Are pectoralis minor length and posterior shoulder tightness associated with patient-reported shoulder pain and disability?

Background: Pectoralis minor (PM) shortening and posterior shoulder tightness (PST) are considered potential soft tissue alterations associated with rotator cuff related shoulder pain (RCRSP). Yet, their precise contribution to pain and disability remains unclear.

Purpose: To explore the association between both PM length and PST and self-reported shoulder pain and disability in individuals with and without RCRSP. Demographic characteristics and shoulder active range of motion (AROM) were also considered for their potential contributions to RCRSP.

Study design: This was a cross-sectional study.

Methods: Using Shoulder Pain and Disability Index (SPADI), 144 individuals were grouped by pain and disability severity: SPADI total score ≤20 and SPADI total score >20. PM length was measured using a tape measure. PST, glenohumeral joint flexion, internal (IR) and external (ER) rotation AROM were quantified using an inclinometer. Demographic and AROM measurements were compared between groups and regression analyses identified SPADI predictors.

Results: Age, PST, glenohumeral flexion, and ER AROM were associated with SPADI total score (p < 0.05). Higher age (odds ratio (OR [95%CI]): 1.07 [1.02-1.12]) and increased PST (OR: 1.16 [1.04-1.29]) were associated with higher self-reported shoulder pain and disability scores (SPADI score >20). In contrast, increased flexion (OR: 0.93 [0.88-0.97]) and ER AROM (OR: 0.96 [0.93-0.99]) served as protective factors against increased levels of self-reported shoulder pain and disability. No other variables were associated with SPADI (p > 0.05).

Conclusions: PST is associated with increased levels of self-reported shoulder pain and disability, as are age, while PM length and IR AROM were not significantly associated variables. Glenohumeral flexion and ER AROM prevented increased levels of self-reported shoulder pain and disability.