Knee replacement surgery is the first step to reclaiming your mobility and life when medication, physiotherapy and walking aids don’t work. It is the answer to end stage osteoarthritis.
Total knee replacement surgery is one of the most successful and life enhancing procedures. It relieves almost 95% of pain and improves mobility, hence enabling patients to return to work and lead a near normal life. Knee replacement surgery is a safe and effective surgery. Doctors usually suggest a replacement surgery as a treatment modality after trying medication, walking aids and physiotherapy.
A normal knee functions as a hinge joint between the upper leg bone (femur) and the lower leg bone (tibia) and the knee cap (patella). Total knee replacement, or total knee arthroplasty, is a surgical procedure in which damaged surface of the knee joint is resurfaced with artificial parts (prostheses) made of plastic and metal.
It replaces the worn out parts of the knee joint with man-made parts. The cartilage of the knee when worn out or damaged, can result in the top of the shin bone rubbing against the lower end of the thigh bone, causing pain and deformity.
In this surgery, the upper end of the shin bone and the lower end of the thigh bone are replaced with a plastic inserted between the two. In some cases, the knee cap is also replaced.
This is done when other options like physiotherapy and medication do not provide adequate relief. This may be due to osteoarthritis (age related degeneration), injury or rheumatoid arthritis. Regardless of the diagnosis, all patients with severe disabling knee pain that interferes with quality of life and activities of daily living qualify for this surgery. Usually it takes 2-3 months after surgery to see the full benefits of the surgery.
The most common condition requiring knee replacement is osteoarthritis, (an aging process) with injury being the next common cause. This means the cartilage of the knee has worn out resulting in the bones being exposed. When the bones rub against each other, it is very painful. Total knee replacement is done to relieve chronic progressive pain, correct deformity and improve stability and mobility of the patient
When is knee replacement surgery not advised?
Medical fitness for surgery is a must. For instance, a patient with a history of heart attack in the previous 6 months would not be a suitable candidate.
- Other serious medical conditions like uncontrolled diabetes, hypertension etc., need to be optimised.
- Active infection in any part of the body
Expected outcomes of knee replacement surgery
- 95% of patients experience relief from pain.
- Improvement in stiffness
- Improvement of mobility and quality of life
Risks and complications
These can be treated with little or no impact on the outcome of surgery and include but are not limited to:
- Post operative nausea and vomiting
- Nerve injury causing numbness or weakness in the foot
- Blood clots in the legs
- Heart attacks
- Pulmonary embolism
- Bleeding requiring transfusion
- Allergic reaction to medication
Is the procedure painful?
The procedure itself is done under general or spinal anaesthesia and you will not experience pain. Most patients experience pain in the first week after surgery, which with medication gradually reduces.
Will I need physiotherapy?
All patients need physiotherapy following surgery. This is started on the immediate post operative day and at discharge, you will be advised to see a physiotherapist to assist with leg exercises. Home physiotherapy is also available. Exercises will gradually be increased and over time you will be able to switch over to walking and exercising by yourself.
Once you are comfortable, you can do stationary bicycling, golf, swimming and walking. Activities like jogging, football, gymnastics, rock climbing etc. are not permitted.
How long will the knee replacement last?
This depends on the patient's weight and demands placed on the implant. Typically, an implant is expected to last between 10-20 years. Newer implants have better longevity and can tolerate higher impact activity.
Your surgeon will give you more information on which implant is suitable for you, along with its advantages, disadvantages and cost.
Anatomy of the knee
The knee is the largest joint in the body and is a hinge joint made up of the lower end of the thigh bone and the upper end of the shin bone and the knee cap. The surfaces of the three bones are covered with a cartilage at the point of contact and it helps in the smooth movement of the joint. There are C-shaped wedges located between the thigh and shin bone surfaces called menisci which act as shock absorbers and cushion the joint. Ligaments around the joint hold the bones together and provide stability, while the thigh muscles give the joint its strength.
The joint surface is covered by a thin membrane called the synovial membrane which release fluid to keep the joint well-oiled and reduces friction.
All these parts work together in harmony normally and if this is disrupted due to wear and tear or injury, it results in pain, muscle weakness and deformity with loss of mobility
What is a total knee replacement?
A knee replacement is also called knee arthroplasty and can be described as a resurfacing as only the surface of the bones of the joint are replaced. After surgery there is pain relief and this improves the ability to walk. A total knee replacement needs hospitalisation for 3-5 days. The procedure is done under general anaesthesia, spinal anaesthesia or a combination of both.
A total knee replacement involves removing the end of a thigh bone and the top of the shin bone and resurfacing them with artificial knee implants, which is made of metal alloy and high density plastic. The thigh bone surface (femoral component) is made of curved polished metal, the surface of the shin bone is covered with high density plastic and the knee cap is plastic. The surgery itself takes 1-2 hours. After surgery the patient will be in the recovery room till the anaesthesia recovery criteria is met.
Four steps are involved in the surgery:
Step 1: Preparation: The damaged cartilages covering the lower end of the thigh bone and the upper end of the shin bone are removed along with a few millimetres of underlying bones.
Step 2: Positioning metal implants: The removed cartilage and bone are replaced with metal components to recreate the joint surface. These are cemented into the bone with methyl metacrylate or special coatings which encourage bone growth.
Step 3: Resurfacing the knee cap: The undersurface of the knee cap is cut and resurfaced with a plastic part. This step may not be done depending on the need.
Step 4: Inserting a spacer: A medical grade plastic spacer is inserted between the metal components to create a smooth gliding surface.
Indications for surgery
- Those with severe knee pain or stiffness which limits mobility and therefore affects normal life
- Difficulty in performing daily activities like walking, climbing stairs, getting up from a chair or sitting down, support in the using the toilet etc.
- Moderate to severe pain even at rest, often leading to disturbed sleep
- No respite from symptoms despite medicines, rest, physiotherapy or use of walking aids
- Knee deformity like bowing of legs
- Failure of treatment such as anti-inflammatory drugs, cortisone injections, lubricant injections, physiotherapy or other surgeries
How to ensure good results of surgery?
- Weight loss in those who are overweight
- Adherence to physiotherapy regimen
- Adequate and correct exercises
Risks associated with total knee replacement
Complications following total knee replacement are low. As with any surgery there are anaesthesia related risks, exacerbation of associated medical problems and allergic reactions to medication. Complications specific to total knee replacement although uncommon range from minor to serious life-threatening problems.
Difficulty passing urine occurs in 20% of patients and may necessitate the need for a bladder catheter for a day or two. Nausea and vomiting is seen in the immediate post operative period in 10% of cases.
Delayed wound healing It is common in obese individuals, diabetics and those who have a poor immune system. This is often seen in redo surgeries. It should be managed promptly to avoid infections.
Infection Despite all precautions taken during surgery, infection may occur and is cited at less than 2% of patients undergoing the procedure. This is more common in those who are elderly, diabetics, cancer patients or on immunosuppressant medicines after transplants. Infection can be in the wound or deep seated around the implant. Some infections like MRSA (methicillin resistant ataphylococcus aureus) may be resistant to common antibiotics and more difficult to treat. Minor infections may be treated with antibiotics but if the implant gets infected, it may need to be removed and replaced at a later date. Infections can also occur many years after the surgery, especially in immunocompromised patients.
Deep vein thrombosis (DVT) It is a blood clot in the deep veins of the calf or top of the inner thigh. If a clot develops and breaks free, it can travel to the lungs and cause a condition known as pulmonary embolus, which is potentially life threatening. Without adequate preventive measures, the incidence of DVT is cited at 40–88% and mortality due to pulmonary embolism up to 2%. The incidence falls dramatically to less than 1%, if DVT prophylaxis is followed. Patients of total knee replacement will be given stockings to improve circulation and also medicines to thin blood. The physiotherapist assists in exercises and also helps the patient mobilise as soon as possible after the operation. Elevation of the limb and lower leg exercises to improve circulation also help to prevent formation of clots.
Neurovascular injury It occurs due to pressure or injury to the nerves or blood vessels outside the knee joint and is usually resolves by itself. Symptoms include tingling, numbness and rarely, foot drop are known but occur in less than 0.25 % cases.
Wearing out and loosening of implant The lifespan of a total knee replacement is 10-20 years. Over time the knee replacement components may wear away and become loose needing surgical correction. This may also occur due to trauma, migration of the prosthesis or bone degeneration. Wearing out of the implants may be prolonged, up to about 30 years, by using the latest CERAMIC implants but these are costlier and are beneficial in relatively younger patients (around 50 year rest of age)
Stiffness and inability to move the joint freely This can usually be corrected with exercises. Although an average of 115° range of motion is anticipated after surgery, scarring of the knee can occur limiting movement, especially in those who had limited movement before surgery. It is seen in about 10% of patients. Treatment options are manipulation under
Continued pain: It is rare but happens in a few cases.
Haematoma In the thigh,it is seen in 5% of patients where swelling occurs due to bleeding.
Evaluation before total knee replacement
This is a screening to ensure fitness for surgery. The doctor will explain what is done during the surgery, follow-up, give post operative advice and when you are likely to be fit for surgery before taking your consent for surgery. Physiotherapy and occupational therapy requirements will also be explained.
Advice before surgery
- Some medicines like hormone replacement therapy, contraceptives etc. will be stopped at least 6 weeks before surgery.
- One needs to stop smoking at least 6 weeks before surgery, as this causes changes in blood flow patterns, delays healing and slows recovery.
- Weight reduction: BMI > 30 increases the risk of anaesthesia and surgery. It also reduces the life span of the artificial knee.
- Address dental problems before surgery in order to prevent any post operative infection being triggered.
- Practice sleeping on your back as sleeping on the side is uncomfortable for at least 6 weeks after TKR.
- A medical history of the current symptoms, extent of pain and range of movements, functional disability and current level of activity
- A history of associated diseases like diabetes, asthma, obesity and treatment taken
- History of allergies
- Treatment taken previously for the knee joint problem
- A physical examination to assess knee motion, stability, strength and leg alignment
- X-rays to determine the extent of damage and deformity in the knee
- Routine blood tests like complete blood count, blood sugar level, routine urine test, chest x-ray, ECG and ECHO if needed will be advised.
- Depending on the age and associated diseases like diabetes, hypertension, one may be advised clearances by a cardiologist, diabetologist and others.
- Those with urinary issues should have a urological evaluation as this may be a source of infection later.
- In some cases, an MRI may be done to determine the condition of the bone and soft tissues of the knee.
A preanaesthetic check will be done and the anaesthetist will inform you of the type of anaesthesia to be given and all risks associated with it. One is asked not to eat or drink anything for 6 hours before surgery. Advice on what medicines you may take on the day of surgery from your regular medicines will be told to you by the anaesthetist. You may be asked to stop some medication like blood thinners, a few days before the surgery. An informed consent will be taken for performing the procedure. Your doctor will explain in detail about the surgery and post operative requirements, including rehabilitation at home. You will be given an opportunity to clarify all your doubts and fears before signing the consent.
Recovery at home
Strictly follow all post operative advice given.
Wound care The wound at the operation site is stitched with staples. This needs to be removed about three weeks after the surgery. Care should be taken not to get the wound wet until it is thoroughly healed. The wound will need dressing to prevent irritation from clothing or support stocking.
Diet A balanced diet with an iron supplement is advised to ensure quick healing and restoration of muscle strength.
Activity Exercise is very important for a good recovery after surgery. It takes 3-6 weeks to resume most normal activities of daily living after surgery. A graduated walking programme to slowly increase the amount of walking is to be planned. The physiotherapist will teach you the exercises to be performed several times a day. Initially, you may need help and support but gradually you may be able to do them on your own.
Post operative period
A post operative stay of 3-5 days is required. There will be a bulky bandage and small drainage tubes emerging from the wound. An intravenous drip may be given till you resume taking fluids. There may be an oxygen mask also. All these will be removed as soon as possible after the surgery. You will be mobilised as soon as possible. The physiotherapist will help you with this. Over the next few days you will be taught exercises, how to use walking aids and how to climb stairs.
- Pain management: After surgery, some pain and discomfort is common. Pain relief medication and ice packs will be given. These medicines will be continued orally after discharge depending on the patient‘s tolerance to pain.
- Swelling and pain will persist for some time and will resolve over time. You will be advised to sit with lower limb elevated and not to stand in one position for long.
- Blood clot prevention: The surgeon may prescribe compression stockings, a DVT pump and blood thinners while in the hospital. The stockings and oral blood thinners may be continued after discharge for some time. Foot and ankle movement is encouraged immediately after surgery to increase blood flow and prevent blood clots.
- Preventing pneumonia: In the early post operative period, shallow breathing is common especially in the elderly and smokers. Anaesthesia, pain medication and prolonged stay in bed contribute to this. Shallow breathing can lead to retention of secretions that can cause partial lung collapse and pneumonia. To prevent this, the physiotherapist will encourage you to take frequent deep breaths and provide you with a simple tool called a spirometer to help you with breathing improvement.
- Walking: It is advised on the first or second post operative day with walking aids and someone beside you. It is necessary to improve walking pattern while in the hospital. While walking with aids, follow the steps as given. First move the aid, then step forward with the operated leg and then bring up the other leg. Avoid twisting or pivoting the new knee. Walking, while essential, should not be overdone as it will cause swelling. Increase the walking speed and distance gradually.
- Physiotherapy: Knee exercises are started on the day after surgery. The physiotherapist will help you with specific exercises to strengthen the leg and restore knee movements.
- Climbing the stairs: Learn how to use stairs from the physiotherapist. Use railings or banister and walking aids while climbing up or down the stairs.
- Going up: Go up one step with the non-operated leg and bring up the operated leg and then bring the crutch or stick up.
- Going down: Take the crutch one step down and place the operated leg down a step beside the crutch. Then bring the non-operated leg to meet the other.
- Sitting: Use a firm, upright chair, preferably with arms. When sitting, the knees should be lower than the hips. In the initial stages when rising from the chair, push yourself up on the arms of the chair, taking weight on the un-operated leg. Regain balance and then shift weight to the crutches.
- Kneeling is not advised during the first few months following surgery.
- Discharge: Most patients are discharged on the 3 rd or 5th post operative day.
Outcomes of total knee replacement
- Most people who undergo total knee replacement have a dramatic reduction in pain in the knee and significant improvement in their mobility and ability to perform normal activities of daily living.
- But total knee replacement will not allow one to do more than what one was able to do before developing arthritis. Kneeling may be uncomfortable but not harmful. Some numbness is felt around the incision on the skin. Some stiffness is possible particularly with excessive bending.
- With normal level of activity, the plastic spacer in the implant will start to wear away in time. Excessive activity or weight will speed up the wear and tear, which may cause the implant to loosen and become painful.
- Hence, high impact activities like jogging, athletics or sports like football are generally to be avoided. One can indulge in walking, swimming, driving, biking, dancing and sports like golf.
- The lifespan of knee replacements can be increased with appropriate activity modification. The average length of a total knee replacement is 10-20 years depending on the activity.
- Most people hear some clicking of metal or plastic with walking or knee bending. This will diminish with time.
- The knee implant may activate metal detectors at airports. You need to carry a card or letter that informs security about your implants.
How to prevent problems after TKR?
Prevention of blood clots in the leg The risk is high in the first several weeks after surgery as mobility is reduced. If these clots break off, they may migrate to the lungs and cause a highly fatal condition called pulmonary embolism. Compression stockings and blood thinners will be advised at discharge for several weeks.
Warning signs of blood clots in the leg include:
- Increasing pain in the calf
- Tenderness or redness above or below the knee
- New or increasing swelling in the calf, ankle or foot
Warning signs of pulmonary embolism include:
- Sudden onset, shortness of breath
- Sudden onset chest pain
- Localised chest pain with cough
- Sputum which is blood tinged
Infection of the implant can occur from bacteria in the blood stream. The bacteria may come from dental procedures, urinary tract infections or skin infections. After total knee replacement, patients may need to take a course of antibiotics for dental work or other surgeries, however small.
Warning signs of infection
- Persistent fever (higher than 100°F)
- Chills and rigours
- Increasing redness, tenderness or swelling of the knee wound
- Drainage from operation site
- Pain both at rest and on movement
Falls can damage the knee and a redo surgery may be needed. Stairs are to be avoided until the strength in the knee returns with improved flexibility and balance.
After TKR, exercise is an important component of recovery and rehabilitation. The day after surgery, the physiotherapist will help you walk with the aid of a walker. You can gradually progress to crutches or a walking stick, until you can walk without pain or a limp. This may be after 6 weeks.
Standing from a chair
- Place the operated leg out in front of you.
- Push up with both hands on the arms of the chair.
- Once balanced, place hands on the frame.
- Do not use the walker to pull yourself up.
- Stand close to the chair and feel it against the back of your legs.
- Place operated leg out in front of you.
- Place one hand on the arm of the chair.
- Lower yourself down.
- To begin with, go up or down the stairs one step at a time.
- Place the crutch or stick in one hand and support yourself on the rails.
- Going up you, should place the un-operated leg on the step above and then pull up the operated leg and the crutch or stick.
- Coming down the stairs you should place your operated leg and crutches or stick on the step below and then bring the un-operated leg down.
- Once the scar is healed, start by kneeling on a soft surface.
- Later you can kneel on a firmer surface.
- Avoid jarring and twisting activities for 6-8 weeks.
- You should avoid getting the wound wet. Use a hand support in the shower and an anti-skid mat. Sit on a stool or chair, with the operated leg stretched out onto another chair, while having a bath.
- Wear loose fitting clothes. Pull the clothes over your operated leg first.
- Avoid standing for long periods. Cooking can be done sitting in a chair.
Day 1 The following exercises need to be done regularly throughout the day to prevent blood clots in the calves or chest infections:
- Breathe in through the nose.
- Hold for 2-3 seconds.
- Breathe out through the mouth.
- Do 3-4 deep breaths and rest for a short time in between.
- Repeat 10-12 times.
To improve circulation
- Point and bend ankles.
- Rotate ankles in clockwise and anticlockwise movements.
- Repeat 20 times.
The following exercises are to be done 10 times at each sitting and 3-4 times a day
- Sit or lie on your back with legs stretched out.
- Tense your thigh muscles, then lift your leg about 2” off the ground.
- Hold for slow count of ten.
- Repeat 10 times.
Straight leg raise
- Sit or lie on your back with legs stretched out
- Tense your thigh muscles, pulling the toes up, then lift your leg about 2” off the ground
- Hold for slow count of ten
- Repeat 10 times
- Sit or lie with your leg straight in front of you.
- Pull your heel into the bed by tightening the muscle at the back of your thigh.
- Hold for a slow count of 10.
- Repeat 10 times.
- Tense your bottom muscles.
- Hold for a count of 10.
- Repeat 10 times.
Knee flexion on the bed
- Sit with your back supported or lie flat.
- Bend your knee up towards you and then slowly lower it back down.
- Repeat 10 times.
The following exercises can be started as soon as you are able to sit in the chair.
Inner range quads
- Sit supported or lie on the bed.
- Place a rolled up towel wrapped around something solid like a tin under your knee.
- Straighten your knee, lifting your heel off the bed.
- Hold for a slow count of 10.
- Relax and repeat 10 times.
Full range quads
- Sitting on the edge of the bed or in a chair.
- Pull up the toes of the operated leg, tense the muscles at the front of the thigh and straighten the knee.
- Hold for a slow count of 10 then relax.
- Repeat 10 times.
Knee flexion in sitting
- Sit on the edge of the bed or in a chair With your foot on the floor bend the knee as far as possible.
- Hold for 2-3 seconds then relax.
- Repeat 10 times.
Once you can mobilise independently with a frame, you will be progressed to crutches or sticks.
Cause of chronic knee pain and disability
The most common cause of chronic knee pain is arthritis.
- Osteoarthritis: It is an age related wear and tear of the joint where the cartilage or cushions covering the bones of the joint soften and wear away. The friction caused by the bones rubbing against each other causes pain and stiffness, which in turn leads to deformity. With age, water content of the cartilage increases and protein in the cartilage begins to degenerate.
- Rheumatoid arthritis: It is a disease in which the synovial membrane lining the joint surfaces become inflamed and thickened, leading to degeneration of the cartilage resulting in pain and deformity. The cause of this is attributed to the body treating its own cells as foreign and produces antibodies against it.
- Post traumatic arthritis: It occurs as a result of injury, which may be a single injury to the joint and bones or chronic injury such as sports injuries. Tears in the ligament or damage to bones and cartilage are the cause of symptoms.
Alternatives to total knee replacement surgery
The doctor will at first offer treatments like medication, physiotherapy, weight loss or walking aids. When the disability continues despite these alternatives, the surgeon will suggest a replacement surgery.