# Restoration of Hip Kinematics After Arthroscopy for Femoroacetabular Impingement Syndrome: A 1-Year Evaluation of Gait and Stair Performance

## TL;DR

Hip arthroscopy for femoroacetabular impingement syndrome improves hip movement during walking and stairs, but these changes don't match patient-reported improvements in function and pain.

## Contribution

This study shows that hip arthroscopy restores hip movement in patients with FAIS during dynamic tasks, though improvements in movement don't correlate with patient-reported outcomes.

## Key findings

- Hip arthroscopy significantly improved hip flexion, abduction, and external rotation during gait and stair tasks.
- Patient-reported outcomes improved significantly at 1 year post-surgery, but these did not correlate with kinematic improvements.
- Preoperative hip kinematics showed deficits compared to the contralateral hip, which were corrected postoperatively.

## Abstract

Femoroacetabular impingement syndrome (FAIS) is common in athletes, and the effect of biomechanics and biomechanical alterations after hip arthroscopy continues to be investigated. This study aimed to assess the effect of hip arthroscopy on biomechanical function in patients with FAIS during gait, stair ascent, and stair descent.

Patients with FAIS would exhibit decreased motion preoperatively compared with contralateral asymptomatic hips, but these differences would be corrected postoperatively and these changes would correlate to improvements in patient-reported outcome measures (PROMs).

Case series; Level of evidence, 4.

Ten patients undergoing hip arthroscopy for FAIS were included and completed PROMs as well as kinematic assessment at baseline and 1 year postoperatively. 3D motion tracking was performed using a 10-camera system while patients performed gait, stair ascent, and stair descent. Joint kinematic parameters were calculated in the sagittal, coronal, and transverse planes for the symptomatic and contralateral side. Peak and valley angles for each joint during each task were compared between limbs using linear mixed-effects models. Significant changes in kinematics were correlated to PROMs.

Preoperatively, the symptomatic hip demonstrated significant deficits in gait and stair ascent compared with the contralateral hip. During gait, hip kinematics increased compared with before surgery with respect to flexion (+7.7°± 7.3°), abduction (+2.4°± 3.2°), and external rotation (ER) (+3.0°± 4.9°) (P < .01). During stair ascent, hip abduction (+2.8°± 1.7°) and ER (+2.8°± 5.7°) were significantly increased (P < .01). During stair descent, hip flexion (+2.5°± 6.4°), extension (+3.9°± 8.3°), abduction (+2.3°± 2.6°), and ER (+4.8°± 4.3°) were significantly increased (P < .01). Significant improvements were seen in patient-reported outcomes, but these did not correlate to hip kinematics.

Hip arthroscopy for FAIS improved hip flexion, abduction, and ER during dynamic tasks such as gait, stair ascent, and stair descent comparable with the contralateral extremity. Additionally, patients reported significant improvement in function and pain at 1 year postoperatively, but these improvements did not correlate with improvements in hip kinematics.