Saturday, June 6, 2009

Plating of Fractures

By Jonathan Blood Smyth

Because of the large number of locations where fractures occurs and the different bones involved there is a variety of plates available. The dynamic compression plate or DCP allows a sliding technique to be used because of the screw holes being angled away from a central point. Once the screws are inserted and tightened they apply an inwards compression force, bringing the fragments into stronger contact. The ulna and the ankle lateral malleolus are fixed with thin plates of about one mm in thickness which can be shaped to the area required. Fractures close to a joint need specially designed plates to facilitate fixation and reduce impingement.

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 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.

If there is enough room for easy fixation and the fracture is of a more stable type then conventional plating techniques may be used for fixing breaks of the shafts of bones such as the radius, ulna and humerus. Locking screws are more appropriate if the bone is osteoporotic or the fixation options are limited. Future development will likely lead towards locking techniques being the first option for all fractures, but they are much more expensive and wider use awaits reduction in costs. If the costs of revising the fixation due to malunion by conventional plating are factored in then the more expensive initial system looks more cost neutral.

Nails

Nailing techniques were standardised in the 1930s by Kuntscher, who made them the default management options for femoral shaft fractures, the option gradually being extended to breaks in the tibia and humerus as well as femoral fractures nearer the bone ends. Inserting a nail stabilises the fracture for early joint mobilisation and ambulation. - 14130

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