Following any fracture around the knee the most important principle is to accurately reconstruct the joint surface as this will reduce the probability of arthritis developing in the joint. If possible, early active motion of the joint is encouraged to prevent stiffness. The various fractures that involve the knee joint are discussed below.
If the fracture is a straight break across the kneecap then accurate reduction and fixation with a screw and a ring of wire is possible. If the fracture is in several pieces (typically following a fall directly onto the kneecap) the patella is normally reconstructed with two wires and a figure of eight shaped wire wrapped around them to hold the pieces together. Rarely, if the patella is smashed into many tiny pieces, the patella may need to be removed completely.
TIBIAL PLATEAU FRACTURES
Fractures of the upper end of the shin bone range from minor to very complex. For those fractures that are at the minor end of the scale, it may be possible to fix the fracture with a couple of crews passed through small holes in the skin using X-ray and arthroscopic guidance. For the more complex fractures, a full open operation may be required with the use of plates, screws and bone graft to obtain an accurate reconstruction of the joint surface. In the very complex fractures, a circular ring external fixator may be required to support the fracture while it heals. The x-ray below shows arthritis as a result of poor fixation of a tibial fracture.
Fractures of the lower end of the thigh bone are often reconstructed by the combination of screws and a plate.
ACL/PCL AVULSION FRACTURES
Occasionally, especially in younger patients, instead of rupturing the ACL or PCL in an injury, a piece of bone is pulled off attached to the ligament. In these cases the bone is screwed back into place and frequently further reconstruction is not required.
In the case of a large osteochondral fracture it may be possible to fix the fragment back in place if the piece of bone in the fragment is large enough. This is performed using a small screw without a head so that the screw can be buried so as not to rub in the surface of the joint.