Double blind randomized clinical trial examining the efficacy of bupivacaine suprascapular nerve blocks in frozen shoulder

Objective. To determine whether the pain, contracture, and disability assoc iated with idiopathic frozen shoulder are diminished by a series of 3 indir ect bupivacaine suprascapular nerve blocks delivered in an ambulatory care clinic. Methods. A double blind randomized controlled trial of patients referred by primary care and specialty clinics in Montreal to an ambulatory tertiary c are academic facility, Patients and controls underwent a series of 3 indire ct suprascapular nerve blocks at 7 day intervals using either 10 cc bupivac aine 0.5 (Marcaine) in the treatment group or 10 cc of physiological saline in controls. Subjects in both groups were taught a program of shoulder ran ge of motion exercises to be done at home. The primary outcome measure was the McGill-Melzack Pain Questionnaire (MPQ) short form at 1 month post-rand omization (2 weeks after last injection). The secondary outcome measures we re disability measured by the simple shoulder rest and glenohumeral joint c ontracture measured by shoulder range of motion measurements. Results, Thirty-four subjects were randomized from 58 screened. Average age of subjects was 52 years. Mean duration of pain prior to randomization was one year. Dropout rate was 11% in the treatment group, 30% in the placebo group. A 64% reduction in pain in the treatment group versus 13% in the pla cebo group was observed at one month as measured by the MPQ multidimensiona l pain descriptors score (p = 0.03), A nonsignificant 15.8% improvement in shoulder function in the treatment group versus 4% in the placebo group (p = 0.24) was also noted. No improvement in shoulder range of movement was no ted. No side effects other than transient vagal symptoms and local tenderne ss at the injection site were reported. Conclusion. The use of bupivacaine suprascapular nerve blocks was effective in reducing the pain of frozen shoulder at one month, Clinical studies wit h a larger number of subjects and a longer study period will help determine the duration and nature of the effect of bupivacaine suprascapular nerve b locks in treating the pain, disability, and glenohumeral joint contracture of frozen shoulder.