American Society for Peripheral Nerve

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A Comparison of Manual and Quantitative Shoulder Strength Testing
Leili Shahgholi, MD; Keith A. Bengtson, MD; Alexander Y. Shin, MD; Allen T. Bishop, MD; Robert J. Spinner, MD; Kenton R. Kaufman, PhD
Mayo clinic, Rochester, MN, USA

Objective: To compare estimates of shoulder abduction and external rotation strength obtained by skilled clinicians on physical examination with the values obtained through quantitative testing. Manual muscle testing (MMT) in which muscle strength is typically assessed on 0-to-5 scale has been in use for more than 60 years due to its convenience and overall acceptance . The inaccuracies of the test and its subjective nature are widely acknowledged but the extent and nature of these inaccuracies has been minimally documented. The complexity of shoulder movement is additional reason for limited research.

Design: Retrospective review of clinical records comparing MMT values with quantitative testing results

Participants: seventy five (75) people between the ages of 14 and 62 years with traumatic brachial plexus injuries.

Method: Manual muscle strength of shoulder abduction and external rotation was performed using the 5-point British Medical Research Council Scale (5/5 “normal,” 0/5 absent). In the same patients age normalized quantitative shoulder abduction and external rotation strength measured with hand held dynamometer. In half of subjects, comparison was done with their own uninjured side as well. The results were analyzed in JMP with respect to one way ANOVA and Wilcoxon analysis of variances.

Results: Half the subjects graded as having normal (5/5) shoulder abduction strength on MMT were found to have less than 39% of their age-expected strength when assessed with quantitative testing. Similarly, half of subjects displaying normal shoulder external rotation strength on manual testing had less than 26% of their age-expected values on quantitative testing. Significant differences between manual and quantitative findings were not detected for the lesser (0- 4) strength grades.

Conclusion: Manual muscle testing, even when performed by experienced clinicians, may be more misleading than expected for subjects graded as having normal (5/5) strength. Manual strength estimates for the lesser strength grades (1-4) is not able to adequately differentiate between adjacent grades.

Key words: Muscle Strength, Muscle weakness, Manual muscle test, Biomechanics


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