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Background There are a number of reports of polyethylene liner dissociation of third-generation modular acetabular components. This study compares our experience with 2 contemporary systems to determine whether this is an implant- or class-specific problem. Methods This is a single-center retrospective study of 961 primary total hip arthroplasties using 2 third-generation modular cementless acetabular shells: Pinnacle (535) and R3 (426) with a polyethylene liner. Details of all revisions were obtained from local databases and the New Zealand Joint Registry. Kaplan-Meier survival curves were calculated for all-cause revision, acetabular reoperation (including liner exchange), and liner dissociation. Results There were 17 revisions in group 1 (Pinnacle; DePuy Synthes): 17 for recurrent dislocation, 6 for liner dissociations (1.12%), 3 for femoral loosening, and one for deep infection. In group 2 (R3; Smith and Nephew), there were 4 revision procedures: one for infection, 2 for dislocation, and one femoral revision for periprosthetic fracture. There were significantly higher proportions revised in group 1 for all-cause revision, acetabular reoperation, and dissociation (P = .024 to 0.038). The 7-year survival for all-cause revision was 96.1% for Pinnacle and 99.0% for R3 (P = .022), and that in the acetabular reoperation group was 96.9% for Pinnacle and 99.3% for R3 (P = .035). Conclusions There was a higher revision rate for the Pinnacle acetabular component than for the R3 at 7 years. This was mainly due to polyethylene liner dissociation that can occur early or late. It appears to be a problem specific to the Pinnacle cup design rather than a feature of similar third-generation acetabular components.

Between 2007 and 2018, 535 total hip arthroplasties using the uncemented Pinnacle acetabular component (DePuy Synthes, Warsaw, IN) and polyethylene liner were implanted in our unit. Of these, 6 patients presented acutely with liner polyethylene dissociation, giving a rate of liner dissociation of 1.11%. All dissociations were atraumatic. Failure occurred at mean 37 months (range 4.5 to 130 months). Radiologically, all acetabular components were within safe zone of abduction and mean anteversion was 10 degrees (range 2-20). In one case, there was posterior impingement against the femoral neck due to femoral malalignment. All patients underwent head and liner exchange with no repeat failures. Despite excellent long-term results, the frequency of dissociated polyethylene liners is a cause of concern with the Pinnacle acetabular component. Keywords: Pinnacle, Liner dissociation, Acetabular cup

Intravesicular application of Bacillus Calmette-Guérin (BCG), a live attenuated strain of Mycobacterium bovis, is effective in the treatment of bladder cancer. However, systemic dissemination and subsequent infection of implants have been reported. We present a case of M. bovis infection of a total hip arthroplasty 5 years after BCG instillation for bladder cancer. He was treated with debridement, antibiotics, irrigation, and prosthesis retention with appropriate antituberculous therapy. At 4 years after surgery and 3 years after cessation of treatment, he has had no recurrence of infection with a good functional outcome. This case highlights the need to consider Mycobacteria infection in patients who have received intravesicular BCG. Debridement and retention of well-fixed implants can be successful in combination with appropriate antituberculous therapy. Keywords: Bacillus Calmette-Guérin, Total hip arthroplasty, Prosthetic joint infection, Mycobacterium bovis, DAIR

Summary: Objectives: To combine cross-sectoral stakeholders’ preferences over interventions for knee osteoarthritis (OA) with guideline recommendations and evidence about interventions, and to investigate if these preferences differ by stakeholder group. Design: A survey based on multi-criteria decision analysis was implemented whereby the stakeholders revealed the relative importance, represented as weights, of eight criteria for choosing or recommending knee OA interventions. Using data from an OA clinical guideline, 15 recommended interventions were rated on the criteria and ranked by their total scores, calculated by summing the corresponding weights. Associations between the weights and stakeholder groups were explored using regression analysis. Results: Participants comprised 58 consumers with OA, 5 Māori health advocates, 79 healthcare providers, 24 policy-informants and 12 OA-researchers (N = 178; 63% female, [mean age±SD] 54 ± 13 years). Mean weights on the eight criteria, in decreasing order of importance, are: recommendation: 19.0%; quality of evidence: 17.7%; effectiveness: 15.0%; duration of effect: 13.2%; risk of serious harm: 12.8%; risk of mild/moderate side-effects: 9.4%; cost: 6.6%; and accessibility: 6.3%. For first-, second- and third-line OA interventions respectively, all land-based exercise (total score = 71.7%), NSAIDs (topical) (74.2%) and total joint replacement (74.3%) were ranked first. At all care phases, the recommended core interventions of weight management and self-management education ranked between 11th and 15th (48.0%–56.0%). Regression analysis identified only small differences in weights (≤5.7%; p

Background Osteoarthritis is the most common form of arthritis, principally affecting the older population. Highly prevalent, disabling diseases such as osteoarthritis strain the capacity of health systems, and can result in unmet need for services. The Joint Clinic was initiated to provide secondary care consultations and access to outpatient services for people with advanced hip or knee osteoarthritis, who were referred by their general practitioner for orthopaedic consultation but not offered an orthopaedic specialist appointment. Methods This longitudinal programme evaluation comprised four components: a proof-of-concept evaluation; an implementation evaluation; a process evaluation; and an outcomes evaluation. Interviews and surveys of general practitioners, staff, and patients were conducted pre- and post-implementation. Interviews were transcribed, and thematic analysis was completed. In addition, Joint Clinic patient visits and outcomes were reviewed. Results One hundred and eleven primary care physicians (GPs) and 66 patients were surveyed, and 28 semi-structured interviews of hospital staff and GPs were conducted. Proof of concept was satisfied. Interim and final implementation evaluations indicated adherence to the concept model, high levels of acceptance of and confidence in the programme and its staff, and timely completion within budget. Process evaluation revealed positive impacts of the programme and positive stakeholder perceptions, with some weaknesses in communication to the outer context of primary care. The Joint Clinic saw a total of 637 patient visits during 2 years of operation. Unmet need was reduced by 90%. Patient and referring physician satisfaction was high. Hospital management confirmed that the programme will continue. Conclusions This evaluation indicates that the Joint Clinic concept model is fit for purpose, functioned well within the organisation, and achieved its primary objective of reducing unmet need of secondary care consultation for those suffering advanced hip or knee osteoarthritis. Electronic supplementary material The online version of this article (10.1186/s12891-019-2702-1) contains supplementary material, which is available to authorized users.

Alendronic acid (Fosamax, Merck) is a potent oral bisphosphonate licensed for prevention (5 mg daily) and treatment of postmenopausal osteoporosis (70 mg weekly or 10 mg daily).1 A 69 year old woman had been treated for osteoporosis with disodium etidronate (Didronel, Procter & Gamble) for four years. She had a history of asthma but was not taking prednisolone. She started taking 70 mg alendronic acid a week but within …