Repeated magnetic resonance imaging in 154 hips with large-diameter metal-on-metal hip replacement

Background and purpose —

The US Food and Drug Administration and the UK Medicines and Health Regulation Agency recommend using MRI in the evaluation of patients with large-diameter metal-on-metal (LD-MoM) hips. Such recommendations do not take into account the relevance of repeated cross-sectional imaging. We therefore investigated the natural course of pseudotumors in patients with LD-MoM hip replacements.

Patients and methods —

Of 888 ASR patients (1,036 hips) 674 patients (798 hips) underwent 2 follow-up visits at our institution. Of these, we identified 124 patients (154 hips) who had undergone repeated clinical assessment including MRI and whole-blood metal ion assessment.

Results —

A change in classification in imaging findings between the 2 MRIs was seen in 17 of the 154 hips (11%). In 13 hips (8%), a significant progression of the pseudotumor was evident, while in 4 (3 %) there was a retrogressive change. 10 of these 13 hips had had a normal first MRI. Patients with a progressive change in the scans did not differ significantly from those without a change in MRI classification regarding follow-up time, time interval between MRIs, or changes in whole-blood Cr and Co levels between assessments.

Interpretation —

A change in classification was rare, considering that all patients had a clinical indication for repeated imaging. Progression of the findings did not appear to correlate clearly with symptoms or whole-blood metal values.Wear-related adverse soft tissue reactions remain a major concern in patients who have received large-diameter metal-on-metal (LD-MoM) hip replacements. The umbrella term ARMeD (adverse reactions to metal debris) has been proposed to describe all variable manifestations of these reactions (Langton et al. 2010). Intra-capsular findings include metallosis, synovitis, synovial hypertrophy, and capsular necrosis (De Smet et al. 2008, Nishii et al. 2012). In some patients, ARMeD may manifest as an aggressive pseudotumor. Magnetic resonance imaging (MRI) features of pseudotumors adjacent to MoM devices vary greatly (Hart et al. 2012, Hauptfleisch et al. 2012), and there is no consensus regarding the definition of pseudotumor. Pseudotumors appearing partly or fully solid in MRI have been reported to require revision most often (Hauptfleisch et al. 2012). Massive periarticular tissue destruction including osteolysis and tendon avulsion can be found in some of these cases (Fang et al. 2008, Toms et al. 2008, Chang et al. 2012, Hayter et al. 2012). However, occasionally only a thin-walled extracapsular fluid collection adjacent to a MoM hip is detected (Nishii et al. 2012).The clinical significance of these bursa-like or cystic pseudotumors with typical fluid signals in MRI is not known (Hart el al. 2012, Nishii et al. 2012). This type of soft-tissue lesion has been reported in several papers in recent years, and some authors consider them to be pseudotumors (Hart et al. 2012, Hauptfleischet al. 2012). However, these lesions have also been described in patients with metal-on-polyethylene and ceramic-on-ceramic hips (Carli et al. 2011, Mistry et al. 2011). The natural history of these lesions is, however, largely unknown.Both the US Food and Drug Administration and the UK Medicines and Health Regulation Agency recommend using MRI in the evaluation of patients with LD-MoM hips (Medicines and Healthcare Products Regulation Agency 2012, U.S. Food and Drug Administration 2012). Recommendations do not take into account the relevance of repeated cross-sectional imaging. In a recent study, no relevant changes were seen after 1 year in 14 hips with a pseudotumor using repeated MR imaging (van der Weegen et al. 2013). In a larger study, progression in MRI was seen in 15 of 103 MoM 28-mm total hip replacements (THRs) (Ebreo et al. 2013).Our main aims were (1) using MRI, to investigate the natural course of pseudotumors in patients with LD-MoM hip replacements who did not require revision surgery, and (2) to determine whether any new pseudotumors emerged in this cohort during the follow-up. A secondary aim was to document the temporal changes in these patients regarding MRI findings, clinical outcomes, and whole-blood chrome (Cr) and cobalt (Co) levels.     

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.     

Hospital volume affects outcome after total knee arthroplasty: A nationwide registry analysis of 80 hospitals and 59,696 replacements

ResultsThe greater the volume of the hospital, the shorter was the average LOS and LUIC. Smaller hospital volume was not unambiguously associated with increased revision, re-admission, or MUA rates. The smaller the annual hospital volume, the more often patients were discharged home.InterpretationLOS and LUIC ought to be shortened in lower-volume hospitals. There is potential for a reduction in length of stay in extended institutional care facilities.Total knee replacement (TKR) is one of the most common orthopedic procedures, and it is expected to increase markedly in volume (Kurtz et al. 2007). Due to the potentially severe complications and the high economic impact of the procedure, efforts to minimize the risks and optimize perioperative efficiency are important.It has been suggested that increased hospital volume and reduction in length of stay (LOS) at the operating hospital after TKR are related, but there is no consensus (Yasunaga et al. 2009, Marlow et al. 2010, Paterson et al. 2010, Bozic et al. 2010, Styron et al. 2011). In addition, results on the association of hospital volume with re-admission rates (Soohoo et al. 2006b, Judge et al. 2006, Bozic et al. 2010, Cram et al. 2011) and revision risk have been inconclusive (Shervin et al. 2007, Manley et al. 2009, Bozic et al. 2010, Paterson et al. 2010). No-one has tried to study the association between length of uninterrupted institutional care (LUIC), incidence of manipulation under anesthesia (MUA) after TKR, and hospital volume.By combining 5 national-level registries, we examined possible associations between hospital volume and LOS, LUIC, discharge disposition, number of re-admissions within 14 and 42 days, MUA, and revisions after TKR for all knee arthroplasties performed in Finland between 1998 and 2010.     

Perioperative mortality after hemiarthroplasty related to fixation method

Background and purpose

The appropriate fixation method for hemiarthroplasty of the hip as it relates to implant survivorship and patient mortality is a matter of ongoing debate. We examined the influence of fixation method on revision rate and mortality.

Methods

We analyzed approximately 25,000 hemiarthroplasty cases from the AOA National Joint Replacement Registry. Deaths at 1 day, 1 week, 1 month, and 1 year were compared for all patients and among subgroups based on implant type.

Results

Patients treated with cemented monoblock hemiarthroplasty had a 1.7-times higher day-1 mortality compared to uncemented monoblock components (p < 0.001). This finding was reversed by 1 week, 1 month, and 1 year after surgery (p < 0.001). Modular hemiarthroplasties did not reveal a difference in mortality between fixation methods at any time point.

Interpretation

This study shows lower (or similar) overall mortality with cemented hemiarthroplasty of the hip.The frequency of hip fractures is increasing with our ageing population, with an annual incidence of between 1.4 and 5 per 103 per year (Lonnroos et al. 2006, Icks et al. 2008, Varez-Nebreda et al. 2008). Health model projections have estimated that 6.3 million hip fractures will occur annually worldwide within the next 40 years (Cooper et al. 1992), imposing a significant economic health burden. There is a large reported perioperative mortality rate in this population, ranging from 2.4% to 8.2% at 1 month (Parvizi et al. 2001, Radcliff et al. 2008) and over 25% at 1 year (Elliott et al. 2003, Jiang et al. 2005). Furthermore, it was recently reported that the current mortality rate is higher now than 25 years ago (Vestergaard et al. 2007a). Today, it is generally accepted that displaced intracapsular fractures are best treated with arthroplasty rather than internal fixation (Keating et al. 2006, Leighton et al. 2007). In the at-risk population, however, multiple comorbidities are common and the best form of component fixation is in question.Bone cement implantation syndrome is a well-described complication of cemented hip arthroplasty. It is characterized by a systemic drop in systolic blood pressure, hypoxemia, pulmonary hypertension, cardiac dysrhythmias, and occasionally cardiac arrest and death (Rinecker 1980, Orsini et al. 1987, Parvizi et al. 1999). The prevailing theory to explain the pathophysiology of this phenomenon is embolism of fat, marrow contents, bone, and to some degree methylmethacrylate to the lung (Rinecker 1980, Elmaraghy et al. 1998, Parvizi et al. 1999, Koessler et al. 2001). An increased degree of pulmonary insult with fat microemboli has been demonstrated (mostly in randomized controlled trials) during insertion of a cemented femoral stem rather than an uncemented implant (Orsini et al. 1987, Ries et al. 1993, Christie et al. 1994, Pitto et al. 1999), presumably due to increased intramedullary femoral canal pressures in the cemented group (Kallos et al. 1974, Orsini et al. 1987). These pressures can be reduced by the use of distal venting holes in the femur during stem insertion (Engesæter et al. 1984). It has been shown previously by single-institutional review that patients undergoing cemented hip arthroplasty have a higher intraoperative mortality rate relative to uncemented arthroplasty, presumably due to a reduced incidence of fat embolism in the latter group (Parvizi et al. 1999). The increased mortality risk was also present at 30 days in the treatment of acute fractures with cemented arthroplasty, also from a single-institutional review (Parvizi et al. 2004). Although cement-related mortality is rare (Dearborn and Harris 1998, Parvizi et al. 1999, 2001, 2004, Weinrauch et al. 2006), it is a devastating complication—often reported through observational studies or literature reviews. Proponents of uncemented hip arthroplasty often cite this concern to support their reluctance to use cemented hip arthroplasty in both elective procedures and fracture management. However, many different types of studies have been unable to identify any increased mortality risk with the use of cement (Lausten and Vedel 1982 (observational), Emery et al. 1991 (RCT), Lo et al. 1994 (observational), Khan et al. 2002a,b (literature review), Parker and Gurusamy 2004 (literature review)) and others have shown a decrease in mortality at 30 days when cement is used (Foster et al. 2005).Cemented hip hemiarthroplasty appears to offer improved rate of return to baseline function, reduced postoperative pain, and superior long-term survivorship relative to uncemented arthroplasty (Khan et al. 2002a, b, Parker and Gurusamy 2004). We reasoned that failure to return to baseline function after hemiarthroplasty may be another risk factor for perioperative mortality (Hannan et al. 2001, Braithwaite et al. 2003). Lower revision rates for cemented prostheses and increased mortality at revision surgery contribute further to reducing the overall mortality risk. We evaluated the relationship between the method of fixation of hip arthroplasty and perioperative mortality using a large national joint replacement registry.     

Silent soft tissue pathology is common with a modern metal-on-metal hip arthroplasty

Background and purpose

Adverse reactions to metal debris have been reported to be a cause of pain in metal-on-metal hip arthroplasty. We assessed the incidence of both symptomatic and asymptomatic adverse reactions in a consecutive series of patients with a modern large-head metal-on-metal hip arthroplasty.

Methods

We studied the early clinical results and results of routine metal artifact-reduction MRI screening in a series of 79 large-head metal-on-metal hip arthroplasties (ASR; DePuy, Leeds, UK) in 68 patients. 75 hips were MRI scanned at mean 31 (12–52) months after surgery.

Results

27 of 75 hips had MRI-detected metal debris-related abnormalities, of which 5 were mild, 18 moderate, and 4 severe. 8 of these hips have been revised, 6 of which were revised for an adverse reaction to metal debris, diagnosed preoperatively with MRI and confirmed histologically. The mean Oxford hip score (OHS) for the whole cohort was 21. It was mean 23 for patients with no MRI-based evidence of adverse reactions and 19 for those with adverse reactions detected by MRI. 6 of 12 patients with a best possible OHS of 12 had MRI-based evidence of an adverse reaction.

Interpretation

We have found a high early revision rate with a modern, large-head metal-on-metal hip arthroplasty. MRI-detected adverse rections to metal debris was common and often clinically “silent”. We recommend that patients with this implant should be closely followed up and undergo routine metal artifact-reduction MRI screening.Metal-on-metal (MoM) total hip replacements have been used since the 1960s. Failure in early designs was attributed to mechanical loosening caused by poor bearing tolerances producing high friction (Amstutz and Grigoris 1996, Kothari et al. 1996). Improved manufacturing and engineering techniques enabled the development of a new generation of MoM hip replacements. In the 1990s, the Birmingham Hip Resurfacing (BHR) was developed, and good early to medium-term results have been published (Daniel et al. 2004, Treacy et al. 2005, Heilpern et al. 2008). Similar implants, both resurfacings and large MoM bearings, coupled with standard femoral stems were subsequently developed and marketed by other manufacturers.The development of magnetic resonance imaging (MRI) metal artifact reduction (MAR) sequences has enabled good visualization of the periprosthetic tissues (Toms et al. 2008), and been reported to be a clinically useful part of the assessment of painful MoM hip replacements (Hart et al. 2009). A number of authors have described the appearance of collections of fluid and inflammatory masses around painful MoM hip arthroplasties (Boardman et al. 2006, Pandit et al. 2008, Toms et al. 2008). These have been grouped under a variety of headings such as “aseptic lymphocyte-dominated vasculitis-associated lesions” (Willert et al. 2005), “pseudotumors” (Pandit et al. 2008), or “adverse reactions to metal debris (ARMD)” (Langton et al. 2010). Although these lesions have been previously described in patients investigated for pain, there have been no studies on the overall incidence of these lesions in an unselected series of patients, including those with no, or few, symptoms. It is not known whether these lesions may occur in the absence of symptoms.At our institution, we have a policy of offering routine MAR MRI imaging to patients who have undergone MoM total hip replacement or resurfacing. We determined the early clinical outcome, revision rate, and incidence of ARMD using MAR MRI screening in a consecutive series of patients with an ASR THR or resurfacing (ASR; DePuy, Leeds, UK).     

Increased risk of revision of cementless stemmed total hip arthroplasty with metal-on-metal bearings: Data from the Nordic Arthroplasty Register Association

Background and purpose

Data from the national joint registries in Australia and England and Wales have revealed inferior medium-term survivorship for metal-on-metal (MoM) total hip arthroplasty (THA) than for metal-on-polyethylene (MoP) THA. Based on data from the Nordic Arthroplasty Register Association (NARA), we compared the revision risk of cementless stemmed THA with MoM and MoP bearings and we also compared MoM THA to each other.

Patients and methods

We identified 32,678 patients who were operated from 2002 through 2010 with cementless stemmed THA with either MoM bearings (11,567 patients, 35%) or MoP bearings (21,111 patients, 65%). The patients were followed until revision, death, emigration, or the end of the study period (December 31, 2011), and median follow-up was 3.6 (interquartile range (IQR): 2.4–4.8) years for MoM bearings and 3.4 (IQR: 2.0–5.8) years for MoP bearings. Multivariable regression in the presence of competing risk of death was used to assess the relative risk (RR) of revision for any reason (with 95% confidence interval (CI)).

Results

The cumulative incidence of revision at 8 years of follow-up was 7.0% (CI: 6.0–8.1) for MoM bearings and 5.1% (CI: 4.7–5.6) for MoP bearings. At 6 years of follow-up, the RR of revision for any reason was 1.5 (CI: 1.3–1.7) for MoM bearings compared to MoP bearings. The RR of revision for any reason was higher for the ASR (adjusted RR = 6.4, CI: 5.0–8.1), the Conserve Plus (adjusted RR = 1.7, CI: 1.1–2.5) and “other” acetabular components (adjusted RR = 2.4, CI: 1.5–3.9) than for MoP THA at 6 years of follow-up.

Interpretation

At medium-term follow-up, the survivorship for cementless stemmed MoM THA was inferior to that for MoP THA, and metal-related problems may cause higher revision rates for MoM bearings with longer follow-up.Wear particles from the polyethylene liner in metal-on-polyethylene (MoP) bearings in total hip arthroplasty (THA) are associated with osteolysis and aseptic loosening of the implant (Jacobs et al. 1994). Surgeons therefore became interested in alternatives such as metal-on-metal (MoM) bearings. The main justification for using large-diameter-head (LDH) MoM bearings in THA was less wear and the hope of lower revision rates. However, a lower risk of revision has only been found for revision due to dislocation (Kostensalo et al. 2013), whereas the total risk of revision has been found to be increased in some studies (Smith et al. 2012, Huang et al. 2013). In addition, LDH MoM was introduced in order to achieve increased range of motion and better function (Burroughs et al. 2005, Davis et al. 2007), but that has not been shown clinically (Penny et al. 2013).Several concerns about the use of MoM bearings in hip surgery have been voiced in recent years: excessive failure rates for certain brands and implant combinations used with MoM components have been reported (Langton et al. 2011, Australian Orthopaedic Association 2013). Some designs are associated with increased frequency of aseptic loosening (Australian Orthopaedic Association 2013), and large head sizes placed on conventional stems may cause taper junction failure (Langton et al. 2012). Exposure to chromium and cobalt may cause adverse reactions to metal debris (ARMD) (Langton et al. 2010) such as pseudotumors (Pandit et al. 2008) and hypersensivity reactions (Willert et al. 2005) locally in the hip joint. Furthermore, metal ions may be genotoxic (Daley et al. 2004).Only a few population-based studies on MoM bearings in stemmed THAs from hip arthroplasty registries have been published (Smith et al. 2012, Mokka et al. 2013b, Furnes et al. 2014), with only 1 population-based study focusing on causes of revision resulting from specific combinations of acetabular and femoral components (Mokka et al. 2013b). We compared the 6-year revision risk for MoM bearings with that for MoP bearings in cementless stemmed THA. In addition, we studied different designs of stemmed MoM THAs and the causes of revision in a population-based follow-up study using data from the Nordic Arthroplasty Register Association (NARA).     

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.     

Hydroxyapatite coating does not improve uncemented stem survival after total hip arthroplasty!: An analysis of 116,069 THAs in the Nordic Arthroplasty Register Association (NARA) database

ResultsUnadjusted 10-year survival with the endpoint revision of any component for any reason was 92.1% (CI: 91.8–92.4). Unadjusted 10-year survival with the endpoint stem revision due to aseptic loosening varied between the stem brands investigated and ranged from 96.7% (CI: 94.4–99.0) to 99.9% (CI: 99.6–100). Of the stem brands with the best survival, stems with and without HA coating were found. The presence of HA coating was not associated with statistically significant effects on the adjusted risk of stem revision due to aseptic loosening, with an HR of 0.8 (CI: 0.5–1.3; p = 0.4). The adjusted risk of revision due to infection was similar in the groups of THAs using HA-coated and non-HA-coated stems, with an HR of 0.9 (CI: 0.8–1.1; p = 0.6) for the presence of HA coating. The commonly used Bimetric stem (n = 25,329) was available both with and without HA coating, and the adjusted risk of stem revision due to aseptic loosening was similar for the 2 variants, with an HR of 0.9 (CI: 0.5–1.4; p = 0.5) for the HA-coated Bimetric stem.InterpretationUncemented HA-coated stems had similar results to those of uncemented stems with porous coating or rough sand-blasted stems. The use of HA coating on stems available both with and without this surface treatment had no clinically relevant effect on their outcome, and we thus question whether HA coating adds any value to well-functioning stem designs.Hydroxyapatite (HA) is thought to improve early implant ingrowth and long-term stability in bone (Overgaard et al. 1997), and many stems intended for uncemented total hip arthroplasty (THA) are thus manufactured with HA coating. Several uncemented stems are only available with HA coating. Some HA-coated stems have excellent long-term outcomes in terms of the risk of revision, both for any reason and due to aseptic loosening (Capello et al. 2003, Shah et al. 2009). Registry data from Norway and Finland also indicate that certain HA-coated stems have excellent survivorship up to 10 years (Eskelinen et al. 2006, Hallan et al. 2007, Makela et al. 2008).On the other hand, a number of studies on stem survival in the setting of randomized trials or smaller observational studies have failed to show beneficial effects of HA coating on clinical outcome and implant survival when compared to alternatives such as porous coating and sand-blasted rough surfaces (McPherson et al. 1995, Tanzer et al. 2001, Kim et al. 2003, Parvizi et al. 2004, Sanchez-Sotelo et al. 2004). Meta-analyses that have pooled data from randomized or cohort studies have come to the conclusion that there is “[…] no clinically beneficial effect to the addition of HA to porous coating alone in primary uncemented hip arthroplasty” (Gandhi et al. 2009, Li et al. 2013). In addition, a Danish registry analysis found that the use of HA coating does not reduce the risk of stem revision (Paulsen et al. 2007). Furthermore, a comparison of 4,772 uncemented Bimetric stems with or without HA coating implanted between 1992 and 2009 did not reveal any difference in survival between the 2 variants (Lazarinis et al. 2011).HA was initially introduced as an implant coating to speed up and facilitate ongrowth and ingrowth of bone and thereby improve fixation, based on comprehensive preclinical and promising clinical documentation (Geesink et al. 1987, Bauer et al. 1991, Overgaard et al. 1997, Karrholm et al. 1998). Later on, concerns were raised due to findings of delamination and generation of HA particles originating from the coating with the potential to trigger osteolysis, acceleration of polyethylene wear, and subsequent implant loosening (Bloebaum and Dupont 1993, Morscher et al. 1998, Lazarinis et al. 2010). Today, there is renewed interest in HA coatings due to possible properties as a carrier for agents aimed at preventing infection (Ghani et al. 2012). Theoretical arguments for and against the use of HA coating can therefore be found. Given the renewed interest in uncemented stems—instigated by favorable outcomes after uncemented stem fixation in younger patients—the question of whether HA coating is beneficial or not is highly relevant (Eskelinen et al. 2006, Hooper et al. 2009, Swedish Hip Arthroplasty Register 2011). We therefore investigated uncemented stems with and without HA coating that are in frequent use in the Nordic countries, regarding early and long-term survival.     

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.     

Failure of aseptic revision total knee arthroplasties: 145 revision failures from the Norwegian Arthroplasty Register, 1994–2011

MethodThis study was based on 1,016 aseptic revision total knee arthroplasties reported to the Norwegian Arthroplasty Register between 1994 and 2011. Revisions done for infections were not included. Kaplan-Meier and Cox regression analyses were used to assess the survival rate and the relative risk of re-revision with all causes of re-revision as endpoint.Results145 knees failed after revision total knee arthroplasty. Deep infection was the most frequent cause of re-revision (28%), followed by instability (26%), loose tibial component (17%), and pain (10%). The cumulative survival rate for revision total knee arthroplasties was 85% at 5 years, 78% at 10 years, and 71% at 15 years. Revision total knee arthroplasties with exchange of the femoral or tibial component exclusively had a higher risk of re-revision (RR = 1.7) than those with exchange of the whole prosthesis. The risk of re-revision was higher for men (RR = 2.0) and for patients aged less than 60 years (RR = 1.6).InterpretationIn terms of implant survival, revision of the whole implant was better than revision of 1 component only. Young age and male sex were risk factors for re-revision. Deep infection was the most frequent cause of failure of revision of aseptic total knee arthroplasties.Globally, the number of knee arthroplasty operations is increasing. In the USA, the incidence of primary total knee arthroplasty (TKA) has increased from 51 per 10⁵ inhabitants in 1990 (Kurtz et al. 2007) to 215 per 10⁵ in 2008 (Carr et al. 2012). In Sweden, the incidence of knee arthroplasty increased from 115 per 10⁵ inhabitants in 2007 (Robertsson et al. 2010) to 135 per 10⁵ in 2011 (Sundberg et al. 2012). In Norway, the incidence increased from 35 per 10⁵ inhabitants (Furnes et al. 2002) in 1999 to 90 per 10⁵ in 2011 (Furnes et al. 2012).With an increasing aging population and increase in the use of joint arthroplasty in younger people, the increase in knee arthroplasty surgery will continue (Carr et al. 2012)—as will the need for revision TKA (Kurtz et al. 2007). In the United States, for example, projections suggest that the number of revision TKAs will have increased from 38,000 in 2005 to 268,000 by the year 2030 (Kurtz et al. 2007). In Norway, the revision burden, defined as the ratio of revision arthroplasties to the total number of arthroplasties, increased from 6.9% in 1994 to 8.5% in 2011 (Furnes et al. 2012).Many studies on knee arthroplasty have been based on data from the Norwegian Arthroplasty Register (NAR), but all of them concerned primary TKAs (Furnes et al. 2002, 2007, Lygre et al. 2010a, b, Lygre et al. 2011, Gothesen et al. 2013). No studies on the survivorship and the mode of failure of revision TKAs have been conducted in Norway, even though revision of joint arthroplasties is becoming a challenge both medically and economically (Greidanus et al. 2011). Moreover, different surgical techniques have been described on how to approach revision knee arthroplasties with regard to fixation (Sheng et al. 2006, Whiteside 2006, Beckmann et al. 2011, Cintra et al. 2011), role of constraint and stem use (Fehring et al. 2003, Hwang et al. 2010), and whether or not to resurface the patella (Masri et al. 2006, Patil et al. 2010). However, there have been very few comprehensive studies on the outcome of revision TKA. Thus, the main aim of this study was to analyze the survival rate of revision TKAs and to study the causes of failure of revision TKAs based on data in a national registry. A secondary aim was to determine whether the survival of revision TKAs is influenced by type of fixation, brand of prosthesis, and resurfacing of the patella. The study hypothesis was that type of fixation, brand of prosthesis, and resurfacing of the patella would have no influence on the survival rate of revision TKAs.     

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.     

Early migration of tibial components is associated with late revision: A systematic review and meta-analysis of 21,000 knee arthroplasties

Purpose

We performed two parallel systematic reviews and meta-analyses to determine the association between early migration of tibial components and late aseptic revision.

Methods

One review comprised early migration data from radiostereometric analysis (RSA) studies, while the other focused on revision rates for aseptic loosening from long-term survival studies. Thresholds for acceptable and unacceptable migration were determined according to that of several national joint registries: < 5% revision at 10 years.

Results

Following an elaborate literature search, 50 studies (involving 847 total knee prostheses (TKPs)) were included in the RSA review and 56 studies (20,599 TKPs) were included in the survival review. The results showed that for every mm increase in migration there was an 8% increase in revision rate, which remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. Consequently, migration up to 0.5 mm was considered acceptable during the first postoperative year, while migration of 1.6 mm or more was unacceptable. TKPs with migration of between 0.5 and 1.6 mm were considered to be at risk of having revision rates higher than 5% at 10 years.

Interpretation

There was a clinically relevant association between early migration of TKPs and late revision for loosening. The proposed migration thresholds can be implemented in a phased, evidence-based introduction of new types of knee prostheses, since they allow early detection of high-risk TKPs while exposing only a small number of patients.Worldwide, several hundred thousand total knee prostheses (TKPs) are implanted each year and this number is expected to increase by a factor of 6 within the next 2 decades (Kurtz et al. 2005, 2007). Most of the new TKP designs have been introduced to the market without being shown to be safe or effective (Sheth et al. 2009). This has resulted in the widespread use of TKPs with failure rates exceeding 10 times the standard of national joint registries (< 5% failures at 10-year follow-up), such as the Accord, St Leger, and Journey-Deuce (Norton et al. 2002, Gilbert et al. 2009, Sheth et al. 2009, Palumbo et al. 2011 (personal communication)). To guarantee patient safety, several countries have developed guidelines, e.g. the NICE guidelines for total hip prostheses (2003). Furthermore, it has become increasingly evident that a phased, evidence-based introduction, as is common for pharmaceuticals, is needed to regulate the introduction of new TKPs to the market (Malchau 2000, McCulloch et al. 2009, Schemitsch et al. 2010). This should include systematic assessment and early detection of the major cause of TKP failure, which is aseptic loosening of the tibial component necessitating revision surgery (2003, AJR 2010).Although it can take 10 years before loosening causes symptoms, it is possible to detect loosening early postoperatively using radiostereometric analysis (RSA) (Selvik 1989, Grewal et al. 1992, Karrholm et al. 1994, Ryd et al. 1995). Since RSA allows in vivo, 3D measurement of the migration of TKPs with an accuracy of 0.2 mm for translations and 0.5 degrees for rotations, only a small number of patients need be exposed to potentially unsafe TKPs (Grewal et al. 1992, Ryd et al. 1995, Nelissen et al. 1998). RSA could therefore play an important role in the phased, evidence-based introduction of new TKPs (Selvik 1989, Karrholm et al. 1994, Ryd et al. 1995). However, the evidence for the relationship between early migration and TKP revision for aseptic loosening is limited to a few studies from the 1990s (Grewal et al. 1992, Ryd et al. 1995). Furthermore, the applicability of these studies is restricted, because surgical technique, fixation methods, implant design, and polyethylene have evolved since their publication.We hypothesized that early migration of the tibial component, measured through RSA, is associated with late revision for aseptic loosening of TKPs. We therefore systematically reviewed the association between early migration and late aseptic revision for the tibial component in TKPs. This could ultimately lead to clinical guidelines to be used in a phased introduction of new TKPs.     

Risk factors for revision due to infection after primary total hip arthroplasty: A population-based study of 80,756 primary procedures in the Danish Hip Arthroplasty Registry

Background and purpose

There has been a limited amount of research on risk factors for revision due to infection following total hip arthroplasty (THA), probably due to low absolute numbers of revisions. We therefore studied patient- and surgery-related risk factors for revision due to infection after primary THA in a population-based setting.

Materials and methods

Using the Danish Hip Arthroplasty Registry, we identified 80,756 primary THAs performed in Denmark between Jan 1, 1995 and Dec 31, 2008. We used Cox regression analysis to compute crude and adjusted relative risk (RR) of revision due to infection. Revision was defined as extraction or exchange of any component due to infection. The median follow-up time was 5 (0–14) years.

Results

597 primary THAs (0.7%) were revised due to infection. Males, patients with any co-morbidity, patients operated due to non-traumatic avascular femoral head necrosis, and patients with long duration of surgery had an increased RR of revision due to infection within the total follow-up time. A tendency of increased RR of revision was found for patients who had received cemented THA without antibiotic and hybrid THA relative to patients with cementless implants. Hip diagnosis and fixation technique were not associated with risk of revision due to infection within 1 year of surgery (short-term risk).

Interpretation

We identified several categories of THA patients who had a higher risk of revision due to infection. Further research is required to explain the mechanism underlying this increased risk. More attention should be paid by clinicians to infection prevention strategies in patients with THA, particularly those with increased risk.As with any other surgical operation, serious complications in patients undergoing total hip arthroplasty (THA) include infections. Most infections stem either from contamination in the operating room or from later hematogenous spread. Deep infection is the third most common cause of revision of THAs in Denmark (DHR Annual repport 2008). In the last 2 decades, advances in theater design and the prophylactic use of antibiotics, either systemically or incorporated in cement, have substantially reduced the incidence of infection after hip replacement (Zimmerli and Ochsner 2003, Ridgeway et al. 2005, Phillips et al. 2006). However, recent studies in the United States and Norway have found increasing infection rates (Dale et al. 2009, Kurtz et al. 2010).Research on risk factors for revision due to infection following THA has been limited, probably due to low absolute numbers of revisions. However, in the last few years several reports have suggested that some patient- and surgery-related factors may play a role (Furnes et al. 2001, Saleh et al. 2002, Ridgeway et al. 2005, Engesaeter et al. 2006, Bongartz et al. 2008, Pulido et al. 2008, Dale et al. 2009, Hooper et al. 2009, Ong et al. 2009). Comparison of these studies is difficult due to different inclusion criteria for the study population and different definitions of infection, sometimes including both joint infections and superficial infections, or infections in general. We studied only the infections that were followed by revision of the implant.For this reason, we conducted a nationwide follow-up study using the Danish Hip Arthroplasty Registry to examine potential patient- and surgery-related risk factors for revision due to infection.     

Prognostic factors in lumbar spinal stenosis surgery: A prospective study of imaging- and patient-related factors in 109 patients who were operated on by decompression

Background and purpose

A considerable number of patients who undergo surgery for spinal stenosis have residual symptoms and inferior function and health-related quality of life after surgery. There have been few studies on factors that may predict outcome. We tried to find predictors of outcome in surgery for spinal stenosis using patient- and imaging-related factors.

Patients and methods

109 patients in the Swedish Spine Register with central spinal stenosis that were operated on by decompression without fusion were prospectively followed up 1 year after surgery. Clinical outcome scores included the EQ-5D, the Oswestry disability index, self-estimated walking distance, and leg and back pain levels (VAS). Central dural sac area, number of levels with stenosis, and spondylolisthesis were included in the MRI analysis. Multivariable analyses were performed to search for correlation between patient-related and imaging factors and clinical outcome at 1-year follow-up.

Results

Several factors predicted outcome statistically significantly. Duration of leg pain exceeding 2 years predicted inferior outcome in terms of leg and back pain, function, and HRLQoL. Regular and intermittent preoperative users of analgesics had higher levels of back pain at follow-up than those not using analgesics. Low preoperative function predicted low function and dissatisfaction at follow-up. Low preoperative EQ-5D scores predicted a high degree of leg and back pain. Narrow dural sac area predicted more gains in terms of back pain at follow-up and lower absolute leg pain.

Interpretation

Multiple factors predict outcome in spinal stenosis surgery, most importantly duration of symptoms and preoperative function. Some of these are modifiable and can be targeted. Our findings can be used in the preoperative patient information and aid the surgeon and the patient in a shared decision making process.Decompressive surgery for lumbar spinal stenosis is the most frequently performed spine operation in many countries (Weinstein et al. 2006, Strömqvist et al. 2009). However, one third of patients are not satisfied with the outcome because of residual leg and back pain, inferior function, and poor health-related quality of life (Katz et al. 1995, Airaksinen et al. 1997, Jönsson et al. 1997, Jansson et al. 2009, Strömqvist et al. 2009, Hara et al. 2010).2 recent randomized studies have shown surgery to be superior to nonoperative treatment in lumbar spinal stenosis (Malmivaara et al. 2007, Weinstein et al. 2008), but many patients improve without surgical treatment (Malmivaara et al. 2007). The question remains as to who benefits most from surgery. Identification of prognostic factors that can aid in selection of patients for surgery is therefore important. Prognostic factors in lumbar spinal stenosis surgery have been studied, but they are not well defined (Turner et al. 1992, Aalto et al. 2006). Aalto et al. (2006) reviewed studies of lumbar spinal stenosis surgery and found that only 21 studies of 885 were of sufficient quality to merit identification of prognostic factors. The main reason for exclusion was a retrospective study design and a limited number of predictors. Cardiovascular and overall comorbidity, disorders influencing walking ability, self-rated health, income, severity of central stenosis, and severity of scoliosis were found to be predictors of outcome, but no single study could identify more than one of these predictors. More recently, smoking, depression, psychiatric illness, and high body mass index have been found to be predictive of negative outcome, as have long duration of symptoms and preoperative resting numbness (Ng et al. 2007, Hara et al. 2010, Athiviraham et al. 2011, Radcliff et al. 2011, Sandén et al. 2011, Sinikallio et al. 2011).Cross-sectional imaging (most often MRI) has an important role in confirming the diagnosis of spinal stenosis, and is essential for surgical planning. Even so, the prognostic value of the narrowness of the dural sac area is not well established (Jönsson et al 1997, Amundsen et al. 2000, Yukawa et al. 2002). Studies incorporating both imaging and patient-related factors in a systematic way have been exceedingly rare (Amundsen et al. 2000, Yukawa et al. 2002).We used patient data from the Swedish Spine Register protocol (Strömqvist et al. 2009) and MRI measurements of central dural sac area, multilevel stenosis, and spondylolisthesis to find predictors of outcome in terms of function, HRLQoL, and leg and back pain after decompression for lumbar spinal stenosis.     

Metal-backed versus all-polyethylene tibial components in primary total knee arthroplasty

Background and purpose

The choice of either all-polyethylene (AP) tibial components or metal-backed (MB) tibial components in total knee arthroplasty (TKA) remains controversial. We therefore performed a meta-analysis and systematic review of randomized controlled trials that have evaluated MB and AP tibial components in primary TKA.

Methods

The search strategy included a computerized literature search (Medline, EMBASE, Scopus, and the Cochrane Central Register of Controlled Trials) and a manual search of major orthopedic journals. A meta-analysis and systematic review of randomized or quasi-randomized trials that compared the performance of tibial components in primary TKA was performed using a fixed or random effects model. We assessed the methodological quality of studies using Detsky quality scale.

Results

9 randomized controlled trials (RCTs) published between 2000 and 2009 met the inclusion quality standards for the systematic review. The mean standardized Detsky score was 14 (SD 3). We found that the frequency of radiolucent lines in the MB group was significantly higher than that in the AP group. There were no statistically significant differences between the MB and AP tibial components regarding component positioning, knee score, knee range of motion, quality of life, and postoperative complications.

Interpretation

Based on evidence obtained from this study, the AP tibial component was comparable with or better than the MB tibial component in TKA. However, high-quality RCTs are required to validate the results.The design of the tibial component is an important factor for implant failure in total knee arthroplasty (TKA) (Pagnano et al. 1999, Forster 2003, Gioe et al. 2007b, Willie et al. 2008, Garcia et al. 2009, KAT Trial Group 2009). The metal-backed (MB) design of tibial component has become predominant in TKA because it is thought to perform better than the all-polyethylene (AP) design (Muller et al. 2006, Gioe et al. 2006, 2007a,b). In theory, the MB tibial component reduces bending strains in the stem, reduces compressive stresses in the cement and cancellous bone beneath the baseplate (especially during asymmetric loading), and distributes load more evenly across the interface (Bartel et al. 1982, 1985, Taylor et al. 1998). However, critics of the MB tibial component claim that there are expensive implant costs, reduced polyethylene thickness with the same amount of bone resection, backside wear, and increased tensile stresses at the interface during eccentric loading (Bartel et al. 1982, 1985, Pomeroy et al. 2000, Rodriguez et al. 2001, Li et al. 2002, Muller et al. 2006, Blumenfeld and Scott 2010, Gioe and Maheshwari 2010).In the past decade, several randomized controlled trials (RCTs) have been performed to assess the effectiveness of the MB tibial component (Adalberth et al. 2000, 2001, Gioe and Bowman 2000, Norgren et al. 2004, Hyldahl et al. 2005a, b, Muller et al. 2006, Gioe et al. 2007, Bettinson et al. 2009, KAT Trial Group 2009). However, data have not been formally and systematically analyzed using quantitative methods in order to determine whether the MB tibial component is indeed optimal for patients in TKA. In this study, we wanted (1) to determine the scientific quality of published RCTs comparing the AP and MB tibial components in TKA using Detsky score (Detsky et al. 1992) and (2) to conduct a meta-analysis and systematic review of all published RCTs that have compared the effects of AP and MB tibial components on the radiographic and clinical outcomes of TKA.     

Infection after primary hip arthroplasty: a comparison of 3 Norwegian health registers

Background and purpose

The aim of the present study was to assess incidence of and risk factors for infection after hip arthroplasty in data from 3 national health registries. We investigated differences in risk patterns between surgical site infection (SSI) and revision due to infection after primary total hip arthroplasty (THA) and hemiarthroplasty (HA).

Materials and methods

This observational study was based on prospective data from 2005–2009 on primary THAs and HAs from the Norwegian Arthroplasty Register (NAR), the Norwegian Hip Fracture Register (NHFR), and the Norwegian Surveillance System for Healthcare–Associated Infections (NOIS). The Norwegian Patient Register (NPR) was used for evaluation of case reporting. Cox regression analyses were performed with revision due to infection as endpoint for data from the NAR and the NHFR, and with SSI as the endpoint for data from the NOIS.

Results

The 1–year incidence of SSI in the NOIS was 3.0% after THA (167/5,540) and 7.3% after HA (103/1,416). The 1–year incidence of revision due to infection was 0.7% for THAs in the NAR (182/24,512) and 1.5% for HAs in the NHFR (128/8,262). Risk factors for SSI after THA were advanced age, ASA class higher than 2, and short duration of surgery. For THA, the risk factors for revision due to infection were male sex, advanced age, ASA class higher than 1, emergency surgery, uncemented fixation, and a National Nosocomial Infection Surveillance (NNIS) risk index of 2 or more. For HAs inserted after fracture, age less than 60 and short duration of surgery were risk factors of revision due to infection.

Interpretation

The incidences of SSI and revision due to infection after primary hip replacements in Norway are similar to those in other countries. There may be differences in risk pattern between SSI and revision due to infection after arthroplasty. The risk patterns for revision due to infection appear to be different for HA and THA.Increasing incidence of revision due to infection after primary total hip arthroplasty (THA) has been observed in different countries during the last decade (Kurtz et al. 2008, Dale et al. 2009, Pedersen et al. 2010). There have been several studies on incidence of and risk factors for infection based on data from surveillance systems (Ridgeway et al. 2005, Mannien et al. 2008), arthroplasty (quality) registers (Berbari et al. 1998, Dale et al. 2009, Pedersen et al. 2010), and administrative databases (Mahomed et al. 2003, Kurtz et al. 2008, Ong et al. 2009). There have been reviews on incidence of and risk factors for infection after hip arthroplasty, based on publications from databases with different definitions of infection (Urquhart et al. 2009, Jämsen et al. 2010a). Superficial surgical site infections (SSIs) may have risk factors that are different from those of full surgical revisions due to infection. Furthermore, THA and hip hemiarthroplasty (HA) may have different patterns of risk of infection (Ridgeway et al. 2005, Cordero–Ampuero and de Dios 2010).In the present study, we used data from 3 national health registries in Norway to assess incidence and some risk factors for infection after primary hip arthroplasty. Differences in risk patterns between SSI and revision due to infection were investigated for HA and THA.     

Fast-track revision knee arthroplasty. A feasibility study

Background and purpose

Fast-track surgery has reduced the length of hospital stay (LOS), morbidity, and convalescence in primary hip and knee arthroplasty (TKA). We assessed whether patients undergoing revision TKA for non-septic indications might also benefit from fast-track surgery.

Methods

29 patients were operated with 30 revision arthroplasties. Median age was 67 (34–84) years. All patients followed a standardized fast-track set-up designed for primary TKA. We determined the outcome regarding LOS, morbidity, mortality, and satisfaction.

Results

Median LOS was 2 (1–4) days excluding 1 patient, who was transferred to another hospital for logistical reasons (10 days). None of the patients died within 3 months, and 3 patients were re-admitted (2 for suspicion of DVT, which was not found, and 1 for joint mobilization). Patient satisfaction was high.

Interpretation

Patients undergoing revision TKA for non-septic reasons may be included in fast-track protocols. Outcome appears to be similar to that of primary TKA regarding LOS, morbidity, and satisfaction. Our findings call for larger confirmatory studies and studies involving other indications (revision THA, 1-stage septic revisions).For more than a decade, favorable outcomes following fast-track protocols rather than more conventional hospital stays have been reported from numerous studies on primary THA and TKA. In the last few years, outcomes have been further improved, mainly due to improved multimodal opioid-sparing analgesia and early mobilization, allowing patients to fulfill functional discharge criteria within 2–3 days (Husted et al. 2008, 2010 a,b,c,d, Larsen et al. 2008 a,b,c, 2009, Andersen et al. 2009, Barbieri et al. 2009, Rotter et al. 2010). The addition of local infiltration analgesia (LIA) has improved early analgesia and facilitated early recovery, allowing patients to ambulate with full weight bearing within 2–3 hours of surgery (Andersen et al. 2008 a,b, 2009, Holm et al. 2010).So far, however, no one has reported the potential benefits of the fast-track methodology (including multimodal opioid-sparing analgesia, perioperative LIA, and early mobilization) for revision TKA, with its more extensive surgical trauma leading to a corresponding increase in the surgical stress responses. We therefore investigated the feasibility of our well-documented fast-track primary TKA program on a consecutive cohort of revision TKA patients.     

Changes in blood ion levels after removal of metal-on-metal hip replacements: 16 patients followed for 0–12 months

Background and purpose

In patients with metal-on-metal (MoM) hip prostheses, pain and joint effusions may be associated with elevated blood levels of cobalt and chromium ions. Since little is known about the kinetics of metal ion clearance from the body and the rate of resolution of elevated blood ion levels, we examined the time course of cobalt and chromium ion levels after revision of MoM hip replacements.

Patients and methods

We included 16 patients (13 female) who underwent revision of a painful MoM hip (large diameter, modern bearing) without fracture or infection, and who had a minimum of 4 blood metal ion measurements over an average period of 6.1 (0–12) months after revision.

Results

Average blood ion concentrations at the time of revision were 22 ppb for chromium and 43 ppb for cobalt. The change in ion levels after revision surgery varied extensively between patients. In many cases, over the second and third months after revision surgery ion levels decreased to 50% of the values measured at revision. Decay of chromium levels occurred more slowly than decay of cobalt levels, with a 9% lag in return to normal levels. The rate of decay of both metals followed second-order (exponential) kinetics more closely than first-order (linear) kinetics.

Interpretation

The elimination of cobalt and chromium from the blood of patients who have undergone revision of painful MoM hip arthroplasties follows an exponential decay curve with a half-life of approximately 50 days. Elevated blood levels of cobalt and chromium ions can persist for at least 1 year after revision, especially in patients with high levels of exposure.After a dramatic rise in initial popularity, the use of metal-on-metal (MoM) hip arthroplasties has declined precipitously, both in hip resurfacings and conventional hip replacement, due to an alarming incidence of adverse inflammatory reactions (van der Weegen et al. 2011, NJR 2012).There are now serious concerns about potential adverse biological effects, both local and systemic, arising from wear debris generated by MoM articulations (Matthies et al. 2011). The nano-scale particles generated through wear of MoM bearings can enter the reticulo-endothelial system and cross over into the circulation as early as 5 days after implantation (Daniel et al. 2007). The specific surface area (surface area to mass ratio) of these particles makes them susceptible to corrosion in vivo (Hart et al. 2010), leading to elevated levels of cobalt and chromium ions in the blood, usually ranging from 5 to 10 times normal values (Jacobs et al. 1996, Brodner et al. 1997, Skipor et al. 2002, Dunstan et al. 2005, Daniel et al. 2009, Hart et al. 2009, van der Weegen et al. 2011). Possible complications from long-term elevated metal ion levels include immune reactions (Pandit et al. 2008), necrosis (Campbell et al. 2010), toxicity (Keegan et al. 2007, Tower et al. 2010, Corradi et al. 2011), chromosomal aberrations (Ladon et al. 2004), and carcinogenicity (Case et al. 1994). However, the most common short-term complication is joint pain associated with inflammatory reactions (Milosev et al. 2005). In many cases where there is pain with soft-tissue masses, often in association with elevated levels of cobalt and chromium ions, removal of the implanted components is necessary. This form of failure is more common in female patients than in male patients, and it has been reported in 1–20% of cases at 5 years (Schmidt et al. 1996) depending on the design of the prosthesis.Although revision is performed in the hope that the elevation of ion levels and symptoms will resolve, little is known about the kinetics of storage and turnover of these ions in the body. We examined the kinetics of cobalt and chromium ion decay after revision of MoM hip replacements. Our principal goals were to characterize the decay curves of cobalt and chromium ions after revision procedures and to determine when blood concentrations return to levels below the MHRA action level of 7 ppb, in order to determine exposure risk (MHRA 2010). We hypothesized that: (1) removal of MoM components results in a rapid drop in the level of metal ions in the blood followed by a slow steady-state decline; (2) chromium concentrations will decrease more slowly than cobalt concentrations; (3) the total body exposure to ions is orders of magnitude higher with poorly functioning or loose implants than with well-functioning components.     

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.     

Dissatisfied patients after total knee arthroplasty: A registry study involving 114 patients with 8–13 years of follow-up

Background and purpose

In 2003, an enquiry by the Swedish Knee Arthroplasty Register (SKAR) 2–7 years after total knee arthroplasty (TKA) revealed patients who were dissatisfied with the outcome of their surgery but who had not been revised. 6 years later, we examined the dissatisfied patients in one Swedish county and a matched group of very satisfied patients.

Patients and methods

118 TKAs in 114 patients, all of whom had had their surgery between 1996 and 2001, were examined in 2009–2010. 55 patients (with 58 TKAs) had stated in 2003 that they were dissatisfied with their knees and 59 (with 60 TKAs) had stated that they were very satisfied with their knees. The patients were examined clinically and radiographically, and performed functional tests consisting of the 6-minute walk and chair-stand test. All the patients filled out a visual analog scale (VAS, 0–100 mm) regarding knee pain and also the Hospital and Anxiety and Depression scale (HAD).

Results

Mean VAS score for knee pain differed by 30 mm in favor of the very satisfied group (p < 0.001). 23 of the 55 patients in the dissatisfied group and 6 of 59 patients in the very satisfied group suffered from anxiety and/or depression (p = 0.001). Mean range of motion was 11 degrees better in the very satisfied group (p < 0.001). The groups were similar with regard to clinical examination, physical performance testing, and radiography.

Interpretation

The patients who reported poor response after TKA continued to be unhappy after 8–13 years, as demonstrated by VAS pain and HAD, despite the absence of a discernible objective reason for revision.The results of TKA are regarded as being favorable (Robertsson et al. 2000, Kane et al. 2005, Nilsdotter et al. 2009, Carr et al. 2012) with few surgical complications and a revision rate of less than 5% after 10 years (Vessely et al. 2006, Robertsson et al. 2010). Poor outcome after primary TKA, apart from the revision, is between 6% and 14% (Anderson et al. 1996, Hawker et al. 1998, Heck et al. 1998, Robertsson et al. 2000, Robertsson and Dunbar 2001, Brander et al. 2003, Noble et al. 2006, Fisher et al. 2007, Wylde et al. 2008, Kim et al. 2009, Bourne et al. 2010, Scott et al. 2010). The reason for poor outcome after TKA may be related to problems with the knee surgery itself, although it has been suggested that extra-articular causes such as hip disease, spine disorder, vascular disease, or reflex sympathetic dystrophy may contribute. Some studies have suggested that factors not primarily related to structural tissue changes, but of psychological nature instead, may be involved (Wylde et al. 2007, Rolfson et al. 2009).The Swedish Knee Arthroplasty Register (SKAR) registers primary arthroplasties performed in Sweden as well as revisions, and has been estimated to capture 97% of the surgeries performed (SKAR 2012). The SKAR sends questionnaires regarding satisfaction to patients who were operated on during certain time periods (Robertsson et al. 2000, and Dunbar 2001). We used the SKAR to identify patients who had not undergone revision surgery and who were dissatisfied with their outcome 2–7 years after TKA surgery. As a reference we chose an age-, sex-, date-of-surgery-, and hospital-matched control group of highly satisfied patients who were operated during the same period. Our aim was to assess the differences between these 2 patient groups.