Abstract
Introduction
Cross linked polyethylene (XLPE) has gained popularity as a bearing surface of choice for younger patients despite only medium term results being available for wear rates. Concern remains regarding the long-term stability and durability of these materials. In order to address these issues we present the longest radiological and clinical follow-up of XLPE.
Patients/Materials & Methods
Since 1986, we have prospectively studied a group of 17 patients (19 hips) that underwent a cemented Charnley low friction arthroplasty using a combination of 22.225mm alumina ceramic femoral head, a modified Charnley flanged stem and a chemically cross-linked polyethylene cup. We now report the 28 year clinical and radiological results.
Results
At the latest review nine patients (11 hips) were still attending for clinical and radiographic follow-up at a mean of 27.5 years (26 – 28). The mean age at surgery in this group was 47 years (26 – 58). Seven patients died whilst still under follow-up, and one was revised at 17 years for late deep infection following urological surgery.
There have been no mechanical failures of the components and no aseptic loosening. The mean initial penetration rate at 1 year was 0.13mm/year; between one and four years was 0.034mm/year; and between 4 years and latest follow-up (mean 27.5 years) was 0.007mm/year. One patient in this group subsequently had a contralateral Charnley metal on UHMWPE hip replacement and had a total cup penetration of 6.1mm at 27 years, compared to 0.41mm at 28 years in the XLPE and alumina ceramic combination.
Conclusion
The clinical and radiological results in this group of patients remain excellent with no aseptic loosening. There was an initial bedding in period, after which there was an extremely low wear rate. The results highlight the long term stability and durability of cross-linked polyethylene when used in combination with a small diameter alumina ceramic head.
