Ultrasound and Ultrasound-Guided Hip Injection Have High Accuracy in the Diagnosis of Femoroacetabular Impingement With Atypical Symptoms

Purpose: To evaluate the diagnostic value of ultrasound and ultrasound-guided hip injection in the diagnosis of femoroacetabular impingement (FAI) with atypical symptoms.

Methods: We evaluated consecutive patients diagnosed with FAI and with atypical symptoms who underwent ultrasound-guided hip injection between January 2017 and February 2019. All patients underwent systematic physical examination, ultrasound examination, magnetic resonance imaging (MRI) examination, and ultrasound-guided injection before surgery. Patients with positive response to ultrasound-guided hip injection were recommended to undergo arthroscopic surgery to treat intra-articular pathology. Sensitivity, specificity, accuracy, and positive predictive value (PPV) of ultrasound and MRI were calculated by using arthroscopic surgery as the gold standard. The accuracy of ultrasound-guided hip injection was recorded. Preoperative and postoperative patient-reported outcomes included visual analog scale for pain and modified Harris Hip Score.

Results: A total of 78 patients with atypical symptoms were diagnosed with FAI. Among these 78 patients, 50 patients had positive responses to injection and 28 patients had negative responses to injection. A total of 36 patients finally underwent arthroscopic surgery. Response to the ultrasound-guided intra-articular injection was 91.7% accurate for detecting the presence of intra-articular abnormality. There were no complications of injection in any of the patients. The sensitivity, PPV, and accuracy by ultrasound diagnosis of cam impingement were 82.9%, 96.7%, and 80.6%, respectively. The sensitivity and accuracy by ultrasound diagnosis of anterosuperior labral tear were both 72.2%. For MRI diagnosis of cam impingement, the sensitivity, PPV and accuracy were 72.2%, 96.3%, and 74.3%, respectively. For MRI diagnosis of labral tear, the sensitivity and accuracy were both 88.9%. Thirty-four patients (94.4%) surpassed the minimal clinically important difference, and 33 patients (91.7%) achieved the patient acceptable symptomatic state.

Conclusions: Ultrasound and ultrasound-guided hip injection have high accuracy in the diagnosis of femoroacetabular impingement with atypical symptoms.

Level of evidence: IV, case series.