Abstract. Introduction. There is little literature exploring clinical outcomes of secondarily displaced proximal humerus fractures. The aim of this study was to assess the rate of secondary displacement in undisplaced proximal humeral fractures (PHF) and their clinical outcomes. Methods. This was a retrospective cohort study of undisplaced PHFs at Royal Derby Hospital, UK, between January 2018-December 2019. Radiographs were reviewed for displacement and classified according to Neer's classification. Displacement was defined as translation of fracture fragments by greater than 1cm or 20° of angulation. Patients with pathological, periprosthetic, bilateral, fracture dislocations and head-split fractures were excluded along with those without adequate radiological follow-up. Results. In total, 681 patients were treated with PHFs within the study period and out of those 155 were excluded as above. There were 385 undisplaced PHFs with mean age 70 years (range, 21–97years) and female to male ratio of 3.3:1. There were 88 isolated greater tuberosity fractures, 182 comminuted PHFs and 115 surgical neck fractures. Secondary displacement occurred in 33 patients (8.6%). Mean time to displacement was 14.8 days (range, 5–45days) with surgical intervention required in only 5 patients. In those managed nonoperatively, three had malunion and one had nonunion. No significant differences were noted in ROM between undisplaced and secondarily displaced PHFs. Conclusion. Undisplaced fractures are the most common type of PHF. Rate of secondary displacement is low at 8.6% and can occur up to 7 weeks after injury. Displacement can lead to surgery, but those managed conservatively maintain their ROM at final follow up

Purpose:. Tuberosity healing in hemiarthroplasty for proximal humerus fractures remains problematic. Improved implant design and better techniques for tuberosity fixation have not been met with improved clinical results. The etiology for tuberosity failure is multifactorial; however thermal injury to host bone is a known effect of using polymethylmethacrylate for implant fixation. We hypothesized that the effect of thermal injury at the tuberosity shaft junction could be diminished by utilizing an impaction grafting technique for hemiarthroplasty stems. Methods:. Five matched pairs of cadaveric humeri were skeletonized and hemiarthroplasty stems were implanted in the proximal humeri in two groups. The first group had full cementation utilized from the surgical neck to 2 cm distal to the stem (cement group) and the second group had distal cementation with autologous cancellous bone graft impacted in the proximal 2.5 cm of the stem (impaction grafting group). Thermocouples were used to measure the inner cortical temperature at the tip of the stem, surgical neck, and at the level of the cement-graft interface for both treatment groups (see Fig. 1). Experiments were initiated with the humeri fully submerged in 0.9% sodium chloride and all three thermocouples registering a temperature of 37 ± 1°C. Statistical analyses were performed with a one-sided, paired t-test. Results:. The maximum recorded cortical bone temperature at the surgical neck was significantly decreased by 23% from 52.4 ± 8.1°C in the cement group to 40.4 ± 4.8°C in the impaction grafting group (p = 0.037). We identified no significant differences in maximum recorded temperature at the cement-graft interface between the impaction grafting group (44.3 ± 6.3°C) and the cement group (47.4 ± 6.4°C) (p = 0.254). A similar finding was observed between groups at the tip of the hemiarthroplasty stem (impaction grafting group 54.2 ± 5.7°C; cemented group 52.3 ± 7.3°C, p = 0.303). Conclusion:. Given the known threshold of 47°C as the onset of permanent thermal injury to bone,. 1. impaction grafting maintains the temperature at the surgical neck during cementation below this critical value. Impaction grafting may serve as a beneficial surgical technique to mitigate the effects of thermal injury on tuberosity healing in proximal humeral hemiarthroplasty for fracture

A reverse shoulder arthroplasty has become increasingly common for the treatment of proximal humerus fractures. A reverse shoulder arthroplasty is indicated especially in older and osteopenic individuals in whom the osteopenia, fracture type or comminution precludes fixation. However, there are many other ways to treat proximal humerus fractures and many of these are appropriate for different indications. Percutaneous pinning remains an option in certain surgical neck or valgus impacted proximal humerus fractures with minimal or no comminution at the medial calcar. In general, a fracture that is amenable to open reduction and fixation should be fixed. Open reduction and internal fixation should be the gold standard treatment for three-part fractures in younger and middle-aged patients. Four-part fractures should also be fixed in younger patients. Hemiarthroplasty results are less predictable as they are very dependent on tuberosity healing. While a reverse shoulder replacement may be considered in patients with severe comorbidities, patients always have better outcomes in the setting of an appropriately reduced and stably fixed proximal humerus fracture

Introduction. Locking plates can provide greater stability than conventional plates; however, reports revealed that fractures had a high incidence of failure without medial column support; the mechanical support of medial column could play a significant role in humeral fractures. Recent studies have demonstrated the importance of intramedullary strut in proximal humeral fracture fixation, the relationship to mechanical stability and supporting position of the strut remain unclear. The purpose of this study was to evaluate the influence of position of the intramedullary strut on the stability of proximal humeral fractures using a locking plate. Materials and methods. Ten humeral sawbone (Synbone) and locked plates (Synthes, cloverleaf plate), with and without augmented intramedullary strut (five in each group) for proximal humerus fractures, were tested using material testing machine to validate the finite element model. A 10 mm osteotomy was performed at surgical neck and a strut graft (10 cm in length) was inserted into the fracture region to lift the head superiorly. Each specimen was statically tested at a rate of 5 mm/min until failure. To build the finite element (FE) model, 64-slices CT images were converted to create a 3D solid model. The material properties of screws and plates were modeled as isotropic and linear elastic, with an elastic modulus of 110 GPa, (Poisson's ratio, n=0.3). The Young's moduli of cortical and cancellous bones were 17 GPa and 500 MPa (n=0.4), respectively. Three alter shifting toward far cortex by 1, 2, and 3 mm in humeral canal were installed in the simulating model. Results and discussion. The test result showed stiffness for only locked plate was 149.2±21.3 N/mm; and the plating combined with an intramedullary strut was 336.5±50.4 N/mm. On average, the stiffness was increased by 2.2 times in the augmented fixation relative to the only locking plate fixation. The finite element analytical results showed stiffness of 162 N/mm for fixation without strut, and 372 N/mm for those with strut augmentation. The stiffness between experiment and FE analysis agreed in 8.6% for the only locking plate case; and agreed in 10.5% for the case fixed with intramedullary strut. FE analysis showed the stability of construct increased 7%, 11% and 20% as the strut shift by 1, 2, and 3 mm, respectively. Gardner (2007) reported the importance of mechanical support at the medial region for maintenance of reduction when proximal humerus fracture treated with locking plates. Conclusion. The intramedullary strut may provide superior stability than the only locking plate fixation. The FE model provides a useful implement to find the optimal configuration of plate fixation. Acknowledgements. All authors thank the funding support from National Science Council (NSC 102-2628-B-650-001) and E-Da Hospital (EDPJ1020027)

Purpose. Locking plate constructs for proximal humerus fractures can fail due to varus collapse, especially in the presence of osteoporosis and comminution of the medial cortex. Augmentation using a fibular allograft as an intramedullary bone peg may strengthen fixation preventing varus collapse. This study compared the ability of the augmented locking plate construct to withstand repetitive varus stresses relative to the non-augmented construct in cadaveric specimens. Method. Proximal humerus fractures with medial comminution were simulated by performing wedge-shaped osteotomies at the surgical neck in cadaveric specimens. For each cadaver (n=8), one humeral fracture was fixated with the locking plate construct alone and the other with the locking plate construct plus ipsilateral fibular autograft augmentation. The humeral head was immobilized and a repetitive, medially-directed load was applied to the humeral shaft until failure (significant construct loosening or humeral head screw pull-out). Results. No augmented construct failed, withstanding either 20 000 cycles or five times the cycles of the contralateral non-augmented construct [average (standard deviation) = 27958 (4633) cycles], while six of the eight non-augmented constructs failed (p=0.007). Failure in the six non-augmented constructs occurred after an average of 5928 (2543) cycles. Conclusion. Fibular allograft augmentation increased the ability of the locking plate construct to withstand repetitive varus loading. Clinically, this may assist proximal humerus fracture fixation in osteoporotic bone with medial cortex comminution