Background: There were no reports using electrophy siological evaluation of the rotator cuff tear.
Methods: The purpose of this study was to evaluate the correlation between the tear size and fatty degeneration of rotator cuff muscle in MRI, and the amplitude of the nerve conduction study. One hundred and eighty nine patients with a mean age of 62.7 years who had no rotator cuff tear on the other side using ultrasound study and had no previous shoulder surgery or neurological disease were enrolled in this study. Tear sizes were shown as followed; bursal side tear; 24 cases, small size; 31 cases, medium size; 48 cases, large size; 61 cases and massive tear; 25 cases. Electro-stimulation at Erb's point was used to evaluate the amplitude of the supraspinatus and infraspinatus and the ratio of the normal side to the operative side of the amplitude were used. Fatty degeneration was evaluated using the Goutallier's classification.
Results: As the tear size became larger, the amplitude of the supraspinatus and infraspinatus became significantly lower (p<0.05). Moreover, the fatty degeneration of the supraspinatus and infraspinatus negatively correlated with the amplitude of these muscles.
Conclusion: This study showed that the larger the tear sizes become, the lower the amplitude of the supraspinatus and the infraspinatus. Moreover, the more severe the fatty degeneration becomes, the lower the amplitude of the supraspinatus and the infraspinatus. These data suggested that a nerve conduction study would be helpful to evaluate the pre-operative condition of the supraspinatus and infraspinatus muscles.
