Abstract
Introduction: This report details the author’s experience with custom femoral implants for femoral replacement in total hip arthroplasty from 1988. The concepts, technology and results help define the role custom implants may play for present day arthroplasty.
Methods: Custom femoral components were used in 48 patients, (22 female, 26 male). There were 52 primary THAs and 6 revision THAs. Initial diagnoses included osteoarthritis, developmental dysplasia, and osteonecrosis. The average patient age at surgery was 48.3 years. Clinical and radiographic results were by standard methodologies.
Results: Mean follow-up was 119 months. These 3 stem variations were used – TiAlVa alloy stem with anterior, posterior and medial porous mesh pads (Ti-Mesh, Tech-medica), the same design with circumferential HA coating (TI-HA, Techmedica), and a TiAlVa alloy stem with circumferential plasma sprayed Ti with HA (PSHA, Biomet). A variety of acetabular components were used. Harris Hip Scores averaged 65 points pre-operatively and 83 at most recent follow-up. Forty stems (69%) showed hypertrophic cortical remodeling in more than two zones all with bone ingrowth. Eight stems (14%) showed osteolysis around the stem – all of the Ti-Mesh design. Eight cups showed loosening, 2 showed osteolysis, and 23 (39.7%) showed radiographic evidence for wear. Eight hips were revised: three for osteolysis; 4 stems for loosening; and one stem revision for recurrent dislocation (5 hip stems revised). All revised stems were of the Ti-Mesh design. There have been no failures of the HA coated implants at this time.
Discussion: The results of this study suggest that fit and fill alone are not sufficient to provide durable fixation for uncemented THA. The use of circumferential coating substantially improved the performance of these devices. The technology associated with these devices is now available for use in complex revision arthroplasty, where customized approaches will find a permanent role.
The abstracts were prepared by Nico Verdonschot. Correspondence should be addressed to him at Orthopaedic Research Laboratory, University Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands.