Aims. Our aim was to determine whether, based on the current literature, bariatric surgery prior to total hip (THA) or total knee arthroplasty (TKA) reduces the complication rates and improves the outcome following arthroplasty in obese patients. Methods. A systematic literature search was undertaken of published and unpublished databases on the 5 November 2015. All papers reporting studies comparing obese patients who had undergone bariatric surgery prior to arthroplasty, or not, were included. Each study was assessed using the Downs and Black appraisal tool. A meta-analysis of risk ratios (RR) and 95% confidence intervals (CI) was performed to determine the incidence of complications including wound infection, deep vein thrombosis (DVT), pulmonary embolism (PE), revision surgery and mortality. Results. From 156 potential studies, five were considered to be eligible for inclusion in the study. A total of 23 348 patients (657 who had undergone bariatric surgery, 22 691 who had not) were analysed. The evidence-base was moderate in quality. There was no statistically significant difference in outcomes such as superficial wound infection (relative risk (RR) 1.88; 95% confidence interval (CI) 0.95 to 0.37), deep wound infection (RR 1.04; 95% CI 0.65 to 1.66), DVT (RR 0.57; 95% CI 0.13 to 2.44), PE (RR 0.51; 95% CI 0.03 to 8.26), revision surgery (RR 1.24; 95% CI 0.75 to 2.05) or mortality (RR 1.25; 95% CI 0.16 to 9.89) between the two groups. Conclusion. For most peri-operative outcomes, bariatric surgery prior to THA or TKA does not significantly reduce the complication rates or improve the clinical outcome. This study questions the previous belief that bariatric surgery prior to arthroplasty may improve the clinical outcomes for patients who are obese or morbidly obese. This finding is based on moderate quality evidence. Cite this article: Bone Joint J 2016;98-B:1160–6

Following arthroplasty of the knee, the patient’s perception of improvement in symptoms is fundamental to the assessment of outcome. Better clinical outcome may offset the inferior survival observed for some types of implant. By examining linked National Joint Registry (NJR) and patient-reported outcome measures (PROMs) data, we aimed to compare PROMs collected at a minimum of six months post-operatively for total (TKR: n = 23 393) and unicondylar knee replacements (UKR: n = 505). Improvements in knee-specific (Oxford knee score, OKS) and generic (EuroQol, EQ-5D) scores were compared and adjusted for case-mix differences using multiple regression. Whereas the improvements in the OKS and EQ-5D were significantly greater for TKR than for UKR, once adjustments were made for case-mix differences and pre-operative score, the improvements in the two scores were not significantly different. The adjusted mean differences in the improvement of OKS and EQ-5D were 0.0 (95% confidence interval (CI) -0.9 to 0.9; p = 0.96) and 0.009 (95% CI -0.034 to 0.015; p = 0.37), respectively. We found no difference in the improvement of either knee-specific or general health outcomes between TKR and UKR in a large cohort of registry patients. With concerns about significantly higher revision rates for UKR observed in worldwide registries, we question the widespread use of an arthroplasty that does not confer a significant benefit in clinical outcome

Aims

Mobile-bearing unicompartmental knee arthroplasty (UKA) with a flat tibial plateau has not performed well in the lateral compartment, leading to a high rate of dislocation. For this reason, the Domed Lateral UKA with a biconcave bearing was developed. However, medial and lateral tibial plateaus have asymmetric anatomical geometries, with a slightly dished medial and a convex lateral plateau. Therefore, the aim of this study was to evaluate the extent at which the normal knee kinematics were restored with different tibial insert designs using computational simulation.

There is a large amount of evidence available about the relative merits of unicompartmental and total knee arthroplasty (UKA and TKA). Based on the same evidence, different people draw different conclusions and as a result, there is great variability in the usage of UKA. The revision rate of UKA is much higher than TKA and so some surgeons conclude that UKA should not be performed. Other surgeons believe that the main reason for the high revision rate is that UKA is easy to revise and, therefore, the threshold for revision is low. They also believe that UKA has many advantages over TKA such as a faster recovery, lower morbidity and mortality and better function. They therefore conclude that UKA should be undertaken whenever appropriate. . The solution to this argument is to minimise the revision rate of UKA, thereby addressing the main disadvantage of UKA. The evidence suggests that this will be achieved if surgeons use UKA for at least 20% of their knee arthroplasties and use implants that are appropriate for these broad indications. . Cite this article: Bone Joint J 2015;97-B(10 Suppl A):3–8

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This study aimed to evaluate calprotectin in synovial fluid for diagnosing chronic prosthetic joint infection (PJI) .

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The aim of this study was to investigate whether the use of antibiotic-loaded bone cement influenced the risk of revision surgery after primary total hip arthroplasty (THA) for osteoarthritis.

Aims

To compare the in vivo long-term fixation achieved by two acetabular components with different porous ingrowth surfaces using radiostereometric analysis (RSA).

Objectives. Initial stability of tibial trays is crucial for long-term success of total knee arthroplasty (TKA) in both primary and revision settings. Rotating platform (RP) designs reduce torque transfer at the tibiofemoral interface. We asked if this reduced torque transfer in RP designs resulted in subsequently reduced micromotion at the cemented fixation interface between the prosthesis component and the adjacent bone. Methods. Composite tibias were implanted with fixed and RP primary and revision tibial trays and biomechanically tested under up to 2.5 kN of axial compression and 10° of external femoral component rotation. Relative micromotion between the implanted tibial tray and the neighbouring bone was quantified using high-precision digital image correlation techniques. Results. Rotational malalignment between femoral and tibial components generated 40% less overall tibial tray micromotion in RP designs than in standard fixed bearing tibial trays. RP trays reduced micromotion by up to 172 µm in axial compression and 84 µm in rotational malalignment models. Conclusions. Reduced torque transfer at the tibiofemoral interface in RP tibial trays reduces relative component micromotion and may aid long-term stability in cases of revision TKA or poor bone quality. Cite this article: Mr S. R. Small. Micromotion at the tibial plateau in primary and revision total knee arthroplasty: fixed versus rotating platform designs. Bone Joint Res 2016;5:122–129. DOI: 10.1302/2046-3758.54.2000481

Periprosthetic joint infection (PJI) is one of the most feared and challenging complications following total knee arthroplasty. We provide a detailed description of our current understanding regarding the management of PJI of the knee, including diagnostic aids, pre-operative planning, surgical treatment, and outcome. Cite this article: Bone Joint J 2015;97-B(10 Suppl A):20–9

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Tibial plateau fractures are serious injuries about the knee that have the potential to affect patients’ long-term function. To our knowledge, this is the first study to use patient-reported outcomes (PROs) with a musculoskeletal focus to assess the long-term outcome, as compared to a short-term outcome baseline, of tibial plateau fractures treated using modern techniques.

Aims

The diagnosis of periprosthetic joint infection (PJI) has always been challenging. Recently, D-dimer has become a promising biomarker in diagnosing PJI. However, there is controversy regarding its diagnostic value. We aim to investigate the diagnostic value of D-dimer in comparison to ESR and CRP.

Aims. Total joint arthroplasty (TJA) is commonly performed in elderly patients. Frailty, an aggregate expression of vulnerability, becomes increasingly common with advanced age, and independently predicts adverse outcomes and the use of resources after a variety of non-cardiac surgical procedures. Our aim was to assess the impact of frailty on outcomes after TJA. Patients and Methods. We analysed the impact of pre-operative frailty on death and the use of resources after elective TJA in a population-based cohort study using linked administrative data from Ontario, Canada. Results. Of 125 163 patients aged > 65 years having elective TJA, 3023 (2.4%) were frail according to the Johns Hopkins ACG frailty-defining diagnoses indicator. One year follow-up was complete for all patients. Frail patients had a higher adjusted one year risk of mortality (hazard ratio 3.03, 95% confidence interval (CI) 2.62 to 3.51), a higher rate of admission to intensive care (odds ratio (OR) 2.52, 95% CI 2.21 to 2.89), increased length of stay (incidence rate ratio 1.62, 95% CI 1.59 to 1.65), a higher rate of discharge to institutional care (OR 2.09, 95% CI 1.93 to 2.25), a higher rate of re-admission (OR 1.33, 95% CI 1.07 to 1.66) and increased costs at 30, 90 and 365 days post-operatively. Frailty affected outcomes after total hip arthroplasty more than after total knee arthroplasty. Take home message: Frailty is an important risk factor for death after elective TJA, and increases post-operative resource utilisation across many metrics. Processes to optimise the outcomes and efficiency of TJA in frail patients are needed. Cite this article: Bone Joint J 2016;98-B:799–805

We evaluated the rates of survival and cause of revision of seven different brands of cemented primary total knee replacement (TKR) in the Norwegian Arthroplasty Register during the years 1994 to 2009. Revision for any cause, including resurfacing of the patella, was the primary endpoint. Specific causes of revision were secondary outcomes. Three posterior cruciate-retaining (PCR) fixed modular-bearing TKRs, two fixed non-modular bearing PCR TKRs and two mobile-bearing posterior cruciate-sacrificing TKRs were investigated in a total of 17 782 primary TKRs. The median follow-up for the implants ranged from 1.8 to 6.9 years. Kaplan-Meier 10-year survival ranged from 89.5% to 95.3%. Cox’s relative risk (RR) was calculated relative to the fixed modular-bearing Profix knee (the most frequently used TKR in Norway), and ranged from 1.1 to 2.6. The risk of revision for aseptic tibial loosening was higher in the mobile-bearing LCS Classic (RR 6.8 (95% confidence interval (CI) 3.8 to 12.1)), the LCS Complete (RR 7.7 (95% CI 4.1 to 14.4)), the fixed modular-bearing Duracon (RR 4.5 (95% CI 1.8 to 11.1)) and the fixed non-modular bearing AGC Universal TKR (RR 2.5 (95% CI 1.3 to 5.1)), compared with the Profix. These implants (except AGC Universal) also had an increased risk of revision for femoral loosening (RR 2.3 (95% CI 1.1 to 4.8), RR 3.7 (95% CI 1.6 to 8.9), and RR 3.4 (95% CI 1.1 to 11.0), respectively). These results suggest that aseptic loosening is related to design in TKR. Cite this article: Bone Joint J 2013;95-B:636–42