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Knee Replacement Surgery FAQs

Dr Jayateerth W Kulkarni

 
1. What does knee replacement surgery involve?

The knee joint is the articulation between the thigh bone (femur) and leg bone (tibia). The knee cap articulates with the femur.

Knee replacement involves resection of the articulating surfaces of these bones and replacing them with metal and plastic bearing surfaces. The implants are generally fixed using bone cement (polymethyl methacrylate).

2. For whom is knee replacement indicated?

Knee replacement is advised for patients when their pain due to arthritis cannot be controlled by other means.

3. What are the contra-indications?
Infection in and around the knee is an absolute contra-indication, and surgery is not performed in such patients.
Other relative contraindications include neuropathic joint, paralysis in the affected leg, severe muscle wasting in the affected leg, severe circulatory deficiency in the leg, very poor bone quality, severe systemic disease like heart disease, lung disease, etc.

4. What are the tests and other requirements before the operation?
Routine tests of blood, ECG, sometimes chest X-ray and echocardiography may be necessary.
Control of medical problems like hypertension, diabetes mellitus, asthma, etc is necessary.
Patient should undergo any treatment of dental/oral sepsis, bladder infections, etc. before surgery.
2 units of blood are generally required for the operation. Auto-transfusion programmes and use of cell-saver devices can obviate the need for routine transfusions.
The operation is done usually under epidural anesthesia. It may also be done under general anesthesia, spinal anesthesia or regional blocks.

5. What is the postoperative course?
The patient is kept under close observation for about 24 hours. The leg is supported in a knee brace. One or two plastic tubes (drains) are placed to drain excess blood from the knee. The patient is given antibiotics, painkillers and a blood-thinning agent.
The patient is made to sit up and walk with support the next day. The drains are removed after 24-48 hours.
The patient is discharged 4-7 days after the operation. The sutures are removed between 10-14 days, and physiotherapy is instituted to regain movements. Physiotherapy may be required for 3-6 weeks (sometimes longer), and is continued after discharge on an out-patient basis.

6. What are the precautions patients need to follow after knee replacement?
For 3-6 weeks after surgery patient will require help with walking, standing, climbing stairs etc.
The patient should avoid sitting on the floor and using Indian style toilets. Newer designs of knees (high flexion knees) permit even these activities in properly selected patients.
Some other modifications may also be required such as using a raised toilet seat, installing handle bars beside toilet seats, using high–seating chairs, etc.
The patient should not indulge in athletic activities or contact sports, horse riding, high impact sports, skiing, etc.
Whenever there is any suspicion of infection anywhere in the body - such as infection of the skin, urinary tract, ear, tooth, or chest – the patient should seek immediate medical attention to commence treatment with antibiotics.

7.Can both knees be replaced together? Yes, both knees can be replaced together. Usually one knee is replaced and the other is replaced after a variable interval (few days to few weeks). This allows patient some time to recover between the two surgeries. Both knees can also be replaced at one sitting, if the patient's general condition is good.

8. What is the expected outcome after surgery?
The most important benefit of the surgery is the abolition of pain. This permits the patient to perform his/her routine activities without any limitations. However, sitting on the floor should be avoided, and contact sports and high impact activities should not be undertaken. A number of patient factors also influence the final result.

9. Are there any risks or complications of knee replacement surgery? The risk of the surgery is relatively low. This is mostly because preoperative conditions such as diabetes, blood pressure, etc are controlled prior to surgery. Strict pre-operative, intra-operative and post-operative guidelines are followed to minimize any complications.
Risks specific to knee replacement involve infection, nerve and blood-vessel injury, stiffness of knee, persistent pain, aseptic loosening and wear.
Certain risks which are likely after any major surgery can occur after knee replacement. These include blood clots in legs (thrombosis, embolism), bleeding, anesthesia-related or medical-related complications like stroke, etc.

Infection: of the knee can occur immediately after, or at a later date. The risk of infection is higher in diabetic patients and in those suffering from rheumatoid arthritis. Preventive measures include pre-operative and post-operative antibiotics, and strict infection control measures in the operation theatre. Prevention of delayed infection is addressed by proper control of diabetes and other medical conditions, and the prompt treatment of infection on any part of the body such as the teeth, urinary tract, skin, ear etc.

In the event of infection, treatment usually involves reoperation to wash the knee joint and remove any infected tissues. It may also be necessary to remove the prosthesis and implant a new one later. Sometimes arthrodesis (fusing the femur to the tibia) may be required.
 
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