Abstract
Objectives
Total hip arthroplasty (THA) is one of the most successful surgical procedures; several bearing technologies have been used, however none of these is optimal. Metal on polycarbonate-urethane (PCU) is a new bearing technology with several potential advantages: PCU is a hydrophilic soft pliable implant quite similar in elasticity to human cartilage, offers biostability, high resistance to hydrolysis, oxidation, and calcification, no biodegradation, low wear rate and high corrosion resistance and can be coupled with large metal heads (Tribofit Hip System, THS).
The aim of this prospective study was to report the survivorship and the clinical and radiographic outcomes and the metal ions dosage of a group of patients operated with metal on PCU arthroplasty featuring large metal diameter heads, at 5 years from surgery.
Study Design & Methods
68 consecutive patients treated with the THS were included. The patients have been contacted by phone call and invited to return to our centre for clinical (Oxford Hip Score, OHS, and Harris Hip Score, HHS), radiographic exam and metal ion levels evaluation. All the patients were operated with uncemented stems.
Results
The survival rate is 100% and no major complications were seen. The average preoperative OHS was 17 (6–34), at follow-up it was 44 (40–48). The average preoperative HHS was 48 (12–76), at follow-up it was 93 (84–100). On the x rays taken at follow-up, no signs of periprosthetic bone rarefaction and/or osteolysis were seen. No signs of PCU liner wear were visible. At follow up mean Co serum level was 0.52 ng/mL (<0.1–2.5, sd 0.5), mean Cr level was 0.27 ng/mL (0.1–2.2, sd 0.2). In this prospective study at a mean follow up of 5 years, all implants were well functioning, with no radiological signs of loosening and normal serum levels of cobalt and chrome. Although large diameter metal heads and metal sleeve were used no trunnionosis occurred.
Conclusions
We believe that these positive outcomes are due the positive biomechanical characteristics of PCU. These results need to be confirmed at a longer follow up and in a more active younger patient population.
