Comparison of Outcomes of Two Different Corticosteroid Injection Approaches for Primary Frozen Shoulder: A Randomized Controlled Study

Abstract

Objective: Corticosteroid injection is a common treatment for primary frozen shoulder, but controversy remains regarding whether different injection approaches to the glenohumeral joint have similar clinical benefits. Design: Randomized controlled clinical trial. Patients: A total of 60 patients with primary frozen shoulder were divided randomly into either anterior or posterior approach groups. Methods: Both groups received a 5-mL drug injection, including 1 mL 40 mg/mL triamcinolone acetonide and 4 mL 2% lidocaine. Follow-up time-points were 4, 8 and 12 weeks post-injection. Outcome measures included visual analogue scale score, Constant-Murley score, and passive range of motion of the shoulder joint. Results: All outcome measures improved over the follow-up period compared with those of previous follow-up time-points within the groups. The primary finding was that the visual analogue scale score in the anterior group was better than that in the posterior group at each follow-up time-point (all p < 0.05). In addition, improvement in function score and external rotation was faster and significant in the anterior group in the early stages (p = 0.02). Conclusion: The anterior approach achieves more satisfactory results in pain control and offers better recovery of functional activity than posterior approach in the early period for primary frozen shoulder. LAY ABSTRACT Although many studies have been published in recent years on corticosteroid injection in the glenohumeral joint for primary frozen shoulder, the injection approaches described by current reports are not consistent and not described in detail, which is not conducive for their use to be repeated by clinicians. Meanwhile, controversy remains regarding whether different approaches have similar clinical outcomes. This study used a modified anterior approach based on anatomical landmarks, taking the acromioclavicular joint as a reference, to accurately and quickly complete the injection process. The study showed that the anterior approach could reduce pain severity more significantly than the regular posterior approach, and this advantage can be maintained for 3 months. Meanwhile, the function score of the anterior approach could recover to the maximum more quickly. In addition, recovery of external rotation in the anterior approach was faster and greater that for the posterior approach.

Keywords

• frozen shoulder
• adhesive capsulitis
• anterior approach
• posterior approach
• corticosteroid injection