Sandyford, Dublin 18
What is knee arthritis?
The knee can be considered as having three distinct separate but communicating compartments. Orthopaedic surgeons refer to the knee as a ‘tri-compartmental’ joint being composed of patello-femoral, medial, and lateral ‘compartments’. Typically osteoarthritis (OA) or wear and tear starts in the medial compartment of the adult knee and symptoms can vary from mildly irritating pain to severely debilitating pain whereby activities of daily living are impossible.
What is a total knee replacement?
A total knee replacement is a surgical procedure whereby the diseased knee joint is replaced with artificial material. The knee is a hinge joint that provides motion at the point where the thigh meets the lower leg. The thigh bone (or femur) abuts the large bone of the lower leg (tibia) at the knee joint. During a total knee replacement, the end of the femur bone is removed and replaced with a metal shell. The top of the lower leg bone (tibia) is also removed and replaced with a metal table. The two metal pieces are kept apart by a thick piece of plastic (polyethylene) wedged between.
What patients should consider a total knee replacement?
Total knee replacement surgery is considered for patients whose knee joints have been damaged by either progressive wear and tear (degenerative or osteoarthritis), trauma, or other destructive diseases of the joint such as rheumatoid arthritis. The most common reason for knee replacement in Ireland is osteoarthritis. Regardless of the cause of the damage to the joint, the resulting progressively increasing pain and stiffness and decreasing daily function lead the patient to consider total knee replacement. Decisions regarding whether or when to undergo knee replacement surgery are not easy. Patients should understand the risks as well as the benefits before making these decisions.
What are the risks of undergoing a total knee replacement?
Risks of total knee replacement include clots (deep venous thrombosis) in the legs that can travel to the lungs (pulmonary embolism). Other risks include urinary tract infection, nausea and vomiting, on-going chronic knee pain and stiffness, bleeding into the knee joint, nerve damage, blood vessel injury, and infection of the knee, which can require re-operation.
What is involved with the preoperative evaluation for total knee replacement?
Before surgery, joints adjacent to the diseased knee are carefully evaluated. This is important to ensure optimal outcome from the surgery. Replacing a knee joint that is adjacent to a severely damaged joint may not yield significant improvement in function. Furthermore, all medications which the patient is taking are reviewed. Blood-thinning medications such as warfarin and anti-inflammatory medications such as aspirin may have to be adjusted or discontinued prior to surgery. Routine blood tests of liver and kidney function and urine tests are evaluated for signs of anaemia, infection, or abnormal metabolism. A chest x-ray and ECG are performed to exclude significant heart and lung disease which may preclude surgery or anesthesia. Finally, it is less likely to have good long-term outcome if the patient's weight is greater than 100kg or have a high BMI (greater than 35). Excess body weight simply puts the replaced knee at an increased risk of loosening and/or dislocation. A similar risk is encountered in younger patients who may tend to be more active, thereby adding trauma to the replaced joint.
What happens in the postoperative period?
A total knee replacement generally requires between one and a half to three hours of operative time. After surgery, patients are taken to a recovery room, where vital organs are frequently monitored. When stabilized, patients are returned to their hospital room. In males, passage of urine can be difficult in the immediate postoperative period, and this condition can be aggravated by pain medications. A catheter inserted into the urethra allows free passage of urine until the patient becomes more mobile. Physiotherapy is an extremely important part of rehabilitation and requires full participation by the patient for optimal outcome. Patients can begin physiotherapy 24 hours after surgery. Some degree of pain, discomfort, and stiffness can be expected during the early days of physiotherapy. A unique device that can help speed recovery is the continuous passive motion (CPM) machine. The CPM machine is first attached to the operated leg. The machine then constantly moves the knee through various degrees of range of motion for hours while the patient relaxes. Patients will start walking using a Zimmer frame and crutches. Eventually, patients will learn to walk up and down stairs and grades. A number of home exercises are given to strengthen thigh and calf muscles.
How does the patient continue to improve as an outpatient after discharge from the hospital?
It is important for patients to continue in an outpatient physiotherapy program along with home exercises for optimal outcome of total knee replacement surgery. Patients will be asked to continue exercising the muscles around the replaced joint to contracture and maintain muscle strength for the purposes of joint stability. Patients also should watch for warning signs of infection including abnormal redness, increasing warmth, swelling, or unusual pain. It is important to report any injury to the joint to the doctor immediately. Future activities are generally limited to those that do not risk injuring the replaced joint. Sports that involve running or contact are avoided, in favour of leisure sports, such as golf and swimming. Patients with joint replacements should alert their doctors and dentists that they have an artificial joint. These joints are at risk for infection by bacteria introduced by any invasive procedures such as surgery, dental or gum work, urological and endoscopic procedures, as well as from infections elsewhere in the body. Patients are recommended to take antibiotics before, during, and immediately after any elective procedures in order to prevent infection of the replaced joint.
Total Knee Replacement at a Glance
Patients with severe destruction of the knee joint associated with progressive pain and impaired function may be candidates for total knee replacement. Risks of total knee replacement surgery have been identified. Physiotherapy is an essential part of rehabilitation after total knee replacement. Patients with artificial joints are recommended to take antibiotics before, during, and after any elective invasive procedures (including dental work).
Are there any other options to a Total Knee Replacement?
Surgery is never the first choice for the management of osteoarthritis of the knee. There are many potentially beneficial therapies in the surgeon’s armamentarium that should be exhausted prior to ‘reaching for the scalpel’. Non-surgical options include a quadriceps- specific physiotherapy and a dedicated rehabilitation program and the use of a three-point pressure valgus or ‘off-loader’ knee brace, both of which can help in relieving the pressure on the medial side of the knee. Intra-articular injections of hyaluronic acid can be of benefit to approximately 60% of patients with osteoarthritis but this relief can be temporary and often necessitates re-injection. Many surgeons might try a diagnostic/therapeutic arthroscopy on a diseased knee. This has been shown to have symptomatic benefits for many patients with osteoarthritis.
However, for the patient with more debilitating symptoms who has failed conservative management (physiotherapy, bracing and injection therapy) and/or arthroscopic management more involved surgery is often necessary. This can be by way of an osteotomy of the tibia call a ‘high tibial osteotomy’ (HTO) to ‘unload’ the medial compartment or a knee replacement, be it a TKR or a partial/‘unicompartmental’ knee replacement (UKR). The best choice remains controversial, mainly as a result of the lack of prospective randomized trials comparing UKR with TKR or HTO. There are however several radiological and anatomical prerequisites that a patient must satisfy prior to considering a UKR and a patient’s suitability is best determined by a surgeon experienced in performing both UKR and TKR.
IMPORTANT NOTICE: Please note you will need a referral letter from your GP to use any of
the services of UPMC Beacon Centre for Orthopaedics, except for the Physiotherapy department.