Clinical and radiographic outcome of open reduction and internal fixation of 3- and 4-part proximal humerus fractures augmented with impaction bone grafting and a magnesium-based bone filler.

Background: Open reduction and internal fixation (ORIF) of proximal humerus fractures (PHFs) is a challenging operation with high rates of loss of reduction, screw cut out, avascular necrosis, and subsequent unplanned reoperation. Augmentation of the repair with synthetic bone fillers and other alternatives has shown promise in decreasing adverse outcomes. Our aim is to report radiographic and clinical outcome of impaction grafting with cancellous allograft chips and injection of magnesium-based bone filler for ORIF augmentation of PHFs. Methods: All patients that underwent ORIF for a 3- or 4-part PHF with the standardized protocol with a minimum of 6 months radiographic follow-up by a single surgeon (VE) were included. Radiographs were taken at standardized time points up to 6 months, followed by a final radiographic follow-up, to define radiographic healing or failure. Patient-reported outcome measures were collected at final follow-up. Patient characteristics, complications, reoperations and radiographic measures of reduction quality were also recorded. Results: 17 patients were identified with a mean 34.1 months of radiographic follow-up. Median Penn Shoulder Score was 89 (interquartile range 19), American Shoulder and Elbow Surgeons score was 92 (25), Veterans RAND 12-Item Health Survey Mental Component Score was 53.9 (11.9), Veterans RAND 12-Item Health Survey Physical Component Score was 51.6 (12.8), and Single Assessment Numerical Assessment was 85 (18.5). 14 patients (82.3%) had routine radiographic healing. Two patients (11.8%) developed avascular necrosis with screw cutout. Two patients (11.8%) had reoperation including one hardware removal and one conversion to reverse total shoulder arthroplasty for a subsequent rotator cuff tear. No signs of glenohumeral arthritis were present in 12/17 patients (70.6%), and no signs of cuff tear arthropathy were noted in 13/17 patients (76%). Seven out of nine (78%) patients who worked prior to injury returned to work at a mean of 14.7 weeks postoperatively. Conclusion: Augmentation of 3- and 4-part proximal humeral fractures with a standardized protocol utilizing cancellous chips and a synthetic magnesium-based bone filler results in a high rate of maintenance of fracture reduction, radiographic healing, and satisfactory patient outcomes. Further comparative data is needed to evaluate the efficacy of this technique compared to alternative methods of augmentation.