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Functional Anatomy and Biomechanics
Published in Emeric Arus, Biomechanics of Human Motion, 2017
Upward rotation when the scapula’s glenoid fossa faces a little bit upward. Downward rotation is the opposite action of the upward rotation. The glenohumeral joint consists of a nearly hemispherical humeral head and the relatively shallow glenoid cavity on the lateral aspect of the scapula. The glenoid labrum is a fibrous structure around the perimeter of the glenoid cavity and serves to improve stability to the joint.
Development of a more biofidelic musculoskeletal model with humeral head translation and glenohumeral ligaments
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2022
Sujata Khandare, Meghan E. Vidt
There are limitations to our model that must be considered. We validated the model only in the neutral position and compared the predicted translations from CMC simulations using the validated model to clinical assessment of translation in multiple positions of abduction. Although comparable values of model-predicted data to clinical assessments show that model validation was clinically relevant in certain postures, further experimental measurements of HHT in other static positions, and eventually dynamic motions are needed for model comparison. This will allow for more robust predictions of HHT and a better understanding of ligament contributions to GH stability. Experimental measurements of properties used to define ligaments in the model were obtained from donors representing the older population. There was variation in ligament properties, as it is difficult to obtain a large set of ligament property data in multiple shoulder positions. Moreover, ligaments are sometimes absent in people (Turkel et al. 1981; Tuoheti et al. 2005), which might change the mechanics of GH stability. However, having a model enables assessment of the extent to which individual variations in GH ligaments influence movement and joint mechanics. CMC simulations of static postures using our model revealed higher levels of HHT toward the glenoid (medial). This could be because of the lack of representation of other stabilizing structures, like the glenoid labrum in the model. The glenoid labrum is a ring of dense fibrous tissue that spans the circumference of the glenoid fossa and creates intra-articular pressure between the scapula and humerus, keeping the GH joint more stable. Future work should continue to integrate representations of structures that account for GH stability, which will further improve the robustness of predictions of shoulder mechanics and injuries.