The influence of hydroxyapatite coating on continuous migration of a Zweymuller-type hip stem: a double-blinded randomised RSA trial with 5-year follow-up.

BACKGROUND AND PURPOSE: Adding hydroxyapatite to a stem to enhance ingrowth is a matter of debate, even less is known about the long-term effect on stability by adding hydroxyapatite (HA). Continuous migration in the first 2-5 years is an indicator of failed osteointegration or pending failure, enhancing the risk of loosening within 10 years after initial surgery. We performed a double-blinded randomised RSA trial with 5-year follow-up, to compare and analyse migration characteristics of the hydroxyapatite uncoated (HA-) and hydroxyapatite coated (HA+) Zweymuller-type hip stem. PATIENTS AND METHODS: In this single-centre prospective randomised controlled trial 51 patients were randomised to receive either a HA- or a HA+ Zweymuller-type hip stem during total hip replacement. After 5 years, 35 patients were still eligible for follow-up evaluation. The migration pattern was measured by use of radio stereometric analysis (RSA) images up to 2 years to evaluate short-term migration, additionally RSA images were obtained 5 years postoperatively to assess late-term and continuous migration. Furthermore, the improvement of clinical outcome was analysed by HSS and HOOS ADL and pain subscales preoperative and after 5 years. RESULTS: After initial settling of the implant, no significant migration occurred up to 5 years post-surgery for HA+ as well as HA- prostheses. Continuous migration within the 2-5 years' time interval was not observed for both HA+ nor the HA- group in all directions (p < 0.05). No significant difference between both groups was observed (p < 0.10). In both groups the HHS and HOOS improved significantly at 5 years compared to baseline for both groups. Improvement was not altered by the hydroxyapatite coating. No significant difference between both groups was observed (p > 0.58). CONCLUSIONS: Addition of a hydroxyapatite coating did not influence the migration 5 years postoperatively for the Zweymuller-type hip stem.Clinical Trial Protocol number: NL 23524.048.08.

Platelet-Rich plasma Injection Management for Ankle osteoarthritis study (PRIMA): protocol of a Dutch multicentre, stratified, block-randomised, double-blind, placebo-controlled trial.

INTRODUCTION: Platelet-rich plasma (PRP) is a potentially efficacious treatment for ankle osteoarthritis (OA), but its use has not been examined in high-quality studies. Systematic reviews show that PRP injections significantly decrease pain and improve function in patients with knee OA. Ankle OA is more common than hip or knee OA in the young active population; with a prevalence of 3.4%.PRP injections in ankle OA are shown to be safe and improve quality of life over time, but no randomised controlled trial has been conducted. Our randomised controlled trial will evaluate the efficacy of PRP injections for symptom reduction and functional improvement, compared with placebo, in the treatment of ankle (talocrural) OA. METHODS AND ANALYSIS: We will conduct the Platelet-Rich plasma Injection Management for Ankle OA study: a multicentre, randomised, placebo-controlled trial. One hundred patients suffering from ankle OA will be randomised into two treatment groups: PRP injection or placebo (saline) injection. Both groups will receive two injections of PRP or placebo at an interval of 6 weeks. Primary outcome is the American Orthopaedic Foot and Ankle Society score at 26 weeks. Secondary outcomes determined at several follow-up moments up to 5 years, include Ankle Osteoarthritis Score, Foot and Ankle Outcome Score, pain subscale of (0-40), Visual Analogue Scale score (0-100), Ankle Activity Score (0-10), subjective patient satisfaction Short Form Health Survey-36, Global Attainment Scaling and the EuroQol-5 dimensions-3 levels utility score. A cost-effectiveness analysis will be performed at 1 year. ETHICS AND DISSEMINATION: The study is approved by the Medical Ethics Review Committee Amsterdam Medical Center, the Netherlands (ABR 2018-042, approved 23 July 2018) and registered in the Netherlands trial register (NTR7261). Results and new knowledge will be disseminated through the Dutch Arthritis Association (ReumaNederland), Dutch patient federation, conferences and published in a scientific peer-reviewed journal. TRIAL REGISTRATION NUMBER: NTR7261.