Before surgery: pre-operative considerations
Age of patient and co-existing medical problems:
Knee replacement is generally recommended for patients over 60 years. The advanced age is not a bar to surgery. Many patients in their eighties successfully undergo knee replacement.
Many elderly patients have hypertension, diabetes, previous angioplasty or coronary bypass surgery, hypothyroidism, etc. Most of these patients can safely withstand knee replacement. Preoperative assessment by physician, cardiologist, endocrinologist and others may be necessary to optimize the patient’s condition. Patient should undergo any treatment of dental/oral sepsis, bladder infection, skin infection, etc. before surgery.
Pre-operative evaluation:
Routine blood tests, ECG, chest–X ray and echocardiography are necessary. The patient is assessed by physician, anaesthetist and other specialists like cardiologist, pulmonologist, endocrinologist, etc. to optimize his/her condition before the surgery. Two units of blood are reserved.
Bilateral knee replacement:
Both knees can be replaced together. This is done after careful evaluation of the patient’s condition. It avoids the need for another period of hospitalization and recovery. It also helps reduce hospital costs.
During surgery: the operation
Anaesthesia:
Knee replacement is done usually under epidural anesthesia. It is also done under general anesthesia, spinal anesthesia or regional blocks. Epidural and regional anesthesia also provide excellent pain relief in the post-operative period. Regional blocks allow the patient to mobilize a few hours after the operation. The choice of anesthesia will be discussed by the anaesthetist.
Procedure:
Total knee replacement involves removing the worn-out joint surfaces and implanting prosthetic device in place of the damaged surfaces. Only 8 -10 mm of the damaged bone surface is removed. The shape of the implants (prosthesis) closely matches the amount of bone removed. The femoral component is made of metal and has a bi-condylar shape. The tibial component consists of an oval shaped metal tray with a highly cross-linked polyethylene inset. The patellar component is a circular polyethylene disc with convex surface. Resurfacing of the knee cap is optional. The implants are fixed using acrylic bone cement.
The surgery takes about 90 minutes. However, the patient is in the Operation Theatre for about three hours because of the time required for administration of anaesthesia; setting up the patient, equipment and surgical team; and recovery from anaesthesia, dressing and shifting the patient after the procedure.
After surgery: postoperative course & follow-up
Immediate post-operative care:
The patient is kept under close observation for about 24 hours, either in the ICU or High Dependency Unit (HDU). The operated limb is supported in a bulky bandage or splint. One or two plastic tubes (drains) are placed to drain excess blood from the knee. Antibiotics are given for 24-48 hours. Other medications for diabetes, hypertension, etc. are continued with some modifications. Anti-coagulants are started 6-8 hours after the surgery. Food intake is started after 4-6 hours.
Pain control is achieved by various means: infiltration of the soft tissues by local anaesthetics and opiods, intravenous painkillers (regular doses or via Patient Controlled Analgesia device), epidural infusion, regional blocks, transdermal patches, etc.
Patients are made to sit up and walk with support on the next day. Physiotherapy is started for regaining movements, improving muscle strength, improving chest function, and preventing venous thrombosis. The drains are removed after 24-48 hours. Most patients are able to walk the length of the hospital corridor by fourth day. Some patients are also able to climb stairs at this time.
Patients are discharged 4-7 days after the operation. The wound is kept covered with a sterile dressing which should be kept dry. The sutures are removed between 10-14 days. Physiotherapy is continued at home for 4-6 weeks.
Follow-up:
The patient is reviewed in the OPD at regular intervals. Staples are removed at two weeks. Recovery of movements and strength are monitored and appropriate modifications to physiotherapy or exercise programme are suggested. Initially the patient is followed up every 3-6 weeks. After 6 months, yearly follow-up is advised.
Short stay and day-care surgery:
These days, the trend is towards early discharge. Many patients can be discharged after 2-4 days. In carefully selected cases knee replacement can be done as a day-care procedure. This requires a team of patient care co-ordinator, home care nurses, physiotherapists and other staff.
Precautions after knee replacement:
For the first 6 weeks the patient should not engage in any vigorous activity with respect to the operated limb. After that progressive increase in the activity is permitted depending on the patient’s progress. Certain activities like sitting on the floor may have to be avoided. A western toilet with elevated rim is recommended. Care should be taken to avoid falls and injuries.
Normal activities can be started after 6-8 weeks. The patient should not indulge in athletic activities, contact sports or high impact activities.
Prophylactic broad-spectrum antibiotics should be started before undergoing any dental, genito-urinary surgery or any major surgical procedure. Whenever there is any suspicion of infection anywhere in the body – like skin infection, urinary infection, ear infection, tooth infection, chest infection or systemic bacterial infections – the patient should seek immediate medical attention to start antibiotics and take other measures as required.
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