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.

Introduction: The purpose of this study was to review the preliminary clinical outcomes of a clinical study of a new implant for intervening in Stage I & II femoral head osteonecrosis.

Materials & Methods: The porous tantalum (Hedrocel® Trabecular Metal, Zimmer Inc./Implex Corp.) is 80% porous with a modulus of elasticity similar to bone. The implant is 10 mm in diameter, offered in 70 – 130 mm lengths in 5 mm increments, and possesses threads for engagement of the lateral cortex. The investigation is an FDA regulated, prospective IDE study of the implant in comparison to core decompression for patients with Stage I or II osteonecrosis (Steinberg-UPenn). Patients exhibiting unilateral disease are randomized to an implant or core decompression (50–50 chance). All patients exhibiting bilateral disease receive the implant. Clinical outcome measures include HHS and SF-12 scored pre-op, at 6, 12, and 24 months, and radiographic data is collected at these same times, and at 6 and 12 weeks.

Results: Prior to the clinical study, a custom case was performed in 1998, and a second in 1999. Since the study began in June 2000, 12 surgeries have been performed with the implant. All 14 patients are reportedly doing well. Radiographic review shows no evidence of abnormal bone density and no evidence of radiolucencies. All lesions appear similar to the pre-op condition. In one case, at 3-months, there is radiographic evidence that the implant has stabilized a slightly collapsed subchon-dral plate, and that new bone has formed in proximity to the tip of the implant. This patient exhibited mild pain at 8 weeks, which has since subsided.

Discussion: The preliminary clinical experience with this implant is encouraging and suggests that mechanically supporting the subchondral plate with this implant is a viable method of intervening in the early stages of osteonecrosis.