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Three-Dimensional Morphometric Characterization of Femoral Cam Lesions: Quantifying the Radial and Lateral Extents
Elizabeth Y West1, Michael J Rasiej1, Michael Bloom1
1New York Presbyterian Hospital - Columbia University Irving Medical Center, New York, NY.
Insights
Cam lesions in femoroacetabular impingement (FAI) are larger in males, elite athletes, and those with a BMI over 25. Alpha angle, radial, and lateral extents correlate, but normal alpha angles may mask distal lesions.
Area of Science:
- Orthopedic surgery
- Radiology
- Sports medicine
Background:
- Femoroacetabular impingement (FAI) is a hip condition characterized by abnormal bone morphology.
- Cam lesions are a common finding in FAI, potentially leading to cartilage damage and osteoarthritis.
- Accurate quantification of cam lesion extent is crucial for surgical planning and predicting outcomes.
Purpose of the Study:
- To quantify the radial and lateral extents of femoral cam lesions in FAI patients.
- To correlate these extents with the alpha angle (α) and clinical data.
- To identify risk factors associated with larger cam lesions.
Main Methods:
- Retrospective analysis of 81 hips with cam morphology undergoing arthroscopic surgery.
- CT measurements of alpha angle (α), radial, and lateral extents of cam lesions at each hour mark.
- Correlation with clinical and arthroscopic data using statistical analysis (t-test, chi-squared, logistic regression).
Main Results:
- Larger α and extents were observed in males and elite athletes.
- Male sex, BMI > 25, and elite sports participation were independent risk factors for larger radial extents.
- A 16% prevalence of distal cam lesions with normal α angles was noted, potentially underestimating lesion extent.
Conclusions:
- A positive correlation exists between alpha angle, lateral, and radial extents of cam lesions.
- Male sex, elite sports participation, and BMI > 25 are associated with larger cam lesions.
- Normal alpha angles may not exclude distal cam lesions, highlighting the need for comprehensive assessment.
Objective:
To quantify the radial and lateral extents of femoral cam lesions in FAI patients relative to the alpha angle and correlate with clinical data.
Methods:
Retrospective study of 81 hips with femoral cam morphology that underwent arthroscopic surgery between 2017 and 2019. At each hour over the clockface, the alpha angle (α) (abnormal defined as > 55°), radial extent, and lateral extent of cam lesions were measured on CT. These measurements were correlated with clinical and arthroscopic data. Statistics included independent samples t-test and chi-squared test with Bonferroni correction and multivariate logistic regression.
Results:
Larger α at 12:00-4:00 in males vs females (56.6-63.4° vs 44.3-58.5°, P < 0.001) and at 2:00-4:00 with elite sports participation vs without (56.7-70.9° vs 49.6-61.1°, P ≤ 0.004). Independent risk factors for radial extent beyond 12:00-3:00 were: male sex (OR 4.82, 95% CI [1.46, 15.85], P = 0.010), BMI > 25 (OR 4.74, 95% CI [1.61, 14.00], P = 0.005), and elite sports participation (OR 3.28, 95% CI [1.09, 9.82], P = 0.034). Lateral extent increased at 1:00-4:00 in males vs females (7.8-18.6 mm vs 1.6-9.1 mm, P < 0.0001). A 16% prevalence of distal cam lesions was found at locations with normal α, resulting in underestimation of radial extent by an average of 1.7 hours.
Conclusion:
There is a positive correlation between the alpha angle, lateral extent, and radial extent of cam lesions. FAI patients who were male, participated in elite level sports, and had a BMI > 25 had larger cam lesions. A larger alpha angle is a risk factor for cartilage damage. Patients may have distal cam lesions at locations with normal alpha angles, though their significance is unknown.
