The Effect of Sagittal Spinopelvic Parameters and Kinematics on the Morphology and Symptomatology of Femoroacetabular Impingement: A Systematic Review and Meta-analysis.

BACKGROUND

Femoroacetabular impingement (FAI) morphology is common in asymptomatic adults. Spinopelvic alignment modulates hip mechanics and influences hip range of motion. Specific spinopelvic parameters, such as pelvic incidence and dynamic parameters, have been inconsistently associated with FAI. Yet, their specific influence on FAI morphology and symptomatology remains uncertain.

PURPOSE: To determine how morphologic, postural, and dynamic spinopelvic parameters differ according to FAI morphology (cam, pincer) and symptomatology.

STUDY

DESIGN

Meta-analysis; Level of evidence, 3.

METHODS

PubMed, EMBASE, and Scopus were searched from inception to December 23, 2024. Studies reporting spinopelvic parameters in symptomatic or asymptomatic FAI compared with controls were included. Two reviewers independently screened, extracted data, and rated methodological quality (Newcastle-Ottawa Scale [NOS]). Fixed- or random-effects meta-analyses of mean differences were stratified by parameter, FAI type, and concept (morphology vs symptomatology).

RESULTS

A total of 41 studies (n = 3750; 1343 symptomatic, 821 asymptomatic FAI; 1586 controls; median NOS 6/9) were included. Symptomatic cam hips had higher pelvic incidence (PI) than asymptomatic cam hips (mean difference [MD], 4.94° [95% CI, -0.10 to 9.98]; P = .05). Pincer morphology was linked to lower PI versus controls (MD, -5.13° [95% CI, -8.70 to -1.57]; P < .01). No significant differences emerged for pelvic tilt or sacral slope. Cam FAI exhibited reduced posterior pelvic excursion in late-phase squat (MD, -5.23° [95% CI, -7.17 to -3.30]; P < .01) and a modest global excursion increase during gait (MD, 0.38° [95% CI, 0.05 to 0.72]; P = .03).

CONCLUSION

Low PI was linked to pincer morphology, suggesting a primary prevention target during development. Cam hips with higher PI were predisposed to symptoms. Symptomatic cam FAI also showed diminished pelvic rollback and increased anterior pelvic tilt, identifying kinematic targets for conservative management. Finally, dynamic spinopelvic characteristics more consistently demonstrated significant differences than static ones and may be more clinically pertinent in FAI research.