Body Mass Index Is Related to the Recovery After Intra-articular Injection of Triamcinolone Acetonide for the Treatment of Frozen Shoulder: Case Series Study

Abstract Background: Patients with frozen shoulder tend to respond differently to the intra-articular injection of triamcinolone acetonide. The purpose of the present study was to evaluate the clinical effect of glenohumeral injection with triamcinolone acetonide for frozen shoulder and determine the factors related to extent of range of motion (ROM) recovery.Methods: A cohort of patients who underwent intra-articular glenohumeral injection of triamcinolone acetonide under diagnosis of primary frozen shoulder was reviewed. The primary outcome variable of interest was the range of changes in each aspect of ROM at six weeks after injection. The relationship between improvement and unresponsiveness to intra-articular injection for the treatment of frozen shoulder with various factors were evaluated. The analyzed factors were as follows: age, sex, body mass index (BMI), initial ROM before injection, symptom duration, hand dominance, smoking history, and the existence of underlying disease including diabetes mellitus, hypertension, coronary disase, thyroid disease and hypercholesterolemia.Results: A total of 305 patients were reviewed. There were significant improvements in all aspects of ROM at six weeks after injection. The forward flexion (ρ=-0.346, p<0.001) and external rotation (ρ=-0.204, p=0.040) showed a negative correlation with BMI. Multivariate analysis revealed that BMI is the sole factor related to recovery of forward flexion (p=0.032) and external rotation (p=0.007) at six weeks post-injection. Conclusion: Intra-articular injection of triamcinolone acetonide is an effective method for improving ROM in patients with frozen shoulder. Increased BMI showed adverse effects on ROM recovery.