Factors Associated with the Outcome of Ultrasound-Guided Trochanteric Bursa Injection in Greater Trochanteric Pain Syndrome: A Retrospective Cohort Study

Background: Trochanteric bursa injections of corticosteroids and local anesthetics have been shown to provide pain relief for the treatment of greater trochanteric pain syndrome (GTPS). However, symptom recurrence and incomplete symptom relief are common. The reason for the variation in response is unclear but may be related to disease-, treatment-, or patient-related factors. Objective: To determine whether there are factors related to patient, treatment, or disease that can predict either the magnitude or duration of response to ultrasound-guided trochanteric bursa injections for GTPS. Study Design: Retrospective evaluation. Setting: A university hospital outpatient center. Methods: Potential study participants were patients who underwent ultrasound-guided trochanteric bursa injection at an outpatient rehabilitation department. Follow-up interviews were performed in a hospital visit at 1, 3, and 6 months after injection. The Harris Hip Score and the Verbal Numeric Pain Scale were used to evaluate clinical effectiveness of pain reduction and functional improvement at baseline, 1, 3, and 6 months after treatment. Clinical data and ultrasound findings were obtained to assess the possible predictive factors for a good and durable response to ultrasound-guided trochanteric bursa injection. Results: Patients receiving ultrasound-guided trochanteric bursa injections had a statistically significant improvement in pain and hip function at 1, 3, and 6 months after the last injections. Of the 137 patients, 110 (80.3%), 95 (64.9%), and 77 (56.2%) patients achieved successful outcomes according to their 1, 3, and 6-month follow-up evaluations, respectively. Univariate analysis showed that patients with knee osteoarthritis and lumbar facet joint or sacroiliac joint pain experienced less therapeutic effect than those without the conditions at 6 months post-injection. Logistic regression analysis showed that the significant outcome predictors at the 6-month followup were facet joint or S-I joint pain (odds ratio = 0.304, P = .014) and knee osteoarthritis (odds ratio = 0.329, P = .021). Age, gender, body mass index, and pain duration were not independent predictors of a clinically successful outcome. There was no statistically significant association between effective treatment and the ultrasound findings of tendinosis, bursitis, partial or fullthickness tear, and enthesopathic changes. Limitations: Retrospective chart review without a control group. Conclusions: This study suggests that knee osteoarthritis and lower back pain might be associated with a poor outcome of ultrasound-guided trochanteric bursa injection for GTPS. Assessment of these clinical factors should be incorporated into the evaluation and counseling of patients with GTPS who are candidates for ultrasound-guided trochanteric bursa injection. Key words: Bursa injection, corticosteroid, greater trochanteric pain syndrome, knee osteoarthritis, lower back pain, lumbar facet joint, ultrasonography, S-I joint pain