Assessment of the Resistance of a Polymethylmethacrylate (Pmma) Dynamic Compression Plate (DCP) Prototype Tested on Osteotomized Canine Femurs

Abstract

Femur fractures are the most frequent long bone fractures in small animals. Due to the femur’s anatomical position, it is difficult to immobilize, and therefore internal fixations are very useful. Dynamic compression plates (DCP) provide high stability, are durable, minimize fragment movement and promote primary healing of the bone. Advantages of this treatment include anatomical reconstruction, early mobility and carrying capacity of the affected limb. Polymethylmethacrylate (PMMA) is an acrylic resin that has proved very useful in bone tumor treatment, cranial deformation prosthesis, percutaneous vertebroplasty and testicular prosthesis in animals. The purpose of this study was to manufacture DCP-PMMA and test its resistance to the different forces present in a fracture. Forty-eight (48) 3.5MM x 4-hole DCP were made from an alginate mold. Six (6) femurs were obtained from canine cadavers zeighing from 10 to 20 kg, which underwent osteotomy simulating an oblique fracture. The plates were subsequently positioned in the osteotomized bones to submit them to the various forces involved in a fracture. The DCP-PMMA resisted a torque force of 2.83 newton/metres and a compression and flexion force of 0.21 kilonewton. The obtained resistance of the DCP-PMMA was an average of 20 kg per force. The results of this study show that it is possible to make a DCP-PMMA 3.5 mm x 4-hole, the resistance of which is of 20 kg against the three applied forces, and that it can be used to stabilize long bone fractures subjected to a pressure of less than 20 kg.