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. 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.Purpose:
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