Knee Replacement

Overview

Knee disorders such as osteoarthritis (also known as degenerative arthritis), rheumatoid arthritis, and previous damage can wear away the bone and cartilage in the joint. Knee discomfort might result from this wear and strain. If nonsurgical therapy isn't working, knee replacement surgery may be an option for you.

 

What is Knee Replacement?

Knee joint replacement surgery involves the replacement of a knee joint with a man-made prosthetic joint. A prosthesis is an artificial joint. Total knee replacement surgery first became popular in the 1970s. It has since become a very frequent operation. The procedure involves replacing the bottom end of the femur and the top end of the tibia with a man-made prosthetic (prosthesis).

The patella's rear surface is also frequently changed. These gadgets are made of metal, plastic, and, on occasion, ceramic materials. They are attached to the bone either with bone cement or with a rough-surfaced prosthesis that relies on your bone growing on to the implant for long-term stability. Screws on the tibial side may be used to strengthen it. A unique polyethylene plastic liner sits between the two components.

 

Knee Anatomy

The femur, tibia, and patella make up the knee joint. The femur, often known as the thighbone, is the bone that connects the hip to the knee. The tibia, often known as the shinbone, links the knee to the ankle. The patella, often known as the kneecap, is a tiny bone located in front of the knee. On the exterior, the fibula is a shorter and thinner bone that runs parallel to the tibia. The joint functions similarly to a hinge, but with some rotation.

Strong ligaments link the knee and muscles surround it. The ligaments of the knee joint help to stabilize the joint and allow it to function appropriately. The cruciate ligaments (anterior and posterior) are key structures that govern the proper mobility of the knee.

The smooth surfaces at the ends of the femur and tibia are articular cartilage. Arthritis is caused by damage to its surface. The meniscus is a specialized structure located between the femur and tibia in the knee joint. There are two menisci: medial and lateral. These aid in the distribution of load, the absorption of stress, the stabilization of the knee, and the lubrication of the joint.

 

What Causes A Painful Knee?

When one or more portions of the knee are injured, it can cause discomfort and impede movement. Cartilage (the smooth coating at the ends of the bones in the joint) begins to break or wear away over time. When this happens, the bones of the joint rub against one other.

A knee condition might prevent you from participating in activities you like at any age. Pain and stiffness may even restrict your daily activities. Knee joint problems tend to accumulate over time.

 

Any of the problems below may lead to joint damage and hence knee pain:

1. Osteoarthritis

Normal wear and tear can mount up over time. Cartilage may begin to deteriorate (osteoarthritis). The bones grow rough and pitted when they scrape together. Previous menisectomies and anterior cruciate ligament injury invariably result in osteoarthritis.

    2. Inflammatory Arthritis

This is a series of diseases in which the joint lining becomes inflamed and secretes substances that damages the joint cartilage. More than one joint is frequently afflicted in these disorders. Deformity is prevalent, and the joints are heated, swollen, and painful.

    3. Avascular Necrosis

This can happen for no apparent cause (idiopathic) or as a result of a variety of illnesses, such as long-term alcohol or steroid usage. It is caused by a decrease in blood flow to the bone. The joint will become arthritic if the bone dies (necrosis). This discomfort frequently comes on unexpectedly and intensifies quickly. This can occur at any age. There are other alternative reasons of this illness, although they are uncommon.

A significant fall or impact to the knee can cause the bone to shatter (fracture). If the damaged bone does not mend properly, the joint will gradually wear down, much like an unbalanced tyre.

    4. Ligament Injury 

Injuries to the ligaments that cause knee instability can and typically do result in early arthritis.

    5. Childhood Knee Problems

Sometimes knee discomfort is the outcome of a childhood issue, such as osteochondritis dissecans, trauma, or juvenile rheumatoid arthritis.   

    6. Infection

Infection can destroy the cartilage lining leading to osteoarthritis.

• A bad injury that did not heal properly
• Long term exposure to sports or heavy manual labor
• Other rare diseases affecting bones or soft tissues can also cause severe pain in the knee and may lead to arthritis

 

Who needs Knee replacement surgery?

You can require a knee replacement at any age; however, becoming older increases your risk, with those between the ages of 60 and 80 being the most probable. Genetics, past knee injuries, and lifestyle can all influence whether you need a knee replacement, so consult your doctor if you have any symptoms.

Your doctor may recommend knee replacement if:

• You find it difficult carrying out everyday tasks
• You have depression due to pain or reduced mobility
• Your mobility is reduced
• Your quality of life is impacted, including your sleeping
• You’re unable to work or socialize

Knee replacement surgery can alleviate discomfort and allow you to resume normal activities. However, you must be in good enough health to have surgery.

 

Preparing for your knee replacement operation

Your doctor or physiotherapist will recommend activities you may do before surgery to strengthen the muscles around your knee and decrease your recovery time. It's also a good idea to prepare your home for after surgery so you can get around safely and easily. Check that you have:

• Arrange to have crutches or a walking frame ready
• Have a stable bench or chair to use in your shower
• Have a stable chair with back support and a firm seat cushion
• Install: a toilet seat raiser
• safety handrails in your bath or shower
• safety handrails along your stairway
• Make sure important items are easy to reach — arrange your living space so everything you need is on one floor to avoid having to climb stairs
• Remove anything you can trip over

Learn about knee replacement surgery so you can ask your care team any questions you have and know what to anticipate on the day of surgery and during your recovery. You'll have a pre-operative assessment visit with a nurse before your surgery to examine your overall health and discuss any drugs you're presently taking that you may need to discontinue or change before surgery.

The majority of knee replacement surgeries are performed under general anesthesia. Before general anesthesia, you should not eat or drink for at least six hours. You will be advised to avoid certain fluids (milk), in favor of water, black tea, or black coffee. To minimize blood clots in your leg while you're immobilized, you'll also need to wear compression stockings during and after surgery.

 

Knee replacement procedure

You should aim to keep as active as possible before your surgery and strengthen the muscles surrounding your knee to aid recuperation. During the procedure, the surgeon will bend your knee in order to better expose the joint. After that, they will create a 15-25cm incision below your knee and pull your kneecap aside.

They will remove your damaged cartilage as well as the ends of your thigh and shinbone and replace them with an artificial joint — the end of your thigh bone will be replaced with a metal shell, and the end of your shinbone will be replaced with a flat piece of plastic with a metal stem. They may also put a plastic button under your kneecap, depending on the state of your kneecap.

The prosthesis refers to all of the prosthetic pieces that have been implanted in your knee. The prosthesis is pre-measured to fit your joint. After your prosthesis is in place, your surgeon will bend and rotate your knee to ensure that it is functioning appropriately.

The procedure is performed under a general anaesthesia or a spinal or epidural anesthesia, in which you are conscious but unable to feel anything below your waist.

 

Common types of surgery

The four main types of knee replacement surgery are:

• Total knee replacement
• Unicompartmental (partial) knee replacement
• Kneecap replacement (patellofemoral arthroplasty)
• Complex or revision knee replacement.

There are several types of replacement knee joints available, as well as various surgical techniques. Your doctor and orthopedic surgeon should assist you in determining the best option for you based on the state of your knee and your overall health.

 

Read more about the four main types of knee replacement surgery:

1. Total knee replacement

Most complete knee replacement surgeries involve replacing the joint surfaces at the top of your shin bone (tibia (and the end of your thigh bone (femur) 

A smooth plastic dome may be used to replace the undersurface of your kneecap (patella) as part of a complete knee replacement. If feasible, some surgeons prefer to keep the native patella, however this decision must occasionally be made during the procedure.

If you've had a previous procedure to remove the patella entirely (patellectomy), it will not prevent you from getting a knee replacement, but it may influence the sort of replacement portion (prosthesis) the surgeon employs.

Normally, the replacement pieces are glued in place. If no cement is utilized, the component's surface contacting the bone is textured or coated to enable bone to grow onto it, establishing a natural attachment.

Another typical method is to utilize a moveable plastic bearing that is not securely attached to the metal pieces. This may assist to prevent wear on your new joint, but it hasn't been proven to improve long-term results.

 

2. Unicompartimental partial knee replacement

If your arthritis affects only one side of your knee, generally the inner side, a partial (unicompartmental) knee replacement may be an option.

The knee is divided into three compartments: the inner (medial), the outside (lateral), and the kneecap (patellofemoral). If your arthritis affects only one side of your knee, generally the inner side, a half-knee replacement may be an option. Because there is less interference with the knee than with a total knee replacement, this typically results in a faster recovery and improved function.

Partial knee replacements can be performed with a smaller incision (cut) than whole knee replacements, thanks to procedures known as reduced invasive or minimally invasive surgery. A smaller incision may shorten recuperation time even more.

Because you must have strong, healthy ligaments within your knee, partial knee replacement is not for everyone. This is sometimes not discovered until the day of operation.

According to research, persons who have partial knee replacements are more likely to have the knee updated than people who get whole knee replacements - around one out of every ten people requires further surgery after 10 years. Even though there is less interference with the knee, the procedure is generally more difficult than total knee replacement. As a result, your surgeon may want to offer you a more predictable complete knee replacement.

At any age, a partial knee replacement might be considered. It allows younger people to keep more bone, which is beneficial if revision surgery is required later on. For the elderly, partial knee replacement is a less demanding procedure with less discomfort and danger of bleeding. However, the result of the procedure is determined by the type of arthritis rather than your age.

 

3. Kneecap replacement (patellofemoral arthroplasty)

If the undersurface of the kneecap and its groove (the trochlea) are the only sections afflicted by arthritis, a kneecap replacement is performed. If the undersurface of the kneecap and its groove (the trochlea) are the only components damaged by arthritis, they can be replaced. Patellofemoral replacement or patellofemoral joint arthroplasty are other terms for this procedure.

The procedure has a greater failure rate than complete knee replacement, which might be due to arthritis spreading to other portions of your knee. Some doctors choose complete knee replacement because the outcomes are more predictable. Others believe that preserving the remainder of the knee joint if it is not afflicted by arthritis is preferable.

Only roughly 1 in 40 persons with osteoarthritis are candidates for the procedure. However, if the arthritis does not worsen, the prognosis of kneecap replacement can be favorable, and it is a less invasive procedure with faster recovery durations. More study is needed to determine which persons are likely to benefit from this procedure.

 

4. Complex or revision knee replacement

A complex knee replacement may be needed if you're having a second or third joint replacement in the same knee, or if your arthritis is very severe.

Some people may need a more complex type of knee replacement. The usual reasons for this are:

• Major bone loss due to arthritis or fracture
• Major deformity of the knee
• Weakness of the main knee ligaments.

The extended stem of these knee replacements allows the component to be more firmly attached into the bone cavity. To provide stability, the components may additionally interlock in the center of the knee to form a hinge. Extra metal and/or plastic may be utilized to compensate for any removed or severely damaged bone.

This sort of surgery may be required if you are having a second or third joint replacement in the same knee, and it may be preferable if you have extremely severe arthritis from the start.

 

After your operation

You will awaken in the recovery ward, where you will be closely watched until you are ready to be transferred back to your ward. You will be watched here until you are completely awake.

The first post-operative day will be spent in bed. A physiotherapist will come to your home and teach you breathing exercises for your chest as well as leg exercises that you may do while lying in bed. The day following surgery, an x-ray of your knee will be done to ensure that the prosthesis is properly placed.

To lessen the chance of blood clots (DVT) developing in your legs, you will be given blood thinning drugs on a regular basis. You will also be given special stockings (TEDS) to wear on both legs. An inflatable cuff will occasionally compress your calves for the first 24 hours following the surgery to avoid blood flow stagnation. To reduce the chance of infection, you will be given intravenous antibiotics for 24 hours following the procedure.

After the procedure, the dressings will be replaced 48 hours later. Your knee will be swollen and maybe bruised. This is typical. Until you are discharged from the hospital, you will remain under the daily care of a physiotherapist. The goals of these visits are to increase knee mobility, recover ambulation, build muscular strength, and decrease knee swelling.

You will be sent home if you can move about safely, have restored proper knee motion, and your pain is controlled with medication. Some patients require more in-patient treatment and are moved to a rehabilitation facility.

 

Results of Knee Replacement

In overall, this operation is a huge success. It is a fantastic technique for improving a person's quality of life. 95 percent of patients are good or exceptional after this procedure. Excellent indicates no substantial pain or discomfort and good means occasional aches and pains that do not require medicines. Some folks will experience unexplainable discomfort.

In general, 90-95% of knee replacements survive 15 years, however this is dependent on a variety of factors such as your age and degree of exercise. The more you drive on it, the faster it deteriorates. The more cared for and serviced it is, the longer it will last.

 

Complications of Knee replacement surgery

Any business, large or little, has hazards. Any operation can result in the following consequences, and other uncommon issues are also conceivable. It is difficult to explain every problem, and some will occur that no surgeon could have predicted or heard of. To avoid these consequences, extreme caution is exercised at all times throughout operation. The list below is not complete, and several are detailed in further depth in the areas where they may be more suitable.

 

Infection

Infection is one of the hazards associated with total knee replacement. Infections can be superficial (in the skin) or deep (in the body) . The risk is estimated to be 1%. If you have an infection, it will be treated aggressively with medicines, but re-operation may be required to remove the diseased material. In extremely rare cases, the knee replacement is removed and replaced at a later date, usually six to eight weeks after the infection has healed up.

 

Fracture (Break) of the Femur, Tibia or Patella

This can happen during surgery and isn't always obvious. It may necessitate more extensive surgery during the operation, as well as a re-operation a few days later.

 

Stiffness (Lack of Movement)

Following complete knee replacement, some persons develop excessive scar tissue. Total knee replacement has an average long-term bend of 110 degrees. If you are not bending past 90 degrees after six weeks, you may be readmitted to the hospital and the knee is firmly massaged under epidural or spinal anesthesia to break the scar tissue that is preventing your bend.

 

Damage to Nervous or Blood Vessels

Nerves and blood arteries may be injured during the procedure. These may be addressed at the moment if identified, but may need a second surgery to investigate or fix any harm. It is extremely unusual for a damaged nerve to heal on its own. If a damaged nerve does not heal, it might result in impaired leg function below the joint replacement, such as a foot that does not act well owing to weakness or sensory loss.

 

Blood Clots

Blood clots can develop in the calf muscles and spread to the lungs. These can occasionally be severe and even fatal. These blood clots will be treated quickly, and every precaution will be made to prevent them from recurring in the future. During your hospital stay, you will be given a blood thinning drug by injection. Stockings will be supplied to you to help avoid blood pooling in the veins of the calf, and you should wear them for six weeks after surgery. During the procedure on the non-operated leg, a calf pump is also employed. After you leave the hospital, you will be given aspirin to thin your blood.

 

Wear

The wearing of the plastic liner is a long-term problem following total knee replacement. The joint is like a tyre, and if you are rough on it, such as someone who does heavy physical labor, jogs, or is very overweight, it will wear down faster than a more sedentary person.

Most knee replacements have a fifteen-year survival rate of 85 to 95%. There are several factors that influence the survival rate. Continuous technological advancements make these components more likely to endure for a longer amount of time. We believe that today's complete knee replacements will perform better and endure longer than previous models, but we won't know for another ten years.

 

Alternatives to surgery

Before contemplating a knee replacement, most doctors offer non-surgical (conservative) therapy. These are some examples:

• Diet: losing weight will reduce the strain on your knee.
• Exercise. Even though it's tough due to the discomfort, there's typically some sort of non-impact exercise (such as swimming or cycling) that you can begin slowly and that will enhance the strength and flexibility of your knee.
• Drugs: Painkillers can reduce the pain in your joint, while non-steroidal anti-inflammatory drugs (NSAIDs) may help if your knee is swollen.

 

Surgical alternatives

In general, they do not produce the same outcomes as a new knee joint, but they may allow you to postpone a knee replacement surgery for several years. If you've exhausted these treatments, you might wish to consider surgical alternatives to knee replacement:

1. Arthroscopic washout and debridement

Only in extremely restricted conditions can keyhole surgical procedures (arthroscopy) be utilized to smooth damaged cartilage and remove debris from the knee joint. If there are mechanical signs such as 'locking' of the knee, eliminating loose bone and cartilage fragments may prevent the need for a knee replacement at that point. There is no evidence that it is beneficial for arthritis in general.

 

2. Microfracture

This keyhole surgical procedure includes drilling or picking holes in exposed bone surfaces with a drill or pick. This stimulates the formation of new cartilage from the bone marrow. The procedure is not suggested for people with advanced arthritis.

 

3. Osteotomy

This is a procedure that may benefit younger individuals. It entails cutting the shin bone crosswise to form a wedge that shifts the strain away from the arthritis-affected region. Osteotomy may be considered to postpone a knee replacement surgery. However, it can make eventual total knee replacement surgery more challenging, especially if the surgeon needs to cut through the medial collateral ligament on the inside surface of the knee during the osteotomy.

If the outside section of the knee is damaged by arthritis, this procedure on the end of the thigh bone is performed to redistribute weight inwards.

 

4. Autologous chondrocyte therapy (ACT)

If just the hard cartilage is injured, fresh cartilage from your own cells can be generated in a test tube. After that, the new cartilage is put to the injured region. This procedure is primarily intended to treat minor regions of cartilage damage caused by an unintentional lesion to the knee joint. It has not yet been demonstrated to be effective for arthritis and would be best suited for younger individuals with more active cartilage cells. As a result, it is normally only done as part of a research study, as are newer stem cell procedures.

 

Conclusion 

Knee replacement, also known as knee arthroplasty, is a surgical procedure used to replace the weight-bearing surfaces of the knee joint in order to relieve pain and disability. It is most commonly used when conservative measures fail to alleviate joint pain and also for other knee diseases such as rheumatoid arthritis and psoriatic arthritis. Surgery may be more complex and riskier in individuals with significant deformity caused by advanced rheumatoid arthritis, trauma, or long-standing osteoarthritis.