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Biomechanical Evaluation of Locking Plate Fixation of Proximal Humeral Fractures Augmented With Calcium Phosphate Cement

Objectives: To evaluate the influence of calcium phosphate cement augmentation on failure of locking plate fixation of proximal humeral fracture fixation in a cadaveric fracture model. Methods: A 5-mm wedge osteotomy was created in each of 11 paired fresh-frozen human cadaveric humeri (age > 65 years). Specimens were randomly assigned to receive either locked plate fixation (group 1) or locked plate fixation with cement augmentation (group 2). Constructs were tested for axial stiffness, load to failure, and failure mode using a material testing machine. Results: Cement-augmented specimens resisted higher loads (1936 ± 609 N) in comparison to nonaugmented specimens (1373 ± 590 N) (P = 0.01). In group 1, varus displacement and glenohumeral screw perforation occurred in all cases. Varus displacement occurred in 2 cases in group 2, whereas glenohumeral screw perforation did not occur in any of the cases. Cement augmentation led to a significant increase in axial stiffness (P = 0.04). Conclusions: Calcium phosphate cement–augmented locking plates enhanced fixation stability in proximal humeral fractures and reduced glenohumeral screw perforation in this 2-part cadaveric model. The ultimate advantage of this method remains to be determined in vivo.