Piriformis preserving posterior approach STAR for primary and primary complex total hip arthroplasty: Excellent safety and efficacy in a single blinded prospective single surgeon cohort of 522 patients with a mean follow-up of 2 years.

Introduction: STAR (Superior Transverse Anatomic Reconstruction), a piriformis-preserving posterior approach, has not been extensively studied. Our study aimed to assess the STAR approach's safety and efficacy by recording postoperative complication rates and measuring implantation accuracy in a single surgeon prospective cohort with a mean follow-up of two years.

Methods: The study involved 522 patients with elective primary or complex primary total hip arthroplasty (THA) performed by a senior surgeon using the STAR approach between 2019 and 2023. 63.6% of the patients were female. The mean patients' age was 65.6 years. 19.5% of the procedures were primary complex THAs. The mean follow-up and length of stay were 2.13 years and 1.50 days. The ratio of uncemented to hybrid and standard to dual mobility liner THAs were 3:2 and 4:1. Fifty-eight patients received blood transfusions. All patients followed the same postoperative protocol. Two physicians not involved in surgery collected clinical and radiological data. Efficacy was defined as measuring the cup inclination and anteversion, stem alignment, and leg length discrepancy (LLD) using the one-month postoperative standardised supine anteroposterior pelvic X-rays. The postoperative complication rate, including dislocation and infection, defined safety.

Results: The mean cup inclination and anteversion were 42.8⁰ (±4.9) and 19.9⁰ (±8.9), respectively. 97.5% of the stems were placed in neutral and 2.5% in varus position. The mean LLD was 3.3 ± 6.3 mm. A single deep infection was managed with two-stage revision with no recurrence, and an early traumatic dislocation in an 80-year-old woman was managed successfully with closed reduction and hip spica. Three superficial wound infections were treated with oral antibiotics.

Discussion: The STAR approach is safe and has demonstrated excellent early-to-mid-term efficacy profile outcomes. The unobstructed acetabular and femoral intraoperative view facilitated optimal implant positioning and contributed to excellent dislocation outcomes in combination with piriformis preservation.