EFFECT OF LOADING AND FRACTURE MOTIONS ON DIAPHYSEAL TIBIAL FRACTURES

A computerized motion sensor was used to record the three-dimensional components of interfragmentary motion during healing in three patients with closed, low-energy fractures of the tibial diaphysis treated wit h functional braces. At the first measurement session, 2 weeks after f racture, the patients applied approximately 15 kg to the injured limb, Although this produced 1-4 mm of translation of the fragments, this w as recovered when the load was removed. The maximum rotational and ang ulatory displacements often occurred as the patients rose from the cha ir with no weight applied to the limb and frequently were reduced as t he 15 kg of load was applied. Under load, the maximum axial rotation w as 3 degrees and the maximum angular displacement was 1 degrees. As wi th the translations, the initial rotational and angulatory positions o f the fragments were recovered when the load was removed and the patie nt returned to the seated position. At 8 weeks, the patient applied fu ll body weight, producing a maximum interfragmentary translation of 0. 5 mm and maximum axial rotation or angulation of 0.5 degrees. Abundant peripheral callus formed in all three fractures, and they healed by 1 5 weeks through typical gradual consolidation and mineralization of th e callus, accompanied by a corresponding reduction in interfragmentary motions.