Instability is a common cause of failure after total hip arthroplasty. A novel reverse total hip has been developed, with a femoral cup and acetabular ball, creating enhanced mechanical stability. The purpose of this study was to assess the implant fixation using radiostereometric analysis (RSA), and the clinical safety and efficacy of this novel design. Patients with end-stage osteoarthritis were enrolled in a prospective cohort at a single centre. The cohort consisted of 11 females and 11 males with mean age of 70.6 years (SD 3.5) and BMI of 31.0 kg/m2 (SD 5.7). Implant fixation was evaluated using RSA as well as Western Ontario and McMaster Universities Osteoarthritis Index, Harris Hip Score, Oxford Hip Score, Hip disability and Osteoarthritis Outcome Score, 38-item Short Form survey, and EuroQol five-dimension health questionnaire scores at two-year follow-up. At least one acetabular screw was used in all cases. RSA markers were inserted into the innominate bone and proximal femur with imaging at six weeks (baseline) and six, 12, and 24 months. Independent-samples Aims
Methods
Despite being matched by age, gender and modified Charnley classification, there were significant differences in post-operative functional scores. The revision TKR group’s mean WOMAC score was 73 (SD 17), compared to the primary group’s mean score of 84 (SD 14), p=0.002. Similarly, the revision group’s mean SF-12 PCS score was 35 (SD 8) compared to the primary group’s superior score of 44 (SD 10), p<
0.0001. There was no differences detected in post-operative SF-12 mental component scores; 49 (SD 12) for the revision group compared to 53 (SD 10) for the primary group, p=0.11.
