3D CT segmentation of CAM type femoroacetabular impingement-reliability and relationship of CAM lesion with anthropomorphic features.

OBJECTIVE:: Evaluate feasibility and reliability of 3DCT semi-automatic segmentation and volumetrics of CAM lesions in femoroacetabular impingement and determine correlations with anthropometrics.

METHODS:: A consecutive series of 43 patients with CAM type FAI underwent 3DCT. 20 males and 23 females (30 unilateral and 13 bilateral symptomatic hips) were included. 56 CAM lesions and femoral heads were segmented by two readers. Radial images were obtained for alpha angles. Pearson and ICC correlations were used for analysis.

RESULTS:: In 43 patients (male: female = 1 : 1.15), mean ± SD of age, height, BMI were 36.6 ± 11.47 years, 1.72 ± 0.10 meters and 26.25 ± 4.31  kg m- ². Femoral head and bumps were segmented in 4  min. Inter reader reliability was good to excellent for volumetrics and poor for alpha angles. Mean ± SD of CAM lesion and femoral head volumes were significantly larger (6.7 ± 2.5 cc3 and 62.9 ± 10.8 cc3 ) for males than females (p < 0.001) and these increased with increasing patient height (Pearson correlation and p-values = 0.45, 0.0006; 0.82, < 0.0001 respectively).

CONCLUSION:: Volumetric analysis of CAM lesion shows better inter reader reliability than alpha angle measurements. CAM and femoral head volumes exhibit significant positive correlations with patient heights and male gender that may aid in pre-operative planning for femoroplasty.

ADVANCES IN KNOWLEDGE:: Femoral head & CAM volumes are segmented three times faster than alpha angles with superior inter reader reliability than alpha angles. Femoral head & CAM volumes are significantly larger in males and positively correlate with patients' heights.