Objectives. Although many clinical and experimental investigations have shed
light on muscle atrophy and intramuscular accumulation of fat after
rotator cuff disruption, none have reported on their onset in the
absence of muscle retraction. Methods. In 30 rabbits, we detached one supraspinatus (SSP) tendon and
repaired it immediately, thus preventing muscle retraction. The
animals were killed in groups of 10 at one, two and six weeks. Both
shoulders of 15 non-operated rabbits served as controls. We measured
the weight and
This investigation sought to advance the work published in our prior biomechanical study ( A total of 33 adult humeri were used from a previous study where we quantified bone mineral density of the proximal humerus using radiographs and dual-energy x-ray absorptiometry (DEXA), and regional mean cortical thickness and cortical index using radiographs. The bones were fractured in a simulated backwards fall with the humeral head loaded at 2 mm/second via a frustum angled at 30° from the long axis of the bone. Correlations were assessed with ultimate fracture load and these new parameters: cortical index expressed in areas (“areal cortical index”) of larger regions of the diaphysis; the canal-to-calcar ratio used analogous to its application in proximal femurs; and the recently described medial cortical ratio.Objectives
Materials and Methods
