Fractures of the lower end of the femur may involve the knee joint. Fractures that extend into the weight bearing surface of the joint (intra-articular fractures) and disrupt the cartilage surface are more complex and difficult to treat than fractures that do not. The treatment is largely surgical as these fractures tend to displace even in a cast. Treatment is broken down below:
EXTRA-ARTICULAR FRACTURES
If the fracture involves the lower end of the shaft of the femur without involvement of the joint, surgical management can often be performed with minimally invasive surgical techniques utilizing either plates or intra-medullary nails. Both forms of surgical treatment are widely accepted as effective methods of fixation provided the bone is properly aligned. With more complex injuries, formal open reduction may be required. Each type of fixation has advantages and disadvantages. Plates are more rigid and better for fractures with splintering of the bone while nails are more “biologically friendly”.
Surgery usually takes 1-2 hours and the hospital stay ranges from 3-5 days. Most patients with distal femur fractures heal quickly, however crutches are necessary for the first 4-6 weeks after surgery. Pool therapy is very useful during this time as it allows for some motion without putting stress on the surgical repair. A big risk after surgery is the development of blood clots in the veins of the legs and pelvis. Most patients are treated with a low molecular weight heparin medication for the first two weeks after surgery. After 6 weeks, patients begin putting full weight on their leg and start more aggressive physical therapy. Full recovery for most femur fractures takes 6-8 months.
Many patients complain of irritation from the plate on the outer surface of the femur. It may be removed after 12 months. This is a short outpatient surgery that usually takes about an hour to perform and the use of crutches or protected weight bearing after surgery is not indicated.
INTRA-ARTICULAR FRACTURES
If the fracture involves the lower end of the shaft of the femur with involvement of the joint, surgical management focuses on realigning the surface of the joint. Typically the surface of the joint is smooth allowing the bones to glide past one another with very little friction. If the surface is incongruent because the bones are not aligned, chronic damage to the joint occurs. This ultimately leads to arthritis. It is therefore very important to ensure that the surface of the cartilage is repaired as accurately as possible. Surgical repair is recommended in any fracture of the distal femur in which the joint has more than 2 mm of displacement.
Surgical repair involves re-aligning the fracture and holding the repair with plates and screws. Surgery usually takes 2-3 hours and the hospital stay ranges from 3-5 days. The prognosis and post-operative care is similar to that of extra-articular distal femur fractures.