A. Schepers

The 2007 Otto Aufranc Award. Ceramic-on-metal hip arthroplasties: a comparative in vitro and in vivo study.

The performance of novel ceramic-on-metal bearing couples has been compared with metal-on-metal and ceramic-on-ceramic bearing couples in laboratory and short-term clinical studies. Laboratory studies compared ceramic-on-metal with metal-on-metal and ceramic-on-ceramic bearings with diameters of 28 and 36 mm under standard conditions and under adverse conditions with head loading on the rim of the cup. Clinical studies compared metal ion levels in ceramic-on-metal with metal-on-metal, ceramic-on-ceramic, and ceramic-on-polyethylene bearings in a randomized prospective study. In the laboratory studies, friction, wear, and ion levels were lower in ceramic-on-metal bearings compared with metal-on-metal, with results similar to ceramic-on-ceramic couples. Under adverse conditions and rim loading, all bearings showed increased wear with lower wear and absence of stripe wear in ceramic-on-metal compared with metal-on-metal bearings. Short-term studies in 31 patients at 6 months revealed lower metal ion levels (cobalt and chromium) in those with ceramic-on-metal compared with metal-on-metal bearings.Level of Evidence: Level II, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

Ceramic-on-metal bearings in total hip replacement: whole blood metal ion levels and analysis of retrieved components.

This study reports on ceramic-on-metal (CoM) bearings in total hip replacement. Whole blood metal ion levels were measured. The median increase in chromium and cobalt at 12 months was 0.08 microg/1 and 0.22 microg/1, respectively, in CoM bearings. Comparable values for metal-on-metal (MoM) were 0.48 microg/1 and 0.32 microg/1. The chromium levels were significantly lower in CoM than in MoM bearings (p = 0.02). The cobalt levels were lower, but the difference was not significant. Examination of two explanted ceramic heads revealed areas of thin metal transfer. CoM bearings (one explanted head and acetabular component, one explanted head and new acetabular component, and three new heads and acetabular components) were tested in a hip joint simulator. The explanted head and acetabular component had higher bedding-in. However, after one million cycles all the wear rates were the same and an order of magnitude less than that reported for MoM bearings. There were four outliers in each clinical group, primarily related to component malposition.

A Prospective Randomized Clinical Trial Comparing Tibial Baseplate Fixation With or Without Screws in Total Knee Arthroplasty: A Radiographic Evaluation

In a randomized prospective study, we compared the use of tibial screws with screwless tibial baseplate fixation in uncemented total knee arthroplasty and report the results of 154 prostheses at a mean follow-up of 5 years. Patients were mobilized within 24 hours and continued with partial weight-bearing for up to 6 weeks postoperatively. There were no significant differences in radiologic results and revision rates. Radiographic outcomes do not seem to be influenced by the use of screws in tibial baseplate fixation of this prosthesis. The prosthesis studied has a large tibial keel and 4 adjunctive pegs that seem to provide adequate stability and allow bony ingrowth to take place. Longer follow-up will determine whether in this implant design, the use of tibial screws for cementless tibial baseplate fixation can be justified.