The total knee replacement(TKR) surgery is a very successful surgical treatment for chronic (long-standing) knee osteoarthritis with damaged joint surfaces. This surgery also known as total knee arthroplasty (TKA). It replaces the damaged joint surfaces with metal and plastic parts.

There are four types of knee replacement techniques practiced at present time:

1. PKR or UKR,

2. MIPKR

3. TKR and

4. MITKR

[PKR=Partial Knee Replacement; UKR= Unicondylar Knee Replacement; MI=Minimally Invasive; TKR=Total Knee Replacement]

In medical terms, a joint replacement surgery is also known as ARTHROPLASTY. Hence a knee replacement (KR) surgery is also called knee arthroplasty (KA).

Nowadays minimally invasive surgical techniques are being adopted to lessen tissue trauma and improve patient outcomes. In the minimally invasive approach, much smaller incisions than the traditional 10-12 inch incisions are used and the quadriceps muscle and tendon are preserved. This approach results in quicker healing and recovery.

The advantages of the minimally invasive knee joint replacement surgery are:

1. Smaller surgical incision or cut (4 to 6 inches in length).

3. Smaller scar.

4. Shorter hospital stay.

5. Less pain after the operation.

6. Shorter recovery period.

When do we need knee replacement surgery?

We need knee replacement surgery when we experience the following problems /symptoms:

1. Severe knee pain with stiffness and deformity that restricts us from carrying out our everyday activities, such as walking, climbing stairs, getting in and out of vehicles, and getting in and out of chair. (in osteoarthritis and rheumatoid arthritis)

2. Continuous knee pain while sleeping or resting.

3. Long-standing painful knee swelling that does not get better or vanish after taking medicines and rest.

4. A noticeable knee deformity like outward bending of the knee that looks ugly and interferes with standing up, walking, and jogging

5. Depression, resulting from an inability to carry out daily or social activities due to chronic (long-standing) knee pain and deformity.

6. Injury to the knee with complex fractures around the knee joint that could not be reduced and fixed leading to the above symptoms later (post-traumatic severe knee arthritis).

Regardless of the cause, progressively increasing pain, stiffness, and deformity of the knee joint that restricts day-to-day activities, and functioning necessitates some kind of replacement surgery.

Preparation for knee Replacement

A patient should prepare his mind, body, and home during 6-12 weeks prior to actual knee replacement surgery. This can be split into three groups:

Prehabilitation or Pre-surgery rehabilitation or prehab

This refers to strengthening of the muscles surrounding the knee before the surgery.

Starting exercises 12 weeks before actual surgery improves strength, flexibility, motion, balance and overall physical health. The pre-surgery exercise reduces overall pain and stiffness before the procedure. Specific exercise like brisk walking, hydrotherapy and knee strengthening workouts has been shown to reduce pain, improve knee power and improve overall physical and physiological capacity of the patient. Good pre-surgery knee strength helps patient speed-up his return to normal daily life activities after surgery.

A qualified and trained physiotherapist can help set up an effective prehab knee program.

Medical Preparations

The attending surgeon and hospital should clearly communicate any necessary medical preparations well before the day of surgery. Patients should ask questions or raise concerns regarding medical preparations during consultations before surgery.

Typical instructions before knee replacement surgery are:

1. Hold or reduce the dose of certain medications (if have been prescribed before) like: aspirin, non-steroidal anti-inflammatory drugs, blood thinners, steroids, immunosuppressant, and opioids two weeks before surgery.

2. Stop smoking or reduce it drastically for 4-6weeks before surgery.

3. Consult other specialists like physician, cardiologist, chest specialist and anesthetist.

4. Stop alcohol or reduce it drastically for 4-6weeks before surgery.

5. Report any illness such as cough, cold, flu, or fever developing 2-3 weeks before surgery.

6. Take tests (x-rays, blood tests, COVID-19 tests, ECG etc.) as prescribed by the attending surgeon and show him the reports well before.

Home Preparations

The patient should make advanced arrangements and preparations at his or her home in order to minimize the risk of knee injuries during the recovery period.

For example:

1. Find a caregiver such as spouse, friend or a relative to prepare meals and help around the house.

2. Arrange for transportation, as driving is not allowed for the first 4 to 6 weeks after surgery.

3. Keep ready a ground-floor room or a floor with all amenities in order to avoid stairs for few weeks after operation.

4. Arrange for a bed of comfortable height to help ease going in out of the bed.

5. Stairs should have strong railings.

6. Install strong grab bars in toilets and in bathroom.

7. Install a toilet seat of such height as to make it easier for you to sit down and get up without putting much stress on the knees.

8. Get cold packs from the market to apply them on the operated knee, after surgery.

9. Place a stool in the bathroom to avoid standing and slipping.

10. Arrange for an accent chair and ottoman set to keep leg elevated in a comfortable way after surgery to reduce swelling.

11. Practice using walkers, canes and other assistive devices ahead of time to use them comfortably after surgery.

Surgical procedure

Surgery is performed in the operating room under sterile conditions and under spinal or general anesthesia.

The patient lies on his back on the operating table and a tourniquet is applied to his upper thigh to minimize blood loss. The surgeon then makes an incision over the diseased knee to open up the knee joint.

The thigh bone (femur) is done first. The diseased portions of the femur are cut at the appropriate angles using specialized zigs (set of instruments).

Next, the surgeon removes of the diseased areas of the shinbone (tibia).

Balancing is done carefully by releasing soft tissues and removing extra pieces of bones hanging from the main bone (osteophytes) using templates and balancers.

Following this, actual implants are fitted on femur and tibia with or without bone cement or screws as necessary.

Now a well-fitting piece of plastic is inserted between the femoral and tibial components and acts as a cushion to ensure a smooth gliding movement at the interface. This insert replaces the original joint cartilage and allows the thigh bone to move over the shinbone.

Sometimes the kneecap (patella) is also diseased. In such cases the back of the patella is also chopped off and replaced with another piece of plastic.

All these three artificial parts together form a new knee joint.

With all these new implants in place, the knee joint is examined for range of motion and stability. If everything is fine the interior of the knee joint is vigorously washed out and the wound is closed over a drain which is removed later. A surgical dressing and bandage is then applied over the incision.

After Operation

On Day 1:

Take plenty of rest and try to stand with help.
Try to bend and straighten your knee at regular intervals.

On Day 2:

Sit up and stand beside the bed.
Take few steps with help.
Try to bend the knee by at least 10 degrees and to straighten your knee.

On Day 3:

Seek minimal help to stand up, sit, bathe, and dress.
Gradually incease your walking distance and use stairs with a tripod walking stick and stair rails.
Try to achieve 70 to 90 degrees of knee bend.
May take shower.

During weeks 1–3:

Try walking and standing for more than 10 minutes.
Now use a cane instead of crutches.
Keep doing exercises to improve your mobility and knee bend.

During weeks 4–6:

Start doing routine daily activities like kitchen work, driving, travel, and household chores.
Keep improving your mobility and range of motion.

During weeks 7–12:

Try doing low-impact physical activities like swimming and stationary cycling.
Continue strength building and endurance exercises and try to achieve a range of motion of 0–115 degrees.

After 12 weeks:

Start doing higher impact activities as you did previously after consulting your surgeon and physio.
Follow the advice of your physio and surgeon about any ongoing treatments.

Should Young Patients undergo knee replacement?

Currently, the average age of a patient who are offered total knee replacement surgery is around 65 years. The total knee replacements (TKR) are increasing in young patients >45 years of age. In this group a cemented posterior-stabilized implants with fixed bearing are preferred.This is an effective treatment option with durable results for symptomatic osteoarthritis in younger patients.

Researches show that knee replacements work well in this younger age group also. More than 95% of the knee replacements done in these patients are still doing well 10 years after surgery. The main risk of total knee replacement in younger patients is the possibility of wearing and loosening of the implant.

Choice of Implants /components/prostheses for Knee Replacements

There are many different types of implants/components for knee replacements. The choice of prosthesis (implant) depends on the severity of the disease, condition of the bone; age, gender, and weight of the patient; and state of ligaments around the knee. A high-flex design is safe for deep knee bending. Gender-specific versions and implants engineered to match the knee anatomy are available.

One should choose carefully taking into account the advantages, safety, and scientific merits of implant designs. The custom-made knee implants tailored to each patient’s need are available, albeit costly, for most knee replacements. The custom-made implants are made specifically to suit each patient’s size and unique anatomy. CT or MRI imaging is used to determine the precise anatomy of the patient’s knee.

Custom knee replacement is a wonderful development in modern era knee replacement surgery due to the following advantages:

• Better fit of the prosthesis.

• Precise bone cutting during surgery.

• Preservation of the natural joint shape and joint line.

• Custom knee implants are available for both total and partial joint replacements.

Sports activities after knee replacement

Many patients having knee replacement surgery want to know that which activities can they safely perform after this surgery. While surgeons often recommend some sports which could be safe and those to avoid, there is remarkably little research based information or study in this regard.

According to 1999 Knee Society Survey the recommended activities after knee replacement are: Low impact aerobics, Bowling, Croquet, Ballroom dancing, Jazz dancing, Golf, Shooting, and Swimming, among others.

Activities not recommended after knee replacement by 1999 Knee Society Survey are: High impact aerobics, Baseball, Basketball, Football, Gymnastics, Handball, Hockey, Volleyball, Jogging,and Squash, among others.

Patients should always discuss with their surgeon and physio before taking up any sports or athletic activity after knee replacement.