate (21%). Rate of reoperations remained constant during the study period, both for the entire study cohort and for the surgically treated patientsInterpretation — During the study period, treatment changes that are in accordance with recently published treatment recommendations were observed. However, these treatment changes did not affect the reoperation rate. Treatment with a plate, intramedullary nail, or hemiarthroplasty was associated with the highest reoperation rates. The fact that almost every 4th surgical procedure was a reoperation indicates a need for further improvement of modern treatment concepts for PHFs.

Fractures of the proximal humerus are common and are associated with a long-term negative impact on quality of life and excess mortality (Clement et al. 2014, Bergdahl et al. 2020). The optimal treatment is controversial. Displaced proximal humeral fractures (PHF) may result in poor outcome regardless of treatment modality and challenging revision procedures are common (Olerud et al. 2011a, 2011b, Lange et al. 2016).The treatment options for PHFs have evolved rapidly in recent years. The introduction of locking plates at the beginning of this century led to a sharp increase in the surgical fixation of PHFs (Bell et al. 2011, Sumrein et al. 2017). However, this trend was accompanied by an increased rate of complications and reoperations (Bell et al. 2011). In attempts to reduce the failure and revision rate, multiple modified surgical techniques evolved (Barlow et al. 2011, Boileau et al. 2013). Parallel to this development, reversed shoulder arthroplasties (RSAs) became increasingly popular (Han et al. 2016). Compared with the traditional fixation methods, RSA demonstrated lower complication rates (Klug et al. 2019). As a result, RSA use has increased markedly, while plate fixation has decreased (Han et al. 2016, Rajaee et al. 2017).According to the latest Cochrane review on PHF interventions there is a lack of data from randomized controlled trials (RCTs) to support one treatment over another (Handoll and Brorson 2015). The complication rate and need for revision surgery are therefore relevant measurements when evaluating PHF treatment. It is important to examine whether changes in treatment affect the need for repeat surgery. We evaluated trends in treatment methods for PHFs at a large Swedish orthopedic trauma unit and explored the rate of and risk factors for reoperations after primary treatment.     

Similar TKA designs with differences in clinical outcome: a randomized, controlled trial of 77 knees with a mean follow-up of 6 years

Background and purpose

To try to improve the outcome of our TKAs, we started to use the CKS prosthesis. However, in a retrospective analysis this design tended to give worse results. We therefore conducted a randomized, controlled trial comparing this CKS prosthesis and our standard PFC prosthesis. Because many randomized studies between different TKA concepts generally fail to show superiority of a particular design, we hypothesized that these seemingly similar designs would not lead to any difference in clinical outcome.

Patients and methods

82 patients (90 knees) were randomly allocated to one or other prosthesis, and 39 CKS prostheses and 38 PFC prostheses could be followed for mean 5.6 years. No patients were lost to follow-up. At each follow-up, patients were evaluated clinically and radiographically, and the KSS, WOMAC, VAS patient satisfaction scores and VAS for pain were recorded.

Results

With total Knee Society score (KSS) as primary endpoint, there was a difference in favor of the PFC group at final follow-up (p = 0.04). Whereas there was one revision in the PFC group, there were 6 revisions in the CKS group (p = 0.1). The survival analysis with any reoperation as endpoint showed better survival in the PFC group (97% (95% CI: 92–100) for the PFC group vs. 79% (95% CI: 66–92) for the CKS group) (p = 0.02).

Interpretation

Our hypothesis that there would be no difference in clinical outcome was rejected in this study. The PFC system showed excellent results that were comparable to those in previous reports. The CKS design had differences that had considerable negative consequences clinically. The relatively poor results have discouraged us from using this design.Although current results of total knee arthroplasty (TKA) are relatively good, there is still room for improvement. There is constant research and development, with a view to obtaining longer survival rates (Rand et al. 2003, Julin et al. 2010), a better range of motion (high-flex TKA) (McCalden et al. 2009, Choi et al. 2010, Mehin et al. 2010), or a more anatomical reconstruction of the joint—such as posterior and anterior cruciate ligament retaining designs (Ries 2007, Pritchett 2011) and gender-specific TKA (Clarke and Hentz 2008, Kim et al. 2010).We started to use the CKS prosthesis (Stratec Medical, Oberdorf, Switzerland), based on previous research at our institution showing that the natural patella groove does not have an isolated lateral orientation (Barink et al. 2006). In contrast to our standard prosthesis (PFC; DePuy/Johnson and Johnson, Warsaw, IN) with a lateral orientation of the patellar groove, the trochlea of the CKS prosthesis is deeper and has a neutral direction. However, in a retrospective analysis, after 1 year the CKS prosthesis tended to have worse Knee Society scores (KSSs) (Brokelman et al. 2004). We decided to compare the outcome thoroughly and started a randomized, controlled trial between the CKS and the PFC prostheses.Many randomized studies of TKAs with different bearings (Harrington et al. 2009, Rahman et al. 2010), cruciate-retaining or -substituting devices (Kim et al. 2009), gender-specific designs (Kim et al. 2010), and high-flex designs (McCalden et al. 2009, Choi et al. 2010, Mehin et al. 2010) generally fail to show superiority of one of the devices over the other. We therefore hypothesized that the seemingly small differences in design between the CKS and PFC system would not lead to differences in clinical outcome in our study.     

Influence of body mass index and age on day-of-surgery discharge,prolonged admission,and 90-day readmission after fast-track unicompartmental knee arthroplasty

Background and purpose — The indications for unicompartmental knee arthroplasty (UKA) have become less restrictive and, today, high age and high BMI are not considered contraindications by many surgeons. While the influence of these patient characteristics on total knee arthroplasty is well documented, evidence on UKA is lacking. We investigated the effect of BMI and age on day of surgery (DOS) discharge, prolonged admission, and 90-day readmission following UKA surgery.Patients and methods — This retrospective cohort study included 3,897 UKA patients operated on between 2010 and 2018 in 8 fast-track arthroplasty centers. Patients were divided into 5 BMI groups and 5 age groups. Differences between groups in the occurrence of DOS discharge, prolonged admission > 2 days, and 90-day readmission was investigated using a chi-square test and mixed-effect models adjusted for patient characteristics using surgical center as a random effect.Results — Median LOS was 1 day. DOS discharge was achieved in 26% of patients with no statistically significant differences between BMI groups. DOS discharge was less likely in UKA patients aged > 70 years (age 71–80; odds ratio [OR] 0.7 [95% CI 0.6–0.9]). Prolonged admission was not affected by BMI or age in the adjusted analysis. 90-day readmission was more likely in patients with BMI > 35 (OR 1.9 [CI 1.1–3.1]) and patients aged 71–80 (OR 1.5 [CI 1.1–2.1]).Interpretation — Age > 70 years decreased the likelihood of DOS discharge after UKA. High BMI as well as advanced age increased the likelihood of 90-day readmission. This should be noted by surgeons operating on patients with high BMI and age.

The indications for unicompartmental knee arthroplasty (UKA) as treatment for osteoarthritis (OA) have become less restrictive in terms of age and weight. Early contraindications included age < 60 years and weight > 82 kg (Kozinn and Scott 1989). However, recent studies report that revision rates and patient-reported outcomes are not worse in such patients (Pandit et al. 2011, van der List et al. 2016, Hamilton et al. 2017). Current indications focus solely on the pathoanatomy of the knee OA (Goodfellow et al. 1988, Hamilton et al. 2017).Despite being informed of increased risk of certain postoperative complications in high BMI patients and young/old patients, these patients are increasingly undergoing UKA surgery as well as knee arthroplasty in general (Price et al. 2018, Henkel et al. 2019).While length of stay (LOS) and readmissions are not the primary factors when determining indications/contraindications of arthroplasty procedures, they do affect patient satisfaction, logistics and cost-effectiveness (Reilly et al. 2005, Molloy et al. 2017).The few studies investigating the effect of BMI and age on LOS and readmission after UKA have varying conclusions. Some studies have associated higher BMI with increased risk of prolonged admission as well as short-term complications, while others find no such association (Otero et al. 2016, Plate et al. 2017, Sephton et al. 2020). Likewise, day of surgery (DOS) discharge is reported to be less likely in older patients while some do not find this association (Haughom et al. 2015, Matsumoto et al. 2020). Due to the usage of UKA in patients with high BMI and advanced age, it is important to investigate the effect of BMI and age on the postoperative course after UKA.We therefore investigated the association between BMI and age and the proportion of UKA patients with DOS discharge, prolonged admission, and readmission within 90 days of surgery in a prospective unselected multicenter fast-track setup.     

Growth modulation with a medial malleolar screw for ankle valgus deformity: 79 children with 125 affected ankles followed until correction or physeal closure

Background and purpose

Growth modulation with a medial malleolar screw is used to correct ankle valgus deformity in children with a wide spectrum of underlying etiologies. It is unclear whether the etiology of the deformity affects the angular correction rate with this procedure.

Patients and methods

79 children (20 girls) with ankle valgus deformity had growth modulation by a medial malleolar screw (125 ankles). To be included, patients had to have undergone screw removal at the time of skeletal maturity or deformity correction, or a minimum follow-up of 18 months, and consistent radiographs preoperatively and at the time of screw removal and/or follow-up. The patients were assigned to 1 of 7 groups according to their underlying diagnoses. The lateral distal tibial angle (LDTA) was analyzed preoperatively, at screw removal, and at follow-up.

Results

Mean age at operation was 11.7 (7.4–16.5) years. The average lateral distal tibial angle normalized from 80° (67–85) preoperatively to 89° (73–97) at screw removal. The screws were removed after an average time of 18 (6–46) months, according to an average rate of correction of 0.65° (0.1–2.2) per month. No significant differences in the correction rate per month were found between the groups (p = 0.3).

Interpretation

Growth modulation with a medial malleolar screw is effective for the treatment of ankle valgus deformity in patients with a wide spectrum of underlying diagnoses. The individual etiology of the ankle valgus does not appear to affect the correction rate after growth modulation. Thus, the optimal timing of growth modulation mainly depends on the remaining individual growth and on the extent of the deformity.Ankle valgus deformity may occur in children with various disorders. This deformity usually progresses and causes dynamic malalignment and abnormal loading of the joints of the lower extremity. Associated deformities such as planovalgus feet or hallux valgus occur and they may cause significant problems with gait, shoe wear, and brace fit.Ankle valgus is most often seen in children with neuromuscular disorders such as myelomeningocele (MMC) (Dias 1978, Malhotra et al. 1984), poliomyelitis, and cerebral palsy (CP) (Makin 1965), and it may be overlooked in the presence of concurrent foot deformities. It also occurs in children with postaxial hypoplasia, clubfoot (Coventry and Johnson 1952, Thompson et al. 1957, Bohne and Root 1977), pseudarthrosis of the fibula (Langenskiöld 1967, Dooley et al. 1974, Hsu et al. 1974), or hereditary multiple exostoses (HME) (Rupprecht et al. 2011, 2014, Driscoll et al. 2013). Regardless of these different etiologies, the main goals of treatment are correction of the ankle valgus, prevention of further deformities, resumption of normal activities, and prevention of degenerative changes. Apart from nonoperative management with braces in mild cases, there are many surgical procedures—ranging from a tibial supramalleolar osteotomy, distal tibial wave osteotomy (Sharrard and Grosfield 1968, Kumar et al. 1990, Abraham et al. 1996), transepiphyseal osteotomy of the distal tibia (Lubicky and Altiok 2001), to modulation of growth with a medial malleolar screw or staple (Beals and Skyhar 1984, Davids et al. 1997, Rupprecht et al. 2011, Stevens et al. 2011).Until now, it has been unclear whether the underlying diagnosis affects the treatment and results of ankle valgus deformity correction by growth modulation with a medial malleolar screw. We therefore examined the effectiveness of this procedure, the complications associated with it, and the angular correction rate per month with respect to the underlying diagnoses.     

Locking plate osteosynthesis in displaced 4-part fractures of the proximal humerus

Background and purpose

There is considerable uncertainty about the optimal treatment of displaced 4-part fractures of the proximal humerus. Within the last decade, locking plate technology has been considered a breakthrough in the treatment of these complex injuries.

Methods

We systematically identified and reviewed clinical studies on the benefits and harms after osteosynthesis with locking plates in displaced 4-part fractures.

Results

We included 14 studies with 374 four-part fractures. There were 10 case series, 3 retrospective observational comparative studies, 1 prospective observational comparative study, and no randomized trials. Small studies with a high risk of bias precluded reliable estimates of functional outcome. High rates of complications (16–64%) and reoperations (11–27%) were reported.

Interpretation

The empirical foundation for the value of locking plates in displaced 4-part fractures of the proximal humerus is weak. We emphasize the need for well-conducted randomized trials and observational studies.There is considerable uncertainty about the optimal treatment of displaced 4-part fractures of the proximal humerus (Misra et al. 2001, Handoll et al. 2003, Bhandari et al. 2004, Lanting et al. 2008). Only 2 small inconclusive randomized trials have been published (Stableforth 1984, Hoellen et al. 1997). A large number of interventions are used routinely, ranging from a non-operative approach to open reduction and internal fixation (ORIF), and primary hemiarthroplasty (HA).In the last decade, locking plate technology has been developed and has been heralded as a breakthrough in the treatment of fractures in osteoporotic bone (Gautier and Sommer 2003, Sommer et al. 2003, Haidukewych 2004, Miranda 2007). Locking plate technique is based on the elimination of friction between the plate and cortex, and relies on stability between the subchondral bone and screws. Multiple multidirectional convergent and divergent locking screws enhance the angular stability of the osteosynthesis, possibly resulting in better postoperative function with reduced pain. Reported complications include screw cut-out, varus fracture collapse, tuberosity re-displacement, humeral head necrosis, plate impingement, and plate or screw breakage (Hall et al. 2006, Tolat et al. 2006, van Rooyen et al. 2006, Agudelo et al. 2007, Gardner et al. 2007, Khunda et al. 2007, Ring 2007, Smith et al. 2007, Voigt et al. 2007, Egol et al. 2008, Kirchhoff et al. 2008, Owsley and Gorczyca 2008, Brunner et al. 2009, Micic et al. 2009, Sudkamp et al. 2009). The balance between the benefit and harms of the intervention seems delicate.Several authors of narrative reviews and clinical series have strongly recommended fixation of displaced 4-part fractures of the humerus with locking plates (Bjorkenheim et al. 2004, Hente et al. 2004, Hessler et al. 2006, Koukakis et al. 2006, Kilic et al. 2008, Korkmaz et al. 2008, Shahid et al. 2008, Papadopoulos et al. 2009, Ricchetti et al. 2009) and producers of implants unsurprisingly strongly advocate them (aap Implantate 2010, Stryker 2010, Synthes 2010, Zimmer 2010). Despite the increasing use of locking plates (Illert et al. 2008, Ricchetti et al. 2009), we have been unable to identify systematic reviews on the benefits and harms of this new technology in displaced 4-part fractures. Thus, we systematically identified and reviewed clinical studies on the benefits and harms after osteosynthesis with locking plates in displaced 4-part fractures of the proximal humerus.     

Short-segment posterior instrumentation combined with anterior spondylodesis using an autologous rib graft in thoracolumbar burst fractures: Good outcomes in 32 patients

Background and purpose

There are very few data concerning the outcome after short-segment posterior stabilization and anterior spondylodesis with rib grafts in patients suffering from unstable thoracolumbar burst fractures. We have therefore investigated the clinical and radiographic outcome after posterior bisegmental instrumentation and monosegmental anterior spondylodesis using an autologous rib graft for unstable thoracolumbar burst fractures.

Patients and methods

This was a retrospective analysis of 32 consecutive patients at a single center. The monosegmental Cobb angle was measured preoperatively, postoperatively, then 6 and 12 months postoperatively, and also after implant removal. Anterior vertebral fusion was graded on conventional radiographs according to the criteria proposed by Molinari.

Results

Segmental kyphosis at the fracture site was corrected from a median of -20° (95% CI: -21.2 to -18.8) to -1.0° (95% CI: -2.7 to 0.7) postoperatively. 1 year after surgery, the segmental angle had decreased by a median of 2.0° (95% CI: 0.2 to 2.8). The spondylodesis fused in all patients, which was evident from incorporation and remodeling of the rib grafts. The median correction loss after implant removal was 0.0° (95% CI: -0.5 to 0.5). 26 of the 32 patients reported having no back complaints at the last follow-up (2 years postoperatively). 1 patient suffered from intercostal neuralgia, and 5 patients reported mild to moderate back pain.

Interpretation

Short-segment posterior instrumentation and anterior spondylodesis using an autologous rib graft resulted in sufficient correction of posttraumatic segmental kyphosis. There was no clinically relevant correction loss, and the majority of patients had no back complaints at the 2-year follow-up.Thoracolumbar (T11–L2) burst fractures that are unstable (i.e. failure of the anterior and middle column under compression or disruption of the posterior column) or associated with a neurologic deficit are most often treated surgically (Verlaan et al. 2004, Oner et al. 2010). Currently, short-segment posterior stabilization is considered to be the first step towards preserving motion segments, preventing adjacent segment disease, shortening operating time, and reducing intraoperative blood loss (Verlaan et al. 2004, Dai et al. 2007, Zdeblick et al. 2009, Gelb et al. 2010, Kim et al. 2011, Schmid et al. 2011, Tofuku et al. 2012). Furthermore, short-segment posterior stabilization can be performed in a standard emergency surgery setting. However, there has been some controversy concerning the need and type of anterior treatment. Combined posterior and anterior spondylodesis may result in better pain relief (Verlaan et al. 2004) and less correction loss (Bertram et al. 2003, Oner et al. 2010) or instrumentation failure (Been and Bouma 1999) compared to posterior surgery alone in patients suffering from burst fractures with an impaired anterior column. Autologous bone grafting results in superior fusion rates compared to allografts (An et al. 1995). However, donor-site morbidity often impairs clinical outcome (Summers and Eisenstein 1989, Emery et al. 1996, Myeroff and Archdeacon 2011). If thoracotomy is performed to access thoracolumbar burst fractures from anterior, autologous rib grafts can be harvested without additional surgery. To date, little is known about the outcome after anterior spondylodesis with rib grafts in patients suffering from thoracolumbar burst fractures (Buhren and Braun 1993, Vieweg et al. 1996, Nakamura et al. 2001). We have therefore investigated the clinical and radiographic outcome after posterior bisegmental instrumentation and monosegmental spondylodesis combined with anterior monosegmental spondylodesis using an autologous rib graft for treatment of thoracolumbar burst fractures.     

No increased mortality after total hip arthroplasty in patients with a history of pediatric hip disease: a matched,population-based cohort study on 4,043 patients

Background and purpose — Patients with pediatric hip diseases are more comorbid than the general population and at risk of premature, secondary osteoarthritis, often leading to total hip arthroplasty (THA). We investigated whether THA confers an increased mortality in this cohort.Patients and methods — We identified 4,043 patients with a history of Legg–Calvé–Perthes disease (LCPD), slipped capital femoral epiphysis (SCFE), or developmental dysplasia of the hip (DDH) in the Swedish Hip Arthroplasty Register (SHAR) between 1992 and 2012. For each patient, we matched 5 controls from the general population for age, sex, and place of residence, and acquired information on all participants’ socioeconomic background and comorbidities. Mortality after THA was estimated according to Kaplan–Meier, and Cox proportional hazard models were fitted to estimate adjusted hazard ratios (HRs) for the risk of death.Results — Compared with unexposed individuals, patients exposed to a THA due to pediatric hip disease had lower incomes, lower educational levels, and a higher degree of comorbidity but a statistically non-significant attenuation of 90-day mortality (HR 0.9; 95% CI 0.4–2.0) and a lower risk of overall mortality (HR 0.8; CI 0.7–0.9).Interpretation — Patients exposed to THA due to a history of pediatric hip disease have a slightly lower mortality than unexposed individuals. THA seems not to confer increased mortality risks, even in these specific patients with numerous risk factors.

Altered morphology of the hip joint due to pediatric hip diseases, e.g., Legg–Calvé–Perthes disease (LCPD), slipped capital femoral epiphysis (SCFE), or developmental dysplasia of the hip (DDH) is closely linked to early-onset, secondary osteoarthritis (OA) (Jacobsen and Sonne-Holm 2005, Pun 2016) which may lead to total hip arthroplasty (THA) at a young age (Froberg et al. 2011). Thus, the mean age at THA surgery in patients with a history of pediatric hip disease ranges from 38 to 55 years (Traina et al. 2011, Engesaeter et al. 2012), whereas it ranges from 65 to 70 years in patients with primary OA (Engesaeter et al. 2012, Fang et al. 2015, Cnudde et al. 2018). Studies from Nordic countries report that between 4% and 9% of all primary THAs are due to pediatric hip disease (Engesaeter et al. 2012).The long-term outcome and revision rates after THA in patients with previous pediatric hip disease have been studied (Thillemann et al. 2008, Traina et al. 2011), but 90-day mortality and overall mortality after THA in these patients have not yet been investigated. Comorbidities, such as attention deficit hyperactivity disorder (ADHD), depression, cardiovascular disease, hypothyroidism, obesity, and coagulation abnormalities are more common in patients with LCPD and SCFE (Hailer and Nilsson 2014, Perry et al. 2017, Hailer and Hailer 2018, Hailer 2020). In addition, patients with LCPD and SCFE have a higher overall mortality than the general population (Hailer and Nilsson 2014, Hailer 2020). Due to an increased comorbidity burden and possibly increased overall mortality one could therefore fear an increased mortality after THA surgery in these patients.We therefore investigated whether THA surgery in patients with a pediatric hip disease confers an increased 90-day and overall mortality when compared with the general population.