Quantitative Evaluation of Hip Impingement Utilizing Computed Tomography Measurements

* Computed tomography (CT) offers tremendous advantages in the evaluation of femoroacetabular impingement (FAI), as it allows precise measurements of osseous landmarks and relationships preoperatively and postoperatively. * Important femoral measurements to make on CT include the alpha angle, modified beta angle, femoral version, femoral head-neck offset, and femoral neck-shaft angle. * Key acetabular measurements to make on CT include the coronal and sagittal center-edge angles, the Tönnis angle, and the acetabular version. * Three main settings in which CT imaging is utilized for the evaluation of FAI are preoperative surgical planning using 3-dimensional modeling, the assessment of persistent hip pain after hip arthroscopy or a definitive surgical procedure, and the evaluation of patients requiring revision surgery. * Extra-articular hip impingement syndromes, including ischiofemoral impingement, subspine impingement, and trochanteric-pelvic impingement, are increasingly recognized as important causes of atypical hip pain, often with delayed diagnosis due to nonspecific presentation and inadequate clinical and imaging workup.