Clinical presentation of anterior pelvic tilt and trunk muscle endurance among patients with femoroacetabular impingement syndrome: a cross-sectional study.

Background: Femoroacetabular impingement syndrome (FAIS) significantly affects the physical function and quality of life of the young and middle-aged population. Pelvic tilt and trunk muscle endurance are physical features poorly studied in FAIS.

Aim: This study aimed to compare the anterior pelvic tilt and anterior, lateral, and posterior trunk muscles endurance between people with FAIS and healthy individuals, within FAIS sub types and between the symptomatic and asymptomatic hip in people with FAIS.

Design: Cross-sectional study.

Settings: Participants were recruited and screened for potential eligibility at the Rehabilitation, Sports Medicine, and Physiotherapy Unit between April 2021 and February 2022.

Population: Sixty-nine patients with FAIS and 69 controls.

Methods: A study adhering to STROBE guidelines recruited 138 participants (69 FAIS, 69 controls). The degree of pelvic tilt was measured by the palpation meter (PALM) tool. To assess trunk musculature endurance, isometric trunk tests described by McGill were performed (extension resistance test, flexion resistance test, and side plank test). Cases were classified based on FAIS subtypes. Differences between groups and subgroups were performed using t-tests and ANCOVA, respectively.

Results: Significant differences in anterior pelvic tilt were observed between the control and FAIS groups (P<0.001, d=0.72). Participants with FAIS exhibited greater pelvic tilt (MD=1.57, 95% CI=0.83 to 2.3). Trunk muscle endurance showed statistically significant differences (P<0.001, d=0.72) for posterior muscles. In comparisons between symptomatic and asymptomatic hips, significant differences were found in pelvic tilt (P<0.001, d=0.26) and lateral trunk muscle endurance (P<0.001, d=0.43). FAIS subtypes demonstrated significant differences in lateral trunk muscle endurance (P=0.002, ηp2=0.209).

Conclusions: This study found that patients with FAIS present large anterior pelvic tilt and lower posterior trunk muscle endurance. Although anterior pelvic tilt was comparable for all FAIS subtypes, Pincer-type with or without labral tear exhibited lower lateral trunk muscle endurance compared with Cam-type with or without labral tear. In addition, the symptomatic hip of FAIS patients showed lower lateral trunk muscle endurance compared to the asymptomatic hip.

Clinical rehabilitation impact: Incorporating rehabilitation strategies that address pelvic tilt and trunk muscle strengthening in individuals with FAIS might be considered as a potential means to improve these physical impairments, pending careful evaluation of their effectiveness.