Anatomy: The knee joint is made up of three bones. The femur (thigh bone), the tibia (shin bone) and the patella (kneecap). These three bones work together with a complex group of ligaments to form the knee joint. Fractures of the knee are very common and typically require surgical stabilization.
The kneecap transmits the forces from the quadriceps muscle and allows the knee to extend. With a broken kneecap, the knee cannot actively straighten and cannot be held straight during ambulation, resulting in falls and disability. The kneecap sees more stress and torque on it than any other bone in the body (up to 7 times bodyweight), necessitating absolute anatomic alignment of the bone and superior fixation for optimal results. Typically I treat these fractures with FiberWire (suture as strong as metal) to secure the bone. This has the advantage of superior fixation strength as well as minimizing hardware irritation in the front of the knee. A common complication after patella surgery is all of the metal wire irritates the skin and requires a second surgery to remove it after bone healing. However this newer technique with modern technology allows for stronger fixation and virtually no soft tissue irritation. Occasionally I will supplement the FiberWire fixation with screws in the patella bone. These screws are inside the bone and do not irritate the skin, therefore they never need to be removed.
Tibial Plateau Fractures
The tibial bone at the level of the knee is known as the “Tibial Plateau.” These can be very debilitating injuries and almost always require surgery. Most fractures are treated with a plate and screws on the lateral (outside) of the knee. These injuries are well known to have substantial bone loss from the crushing nature of the injury. Sometimes it is necessary to fill the void with cadaver (bone from a deceased person) or synthetic bone cement. The patient’s body will eventually replace the cement or cadaver bone with their own bone. Even with surgery non-weight bearing is necessary for at least 8 weeks, sometimes 12.
Distal Femur Fractures
These fractures are highly unstable fractures that require surgery. Occasionally these fractures can be treated with a rod inserted
through the knee and up the thigh. Early partial weight bearing can sometimes be started after this type of surgery. More often however, the
bone is in too many small pieces for treatment with a rod. A large plate and screws is fixed to the lateral (outside) of the femur bone to hold the
bone rigid during healing. After this surgery typically 12 weeks of non weight bearing is necessary.
Post Operative Course:
Unfortunately knee fractures take a great deal of time to heal. The knee is such an important joint and respect
must be had for the healing process.
Dressing: Should be changed daily starting on postoperative day #3 until you are seen in clinic.
Staples: The staples will need to come out at about 2 weeks.
Weight Bearing: Some fractures allow for weight bearing but most do not. Prolonged non weight bearing up to 12 weeks is common.
Mobilization: Younger and active patients may use crutches. Older and less active patients may need a walker or even a wheelchair at times.
Range of Motion: Knee motion puts stress on the fixation. While some gentle range of motion may be allowed, it is also possible that the knee will have to remain straight and
immobilized for 2-4 weeks postoperatively
Therapy: Knee fractures almost always require therapy to regain motion, to work on walking once weight bearing is allowed, and to regain strength and function of the knee.
Wound Healing: The distal femur and proximal tibial wounds are well known to have high infection rates. Sometimes a special dressing called a wound vac is used to minimize this risk. Patella incisions usually heal without complication.
Long Term: It takes 3 months for the bone to fully heal, although it takes beyond 3 months to regain motion, strength and function. These injuries can take 6 months to a year to fully recover from. Additionally, arthritis can be an issue long term as cartilage cells are damaged at the time of the injury and cannot be repaired.