Anatomical Factors Influencing the Stimulation Intensity of the Functional Electrical Stimulation of the Supraspinatus Muscle

OBJECTIVE: This study was designed to evaluate the contribution of anatomical factors to the stimulation intensity needed for functional electrical stimulation (FES) of shoulder girdle muscles, especially the supraspinatus. METHOD: Anatomical dimensions, including the length of the arm and scapular spine, were measured in twenty three normal subjects. Depth and thickness of the supraspinatus and trapezius muscle were measured ultrasonographically. FES was applied for supraspinatus muscles, and the minimal intensity required to induce contraction was recorded. Correlations of intensity with the anatomical dimensions were investigated statistically. RESULTS: The thickness of the supraspinatus muscle and the length of the scapular spine showed statistically significant correlations with the minimal intensity for FES of supraspinatus muscles. No other anatomical measurements showed significant correlation. CONCLUSION: The intensity required for FES was affected by the thickness and length of muscles, rather than other anatomical variables. The results of this study suggest that one of the major factors contributing to the determination of the intensity of FES is the size of muscles. If the intensity could be estimated before stimulation, based on the size of muscle, unnecessary discomfort of the patients would be avoided.

Expression of Caveolin-3 in the Muscle Cell and Tissue

OBJECTIVE: Caveolae are the microdomain of the plasma membrane that have been implicated in signal transduction and caveolin is a principal component of the caveolae. Caveolin-3, a family of caveolin related protein, is expressed only in muscle tissue. Here we examined the expression of caveolin-3 in the course of myobalst differentiation and within the muscle tissue. METHOD: L6 cell, rat skeletal myoblast, was cultured in the low mitogen medium and caveolin-3 expression was observed both by immunocytochemistry and western blot analysis. Localization of caveolin-3 within the muscle tissue was investigated and compared to that of dystrophin. RESULTS: While caveolin-3 was not expressed in the proliferating myolast, caveolin-3 was expressed in the differentiated myoblast. Caveolin-3 and dystrophin were co-expressed in the membrane of muscle tissue and integrated density of caveolin-3 was elevated in the area of muscle injury. In the Duchenne muscular dystrophy, caveolin-3 was expressed in the membrane of muscle tissue, but dystrophin was not. CONCLUSION: Caveolin-3 was induced during the myobalst differentiation and its expression was increased during the muscle regeneration. Caveolin-3 was physically associated with dystrophin as a complex, but not absolutely required for the biogenesis of dystrophin complex.

Diagnostic Value of MR Imaging in Differentiation of Meniscal Tear Patterns

PURPOSE: To evaluate the diagnostic accuracy of magnetic resonance (MR) imaging in the differentiation ofmeniscal tear patterns of the knee. MATERIALS AND METHODS: MR images of 93 patients with meniscal tear wereincluded in this study. On the basis of arthroscopic findings, the configuration of meniscal tears was classifiedas horizontal (n=44), longitudinal (n=34), transverse (n=11), or oblique (n=5). Oblique sagittal and coronal MRimages were obtained and com-pared with the arthroscopic findings. RESULTS: Among 94 cases ofarthroscopically-proven meniscal tears, 35 of 44 horizontal and 27 of 34 longitudi-nal configurations werecorrectly interpreted on MR images. Sensitivity and specificity for horizontal configu-ration were 80 % and 80 %,respectively, while the corresponding values for longitudinal configuration were 79 % and 95 %. On MR images, tworadial configurations were correctly interpreted from 11 confirmed tears and only one oblique configuration fromfive confirmed tears. CONCLUSION: MR imaging was useful for the differentiation of horizontal and longitudinaltears, but inaccurate in cases involving radial or oblique tears.