Comparative study of callus performance achieved by rigid and sliding plate osteosynthesis based upon dynamic mechanical analysis

Operative management of long bone fractures is considered to be the treatment of choice all over the world. This could be achieved either by intramedullary nailing or plating. The former allows delivery of stresses into the fracture site, but it requires a well-equipped operating theatre and an experienced surgeon who is, unfortunately, continuously exposed to radiation. On the other hand, plates could easily be applied in every orthopaedic clinic, but the existing ones are rigid and protect the fracture site from stresses to which it is ordinarily exposed. Recently, various experimental attempts have been made to provide plates which allow partial loading on the fracture site and enhance callus formation (secondary fracture healing). Bearing that in mind, a two-part sliding plate (SP) has been developed at the Orthopaedic Clinic of Patras University, which allows intermittent loading into the fracture site. Both the conventional AO rigid plate and SP were applied to osteotomized sheep radii. The dynamic properties of the callus were estimated with its two dynamic mechanical characteristics (dynamic modulus of elasticity and the relative loss factor), whereas its static properties (strength) were evaluated by measuring the ultimate bending strength. A superiority of callus produced by the sliding plate was observed concerning all the parameters under consideration.