1000 Monroe Ave Nw
Grand Rapids MI 49503
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License #: 4301096531
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The effects of patellar tendon advancement on the immature proximal tibia. - Journal of children's orthopaedics
The aim of this study is to examine the short-term effects of patellar tendon advancement on the proximal tibial slope in the skeletally immature patient.A retrospective, non-randomized, comparative cohort design was used. Koshino indices and tibial slopes were assessed pre-operatively and post-operatively and compared with age- and sex-matched controls.Nine children with 17 patellar tendon advancements were analyzed for changes in Koshino indices. Of these 17 tibiae, radiographs on changes in tibial slope were available for 16 tibiae which were also compared with controls. Children aged <11Â years had a greater initial posterior tibial slope (69.8Â°Â Â±Â 3.5Â°) than age-matched controls (80.3Â°Â Â±Â 2.7Â°). A decrease in posterior slope was seen in these younger patients (average change 10.3Â°Â Â±Â 4.8Â°) at an average of 1.6Â years of follow-up. Of the nine apophyses in children aged <11Â years of age, seven had undergone premature closure.Patellar tendon advancement appears to have an unreported effect on the proximal tibial growth in the young patient (<11Â years old). These patients appear to be susceptible to apophyseal closure, resulting in subsequent loss of posterior tibial slope. Surgeons should be aware of this effect and monitor younger patients with radiographs if performing this procedure.
Variation in external rotation moment arms among subregions of supraspinatus, infraspinatus, and teres minor muscles. - Journal of orthopaedic research : official publication of the Orthopaedic Research Society
A rotator cuff tear causes morphologic changes in rotator cuff muscles and tendons and reduced shoulder strength. The mechanisms by which these changes affect joint strength are not understood. This study's purpose was to empirically determine rotation moment arms for subregions of supraspinatus, infraspinatus, and for teres minor, and to test the hypothesis that subregions of the cuff tendons increase their effective moment arms through connections to other subregions. Tendon excursions were measured for full ranges of rotation on 10 independent glenohumeral specimens with the humerus abducted in the scapular plane at 10 and 60 degrees . Supraspinatus and infraspinatus tendons were divided into equal width subregions. Two conditions were tested: tendon divided to the musculotendinous junction, and tendon divided to the insertion on the humerus. Moment arms were determined from tendon excursion via the principle of virtual work. Moment arms for the infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly greater when the tendon was only divided to the musculotendinous junction versus division to the humeral head. Moment arms across subregions of infraspinatus (p < 0.001) and supraspinatus (p < 0.001) were significantly different. A difference in teres minor moment arm was not found for the two cuff tendon conditions. Moment arm differences between muscle subregions and for tendon division conditions have clinical implications. Interaction between cuff regions could explain why some subjects retain strength after a small cuff tear. This finding helps explain why a partial cuff repair may be beneficial when a complete repair is not possible. Data presented here can help differentiate between cuff tear cases that would benefit from cuff repair and cases for which cuff repair might not be as favorable.
Variability in isometric force and moment generating capacity of glenohumeral external rotator muscles. - Clinical biomechanics (Bristol, Avon)
Muscles which cause glenohumeral external rotation possess varying ability for generating force and moment due to differences in muscle architecture, moment arm, and the interaction of these two factors. This study's purpose was to determine a complete dataset of muscle-tendon parameters for predicting the moment generating capacity and force-length dependence for external rotation of infraspinatus, supraspinatus and teres minor muscles.Muscle fascicle length, sarcomere length, pennation angle, and muscle volume were measured for sub-regions of infraspinatus and supraspinatus, and teres minor from 10 glenohumeral specimens. Tendon excursion was measured for glenohumeral rotation. From these parameter measurements, optimal fascicle length, physiological cross-sectional area, muscle force-length dependence, and maximum isometric moment generating capacity were calculated.Substantial differences were found for optimal muscle length, physiologic cross-sectional area, and tendon length for the 10 specimens of this study. Muscle sub-region had a significant effect on the force-length relationship for infraspinatus (P<0.001), but was not significant for supraspinatus (P=0.49). For infraspinatus and supraspinatus, maximum isometric rotation moment capacity was greater at 10 degrees versus 60 degrees abduction (P<0.001). Maximum isometric rotation moment capacity for the teres minor was greater at 10 degrees versus 60 degrees abduction (P<0.01). Sub-regions demonstrated significant differences in isometric moment capacity (P<0.001).Functional capabilities of these muscles depend on muscle architecture and moment arm as well as their combined effects. The results allow for development of stochastic and deterministic models of glenohumeral external rotation strength which can be used for prediction of muscle forces and joint moments.
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1000 Monroe Ave Nw Grand Rapids, MI 49503
100 Michigan St Ne Mc 71
100 Michigan St Ne Suite A721
35 Michigan St Ne Suite 3003
330 Barclay Ave Ne Suite 102