Abstract
BACKGROUND: For total hip arthroplasty (THA), minimally invasive surgery (MIS) has been reported to enhance early functional recovery. The conjoined tendon-preserving posterior (CPP) approach is a posterior MIS-THA technique designed to minimise muscle-tendon dissection while preserving the piriformis muscle, conjoined tendon, and the joint capsule covered by the conjoined tendon. This approach is expected to facilitate early postoperative functional recovery; however, clinical outcomes remain unreported. This study aimed to evaluate the impact of muscle preservation on walking ability by comparing THA performed using the CPP and posterolateral (PL) approaches through gait analysis and patient-reported outcome measures (PROMs). METHODS: Seventy-two patients who underwent THA with preoperative and postoperative gait analyses were included. To minimise physical bias, sex, age, height, and weight were matched between groups using propensity score matching, resulting in 14 participants per approach. Walking velocity, cadence, step length, and hip motion angle were assessed preoperatively, as well as at 3, 6, and 12 months postoperatively. Additionally, PROMs were evaluated using the Japanese Orthopaedic Association Hip Disease Evaluation Questionnaire (JHEQ) at each time point. RESULTS: At 3 months postoperatively, the CPP group exhibited significantly higher walking velocity (CPP: 120.4 ± 17.1 cm/s; PL: 103.2 ± 22.5 cm/s, p = 0.041) and cadence (CPP: 118.0 ± 6.1 steps/min; PL: 110.3 ± 9.4 steps/min, p = 0.012) compared to the PL group. However, no significant differences were observed after 6 months. Among the JHEQ scores, only the 'movement' domain was significantly higher in the CPP group at 3 months, mirroring the gait analysis results, with no significant differences thereafter. CONCLUSIONS: Compared to the PL approach, the CPP approach enhanced walking velocity, cadence, and movement-related PROMs during the early postoperative period of up to 3 months.