Hip arthroscopy has good clinical outcomes in the treatment of osteoid osteoma of the acetabulum

BACKGROUND: Osteoid osteoma (OO) of the acetabulum is a relatively rare disease. However, the the clinical outcomes of hip arthroscopy for treatment of OO of the acetabulum are still uncertain. METHODS: We evaluated consecutive patients who were diagnosed with OO of the acetabulum and who underwent hip arthroscopy at our hospital between January 2013 and March 2020. All patients underwent a preoperative physical examination. Preoperative supine anteroposterior hip radiography, cross-table lateral radiographs, computed tomography (CT), and magnetic resonance imaging were performed in all patients. The alpha angle and lateral center-edge angle were measured before surgery. Supine anteroposterior hip radiography and CT were performed in all patients postoperatively. Preoperative patient-reported outcomes (PROs), including Visual Analog Scale (VAS), the International Hip Outcome Tool-12 (iHOT-12) and modified Harris Hip Score (mHHS), and PROs at final follow-up were evaluated. RESULTS: A total of 6 patients (mean age, 18.7 years; age range, 6–31 years; 5 males and 1 females) were included in this study. The average follow-up period after surgery was 28.3 months (range, 6–90 months). Before surgery, the mean mHHS was 45.2 ± 10.5 (range, 33–56), the mean iHOT-12 was 33.3 ± 14.5 (range, 13–49), and mean VAS was 8.2 ± 1.0 (range, 7–9). At one month after surgery, mean mHHS was 78.7 ± 1.9 (range, 77–81), iHOT-12 was 71.0 ± 4.5 (range, 68–80), and mean VAS was 0. At the final post-operative follow-up, mean mHHS was 89.2 ± 2.1 (range, 86–91), iHOT-12 was 93.5 ± 5.0 (range, 88–98), and mean VAS was 0. All results, except VAS between one month after surgery and at final follow-up, demonstrated statistically significant improvement (P < 0.05). One patient underwent revision surgery. CONCLUSIONS: Hip arthroscopy has good clinical outcomes in the treatment of OO of the acetabulum. Further study on the mechanism of secondary femoroacetabular impingement (FAI) caused by OO of the acetabulum is needed. More cases of arthroscopic excision and longer follow-up are also needed to better prove the clinical outcomes of hip arthroscopy for OO of the acetabulum.