A 15 TO 18 YEAR PROSPECTIVE SURVIVAL ANALYSIS OF HYDROXYAPATITE OR POROUS COATING IN AN ANATOMIC HIP STEM

Abstract

Introduction: The aim of this study is long term comparison of hydroxyapatite (HA) coating and porous (PO) coating in an identical stem design.

Material and Methods: 100 consecutive hips from 86 patients scheduled for uncemented primary arthroplasty were quasi-randomized to receive a titanium-alloy anatomic PROFILE stem (DePuy, Warsaw, IN), HA coated in every second hip and PO coated in the remainder 50 hips. Patients receiving bilateral total hip arthroplasty were implanted an HA coated stem in one and a PO coated in the contralateral hip. All surgeries were performed by the posterolateral approach by 2 surgeons (the author PBT being one of them). The acetabular component was either an AML+ or a Duraloc 300 implant with a cobalt chrome 28mm head (DePuy, Warsay, IN).

15 to 18 years postoperatively these patients and their hip radiographs were examined by an independent observer (WD) to establish the long term survival, clinical and radiographical performance of this stem and especially to compare the two coatings. The Harris hip score was employed for clinical evaluation

Results: 16 years and 3 months (range 15y 0m – 17y 8m) postoperatively 21 patients with 23 hips had died and 4 hips (2HA/2 PO) had been revised. This leaves 62 patients with 73 hips (34 HA/39 PO) for evaluation. Life tables showed 18 years cumulative survival (free of revision of any reason) of 95.8% for HA and 95.5% for PO. 18 years cumulative survival (free of revision for aseptic loosening) were 95.8% for HA and 97.5% for PO. There were no infections in either group. Mean HHS was 83.4 ± 14.8 in HA and 86.8 ± 11.5 in PO (P = 0.32). Mean pain score was 39.1 ± 9.4 in HA and 40.9 ± 6.7 in PO (P = 0.69). Radiographs showed osseointegration of the stem except in 1 HA and in 2 PO stems. Lucencies/osteolytic scalloping were only seen in zone 1 and 7. Significant bone remodeling changes were seen. Ectopic ossification developed in 1/3 of hips non progressive stem subsidence of 2 mm were measured in a few hips.

Conclusion: This prospective quasi-randomized study show excellent long term performance and survival of the titanium-alloy anatomic PROFILE stem in primary hip arthroplasty in patients < 66 years with no significant differences between HA and PO coating.