Systemic and local effects of disportional longitudinal growth of bones in foals and lambs and the impact on bone mineral density and content

In the present study the effects of „periosteal stripping“ on bone and cartilage metabolism of foals with angular limb deformities and healthy experimental lambs were examined. Five foals with angular limb deformities were treated surgically by means of „hemicircumferential transection of the periosteum and periosteal stripping“ (HCTP/HP). Before surgery as well as twice after surgery, 1,25(OH)2Vitamin D, bone and cartilage markers in the serum were determined and compared to 5 healthy foals of the same age. In addition 10 healthy lambs were treated by HCTP/HP, in which the same parameters and bone density were determined. At 22 days after surgery the lambs were sacrificed and treated and control bones were sampled and processed for immunohistochemistry. Neither in foals nor in lambs, significant differences could be observed between treated and untreated animals with regard to the parameters measured in serum. Nevertheless, both treated groups revealed a tendency for higher bone remodelling compared to control animals. This could be the result of an increased bone remodelling rate following surgery. No statistically significant difference in bone mineral density between treated and untreated animals could be detected. In contrast local changes of signal transduction related to parathyroid hormone related protein and indian hedgehog (PTHrP/Ihh) were observed using immunhistochemistry. It was concluded that HCTP/HP at the level of epiphysis and metaphysis does not lead to systemic effects, even though local events detected by immunohistochemistry point to an increased bone formation at the treated site.