FP6.5 Borderline Dysplastic Hips Demonstrate Increased Axial Distraction Distance on an Intraoperative Traction Exam

Purpose: To evaluate the intraoperative distraction profile of borderline dysplastic individuals compared to non-dysplastic hips undergoing arthroscopic surgery for femoroacetabular impingement.

Methods: This study was a retrospective analysis of prospectively collected data. Intraoperative distraction profile, radiographic, and patient demographic data were compiled in a database. All patients with borderline dysplastic hips, as determined by the lateral center edge angle of 18°-25°, comprised the borderline dysplastic cohort. A cohort of hips with normal femoral head coverage comprised the normal group. Demographic variables across groups were compared to ensure similarity. Between group comparisons of axial distraction distance at 25, 50, 75 and 100 pounds-force were conducted using Student’s t-test. A multivariable regression was conducted to control for covariates.

Results: One hundred thirty-six normal hips and 36 borderline dysplastic hips were identified for comparison. Demographic variables were similar between groups. The dysplastic group demonstrated greater axial distractibility at 75 (6.47±2.95 vs. 5.07±3.11, p=0.016) and 100 (9.47±2.00 vs. 7.95±2.50, p=0.001) pounds-force of traction force. Multivariable linear regression demonstrated increased distraction associated with female patients, smaller alpha angles, and less coverage measured by the lateral center edge angle.

Conclusions: In a population undergoing hip arthroscopy for femoroacetabular impingement, patients with borderline hip dysplasia demonstrated greater intraoperative axial distraction distance when compared with non-dysplastic hips. These in-vivo biomechanical data demonstrate soft tissue laxity differences in dysplastic patients and should be considered when planning capsular management techniques.

Level of Evidence: III, Retrospective Review