Functional outcome and quality of life after rehabilitation for voluntary posterior shoulder dislocation: a prospective blinded cohort study

Background: Voluntary posterior instability of the shoulder is a rare condition in which the patient is able to cause a subluxation by voluntary muscle activation. A shoulder rehabilitation program aimed to correct abnormal muscle patterns and restore correct scapular motion may provide good results and improve the quality of life of these patients.Methods: Fifteen subjects (six males, nine females; mean age 19 years) underwent physical examination and clinical tests [Disability of the Arm, Shoulder and Hand (DASH) score, Shoulder Pain and Disability Index (SPADI), and modified Rowe score] and compiled the patient global assessment (PGA). Articular or rotator cuff lesions were excluded by X-rays and MRI. The rehabilitation program included three phases: (1) assessment and correction of abnormal muscle patterns, (2) restoration of correct scapular motion, and (3) strengthening of scapular and posterior glenohumeral muscles. Follow-up was at 3, 6, 12, and 24 months.Results: DASH and SPADI scores improved significantly at 3 (p < 0.01), 6 (p < 0.009), 12 (p < 0.001), and 24 months (p < 0.001). The Rowe score was fair at 3 months and good at 6, 12, and 24 months. Active flexion, abduction, and external rotation increased at all follow-up points (p < 0.01), whereas internal rotation remained unchanged (p > 0.05). PGA values were high. Compliance was good without serious adverse events reported during the treatment. A correlation was found between age and DASH changes (Spearman’s ρ −0.56; p = 0.0455).Conclusions: Our findings stress the value of a rehabilitation program that teaches subjects with voluntary instability how to correct abnormal muscle patterns to restore scapular motion, and the importance of adopting home rehabilitation exercises as a part of the normal lifestyle.