Knee Replacement Surgery

Total knee replacement may be considered when more conservative methods of treatment have failed to relieve pain and restore range of motion

The Anaesthetic
There are different types of anaesthetic that can be used. The three main ones are general anaesthesia, spinal and epidural anaesthesia. An anaesthetist will discuss the advantages and possible disadvantages of each type of anaesthetic with the you prior to surgery.

The Operation
A single 6 inch incision is made along the top of the knee. The muscles are then split to expose the knee joint. The damaged bone and cartilage are removed, and replaced with a prosthetic component made of specialized types of metal and plastic.
The type of prosthesis used will be discussed prior to surgery. All prosthesis I use are well established with a good track record of success.

I personally do not carry out unicompartmental (half) knee replacements. If you are deemed to be a suitable candidate, I will refer you to one of my colleagues who carry out this procedure.

After Surgery
Management — Postoperative management includes controlling pain with intravenous or oral medication. Patients are also given an antibiotic (generally for 24 hours following surgery) to prevent infection.
An anticoagulant medication such as low molecular weight heparin will be given to help prevent blood clots in the legs. Compression support stockings are often used to prevent of blood clots. The support stockings are usually worn for several weeks following surgery. You may well be asked to take Aspirin for 6 weeks after discarge from hospital to decrease the risk of clots.
Most patients are able to try standing and walking, with the help of a physiotherapist, as early one day after the procedure.

Rehabilitation — Physical therapy is an important part of the recovery process. Most patients spend four to seven days in the hospital, during which they work with a physiotherapist to develop an exercise and rehabilitation program. The rehabilitation program generally includes exercises to improve range of motion and strengthen the muscles surrounding the knee joint, as well as training in activities of daily life (eg, stair climbing, bending, walking). Patients can usually resume their normal activities within three to six months.
The goal of the rehabilitation period is to regain strength and motion; it is important to avoid overworking or straining the joint during this recovery period. While high-impact sports such as running or contact sports should be avoided, patients can typically participate in activities like walking, cycling, and swimming. Kneeling can be painful, and many patients find this activity difficult after knee replacement surgery.
Most knee replacements last 10 to 15 years or longer, and patients are generally very satisfied with the outcome.

Complications
Serious complications after knee replacement surgery are not common. 85-95% of replacement operations are successful. Complications can occur during surgery, in the immediate postoperative period, or many years after surgery. It is important to understand these potential risks before deciding to undergo knee replacement. For most patients, the benefits of reduced pain and improved function outweigh the small risk of complications.

Complications during surgery.
Very rarely, complications can occur during the actual knee replacement procedure. These include fractures (typically of the femur), injury to the surrounding nerves or blood vessels. Most of these complications can be treated during the course of the surgery.

Thromboembolism
People undergoing knee replacement are at increased risk of developing blood clots after surgery. With appropriate preventive treatments (eg, anticoagulation, compression devices), the risk is minimized as much as possible. Clots can affect the legs most commonly, but occasionally can affect the lungs.

Infection
Infection following knee replacement is uncommon (less than 1% of patients). Numerous measures are taken to keep the infection rate as low as possible. Prompt medical attention is needed if these problems develop. Superficial infection can be successfully treated with antibiotics. Deep infection around the prosthesis is far more serious and will require further surgery.

Periprosthetic fracture
A periprosthetic fracture is a fracture that occurs in a bone near the implant. This occurs in less than 1 percent of knee replacement patients. This type of fracture may be treated nonsurgically (in less severe cases) or surgically (if the fracture is unstable or the prosthesis has failed).

Stiffness
Early rehabilitation helps regain movement in the knee. Most patients achieve over 110 degrees of bend in the knee. Occasionally the knee can remain stiff after surgery. A manipulation under a short anaesthetic can be carried out if further rehabilitation does not improve the range of movement.

Aseptic loosening
Loosening of the joint implant is most often caused by wear of the prosthetic components. Loosening is often painful and is the most common long-term problem associated with total knee replacement, although the incidence is decreasing as improvements in prostheses are made.