The impact of rotator cuff pathology on isometric and isokinetic strength, function, and quality of life

• Published in: Journal of shoulder and elbow surgery Vol. 13; no. 6; pp. 593 - 598
• Main Authors: MacDermid, Joy C., Ramos, Joanne, Drosdowech, Darren, Faber, Ken, Patterson, Stuart
• Format: Journal Article
• Language: English
• Published: New York, NY Mosby, Inc 01.11.2004; Elsevier
• Subjects: Adult; Biological and medical sciences; Case-Control Studies; Diseases of the osteoarticular system; Female; Humans; Linear Models; Male; Medical sciences; Middle Aged; Multivariate Analysis; Muscle Contraction - physiology; Muscle Fatigue; Pain - diagnosis; Pain Measurement; Probability; Quality of Life; Range of Motion, Articular - physiology; Rotator Cuff - physiopathology; Shoulder Impingement Syndrome - physiopathology; Sickness Impact Profile; Human; Self evaluation; Use; Check; Eccentric; Dynamometer; Quality of life; Prevention; Anatomic pathology; Regulation(control); Pain; Rotator; Shoulder; Reliability; Rotator cuff; Strength
• DOI: 10.1016/j.jse.2004.03.009
• ISSN: 1058-2746

The purposes of this study were to determine the reliability of strength and self-reporting measures, the relationship of different strength measures to function, and the impact of rotator cuff pathology on patients’ quality of life. Patients with nonoperated rotator cuff pathology (n = 36) and unaffected control subjects (n = 48) were assessed by use of the LIDO dynamometer to determine isometric and isokinetic (concentric and eccentric) strength of the shoulder rotators. The Shoulder Pain and Disability Index and Short Form-36 were self-reported by patients. Intraclass correlation coefficients (ICCs) were used to assess reliability, and Pearson correlations and multiple linear regression were used to determine the relationship between strength and function. The findings of this study include the following: (1) measures of self-reported physical disability had high reliability (ICC = 0.89); (2) the LIDO dynamometer reliably measured internal and external shoulder rotation strength in both concentric and isometric modes of testing (ICC = 0.78-0.94), whereas eccentric muscle actions had lower reliability; (3) all shoulder rotation strength measures were predictive of disability, with isometric external rotation strength being the most predictive ( r = 0.56); and (4) the presence of rotator cuff pathology was highly predictive of impaired physical health quality of life ( R 2 = 0.71, P < .001).