Structural changes in intact tubular bone after application of rigid plates with and without compression.

The influence of a rigid plate on the structure of intact tubular bone was studied in forty adult rabbits using a four-hole commercial-steel DCP-ASIF plate attached to each tibiofibular bone, with and without compression. The morphological changes in the bone underlying the plate were examined and were assessed quantitatively at one day to thirty-six weeks after operation. The rigid plate induced porotic changes in the cortical bone, which were evident three weeks after the operation and increased rapidly between twelve and eighteen weeks. At thirty-six weeks, resorption cavities occupied 40.6 per cent of the cortical wall of the bones plated with compression and 41.2 per cent of the wall of those plated without compression. The changes were visible slightly earlier in the presence of compression. A rigid plate brought about a statistically significant increase both in the outer diameter of the bone and in the diameter of the medullary space as a result of subperiosteal new-bone formation and concomitant subendosteal bone resorption.