What is a Total Knee Arthroplasty?
Total knee arthroplasty surgery became popular in the 1970s and 1980s as a method of treating the final stage of knee joint degeneration. Much progress has been made since then. A total of nearly 60,000 total knee arthroplasty surgeries is performed in the United Kingdom annually.
In total knee arthroplasty, the lower part of the femur and the upper part of the tibia are replaced by implants. Very often it is necessary to replace the posterior surface of the patella.
There are many different knee prostheses available. Most of them consist of metallic parts that stabilize the lower part of the femur and the upper part of the tibia, by replacing the degenerated surfaces of the articular cartilage, thus reforming the articular surfaces of the knee. Between the two prostheses a special plastic material (polyethylene) is placed, which in some cases is mobile.
Most knee prostheses are designed to be fitted with ‘orthopedic cement’, which acts as a link between the prosthesis and the patient’s bone. There are also prostheses that are placed directly on the patient’s bone without inserting cement. Such prostheses promote bone growth through the prosthesis, thereby providing long-term stability.
Damage to the materials of the total knee arthroplasty is mainly located in the plastic parts (polyethylene) and is proportional to the patient’s activity levels. However, technological development has now offered bearing surfaces that respond to much higher levels of activity and are expected to withstand much more.
In view of the above, patients who are young and active can benefit from new technologies, as the risk of implant failure is significantly reduced.
What Are The Benefits Of Total Knee Arthroplasty?
The majority of patients after knee arthroplasty have the following benefits:
- Elimination or significant reduction of knee pain
- Improvement of the quality of life
- Return to daily activities and low-demand sports
- Sleep without pain
- Improvement in leg strength as a result of returning to normal levels of activity
- Many years of reliable functionality
The Surgery of Total Knee Arthroplasty
Patients usually need to undergo a preoperative examination a few weeks prior to total knee arthroplasty in order to have the required examinations and discuss the details of the procedure.
Knee arthroplasty usually involves staying in the hospital for 2 to 3 days. The admission is usually performed on the day of surgery. The doctor and anesthesiologist will examine the patient before surgery and the affected knee will be marked.
Most arthroplasty surgeries are performed under dorsal anesthesia (where the patient is awake but usually under the influence of sedative-partial sedation); however there are cases where general anesthesia is required.
The affected lower part of the femur is shaped so that the metallic femoral prosthesis can be properly fitted. The upper part of the tibia is removed and replaced by a metallic tibia. A special plastic material (polyethylene) is inserted between the two prostheses. If necessary, the posterior part of the patella is also replaced.
At the end of the procedure, a knee drainage system may be used to remove excess blood. A patch is placed on the wound followed by a bandage on the knee. Special foot pumps, graduated compression stockings and in the majority of cases anticoagulants are used to reduce the risk of clot formation in the legs.
Postoperative Recovery from Total Knee Arthroplasty
Postoperative pain is a common symptom after a knee arthroplasty. It can be alleviated in many ways by pain pumps (Patient Controlled Analgesia), administration of analgesics and anti-inflammatory drugs and usually decreases significantly after 2 or 3 days. Arthritic pain usually disappears within one to two days after arthroplasty.
Sometimes the bladder malfunctions after epidural anesthesia and in this case you may need to have a bladder catheter inserted for one to two days. After catheter removal, patients usually return to normal bladder function.
In the early postoperative period, the patient should undergo blood tests as well as radiological examinations to ensure that blood levels are not significantly altered and that the knee prostheses remain in good position.
Recovery after Total Knee Arthroplasty
Physiotherapists are called upon to help the patient be mobilized after surgery and to oversee the exercise program that was suggested. It is very important that patients follow the exercise program and receive the precautions required for their new joint.
Return to work usually take place after 6 to 12 weeks, but in the case of heavy manual labor, it may take longer.
Within three months most patients can participate in low-activity sports such as golf, bowling, cycling and swimming.
Complications
The majority of patients undergoing total knee arthroplasty have no complications. Specifically, 95-98% of them are particularly happy with arthroplasty and typically report that they got their lives back. However, no operation can guarantee 100% success.
Complications may occur as a result of anesthesia or as a result of the patient being subjected to a major surgery.
Unicompartmental Knee Arthroplasty
Due to the anatomy of the knee, the greater load is exerted on the inner part of the knee. As a consequence the articular cartilage of the respective side, as well as the medial meniscus, tends to wear out faster than those of the outer compartment. As a result, the knee is tilted so that the load on the inner compartment increases significantly.
Over time, it is likely that the majority of patients will develop arthritis in the rest of the compartments, in the lateral compartment and the patello-femoral joint. However, in individuals suffering from arthritis only of the medial compartment of the knee, the symptoms of which cannot be relieved by non-invasive treatments, the so-called unicompartmental knee arthroplasty may be used.
In some cases arthritis is confined either to the patello-femoral joint or to the lateral knee compartment. Unicompartmental knee arthroplasty may also be applied in these cases as well, but it is much less common than that of the inner compartment. The results here are less predictable.
In the United Kingdom, about 2000 unicompartmental arthroplasty surgeries are performed annually.
Contraindications to unicompartmental knee arthroplasty:
- Patients with inflammatory arthritis
- Obese patients
- Patients with non-functioning cruciate ligaments
- Patients with arthritis in more than one compartments
- Patients with severe stiffness or curvature of the knee
The advantages of unicompartmental knee arthroplasty over total knee arthroplasty are:
- Smaller incision and shorter recovery time
- Lower risk of complications
- Knee movements are more “normal”
- A larger range of motion is probably provided
