The Prevalence of Rotator Cuff Weakness in Patients with Injured Hands

Abstract

Listen

Translate article

Purpose: This study compared bilateral rotator cuff strength in patients with a unilateral hand or wrist disorder. The purpose of this study was to document rotator cuff weakness in patients with distal upper extremity disorders. Background: The onset of shoulder pain after hand injuries is an acknowledged risk. These symptoms may be due to rotator cuff weakness and dysfunction. Patients with hand injuries use the upper extremity less, which can lead to deconditioning, rotator cuff weakness and fatigue. The prevalence of rotator cuff weakness in this population is unknown. Methods and Materials: Ipsilateral rotator cuff strength was measured in 57 patients age 18 and older (average age 42) with an injury or disorder of the hand or wrist distal to the distal radius and compared with the uninvolved side. Thirty-four patients were men and 23 were women. Fifty were right hand dominant and seven were left hand dominant. Injuries involved the dominant extremity in 33 cases and the non-dominant extremity in 24. Patients with bilateral symptoms and/or a history of significant upper extremity symptoms were excluded. Information on age, dominance, injury side, time since injury, mechanism of injury and worker's compensation status was collected. Patients were divided into acute (traumatic onset less than six weeks) and chronic (traumatic onset greater than six weeks or insidious). Rotator cuff strength was measured using a hand held dynamometer (Microfet 2; Hoggan Health Industries, Draper, UT). Measurements were done in a standardized manner for each muscle with trials and rest breaks. Specific testing postures are outlined in the article for easy comparison. Both make and break tests were performed and an independent examiner recorded measurements. Results: There was a statistically significant decrease in elevated external rotation strength (infraspinatus) for both make and break tests for the ipsilateral arm. There was also a statistically significant decrease in strength of elevation in the scapular plane (supraspinatus) for breaks tests but not for make tests. There was a statistically significant correlation between decreased strength supraspinatus make and infraspinatus break test and age. Percentage of strength loss was greater for younger patients. Neither time from injury or worker's compensation status was significant in strength loss. There was, however, an increased vulnerability for patients whose injury was in the non-dominant extremity. Discussion: The author acknowledges that despite the presence of shoulder symptoms in some patients with distal upper extremity problems, it is unclear whether there is a causal relationship. This study attempts to address the issue by documenting statistically significant ipsilateral rotator cuff weakness in patients with distal problems. Weakness was found in both the make and break tests for the infraspinatus and the break tests for the supraspinatus. Further research is required to determine if any relationship exists between shoulder pain and ipsilateral distal extremity injuries. The finding of greater vulnerability when the non-dominant injury was involved is consistent with easier substitution during activity for these extremities and the use of dominant extremity despite pain and limitations. Previous studies are cited that found no significant difference in strength between dominant and non-dominant extremities so this was not a factor in the data analysis. The issue of strength loss and time from injury requires further research and the author suggests a study that follows individual patients with acute injuries over time. Weaknesses of this study included the difficulty in totally isolating muscles for testing and errors associated with use of a hand held dynamometer. The dynamometer errors occur because the examiner breaks first. They would have affected the stronger extremity, making it appear weaker, thus decreasing the statistical significance. Since findings were statistically significant for all but the supraspinatus make tests elimination of this weakness would only strengthen the findings. This study points to the need for early and ongoing assessment of rotator cuff strength in our patients. Selective strengthening of rotator cuff muscles may be clinically important to both therapists and surgeons in treating patients with distal upper extremity problems.