COLLARLESS POLISHED TAPERED STEM (CPT). CLINICAL AND RADIOLOGICAL FOLLOW-UP AT A MINIMUM OF 10 YEARS.

Abstract

Introduction: The collarless polished tapered stem (CPT) is a double tapered cemented femoral component designed for primary hip replacement and as a revision stem for impaction bone grafting. We report the outcome at a minimum of 10 years (mean 11 years 1 month).

Methods and patients: Of 191 consecutive primary hip replacements in 174 patients, implanted using contemporary cementing techniques, 63 patients died before 10 years (68 hips). None of these stems had been revised or had radiological signs of failure at their last follow-up. Only 1 patient (2 hips) was lost to radiological follow-up, hence complete radiological data was available on 121 hips and clinical follow-up on 123 hips. The fate of all the hips is known.

Results: Survivorship with revision of the femoral component for aseptic loosening as the endpoint was 100%. The Harris hip scores were good or excellent in 75% of the patients with a mean of 86 (from 39). All the stems subsided vertically within the cement mantle at a mean rate of 0.18mm per year, stabilising to a mean total of 1.95mm (0.21–24mm) after a mean of 11 years 1 month. Unlike Exeter stems there was no change in the alignment of the stems. There was excellent preservation of proximal bone and an extremely low (< 2%) incidence of loosening at the cement bone interface.

Discussion: The study confirms that the CPT subsides within the cement mantle, but without failing. It performs at least as well as the best stems currently available.