A Comparison Between Two Bearing Surfaces for Total Hip Arthroplasty—Ceramic-on-Ceramic and Metal–Polycarbonate–Urethane—A Pseudo-Randomized Study

Polycarbonate-urethane (PCU) is a recently developed bearing surface used in prosthetic hip surgery. It offers several theoretical advantages, including an elasticity modulus similar to that of natural cartilage, good lubrication properties, low wear, and the possibility of using large heads. However, comparative clinical experience is limited. The purpose of this study was to analyze the results of the PCU bearing surface and compare them with those of ceramic-on-ceramic (CoC) bearings using the same femoral stem model. (2) Methods: Following a propensity score matching analysis of a prospectively collected database, patients with a primary total hip arthroplasty aged between 18 and 60 years were included. Subjects were divided into two groups (PCU and CoC). Demographic, patient satisfaction, and implant survival data were recorded. Clinical results were evaluated using the Harris Hip Score (HHS) and the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). (3) Results: A total of 105 patients were included in each group. All patients exhibited a positive evolution on both the HHS and the WOMAC subscales between pre-op and one year post-op, no statistically significant differences being found between the groups with respect to improvement on the HHS (<i>p</i> = 0.172) or the pain (<i>p</i> = 0.523), stiffness (<i>p</i> = 0.448), and physical function (<i>p</i> = 0.255) subscales of the WOMAC. Head sizes in the PCU group were found to be larger, but this was not seen to have any effect on the patients' clinical status or the prostheses' dislocation rate. Although the complication rate was similar across the groups (<i>p</i> = 0.828), the incidence of squeaking was higher in the PCU group (<i>p</i> = 0.010). No differences were observed when comparing the implant survival rate (<i>p</i> = 0.427). nor in mean patient satisfaction (<i>p</i> = 0.138). (4) Conclusions: No differences were found in terms of clinical results, complications, implant survival, or patient satisfaction between the bearing surfaces under analysis, indicating that all of them are valid alternatives in total hip replacement, although the higher proportion of squeaking observed makes it advisable to exercise some caution.