What are the key factors influencing traction force in postless hip arthroscopy: a retrospective case-control study

Perineal post countertraction during hip arthroscopy risks complications. Postless traction avoids the perineal post but requires understanding the factors influencing traction force to optimize safety. This study investigated how gender, body mass index (BMI), traction states, hip rotation, lateral center-edge angle (LCEA), alpha angle, and femoral anteversion affect traction force during postless hip arthroscopy. This retrospective study included patients undergoing postless hip arthroscopy for femoroacetabular impingement syndrome (FAIS) between October 2023 and March 2024. Inclusion criteria comprised confirmed FAIS diagnosis and comprehensive intraoperative traction force documentation across six traction states (initial traction to 40 min post-capsulotomy) and three rotational positions (neutral, internal/external rotation at 15°). Traction force was measured using a force sensor. Preoperative LCEA, alpha angle, and femoral anteversion were radiographically assessed. Mann-Whitney U tests and repeated-measures ANOVA were used to assess sex-, state-, and rotation-related effects on traction force; Pearson or Spearman correlation analyses were used to analyze associations between BMI, alpha angle, LCEA, femoral anteversion, and traction force. A total of 34 patients (10 males, 24 females) were included in this study. Traction forces increased from initial gross traction to needle puncture of the capsule (P < 0.001), then decreased post-puncture (P < 0.001). In the vast majority of traction states, external or internal rotation position required higher forces than the neutral position to achieve adequate joint distraction for surgical visualization (P < 0.001). Males exhibited greater forces than females (P < 0.001). Positive correlations included BMI, LCEA, and alpha angle (P < 0.05). Femoral anteversion angle negatively correlated with traction. It was also found that LCEA was positively correlated with the difference in traction force between different rotational positions, while femoral anteversion was negatively correlated (P < 0.05). Traction force during postless hip arthroscopy increases with higher BMI, larger LCEA, and elevated alpha angle, while greater femoral anteversion reduces traction requirements. Male gender and internal or external hip rotation consistently demand higher forces compared to females and neutral rotation. Traction force decreases after joint puncture and capsulotomy and decrease over time during surgery.