Association Between Lower Limb Kinematics During Single Leg Squat and Patient-Reported Outcomes After Hip Arthroscopy...

Typically, 3 months is an early postoperative time point at which patients with femoroacetabular impingement syndrome (FAIS) demonstrate clinically meaningful improvement, while 6 months represents an important midterm stage for recovery and return to sport.

To assess continuous changes in the kinematics of the involved and uninvolved lower limbs in patients with FAIS at 3 and 6 months after hip arthroscopy as well as to examine their relationships with International Hip Outcome Tool-33 (iHOT-33) and Copenhagen Hip and Groin Outcome Score Sport subscale (HAGOS-Sport) scores.

Cohort study; Level of evidence, 2.

The study included 15 patients who underwent hip arthroscopy between March 2024 and November 2024 as well as a healthy control group of 15 participants, matched to the patients by sex, age, and body mass index, recruited from the community. All participants performed the single-leg squat (SLS), and kinematic data were collected using an 8-camera motion capture system. One-way analysis of variance was used to compare baseline, 3-month postoperative, and 6-month postoperative kinematic data of the FAIS group with those of the healthy control group. Post hoc comparisons were conducted using the Tukey test to determine between-group differences. Correlation analysis was performed to assess the relationship between changes in the hip flexion angle and changes in iHOT-33 and HAGOS-Sport scores.

At 3 months postoperatively, the involved limb hip flexion angle (P = .021), hip adduction angle (P = .0011), knee flexion angle (P = .016), and change in the center of mass (P = .0034) were reduced compared with the healthy control group. At 6 months postoperatively, no significant kinematic differences were observed between the FAIS and healthy control groups. Correlations between changes in the iHOT-33 score at 3 months and changes in the hip flexion angle at 6 months were positive (r = 0.64; P = .0094), and changes in the iHOT-33 score at 6 months were also positively correlated with changes in the hip flexion angle at 6 months (r = 0.53; P = .041).

Patients with FAIS exhibited abnormal kinematics during the SLS at 3 months postoperatively, which showed improvement by 6 months. Furthermore, improvement in sagittal-plane angles of the hip at 6 months postoperatively was correlated with the iHOT-33 score, supporting our hypothesis. Clinicians should not overlook functional recovery after hip arthroscopy for FAIS.