Comparative Efficacy and Patient-Specific Moderating Factors of Nonsurgical Treatment Strategies for Frozen Shoulder: An Updated Systematic Review and Network Meta-analysis

Background: Frozen shoulder is a common shoulder disorder characterized by pain and restriction. Various nonsurgical treatments have been reported, but there is no consensus about their comparative efficacy and the effects of moderators. Purpose: To compare the efficacy of different nonsurgical interventions and identify potential patient-specific moderating factors for frozen shoulder. Study Design: Systematic review and network meta-analysis. Methods: PubMed, Embase, Cochrane Library, and Web of Science databases were searched from their inception to February 18, 2019. The search was supplemented by manual review of relevant reference lists. Randomized controlled trials of participants with frozen shoulder that compared nonsurgical interventions were selected. Measured outcomes included pain, shoulder function in daily activities, and range of motion. Results: Of 3136 records identified, 92 trials were eligible, evaluating 32 nonsurgical interventions in 5946 patients. Intra-articular injection improved pain (pooled standardized mean difference [95% CI]: steroid injection, 1.68 [1.03-2.34]; capsular distension, 2.68 [1.32-4.05]) and shoulder function (steroid injection, 2.16 [1.52-2.81]; distension, 2.89 [1.71-4.06]) to a greater extent than placebo. Capsular distension and extracorporeal shockwave therapy showed the highest ranking for pain relief and functional improvement, respectively. Laser therapy also showed benefits for pain relief (3.02 [1.84-4.20]) and functional improvement (3.66 [1.65-5.67]). Subgroup analyses by disease stages revealed that steroid injection combined with physical therapy provided more benefits during the freezing phase, whereas joint manipulation provided more benefits in the adhesive phase. Adjunctive therapies, female sex, and diabetes were also identified as moderators of effectiveness. Conclusion: Capsular distension is a highly recommended choice for treatment of frozen shoulder, contributing greatly to pain relief and functional improvement; steroid injection is also a prevailing effective intervention. Among new options, extracorporeal shockwave therapy and laser therapy show potential benefits for multiple outcomes. Individualized optimal intervention should be considered, given that treatment effect is moderated by factors including the disease stage, time of assessment, adjunctive therapies, female sex, and diabetes.