Utility of Ultrasound‐Guided Anesthetic Intra‐articular Injection to Estimate the Outcome of Hip Arthroscopy in Patients with Femoroacetabular Impingement Syndrome

OBJECTIVE: To investigate the effectiveness of ultrasound (US) guided intra‐hip joint injection to estimate the outcome of hip arthroscopy in patients with femoroacetabular impingement (FAI) syndrome. METHODS: Patients with FAI syndrome (n = 60) were prospectively enrolled in our study. Before hip arthroscopy, a mix of 4 mL 2% lidocaine and 4 mL 1% ropivacaine were injected into the hip joint under the guidance of US. The clinical efficacy of the intra‐articular injection was evaluated by comparing the visual analog scale (VAS) and international hip outcome tool 12 (iHOT‐12) results before and after the injection. The outcome of hip arthroscopy was evaluated by iHOT‐12, the modified Harris hip score (MHHS), and the patient's satisfaction 12 months after the operation. The outcome of intra‐articular injection and hip arthroscopy were compared. Factors related to the outcomes of hip arthroscopy were evaluated. The correlation between the efficacy of intra‐hip joint injection and arthroscopy was evaluated. RESULTS: The VAS of patients decreased from 11.3 ± 7.7 to 3.3 ± 4.5, and the iHOT‐12 increased from 52.1 ± 23.2 to 84.1 ± 18.1 after intra‐articular injection (all P < 0.001). The iHOT‐12 score increased from 52.1 ± 23.2 to 78.9 ± 19.2, and the MHHS increased from 66.5 ± 6.8 to 81.6 ± 8.1 after hip arthroscopy (all P < 0.001). The satisfaction rate of arthroscopy, including very satisfied and effective patients, was 93.3%. Multi‐variable logistic regression showed that only iHOT‐12 improved value after injection was included in the regression formula of satisfaction, with the β of −0.154, standard error of 0.071, Wald value of 4.720, and OR of 0.857 (95%CI 0.746–0.985) (P = 0.03). Significant correlation was detected between iHOT‐12 scores after intra‐articular anesthesia and at 12 months after arthroscopy (r = 0.784, P < 0.001). So was the iHOT‐12 improved value (r = 0.781, P < 0.001) and the iHOT‐12 improved ratio (r = 0.848, P < 0.001). If we had performed arthroscopy only on patients with post‐injection iHOT‐12 score improvement ≥10, the satisfaction rate of arthroscopy would have increased to 96.6%. CONCLUSIONS: US‐guided intra‐hip joint injection may provide a feasible way to estimate the outcome of hip arthroscopy in patients with FAI syndrome, and could be used as a method for indication selection of hip arthroscopy.