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PubMedDate not supplied

Biomechanics of the Bankart repair: the relationship between glenohumeral translation and labral fixation site.

The specific aim of this study was to quantify glenohumeral translations in cadaveric shoulders after repair of the superior and middle regions of a surgically created Bankart lesion and after repair of the superior, middle, and inferior regions of the same lesion. Anterior-posterior, superior-inferior, and medial-lateral translations in nine cadaveric specimens were tested with shoulders in 0 degree, 45 degrees, and 90 degrees of humeral abduction and varying degrees of humeral rotation. There was statistically significantly less anterior and inferior translation after three-site labral repair compared with after two-site labral repair, and this effect was greatest at 90 degrees of glenohumeral abduction. The decreased translations demonstrated with three-site repair emphasized the importance of careful repair of the labrum to the inferior glenoid rim during a Bankart reconstruction and suggested that failure to do so may be a contributing factor to recurrent instability after anterior shoulder reconstruction.

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PubMedDate not supplied

The mechanobiology of cancellous bone structural adaptation.

The distinguishing morphological feature of cancellous bone is its high level of porosity relative to cortical bone. This porosity leads to more free surfaces and thus to more of the cellular constituents that inhabit those surfaces. As a result, cancellous bone is often more metabolically active and responsive to stimuli than cortical bone. This extends to the relationship between cancellous bone's internal structure and external mechanical loading. Observational investigations established this relationship as early as the late 19th century. These findings point to the interplay between biology and the cellular mechanical environment, forming the underpinnings of the modern term mechanobiology. Interestingly, it has proven to be more straightforward to assay the biological response than to quantify the precise mechanical environment of cancellous bone and the influence of cancellous bone structure. Despite this concern, significant insights into the nature of cancellous bone mechanobiology can be obtained from computational simulations that allow investigators to determine the morphological consequences of quantitative assumptions about cancellous bone mechanobiology. As the power of computers and the sophistication of these modeling techniques continue to grow, we can expect an increased impact in terms of clinical diagnosis and treatment. The next decade will bring improvements in exercise interventions to prevent and reverse bone loss; improved replacement-joint designs, particularly for those joints currently having poor expected outcomes; and an integration of computer simulation technology with clinical scanners.

Adaptation, Physiological↗