Outcomes of a hydroxyapatite ceramic-coated femoral stem in primary total hip arthroplasty: a report of excellent survivorship from a single United Kingdom centre

Abstract

Background: Hydroxyapatite (HA) coated femoral stems were introduced to enhance the biological fixation at the implant-bone interface, aiming to increase the longevity and survival of the prostheses. We aimed to assess the long-term outcomes of an HA ceramic (HAC) coated stem in primary total hip arthroplasty (THA), assess the stem survival, and clinically evaluate the patients using patient-reported outcome measures (PROMs) and radiological evaluation of stem osseointegration. Patients and methods: This was a prospective evaluation of a retrospective cohort of 385 patients (442 hips) who underwent primary THA between June 2008 and December 2018. The mean age was 63.83 years (range, 30–82 years). During the follow-up duration, 23 patients died, and 36 patients (38 hips) were lost to follow-up. Prospective data collected for 326 patients (381 hips) was used to evaluate stem survival with the Kaplan–Meier method using aseptic loosening or any revision as the endpoint. Clinical evaluation was done using the EuroQol five-dimension (EQ-5D) scoring system and PROMs using the Oxford Hip Score (OHS) and Merle D’Aubigne Postel (MDP) score. Radiological assessments were performed using the Engh radiological criteria for stem osteointegration. Results: The mean follow-up duration was 9.39 years (range, 4–14.5 years). The survival of the HAC-coated femoral stem was 100% (95% confidence interval [CI], 96.7–100%) at 14 years with aseptic loosening as the endpoint, and 98.9% (CI, 96.7–100%) at 14 years with stem revision for any reason as the endpoint. The mean OHS was 44.5 (range, 30–48), and the mean MDP score was 15.87 (range, 10–18). Radiological evaluations showed full osseointegration of all stems. Conclusion: This HAC-coated femoral stem has shown excellent survivorship, functional outcomes, and full osseointegration at the final follow-up.