The various bones and fracture positions dictate the different types of plate available. The DCP or dynamic compression plate and the screw holes allow compression of the fracture site to be applied as the screws are tightened up in the angled screw holes. Small plates are used to fix the lateral malleolus of the ankle and the wrist end of the ulna forearm bone and for this job they are often very thin at an easily mouldable one millimetre. Other plates have been designed for use in fractures close to joints and these have reduced device size and thickness and added options for the flexibility in fixation required.
Fractures of the upper femur are fixed by using plates with a 95 degree angle so that the mechanical axis of the upper femur can be restored at this angle. Inserting this kind of fixation requires that the surgeon thinks in three dimensions as are all must be correctly aligned to restore normal anatomy. Reconstruction plates are less thick than dynamic compression plates and can be contoured in three dimensions for the acetabulum and pelvis. Fractures close to or next to prostheses such as hip replacements or knee replacements are fixed with larger plates with the addition of cerclage wires.
High levels of fracture stability can be provided by compression of the fragments and a good restoration of anatomical alignment by the fixation. If firmly stabilised and without any fragment gap then the fracture will heal by primary healing. Absorption of the dead bone at the site of fracture occurs by the action of osteoclasts, with blood vessels growing into the region and then bone producing cells proliferating. Disruption of the blood supply by the plate can produce some osteoporosis under the plate, leading to reduced bone strength from this and the screw holes once the plate is removed, necessitating careful decisions about the amounts of force to be applied to the area.
In normal fixation using a plate the area is opened up and the blood clot is removed and the fracture fragments are restored to the best anatomical alignment possible. After a fracture the blood supply through the bone has been interrupted so the main blood supply around the fracture comes from the periosteum, the bone membrane lining. It is essential that this membrane is not disturbed or stripped off in the operation as this could reduce the blood supply to the fracture area and delay healing. If unstable fractures with many fragments are to be fixed then a plate which bridges across the gap can be used, with limited operative exposure. It is fixed to the major fragments and works by keeping the bone length, alignment and rotation but cannot suffer much in the way of load.
The LISS (Less Invasive Surgical Stabilisation) plating system is a recently developed technique which reduces the contact between the metal and the bone or periosteum, reducing the potential for disruption of the blood supply in the fracture area. Modern designs contour more effectively to the bony anatomy and allow for locking of the screws, which are both advantageous by maintaining the fracture in the correct position whilst allowing increased forces to be applied to it in the healing period. These new designs are most useful in fixing the ends of the bones in fractures of the tibia, femur, radius and humerus.
Conventional plating techniques are adequate to fix fractures where access to the areas is easy and in cases where the fractures are of a stable type, incorporating fractures of bony shafts such as the ulna, humerus and radius. With osteoporotic bone and difficult fixation options the locking systems will be more appropriate. As they are much more expensive than the conventional systems they are not yet the default choice in all cases but look likely to be more widely used as the cost comes down. They may well be cost effective if cases of malunion which require revision are taken into account.
It was in the 1930s that Kuntscher refined the intramedullary nailing technique which then became the treatment of choice for shaft fractures of the femur. Humeral and tibial fractures as well as femoral breaks nearer the bone ends were the next progression. Early joint movement and weight bearing walking is allowed by this.