Abstract
Background and purpose — BoneMaster (BM) is an electrochemically deposited hydroxyapatite (HA) implant-coating, which is evenly distributed, thin, and quickly resorbed. It is designed to stimulate osseointegration and early implant stability and alleviate longer-term HA-induced third-body polyethylene wear. This study evaluates early cup migration and functional outcomes of cementless porous-coated hemispherical cups with or without BM.Patients and methods — In a patient-blinded, randomized, controlled trial 53 patients at mean 64 years (55–75) with coxarthritis were operated with an Exceed cup (Zimmer Biomet) and Bi-Metric stem (Zimmer Biomet) with porous and BM coating (PBM) or with porous coating alone (P). Follow-ups were performed postoperatively and at 3, 6, 12, and 24 months. Effect measures were cup migration measured with RSA and PROMs.Results — At 6-month follow-up, proximal cup migration in the PBM group (0.09 mm, 95% CI 0.02–0.20) was higher than in the P group (0.25 mm, CI 0.15–0.35). At 1- and 2-year follow-up, cup migration in all 6 degrees of freedom was similar between groups (p > 0.2). From before surgery to 2-year follow-up, Oxford Hip Score (OHS) increased by 17 points (CI 14–20). Hip disability and Osteoarthritis Outcome Score (HOOS) increased in all sub-scores, but was more pronounced for PBM cups compared with P cups in the Symptoms sub-score (p = 0.04).Interpretation — Contrary to expectations, PBM cups had higher early migration than P cups. At 2-year follow-up, migration was similar between groups. There seems to be no early benefit of BM coating on acetabular cups.
Highlights
At 6-month follow-up, proximal cup migration in the porous and BM coating (PBM) group (0.09 mm, 95% confidence intervals (CI) 0.02–0.20) was higher than in the P group (0.25 mm, CI 0.15–0.35)
The mean condition number (CN) was 99.8. 4 patients (2 in each group) with CN between 150 and 200 had a sufficient and non-linear bone model as judged by visual evaluation, and were kept in the analyses to maintain power. 1 patient with CN above 200 and 1 patient with only 2 markers were excluded from the RSA data
Proximal cup migration was 0.09 mm (CI –0.06 to 0.24) higher for osteopenic patients compared with patients with normal BMD at 6-month follow-up, this difference was not statistically significant (p = 0.2) (Figure 4)
Summary
Study designIn this patient-blinded, randomized controlled trial, 82 patients were assessed for eligibility between January 2013 and March 2015. Criteria of exclusion were: other diseases of affected hip than primary coxarthrosis at time of inclusion, secondary osteoarthritis, neuromuscular or vascular condition in lower extremity, arthroplasties of other lower-extremity joints, BMI at time of inclusion ≥ 35 or < 18.5, rheumatoid and similar arthritis, metabolic bone disease, reduced kidney function, previous treatment of skeleton with radiation therapy, pharmaceuticals that effect calcium–phosphorus metabolism and bone density, alcohol abuse, medication abuse, and psychological instability. A sample size calculation indicated 23 patients per group based on a clinically relevant difference in migration of 0.6 mm (SD 0.6) with a power of 90% and alpha set to 0.05 (Charnley 1982). To balance for exclusions during the inclusion period, we continued inclusion per block random-
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
