Distal humerus fractures in elderly population are often comminuted and presents multiple challenges. When managed with fixation the results are often complicated with stiffness, pain, and reduced function while total elbow replacement is fraught with lifelong restrictions on load bearing which can significantly affect elderly patients who rely assistive devices for ambulation. Elbow hemiarthroplasty however, presents a viable alternative in these cases. This series evaluates the results of the distal humerus hemiarthroplasty in a single centre. Data was collected retrospectively. Comprehensive case reviews were done to collect demographic, intra-operative and post-operative data. Fractures were classified as per AO classification. The primary outcome was functional outcome and range of motion (ROM). The secondary outcomes were complications and patient satisfaction.Objectives
Designs and methods
Increasing numbers of young people receive metal on metal (CoCr on CoCr) total hip replacements. These implants generate nano-particles and ions of Co and Cr. Previous studies have shown that micro-particles, nano-particles and ions of CoCr cause DNA damage and chromosomal abberrations in human fibroblasts in tissue culture, and in lymphocytes and bone marrow cells in patients with implants. Several surgeons have used these implants in women of child-bearing age who have subsequently had children. Significantly elevated levels of cobalt and cromium ions have been measured in cord blood of pregnant women with CoCr hip implants. The MHRA (Medicines and Healthcare products Regulatory Agency) subsequently stated that there is a need to determine whether exposure to cobalt and chromium represents a health risk during pregnancy. In an attempt to investigate this risk, we used a well established in vitro model of the placental barrier comprised of BeWo cells (3 cells in thickness) derived from the chorion and exposed this barrier to nanometer (29nm) and micron (3.4μm) sized CoCr particles, as well as ions of Co2+ and Cr6+ individually or in combination. We monitored DNA damage in BJ fibroblasts beneath the barrier with the alkaline gel electrophoresis comet assay and with γH2AX staining. The results showed evidence of DNA damage after all types of exposure. The indirect damage (through the barrier) was equal to the direct damage at the concentrations tested. The integrity of the barriers was checked with measurements of electrical resistance (TEER values) and permeability to sodium fluorescein (376Da) and found to be intact. In light of these results and with the knowledge that BeWo cells express the transmembrane protein Connexin 43, we tested the theory that a damaging signal was being relayed via gap junctions or hemi channels in the BeWo cells to the underlying fibroblasts. We used the connexin mimetic peptides Gap19 and Gap26 (known to selectively block hemichannels and gap junctions respectively) and 18α-glycyrrhetinic acid (non-selective gap junction blocker). All of these compounds completely obliterated the indirect damaging effect seen in our previous experiments. We conclude that CoCr particles can cause DNA damage through a seemingly intact barrier, and that this damage occurs via a bystander mechanism. It would be of interest to test whether this is simply a tissue culture effect or could be seen in vivo.
