Reverse total shoulder arthroplasty increases the moment arms of the major abductors, flexors, adductors, and extensors of the glenohumeral joint, thereby reducing muscle effort during common tasks such as lifting and pushing.

The purposes of this study were to determine the contributions of each shoulder muscle to glenohumeral joint force during abduction and flexion in both the anatomical and post-operative shoulder and to identify factors that may contribute to the incidence of glenoid component loosening/failure and joint instability in the shoulder after reverse shoulder arthroplasty (RSA). Eight cadaveric upper extremities were mounted onto a testing apparatus. Muscle lines of action were measured, and muscle forces and muscle contributions to glenohumeral joint forces were determined during abduction and flexion of the pre-operative anatomical shoulder and of the shoulder after arthroplasty. Muscle forces in the middle deltoid during abduction and those in the middle and anterior deltoid during flexion were significantly lower in the reverse shoulder than the pre-operative shoulder (p < 0.017). The resultant glenohumeral joint force in the reverse shoulder was significantly lower than that in the pre-operative shoulder; however, the superior shear force acting at the glenohumeral joint was significantly higher (p < 0.001). Reverse total shoulder arthroplasty reduces muscle effort in performing lifting and pushing tasks; however, reduced joint compressive force has the potential to compromise joint stability, while an increased superior joint shear force may contribute to component loosening/failure. Because greater superior shear force is generated in flexion than in abduction, care should be taken to avoid excessive shoulder loading in this plane of elevation. Reverse total shoulder arthroplasty (RSA) is most commonly a salvage procedure for the treatment of glenohumeral arthritis associated with severe rotator cuff deficiency in patients with low functional demands. This includes traumatic situations: where the proximal humerus is fractured, destroyed, or absent; pseudoparalysis due to arthritis and massive, irreparable cuff tears; and prosthetic revision in a cuff-deficient shoulder. 1,2 While reduced pain, improved strength, and increased range of motion have been reported in patients with primary rotator cuff tear arthropathy, 3 complication rates have ranged from 17% to 50%, 4,5 with significantly greater risks associated with revision surgery. 2,3 Joint compressive force plays a significant role in stabilizing an RSA. 6 but excessive shear forces across the glenoid/baseplate interface may lead to failure of the baseplate fixation. 7 Because the deltoid produces the majority of the elevator torque in the reverse shoulder, 8 its contribution to destabilizing glenohumeral joint forces may be significant, particularly in cases of rotator cuff deficiency in which normal mechanisms of concavity compression are disrupted.Shoulder muscle and joint-contact forces after RSA have been estimated using computational modeling, 9,10 but have not been obtained by direct measurement. Previous studies infer that RSA enhances post-operative joint function as the deltoid moment arms increase relative to the anatomical shoulder, 11...

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Introduction:Orthogeriatric care models have been introduced within many health-care facilities to improve outcomes for hip fracture patients. This study aims to evaluate differences in care between 3 models, an orthopedic model, a geriatric model, and a comanaged model.Materials and Methods:A retrospective analysis was conducted for hip fracture patients treated at Western Health between November 2012 and March 2014. All patients aged 65 years or older were included in the analysis.Results:There were 183 patients in the orthopedic model, 137 in the geriatric model, and 126 in the comanaged model. Demographics and clinical characteristics were similar across the 3 models. Length of stay, mortality, and discharge destination were also consistent across the 3 groups. However, groups involving geriatricians were more likely to receive preoperative medical assessments, have greater recognition of postoperative medical problems, and have implementation of long-term osteoporosis management.Conclusion:The involvement of geriatricians in perioperative care models resulted in more comprehensive medical care without impacting length of stay, mortality, or discharge destination.

The reported annual AE incident rate of approximately 2% is well below the national average: this may be due to pre-selection of general surgery-related AEs or represent under-reporting of incidents. The vast majority of AEs were related to administrative and communicative error. These areas must be addressed if patient safety and outcome is to be significantly improved.