Correlation between Subscapularis Tears and the Outcomes of Physical Tests and Isokinetic Muscle Strength Tests

ABSTRACT

BACKGROUND: The aim of this study was to investigate the correlation between the type of subscapularis tendon tears diagnosed during arthroscopy and the outcomes of physical tests and of isokinetic muscle strength tests. METHODS: We preoperatively evaluated physical outcomes and isokinetic muscle strength of 60 consecutive patients who underwent an arthroscopic rotator cuff repair and/or subacromial decompression. We divided the patients into five groups according to the type of subscapularis tear, which we classified using Lafosse classification system during diagnostic arthroscopic surgery. RESULTS: When we performed a trend analysis between the outcomes of the physical tests and the severity of subscapularis tendon tear, we found that both the incidence of positive sign of the collective physical tests and that of individual physical tests increased significantly as the severity of the subscapularis tear increased (p<0.001). Similarly, the deficit in isokinetic muscle strength showed a tendency to increase as the severity of subscapularis tear increased, but this positive correlation was statistically significant in only the deficit between those with Lafosse type II tears and those with Lafosse type III tears. CONCLUSIONS: Although no single diagnostic test surpasses above others in predicting the severity of a subscapularis tear, our study implies that, as a collective unit of tests, the total incidence of the positive rate of the physical tests and the extent of isokinetic strength deficit may correlate with severity of subscapularis tears.