Purpose The dramatic improvement in clinical function after total hip arthroplasty (THA) has been well documented. However gait studies demonstrate abnormal gait pattern after THA, and patients may complain of thigh pain, leg length inequality, instability and reduced range of motion. Surface replacement arthroplasty (SRA) has the benefit of restoring a more normal hip anatomy and biomechanics, which could improve clinical function and patient satisfaction after surgery.

Method All patients eligible for the study were randomised to receive uncemented metal-metal THA or a hybrid metal-metal SRA. Clinical data were prospectively collected preoperatively and at 3, 6 and 12 months postoperatively. The WOMAC score, SF-36, Merle D’Aubigné, and other clinical data, along with patient satisfaction, were compared.

Summary of Results One hundred and fifty patients were randomized. Patients in both groups demonstrate very high satisfaction rate. Although there was a tendency for the SRA group to participate in more demanding activities at 6 months post operatively, no difference was found in clinical function scores. Two isolated dislocations occurred in the THA group and none in the SRA group. No other significant complication occurred in either group.

Discussion. The few short-term clinical data reported in the literature for new generation SRA implants demonstrates excellent outcome comparable to THA. Despite enthusiasm about total hip resurfacing, there is no direct prospective comparative study with THA published in the literature. This study confirms the safety and benefits of metal-metal surface arthroplasty of the hip in the early post op period.

Purpose: In 1988, metal-on-metal bearing surfaces were reintroduced in hip replacement surgery with a 28 mm diameter femoral head. These bearings have potential advantages such as improved durability, absence of polyethylene particles and no secondary periprosthetic osteolysis. Tribological studies suggest that larger metal-on-metal articulations would produce less wear than smaller diameter components. But recent clinical studies revealed increased release of circulating ions in metal-metal hip resurfacing compared to 28 mm metal-metal articulation. The aim of the present study is to describe whole blood Chrome and Cobalt ions concentration after non-cemented metal-metal total hip arthroplasty (THA) and hybrid metal-metal surface replacement arthroplasty (SRA).

Method: All patients eligible for the study were randomised to receive uncemented THA or a hybrid SRA. Whole blood samples were collected pre-operatively, at three, six months and one year post operatively. Chrome and Cobalt concentration were measured using a spectrophotometer.

Summary of Results: Blood samples have been taken from 78 patients and are pending analysis.

Discussion: Considering the influence of activity level, weight, time after surgery, the renal function, etc. on the wear behaviour of bearing surfaces, a prospective randomised study is important to obtain a valid comparison. To our knowledge, this is the only randomised study comparing whole blood ions concentration in metal-metal THA and SRA.

Significance: We strongly believe that this subject warrants special attention considering the possible toxicity associated with high levels of circulating metal ions.