The mechanical or electrical induction of medullary angiogenesis: will it improve sternal wound healing?

We induced angiogenesis in the tibial medulla and cortex of rabbits by electrical and mechanical stimulation, with the aim of future application to ischemic disease. Sixteen New Zealand rabbits were divided into 4 groups: in Group 1, a K wire was inserted into the medullary channel; in Group 2 a hole was drilled into the tibia; in Group 3, electrical stimulation was applied to the medullary channel; and in Group 4 (the control group), nothing was done. The interventions were applied during a 21-day period, after which all animals were evaluated scintigraphically and histopathologically. All 3 interventional groups were significantly superior to the control group in regard to medullary and cortical vascularity: the P values were 0.021 in all comparisons to control. However, the most fibrotic changes in the medulla occurred in the group that had been treated with electricity (P = 0.008). Slight fibrotic changes occurred in the hole group (P = 0.040), and none occurred in the K-wire group. In sum, all 3 interventions are capable of inducing medullary angiogenesis, but electricity is inferior in regard to fibrotic change. We believe that this present study can establish a baseline for further work that explores clinical applications to problematic ischemic conditions, including delayed sternal wound healing after cardiac surgery.