Early results of surgery for femoroacetabular impingement in patients with osteonecrosis of femoral head

Abstract

Purpose: Femoroacetabular impingement and its surgical treatment have not been described before in osteonecrosis of femoral head. We present here outcomes of 15 patients with femoroacetabular impingement secondary to osteonecrosis of femoral head. This results from partial collapse of femoral head, particularly in the anterosuperior region, secondary to osteonecrosis. With subsequent remodelling, periphery of the femoral head flattens and osteophytes form in this area. All these patients were managed with open/arthroscopic osteochondroplasty of femoral head. Methods: These patients were symptomatic for hip impingement. Cam deformity was studied using computed tomography and magnetic resonance imaging. In six patients open osteochondroplasty was carried out using surgical hip dislocation. In nine patients arthroscopic femoral head osteochondroplasty was done. All the patients were followed up for hip pain (VAS), Harris hip score (HHS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and hip range of motion. Results: A statistically significant improvement in the VAS for pain, HHS, and WOMAC score was noted. Average HHS improved from 71.3 (SD, 13) to 89.7 (SD, 14.5), p-value 0.0079. Average WOMAC improved from 73.6 (SD, 15.4) to 92.4 (SD, 16), p-value 0.0154. Impingement test became negative in all the patients. A significant improvement in hip ROM was noted. There was no conversion to total hip arthroplasty. All patients could sit on the floor cross-legged and squat. Conclusion: Some patients with partial collapse of femoral head due to osteonecrosis present chiefly with symptoms of femoroacetabular impingement. They should be identified as osteochondroplasty gives successful results in these patients. Level of evidence - IV.