Abstract
Introduction: One of the most important factors affecting the outcome of revision THR of the femoral stem is the variability of femoral endosteal geometry after removal of the in-situ stem. A custom made implant would greatly reduce the inventory of the ‘Off the shelf” (OTS) components. This study presents the medium to long-term results of a cohort of patients with this revision prosthesis.
Methods: During the period November 1991 to November 1998, 158 patients were implanted with a computer-assisted design and computer-assisted manufactured (CAD-CAM) revision prostheses (Stanmore Implants Worldwide, Biomedical Engineering Unit, RNOH) by the senior author (SMA). There were 97 males and 61 females. The average age was 63.1 years (34.6 – 85.9). The indications for revision surgery were aseptic loosening (135 cases, 85.4 %), peri-prosthetic fractures (6 cases, 3.8 %), infection (12 cases, 7.6%) and liner wear (3 cases, 1.9%).
Results: At 10 years all patients reported relief of pre-operative pain and the average hip flexion was 95o (90 o –110o). Oxford, Harris and WOMAC hip scores in the pre-operative and post-operative period were 41.1, 44.2 and 52.4 respectively and 18.2, 89.3 and 12.3 respectively (p< 0.0001, p< 0.0001, p< 0.0001).
There were 6 complications (3.8%) in this series; a periprosthetic fracture of the femoral diaphysis (1), posterior dislocation (2), failure secondary to aseptic loosening of the implant (1) and deep vein thromboses (2)
Discussion: These ten year results are encouraging and suggest that there is a role for the use of custom implants in revision THR, particularly where the anatomical variance of the proximal femur makes the use of OTS implants unsuitable.
Correspondence should be addressed to BHS c/o BOA, at the Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London, WC2A 3PE, England.
