Oxidised zirconium (OxZi) has been developed as an alternative bearing surface for femoral heads in total hip arthroplasty (THA). This study has investigated polyethylene wear, functional outcomes and complications, comparing OxZi and cobalt–chrome (CoCr) as part of a three-arm, multicentre randomised controlled trial. Patients undergoing THA from four institutions were prospectively randomised into three groups. Group A received a CoCr femoral head and highly cross-linked polyethylene (XLPE) liner; Group B received an OxZi femoral head and XLPE liner; Group C received an OxZi femoral head and ultra-high molecular weight polyethylene (UHMWPE) liner. At five years, 368 patients had no statistically significant differences in short-form-36 (p = 0.176 mental, p = 0.756 physical), Western Ontario and McMaster Universities Osteoarthritis Index (p = 0.847), pain scores (p = 0.458) or complications. The mean rate of linear wear was 0.028 mm/year (standard deviation (sd) 0.010) for Group A, 0.023 mm/year (sd 0.010) for Group B, and 0.09 mm/year (sd 0.045) for Group C. Penetration was significantly higher in the UHMWPE liner group compared with both XLPE liner groups (p < 0.001) but no significant difference was noted between CoCr and OxZi when articulating with XLPE (p = 0.153). In this, the largest randomised study of this bearing surface, it appears that using a XLPE acetabular liner is more important in reducing THA component wear than the choice of femoral head bearing, at mid-term follow-up. There is a non-significant trend towards lower wear, coupling OxZi rather than CoCr with XLPE but long-term analysis is required to see if this observation changes with time and becomes significant.

Cite this article: Bone Joint J 2015;97-B:883–9.

We Present the results of radiographic assessment of limb length and offset measurements of the first 50 Corin Mini Hips done at Yeovil District Hospital.

All reconstructed Hips were compared with the contra lateral hip for leg length and offset restoration using the method of Murphy et al 2007. Excellent matching with the contralateral hip in terms of leg length and offset were found in 78% of hips and fair matching in 22%. The mean leg length discrepancy was 4 mm and mean offset discrepancy was 2 mm.

Our results show that despite using a different paradigm to conventional hip replacements, this stem allows accurate restoration of hip geometry.

From February 1992 to December 1997, 379 total hip arthroplasties in 342 patients were performed. 13 patients were lost to follow up, with 33 unrelated deaths. All arthroplasties were performed via the posterior approach in the lateral position. All patients were enrolled in an arthroplasty register at the time of surgery by the operating surgeon. Patients underwent clinical and radiological follow up. Kaplan-Meier survivorship analysis was used to determine the failure rate of the prosthesis, with revision surgery or decision to revise as the end-point.

The overall survivorship from all causes of failure at 5–10 years was 99.4%.

There were two stem revisions. One stem was revised for aseptic loosening at 4 years and one revised for recurrent dislocation. The stem aseptic loosening rate was 0.26%.

The cup aseptic loosening rate was 0%. The dislocation rate was 0.53% (2 from 379).

The superficial infection rate was 0.53% (2 from 379). There were no deep infections in this series.

At 12 months 71.2% had no pain (270 from 379), and 53.8% (204 from 379) had normal function. 94.5% said the procedure was worthwhile or very good. At 12 months radiological follow-up revealed progressive radioluceny in 7.65% (29 from 379) acetabuli, and progressive radiolucency in 2.90% (11 from 379) femora (one progressing to revision for aseptic loosening). No acetabular cups required revision.

In patients aged 65 years or younger at the time of surgery the survivorship was 100% for both components. Attention to meticulous and consistent operative technique in acetabular and femoral preparation, in particular a complete cement mantle with good zone 7 cement and osseointegrated cement bone interfaces, enables these results to be achieved.

In 2004 the Charnely Hip replacement remains the Gold Standard hip replacement.

Proponents of the biological theory of aseptic loosening have in recent years tended to concentrate on the production and distribution of particulate ultra-high-molecular-weight polyethylene (UHMWPE) debris around the potential joint space. However, mechanical loading of cemented implants with the differing elastic moduli of metal stems, polymethylmethacrylate (PMMA) cement and bone can result in relative micromotion, implying the potential for production of metal and PMMA particles from the stem-cement interface by fretting wear.

In order to investigate the production and biological reactivity of debris from this interface, PMMA and metal particulate debris was produced by sliding wear of PMMA pins containing barium sulphate and zirconium dioxide against a Vaquasheened stainless steel counterface. This debris was characterised by SEM, energy-dispersive analysis by X-ray (EDAX) and image analysis, then added to cell cultures of a human monocytic cell line, U937, and stimulation of pro-osteolytic cytokines measured by ELISA.

Large quantities of PMMA cement debris were generated by the sliding wear of PMMA pins against Vaquasheened stainless steel plates in the method developed for this study. Both cements stimulated the release of pro-osteolytic TNFα from the U937 monocytic cell line, in a dose-dependent fashion. There was a trend towards greater TNFα release with Palacos cement than CMW cement at the same dose. Palacos particles also caused significant release of IL-6, another pro-osteolytic cytokine, while CMW did not. The particulate cement debris produced did not stimulate the release of GM-CSF or IL1β from the U937 cells. These results may explain the cytokine pathway responsible for bone resorption caused by particulate PMMA debris.

Radio-opaque additives are of value in surgical practice and clinical studies to quantify the relevance of these in vitro findings are required before the use of cement containing radio-opacifier is constrained.

We have examined 26 retrieved, failed titanium-alloy femoral stems. The clinical details, radiological appearances and the histology of the surrounding soft tissues in each patient were also investigated.

The stems were predominantly of the flanged design and had a characteristic pattern of wear. A review of the radiographs showed a series of changes, progressive with time. The first was lateral debonding with subsidence of the stem. This was followed by calcar resorption and fragmentation or fracture of the cement. Finally, osteolysis was seen, starting with a radiolucency at the cement-bone interface and progressing to endosteal cavitation.

Three histological appearances were noted: granulomatous, necrobiotic and necrotic. We suggest that an unknown factor, possibly related to the design of the stem, caused it to move early. After this, micromovement at the cement-stem interface led to the generation of particulate debris and fracture of the cement. A soft-tissue reaction to the debris resulted in osteolysis and failure of fixation of the prostheses.