Terhune, E. Bailey

Background: Contemporary rotating-hinge total knee arthroplasties (RH-TKAs) have shown reasonable short-term survivorship in smaller series, but concerns remain regarding risks of aseptic and septic failure. The purpose of this study was to assess outcomes of contemporary RH-TKAs in one of the largest series to date. Methods: We retrospectively identified 575 RH-TKAs (60% used for aseptic etiologies and 40% used during reimplantation in 2-stage treatment of periprosthetic joint infection [PJI]) from 2002 to 2021 at a single institution. The mean age was 67 years, 58% were female, and the mean body mass index was 33 kg/m 2 . Sixty-five percent had Anderson Orthopaedic Research Institute (AORI) type-2B or 3 bone loss. Kaplan-Meier survivorship analyses were performed. The mean follow-up was 6 years (range, 2 to 19 years). Results: Survivorship free from any revision was 76% at 5 years and 64% at 10 years. The most common revision indications were PJI (54%) and aseptic loosening (20%). RH-TKA used in the primary setting showed better survivorship compared with RH-TKA used during reimplantation after PJI (79% versus 60% at 10 years). Survivorship free from revision for aseptic loosening was 96% at 5 years and 90% at 10 years. Survivorship free from revision for PJI was 84% at 5 years and 81% at 10 years. Survivorship free from revision for PJI was even lower for RH-TKAs used during reimplantation, 74% at 5 years and 73% at 10 years. RH-TKA used during reimplantation in the treatment of PJI was associated with an increased risk of any revision (HR = 2, p < 0.001). Radiographic analysis of 425 knees that were not revised and had radiographs available for review showed that 6% of femoral components and 8% of tibial components had evidence of loosening at the time of final follow-up. The mean Knee Society Score improved from 33 to 69 at 2 years (p < 0.001). Conclusions: The 10-year survivorship free from aseptic loosening was 90% in this large series of RH-TKAs. This represents one of the best survivorships free from aseptic loosening published to date. Knees with prior PJI had markedly poorer survivorship than knees treated for aseptic etiologies, with double the risk of revision. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.

AimsCeramic-on-ceramic (CoC) articulations in total hip arthroplasty (THA) have the advantage of low wear but the unique risk of fracture. After revision for CoC-bearing fracture, third-body ceramic particles can lead to massive wear of cobalt-chrome (CoCr) bearings, causing extremely elevated blood cobalt. We present a multicentre series of five cases where patients sustained fractures of ceramic liners, were revised using a CoCr articulation, and rapidly developed severe cobalt toxicity.MethodsWe identified five cases of cobalt toxicity after fractured CoC THA treated with revision to CoCr on polyethylene bearings. Mean follow-up was three years (5 to 72 months) after re-revision to remove the CoCr bearing.ResultsSymptoms of cobalt toxicity occurred at a mean ten months (6 to 12) after revision for ceramic fracture. All patients developed vision and hearing loss, balance difficulties, and peripheral neuropathy. Several had cardiomyopathy, endocrine abnormalities, and local skin discolouration. Only two reported hip pain. Repeat revision for recognized cobalt toxicity occurred at a mean 22 months after revision for ceramic fracture. Mean serum cobalt level at re-revision was 991 ng/ml (normal value < 1 ng/ml; 734 to 1,302). All CoCr femoral heads exhibited massive wear, and deep tissues showed prominent metal staining. Treatment consisted of debridement and revision to a ceramic femoral head with highly cross-linked polyethylene (HXLPE) liner. Serum cobalt improved to a mean 25 μg/l (1 to 76) at final follow-up. All patients reported partial improvement in vision and hearing, however their peripheral neuropathy and balance difficulties did not recover.ConclusionSystemic cobalt toxicity is a devastating complication of ceramic-bearing fracture in THA treated with CoCr bearings, which may not present with hip symptoms. The diagnosis of this syndrome of systemic cobalt toxicity was significantly delayed following systemic symptoms in this series. Debridement and re-revision to a ceramic-on-HXLPE bearing leads to improvement, but not full resolution, of cobalt toxicity complications.Cite this article: Bone Joint J 2025;107-B(6 Supple B):92–100.

Background: The relative advantages and disadvantages of 2-stage versus 1-stage management of infection following total hip arthroplasty (THA) are the current subject of intense debate. To understand the merits of each approach, detailed information on the short and, importantly, longer-term outcomes of each must be known. The purpose of the present study was to assess the long-term results of 2-stage exchange arthroplasty following THA in one of the largest series to date. Methods: We identified 331 periprosthetic joint infections (PJIs) that had been treated with a 2-stage exchange arthroplasty between 1993 and 2021 at a single institution. Patients were excluded if they had had prior treatment for infection. The mean age at the time of reimplantation was 66 years, 38% of the patients were female, and the mean body mass index (BMI) was 30 kg/m 2 . The diagnosis of PJI was based on the 2011 Musculoskeletal Infection Society criteria. A competing-risk model accounting for death was utilized. The mean duration of follow-up was 8 years. Results: The cumulative incidence of reinfection was 7% at 1 year and 11% at 5 and 10 years. Factors predictive of reinfection included BMI ≥30 kg/m 2 (hazard ratio [HR] = 2; p = 0.049) and the need for a spacer exchange (HR = 3.2; p = 0.006). The cumulative incidence of any revision was 13% at 5 and 10 years. The cumulative incidence of aseptic revision was 3% at 1 year, 7% at 5 years, and 8% at 10 years. Dislocation occurred in 33 hips (11% at 10 years); 15 (45%) required revision. Factors predictive of dislocation were female sex (HR = 2; p = 0.047) and BMI <30 kg/m 2 (HR = 3; p = 0.02). The mean Harris hip score (HHS) improved from 54 to 75 at 10 years. Conclusions: In this series of 331 two-stage exchange arthroplasties that were performed for the treatment of infection, we found a low rate of aseptic revision (8%) and a low rate of reinfection (11%) at 10 years. These long-term mechanical and infection data must be kept in mind when considering a paradigm shift to 1-stage exchanges. Level of Evidence: Therapeutic Level III . See Instructions for Authors for a complete description of levels of evidence.