ePoster #735 - ISHA Annual Scientific Meeting 2016

Role Of Patient Activity Level In The Degenerative Process Associated With Cam Femoral Acetabular Impingement

Jose Smolders, MD, PhD, Ottawa, Ontario CANADA
Andrew Speirs, PhD, Ottawa, Ontario CANADA
Hanspeter Frei, PhD, Ottawa CANADA
Paul Beaule, MD, FRCSC, Ottawa, Ontario CANADA

University of Ottawa/Ottawa Hospital, Ottawa, Ontario, CANADA

FDA Status Not Applicable

Summary: UCLA activity shows a correlation with subchondral stiffening of the cam-deformity region and acetabular rim in cam-type FAI subjects as a result of mechanical overloading at the hip impingement site.

Abstract:
Background Cam morphology in association with femoroacetabular impingement (FAI) is proposed as a leading cause of osteoarthritis. Subchondral stiffness as shown by a higher bone mineral density (BMD), may increase joint contact stresses and lead to accelerated degeneration. The patient’s activity level may be a determining factor for (progression of) these early degenerative changes. Therefore we hypothesized that a higher activity level leads to higher subchondral BMD in FAI subjects. Methods Subjects undergoing surgical correction of a symptomatic cam-type deformity (“Surgical”, n=23), were compared to asymptomatic subjects with a normal alpha angle ("Control", n=18) or having a deformity ("Bump", n=26). Subchondral BMD of expected impingement locations were measured using QCT. Preoperative activity levels of all subjects were determined using the University of California Los Angeles (UCLA) activity score. Pearson correlations were determined between the UCLA activity scores and BMD. Results The UCLA scores of the Bump subjects were significantly higher compared to the Surgical group (8.96 vs 7.13, p=0.046), the difference between Control vs Surgical wasn't significant (8.68 vs 7.13, p=0.012). The Bump subjects showed mainly a positive correlation between activity level and BMD at anterior head-neck junction of the femur and anterior acetabular rim (R=0.398-0.506). The Surgical group showed a positive correlation (R=0.403-0.669) between activity level and BMD at all sections of the cam-deformity location and anterosuperior acetabular rim. Comparisons within the Control group showed no correlations. Conclusion UCLA activity shows a correlation with subchondral stiffening of the cam-deformity region and acetabular rim in cam-type FAI subjects as a result of mechanical overloading at the hip impingement site. No correlations were found in the control group, which supports the hypothesis that activity level does serve as a predictor for subchondral BMD in hip joints of cam-deformity subjects. These findings are consistent with increased activity level being a known risk factor for formation of the cam-deformity during skeletal maturation.