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.
Ninety-five degree angled plates are typically used in fixation of fractures of the upper femoral areas so that the normal alignment of the bone can be restored. Surgeons need to be three dimensional thinkers to insert this kind of fixation and accurately recreate the anatomical relationships in the area. Pelvic and acetabular fractures are more often fixed with reconstruction plates as they are thinner than dynamic compression plates and more easily mouldable. Fractures often occur close to or just below the prostheses of joint replacements and they may be fixed by bigger plates and cerclage wiring.
Strong fragment compression and close anatomical restoration of normal alignment can lead to a very stable fixation and if this is produced by the fixation then primary healing will be the main healing process. There is dead bone close to the fracture site and this is absorbed by bone absorbing cells known as osteoclasts, after which blood vessels grow in along with bone producing cells known as osteoblasts. Osteoporosis under a plate can occur from the interruption in blood supply which can be produced by the fixation. Once the plate is removed the bone is less strong and along with the screw holes this means care needs to be taken in physiotherapy for the patient because of this.
The initial part of performing internal fixation is the exposure of the fracture site and the removal of the accumulated haematoma, followed by aligning the fragments as close to their original position as possible. Fracturing a bone disrupts the blood supply and the periosteal membrane provides the remaining blood supply to the area, a blood supply the surgeons take care not to disrupt by stripping the membrane from the bone during operation. This could delay the healing process due to reduction of blood supply. Fractures which are unstable or have multiple fragments have to be spanned by a bridge plate to restore bone length, rotation and alignment although this fixation cannot take significant load.
The Less Invasive Surgical Stabilisation plating system (LISS) is a modern fixation system which limits the contact between the metal and the bone, lowering the risks of the blood supply in the damaged area becoming compromised. These designs are more mouldable to the bony contours and have the ability to apply locking screws, allowing these designs to keep the desired bony alignment whilst simultaneously managing to resist significant forces during the period of healing. Choice of these newer designs is indicated in managing fractures of the end of bones such as the radius, humerus and femur.
Less unstable fractures such as of the humeral, ulna and radial shafts have room to fix more easily and unite well with normal techniques. Locking screws are used where the options to fix are limited or the bone is osteoporotic. Locking capability will likely be the default option as plating develops and the costs, now much higher than conventional screws, reduces. However, if malunion occurs with conventional plating and the fixation needs to be revised the expense of the newer locking systems looks less prohibitive.
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.