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Does Femoroacetabular Impingement Etiology Correlate with the Location of Labral Tears?

By: Kristi Billard, Dr. Haron Obaid, Dr. Jordan Buchko, & Dr. Ian Lutz

Purpose: Femoroacetabular Impingement (FAI) is a painful hip condition that affects young people. There are many causes for FAI – CAM lesions, acetabular over-coverage, femoral retroversion (FR), and poor pelvic biomechanics. FAI can cause abnormal contact about the hip joint leading to painful labral tears. The purpose of this study is to determine whether the etiology of FAI correlates with the location of these tears.

Method: In this retrospective study, 342 charts were reviewed with referrals for nonarthritic hip pain. Of the 315 cases with FAI, 108 were found to have labral tears, of which 89 were included. The patients were divided into one of four groups: FR, CAM, Mixed (FR + CAM), and Other. Labral tear locations were categorized as Superior or Anterior. Statistical analysis was completed using to determine if any correlation or differences between the groups existed.

Results: The groups were as follows: FR (n=26), CAM (n=19), Mixed (n=35) and Other (n=9). In the FR group, 61.5% had anterior tears; in the CAM group, 84.2% had superior tears. Chi-squared analysis demonstrated a statistically significant difference between all groups for tear location (p=0.0008). A univariate analysis comparing the FR and CAM groups revealed an odds ratio of 8.53 (p=0.004) meaning that patients with anterior tears were 8.53 times more likely to have FR than a CAM.

Conclusion: Biomechanical models suggest that in FAI secondary to FR, the anterior femoral neck comes in contact with the acetabulum, resulting in anterior tearing. This information will be useful in determining the etiology of a patient’s impingement. FR requires 3D imaging to diagnose, and therefore is often missed, leading to poorer outcomes in hip arthroscopy. With this new information, an anterior labral tear should prompt investigation for FR as a possible diagnosis leading to fewer missed diagnoses and better patient outcomes.

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