Pre- and post-operative evaluation of pincer-type femoroacetabular impingement during squat using image-matching techniques: A case report

Introduction Although combined evaluation of hip joint kinematics and bone morphology is necessary for accurate assessment of femoroacetabular impingement (FAI), there are no report which evaluated hip kinematics of pincer-type FAI. Presentation of case The pre- and postoperative hip kinematics of a 46-year-old man, with a pincer-type FAI during squat were evaluated using image-matching techniques and the rim-neck distance was measured. Preoperative simulation of squatting was also performed using patient's bone models and healthy subject's kinematics data to detect the overlapping lesion between the acetabulum and the femur. Post-acetabuloplasty, right coxalgia during squat disappeared, and the Harris Hip Score improved from 79 to 92 at one year after surgery. Posterior pelvic tilt, femoral and hip flexion angle changed from 24.0°, 101.1°, and 70.8° to 23.3°, 92.6°, and 63.3°, respectively. The minimum rim-neck distance at maximum hip flexion improved from 1.8 mm to 7.3 mm. Discussion We could evaluate both of hip kinematics and morphology with image-matching techniques, and could visualize the clearance between the femoral head-neck junction and the acetabular rim. Conclusion Image-matching techniques were clinically useful to assist surgeons in detecting the location of the impingement and confirming resection of the pincer lesion post-operatively.