Arthroscopic Offset Restoration in Femoroacetabular Cam Impingement: Accuracy and Early Clinical Outcome

Purpose: The purpose of this study was to determine the accuracy of arthroscopic restoration of femoral offset as well as the early clinical outcome of arthroscopic debridement and femoral offset restoration and whether there is a correlation between accuracy and outcome. Methods: Twenty-two patients with symptomatic femoroacetabular cam impingement underwent arthroscopic correction of the femoral offset and debridement. The α angle was measured with magnetic resonance imaging preoperatively and postoperatively for quantification of the offset, and the clinical status was determined by documenting the impingement sign, range of motion, intensity of pain on a visual analog scale, Nonarthritic Hip Score, and complications preoperatively and 6 months postoperatively. Results: The α angle improved from a mean of 75° to 54°. Internal rotation increased from a mean of 5° to 22°, flexion increased from a mean of 107° to 124°, and the pain score decreased from a mean of 5.8 to 1.4. The Nonarthritic Hip Score increased from a mean of 49 to 74 points. No major complications were encountered. Patients with early osteoarthritis did substantially worse than those without it. The α angle did not correlate with any clinical outcome measure. Conclusions: The femoral offset can be precisely restored via an arthroscopic technique in the treatment of femoroacetabular cam impingement. The early clinical outcome of arthroscopic offset restoration and debridement is good in patients with no or only mild osteoarthritis. The accuracy of correction is not correlated with the early clinical outcome. Level of Evidence: Level IV, therapeutic case series.

Key Words: Hip arthroscopy, Femoroacetabular impingement, Cam, Offset, Restoration