Magnetic Resonance Based Motion Analysis Of The Shoulder And Glenohumeral Translation Relationships During Elevation

Objcctive: @To perform a motion pattem analysis of shoulder girdle structures duringpassive arm elevation using open magnetic resonance imaging and three-dimensional..image processing. @To analyze humera1 head translation relationships during passiveand active elevation by aPplying an open MR technque and 3D digital postProcessingmethods.Metheds: @Twnty voluneers were examined in five positions of abduction (30degrees-150 degrees) with an open magnetic resonance system. After three-dimensiona1reconstttiction, the relative movemefits between the axis of the suPraspinatlls, hUmerus,clavicle, and the plane of the glenoid were calculated. @Sixteen healthy voluneerswere examined with an open MR system at different abduction positions undermuscular relaxation (30" --l50" ) of abduction and during activity of shoulder muscles(60" --l20" ). After 3D reconstruction, the ceDter of mass of the glenoid and themidPoint of the humeral head were determined and their relative position calculated.Results: @The ratio fOr glenohUmera1 to scaPulothoracic moton was l.5:l at 60degrees and 2.4:l at l20 degrees abduction. At 30 degrees, the axis of the praspinatllswas nearly horizontal, and during abduction a continuous elevation (+l23 degrees atl50 degrees abduction) was measured. In the transverse plane, the angle betwen thesuPraspinatus and the clavicle axes became larger during abduction because of anincreasing retroversion of the clavicle.@During passive elevation, the humeral headtranslated inferiorly from +l.58 nun at 30" to +0.36 mm at l50" of abduction, andposteriorly from +1.55 mm at 30" to -0.07 mm at l50" of abduction. Muscularactivity brough about significam changes in glenohUmeral translation, the humera headbeing in a more inferior position and more centered, particularly at 90" and l20" ofabduction (p<0.01). In anterior/posterior direction the humeral head was more centeredat 60?and 90?of abduction during muscle activity.Conclusions: CD The technique applied and results obtained in this study can be usedfor future studies in patients with pathologic changes of shoulder girdle motion, andprovide basic biomechanics data for operative or non-operative treat of shoulderdiseases.?Effects of neuromuscular control is rather important for providing jointstability. The technique employed can also be used for investigating the effect of muscledysfunction and their relevance on the biomechanics of the shoulder joint...