ePoster #124 - ISHA Annual Scientific Meeting 2016

Arthroscopic Management of Patients with Acetabular Undercoverage

Aman Sharma, MS, Winston-Salem, NC UNITED STATES
Alejandro Marquez-Lara, MD, Winston Salem, NC UNITED STATES
T. David Luo, MD, Winston-Salem, NC UNITED STATES
Elizabeth A. Howse, MD, Walnut Creek, CA UNITED STATES
Austin V. Stone, MD, PhD, Winston-Salem, NC UNITED STATES
Sandeep Mannava, MD, PhD, Winston Salem, NC UNITED STATES
Allston J. Stubbs, MD, MBA, Winston Salem, NC UNITED STATES

Wake Forest University School of Medicine, Winston-Salem, North Carolina, UNITED STATES

FDA Status Not Applicable

Summary: This retrospective review compared the clinical presentation, pathology and arthroscopic procedure in patients with normal- versus under-coverage of the femoral head. Femoral head undercoverage was associated with female gender, lower BMI and reduced likelihood of undergoing arthroscopic acetabuloplasty. Understanding anatomic variability may guide treatment in patients undergoing hip arthroscopy.

Introduction: Acetabular undercoverage is often associated with hip instability and can affect outcomes in patients undergoing hip arthroscopy. However, current hip preservation techniques inadequately assess the effect of femoral head coverage on hip pathology. The purpose of this study was to compare the clinical presentation, pathology and arthroscopic procedure in patients with normal coverage versus undercoverage of the femoral head.
Methods: A database of 791 patients who underwent hip arthroscopy by a single surgeon between 2008 and 2015 was queried. Patients were excluded if they were less than 18 years old, had a diagnosis of hip dysplasia or had pincer-type impingement. The selected cohort was stratified based on coverage of the femoral head. Undercoverage was defined as lateral center edge angle (LCEA) <20°, anterior cell edge angle (ACEA) <20°, Sharp’s acetabular angle >42° and alpha angle <60°. Physical exam findings (internal rotation, terminal flexion), patient demographics, clinical presentation, pre-operative diagnostic imaging studies and arthroscopic intervention were compared between the two cohorts. Logistic regression analysis was performed with a 95% CI to determine the relationship between coverage and hip pathology. A p-value of <0.05 denoted statistical significance.
Results: A total of 499 patients were analyzed of which, 154 (30.9%) met criteria for undercoverage. Based on our defined criteria, hips with undercoverage had lower LCEA (25.5±4.8 vs 30.1±4.4, p<0.001), ACEA (26.7±6.9 vs 30.1±5.1, p<0.001), and higher Sharp’s angle (44.1±2.6 vs 38.8±2.6, p<0.001) compared to control hips. The undercoverage cohort had a greater proportion of females (81.8% vs. 58.8%, p<0.001) and lower body mass index (24.0±4.1 vs. 26.7±5.9 Kg/m2, p<0.001) compared to control hips. There were no significant differences in hip symptoms, pain with activity, duration of symptoms, and pathological findings on diagnostic imaging studies. However, patients with undercoverage demonstrated significantly greater hip internal rotation on both the operative (10.6±12.4 vs. 8.4±10.4, p=0.043) and non-operative sides (19.4±10.8 vs. 16.4±12.4, p=0.015). Logistic regression analysis demonstrated decreased odds of undergoing acetabuloplasty in patients with undercoverage (OR = 0.21, 95%CI: 0.12-0.34, p<0.001).
Discussion and Conclusion: This retrospective review demonstrated that patients with acetabular undercoverage were most likely female and had a lower BMI compared to control hips. In addition, despite similar clinical presentation, patients with hip undercoverage were less likely, than patients with normal hips, to undergo arthroscopic acetabuloplasty. Given the inherent risk of hip instability in patients with acetabular undercoverage, the likelihood of requiring rim resection is low. These findings highlight the importance of understanding the variability in patient anatomy and how it can affect the management of patients undergoing hip arthroscopy.