Early failure associated with adverse reactions to metal debris is an emerging problem after hip resurfacing but the exact mechanism is unclear. We analysed our entire series of 660 metal-on-metal resurfacings (Articular Surface Replacement (ASR) and Birmingham Hip Resurfacing (BHR)) and large-bearing ASR total hip replacements, to establish associations with metal debris-related failures. Clinical and radiological outcomes, metal ion levels, explant studies and lymphocyte transformation tests were performed. A total of 17 patients (3.4%) were identified (all ASR bearings) with adverse reactions to metal debris, for which revision was required. This group had significantly smaller components, significantly higher acetabular component anteversion, and significantly higher whole concentrations of blood and joint chromium and cobalt ions than asymptomatic patients did (all p < 0.001). Post-revision lymphocyte transformation tests on this group showed no reactivity to chromium or cobalt ions. Explants from these revisions had greater surface wear than retrievals for uncomplicated fractures. The absence of adverse reactions to metal debris in patients with well-positioned implants usually implies high component wear. Surgeons must consider implant design, expected component size and acetabular component positioning in order to reduce early failures when performing large-bearing metal-on-metal hip resurfacing and replacement

Introduction. There are several potential biological mechanisms that may influence aseptic implant failure including excessive innate and adaptive immune responses to implant debris. We investigated the hypothesis that patients with painful total joint replacements will exhibit elevated levels of metal reactivity and inflammatory markers compared to patients with well-performing TJA. We evaluated this hypothesis by testing for metal hypersensitivity using in vitro LTT assay and analyzing serum levels of selected inflammatory markers. Methods. Subject Groups: Blinded de-identified data from patients with TJR referred for metal hypersensitivity testing using a lymphocyte transformation test (LTT) and serum markers of inflammation using Luminex Multi-Analyte Assay was approved by Rush University IRB and retrospectively reviewed. None of the patients had radiographically identifiable osteolysis. Two groups of TJA patients were tested: Group 1: Well-functioning implant (<3 yrs. post-op), with no self-reported pain, i.e. <1 on 0–10 VAS scale (n=8) and Group 2: Painful TJR (<3 yrs. post-op), with self-determined pain of >8 on a 0–10 VAS scale at the time of blood draw (n=25). Metal-LTT: Peripheral blood mononuclear cells (PBMCs) were collected from 30mL of peripheral blood by Ficoll gradient separation. PBMCs were cultured with NiCl2. 3H Thymidine was added at day 5 of culture and 3H thymidine incorporation was analyzed using a beta scintillation counter at day 6. A stimulation index (SI) of reactivity was calculated by dividing scintillation counts per minute (cpms) of Ni challenged cells by those of untreated controls. A SI of <2 was considered nonreactive, 2 to <4 was mildly reactive and 4 to <8 was reactive. Luminex Assay: Serum samples were collected from whole blood and were analyzed according to manufacturer's protocols. Statistical analysis: Statistical differences were determined using unpaired t-test with Welch's correction with statistical significance at p≤0.1 (90% confidence interval). Results. To test if differences in metal sensitization exist among individuals with joint pain following TJR vs. well-functioning TJR (no pain), we analyzed each person-specific PBMC SI of reactivity to NiCl2. Painful TJR group exhibited greater sensitivity as demonstrated by significantly higher in vitro metal SI level. In general, inflammatory markers measured in serum among patients with pain following TJR were significantly increased compared to patients with no pain following TJR. Specifically, inflammatory markers that are classified as prototypical markers of a M1 inflammatory macrophage i.e. GMCSF, IL-12, IL-18, IL-1β and TNFα were significantly greater in TJR patients with pain compared to TJR patients with no pain. Due to this increase in inflammatory markers, IL-4, an anti-inflammatory marker was also significantly greater in TJR patients with pain in order to combat/mitigate the inflammatory microenvironment. While VEGF was the only marker that was significantly greater in TJR patients with no pain and is characteristic of M2 anti-inflammatory macrophage phenotype. Discussion. Metal sensitivity reactivity and serum markers of inflammation demonstrated significant differences between groups of patients with painful TJRs vs. well-functioning TJR. Classical markers of M1 phenotype were significantly greater in painful TJR group. Our data suggests that patients with self-reported pain following a TJR demonstrate active innate and adaptive immune responses that are significantly higher than patients with a well-performing TJR and that these differences are associated with detectable serum inflammatory markers. An important limitation of this study however, is that group subject numbers were low and that statistical differences found in these groups suggests these inflammatory markers may be more marked than was anticipated

Objectives

Modern metal-on-metal (MoM) hip resurfacing arthroplasty (HRA), while achieving good results with well-orientated, well-designed components in ideal patients, is contraindicated in women, men with head size under 50 mm, or metal hypersensitivity. These patients currently have no access to the benefits of HRA. Highly crosslinked polyethylene (XLPE) has demonstrated clinical success in total hip arthroplasty (THA) and, when used in HRA, potentially reduces metal ion-related sequelae. We report the early performance of HRA using a direct-to-bone cementless mono-bloc XLPE component coupled with a cobalt-chrome femoral head, in the patient group for whom HRA is currently contraindicated.

We report a 12- to 15-year implant survival assessment of a prospective single-surgeon series of Birmingham Hip Resurfacings (BHRs). The earliest 1000 consecutive BHRs including 288 women (335 hips) and 598 men (665 hips) of all ages and diagnoses with no exclusions were prospectively followed-up with postal questionnaires, of whom the first 402 BHRs (350 patients) also had clinical and radiological review.

Mean follow-up was 13.7 years (12.3 to 15.3). In total, 59 patients (68 hips) died 0.7 to 12.6 years following surgery from unrelated causes. There were 38 revisions, 0.1 to 13.9 years (median 8.7) following operation, including 17 femoral failures (1.7%) and seven each of infections, soft-tissue reactions and other causes. With revision for any reason as the end-point Kaplan–Meier survival analysis showed 97.4% (95% confidence interval (CI) 96.9 to 97.9) and 95.8% (95% CI 95.1 to 96.5) survival at ten and 15 years, respectively. Radiological assessment showed 11 (3.5%) femoral and 13 (4.1%) acetabular radiolucencies which were not deemed failures and one radiological femoral failure (0.3%).

Our study shows that the performance of the BHR continues to be good at 12- to 15-year follow-up. Men have better implant survival (98.0%; 95% CI 97.4 to 98.6) at 15 years than women (91.5%; 95% CI 89.8 to 93.2), and women < 60 years (90.5%; 95% CI 88.3 to 92.7) fare worse than others. Hip dysplasia and osteonecrosis are risk factors for failure. Patients under 50 years with osteoarthritis fare best (99.4%; 95% CI 98.8 to 100 survival at 15 years), with no failures in men in this group.

Cite this article: Bone Joint J 2014;96-B:1298–1306.