Various theories exist regarding the mechanisms of stiff shoulder (SS). Potential etiological factors are adhesive capsulitis, decreased capsular volume, capsular contractions, rotator interval thickening and fibrosis, and subscapularis tendon thickening. Cyriax proposed that stiffness in a shoulder joint capsule would restrict motion in a predictable pattern, a capsular pattern in which external rotation is more limited than abduction, which in turn is more limited than internal rotation. Others authors have indicated that posterior shoulder stiffness is significantly correlated with humeral internal rotation ROM loss. Specifically, several researchers hypothesized that the stiffness of specific muscles (rotator cuff) may contribute to posterior shoulder stiffness. These potential mechanisms provide rationales for treatment protocols options.
Mobilization, stretching, and/or massage are advocated for patients with posterior shoulder tightness and limited glenohumeral internal rotation ROM. Tightness in the posterior shoulder has been associated with a loss of glenohumeral internal rotation range of motion (ROM). It has been found that in cadaver models, tightness in the posterior shoulder has limited glenohumeral internal rotation ROM. In subjects with subacromial impingement syndrome and frozen shoulder syndrome, decreased glenohumeral internal rotation ROM are related to posterior shoulder tightness. Additionally, tightening of the posterior portion of the shoulder is associated with increased anterior and superior humeral head translations on the glenoid, which has been theorized to contribute to shoulder impingement syndrome. Presumably, clinical approaches like mobilization, stretching, and/or massage may decrease shoulder tightness and improve symptoms in subjects with SS.
Although soft tissue massage of the posterior shoulder tissues is often included in rehabilitation of individuals with posterior shoulder tightness, glenohumeral internal rotation ROM deficit, and/or impingement syndrome, evidence to support treatment protocols is limited. Based on a case report, Poser and Casonato suggest that massaging the infraspinatus and teres minor muscles can result in 20 degrees of improvement of internal rotation. However, they did not provide the rationale for different treatment durations for each muscle (7 minutes for the infraspinatus and 3 minutes for the teres minor). It is possible that various muscles may respond differently according to the massage technique. Additionally, improvement of internal rotation cannot reflect the tightness property of each specific muscle after massage. Since the effects of massage on muscle and connective tissue were based on ROM measurement in the majority of studies, the effect of massage on specific muscle tightness is not clear. This is important for clinicians to precisely target the involved anatomical structure (muscle or capsule) that is the source of the joint restriction.
The purpose of this study was to investigate the effect and predictors of effectiveness of massage in the treatment of patients with posterior shoulder tightness. We hypothesized that massage may effectively improve glenohumeral internal rotation in subjects with posterior shoulder tightness, and identify the predictors of effective massage by investigating the characteristics of the responsive subjects. This may help clinicians to decide whether massage is a worthy treatment for a patient with loss of internal rotation and posterior shoulder tightness.