External rotator strength deficits in non-athletic people with rotator cuff related shoulder pain are not associated with pain intensity or disability levels.

BACKGROUND: Strength deficits are often reported in people with rotator cuff related shoulder pain. However, these have mainly been tested in athletic populations and pain interference with testing has not been considered. OBJECTIVES: To examine strength without pain interference in non-athletic people with rotator cuff related shoulder pain and its association with pain intensity and disability. DESIGN: Cross-sectional study. METHODS: Sixty-seven participants with rotator cuff related shoulder pain were assessed for isometric strength of shoulder external rotator and internal rotator muscles without pain interference with a hand-held dynamometer. Strength was normalized (%body weight). Differences in external and internal rotation strength and external:internal rotator strength ratio between symptomatic and asymptomatic sides were examined (Independent t-tests, Wilcoxon rank sum tests). Spearman's rank correlation coefficients were used to examine associations between strength and pain and disability levels. RESULTS: There was no significant difference in internal rotator strength normalized to body weight between symptomatic and asymptomatic sides. There was a significant difference in external rotator strength normalized to body weight (p < .001) and external:internal ratio (p < .001) between sides. No significant correlations were found between strength and pain or disability levels. CONCLUSION: Non-athletic people with rotator cuff related shoulder pain had external rotator strength deficits without pain interference during strength testing, which were not associated with pain and disability levels.

Is rotator cuff related shoulder pain a multidimensional disorder? An exploratory study.

Background and aims Rotator cuff related shoulder pain has been associated with factors from multiple dimensions such as strength changes, psychosocial measures, comorbidities and level of education. However, to date little research has been undertaken to evaluate which factors explain the greatest variance in pain and disability levels in people with rotator cuff related shoulder pain. The objective of this study was therefore to evaluate which multidimensional examination findings were associated with higher pain and disability in a primary care cohort with rotator cuff related shoulder pain. Methods This was an exploratory cross-sectional cohort study. Sixty-seven participants with rotator cuff related shoulder pain were assessed for: pain intensity, disability; demographic, psychological, social and lifestyle characteristics, and isometric strength of shoulder internal and external rotator muscles. Univariable associations between pain intensity/disability and each variable were assessed using linear regression. Variables with univariable associations (p < 0.1) were entered into backwards stepwise multivariable regression models. Results The multivariable model for pain intensity included sleep and perceived persistence and explained 46.5% of the variance (37.6% uniquely by sleep, 5.4% uniquely by perceived persistence). The multivariable model for disability included sleep and sex and explained 26.8% of the variance (4.5% shared by predictors, 16.4% uniquely by sleep, 5.9% uniquely by sex). Conclusions Rotator cuff-related shoulder pain and disability are associated with sleep disturbance, perceived symptom persistence and sex. Rotator cuff related shoulder pain may be considered a multidimensional disorder. Implications Clinicians need to evaluate sleep and perceived symptom persistence in people with rotator cuff related shoulder pain. Future research may examine whether management strategies for RCRSP directed towards these factors afford improved treatment outcomes.