The knee is made up of four bones. The femur or thighbone is the bone connecting the hip to the knee. The tibia or shinbone connects the knee to the ankle. The patella (kneecap) is the small bone in front of the knee and rides on the knee joint as the knee bends. The fibula is a shorter and thinner bone running parallel to the tibia on its outside. The joint acts like a hinge but with some rotation.
The knee is a synovial joint, which means it is lined by synovium. The synovium produces fluid lubricating and nourishing the inside of the joint. Articular cartilage is the smooth surfaces at the end of the femur and tibia. It is the damage to this surface which causes arthritis.
It will be explained to you prior to surgery what is likely to be done but in revision surgery the unexpected can happen and good planning can prevent most potential problems. The surgery is often, but not always, more extensive than your previous surgery and the complications similar but more frequent than the first operation.
The surgery varies from a simple liner exchange to changing one or all of the components. Extra bone (cadaver bone) may need to be used to make up for any bone loss.
The femoral and the tibial component are fixed in place to form the new knee joint. The muscles and tendons are then approximated.
Drains are usually inserted to drain excessive blood.
Complications can be medical (general) or local complications specific to the knee
Medical complications include those of the anaesthetic and your general wellbeing. Almost any medical condition can occur so this list is not complete. Complications include
Ideally your knee should bend beyond 100 degrees but on occasion the knee may not bend as well as expected. Sometimes manipulations are required. This means going to theatre and under anaesthetic the knee is bent for you.
The operation will always cut some skin nerves, so you will inevitably have some numbness around the wound. This does not affect the function of your joint. You can also get some aching around the scar. Vitamin E cream and massaging can help reduce this.
Occasionally you can get reactions to the sutures or a wound breakdown which may require antibiotics or rarely further surgery.
Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates are approximately 1%. If it occurs it can be treated with antibiotics but may require further surgery. Very rarely your knee prosthesis may need to be removed to eradicate the infection.
These can form in the calf muscles and can travel to the lung (Pulmonary embolism). These can occasionally be serious and even life threatening. If you get calf pain or shortness of breath at any stage, you should notify your surgeon.
Also rare but can lead to weakness and loss of sensation in part of the leg. Damage to blood vessels may require further surgery if bleeding is ongoing.
The plastic liner eventually wears out over time, usually 10 to 15 years, and may need to be changed.
The knee may look different than it was because it is put into the correct alignment to allow proper function.
An extremely rare condition where the ends of the knee joint lose contact with each other or the plastic insert can lose contact with the tibia (shinbone) or the femur (thigh bone).
Patella (knee cap) can dislocate. That is, it moves out of place and can break or loosen.
There are a number of ligaments surrounding the knee. These ligaments can be torn during surgery or break or stretch out any time afterwards. Surgery may be required to correct this problem.
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