Relationship Between Cam Lesion Size, Its Excision, and Hip Osteoarthritis Progression: A Contralateral-Controlled Study Using Joint Space Width After Unilateral Hip Arthroscopy

Background: The effect of hip arthroscopy on the natural progression of osteoarthritis is still unclear. Purpose: To clarify the relationship between unilateral hip arthroscopy, the size of the cam lesion, and its excision on the progression of hip osteoarthritis. Study Design: Cohort study; Level of evidence, 3. Methods: A total of 105 patients who underwent unilateral hip arthroscopy due to femoroacetabular impingement and had a minimum of 2 years of follow-up were included. Joint space width (JSW) measurements were made at the medial (MJW), lateral (LJW), and central (CJW) aspects of the sourcil line on anteroposterior supine pelvis radiographs. The alpha angle (α) was measured using preoperative and early postoperative Dunn 45° radiographs. Results: LJW decreased and was more obvious in men than in women in the operated hips. All LJWs, MJWs, and CJWs decreased on the contralateral nonoperated hips ( P < .05). The operated sides had higher MJW compared with the contralateral nonoperated sides (3.58 ± 0.75 mm vs 3.34 ± 0.6 mm; P = .02) and a lower decrease of medial joint space compared with contralateral sides (Δ1, −0.05 mm; Δ3, −0.3 mm; P = .00). At the final follow-up, central joint space was greater in the operated hips compared with the contralateral hips in patients with higher preoperative alpha angle (α 0 ) (≥0.1 mm vs <0.1 mm; preoperative α, 81 vs 79; P = .03). Conclusion: Patients treated with unilateral hip arthroscopy demonstrated a decrease in the LJW, while nonoperated sides had a decrease in all 3 widths, leading to a greater joint space in the operated hip, especially at the MJW. Furthermore, patients having more severe cam deformity preoperatively had better preservation of CJW.