Treatments

Anatomy of the Knee

Joints are the areas where 2 or more bones meet. Most joints are mobile, allowing the bones to move. Basically, the knee is 2 long leg bones held together by muscles, ligaments, and tendons. Each bone end is covered with a layer of cartilage that absorbs shock and protects the knee.
There are 2 groups of muscles involved in the knee, including the quadriceps muscles (located on the front of the thighs), which straighten the legs, and the hamstring muscles (located on the back of the thighs), which bend the leg at the knee.
Tendons are tough cords of connective tissue that connect muscles to bones. Ligaments are elastic bands of tissue that connect bone to bone. Some ligaments of the knee provide stability and protection of the joints, while other ligaments limit forward and backward movement of the tibia (shin bone).
The knee consists of the following:

• Tibia – This is the shin bone or larger bone of the lower leg.
• Femur – This is the thighbone or upper leg bone.
• Patella – This is the kneecap.
• Cartilage – A type of tissue that covers the surface of a bone at a joint. Cartilage helps reduce the friction of movement within a joint.
• Synovial membrane – A tissue that lines the joint and seals it into a joint capsule. The synovial membrane secretes synovial fluid (a clear, sticky fluid) around the joint to lubricate it.
• Ligament – A type of tough, elastic connective tissue that surrounds the joint to give support and limits the joint’s movement.
• Tendon – A type of tough connective tissue that connects muscles to bones and helps to control movement of the joint.
• Meniscus – A curved part of cartilage in the knees and other joints that acts as a shock absorber, increases contact area, and deepens the knee joint.

Reasons for Total Knee Arthroplasty

Knee replacement surgery is a treatment for pain and disability in the knee. The most common condition that results in the need for knee replacement surgery is osteoarthritis. Osteoarthritis is characterized by the breakdown of joint cartilage. Damage to the cartilage and bones limits movement and may cause pain. People with severe degenerative joint disease may be unable to do normal activities that involve bending at the knee, such as walking or climbing stairs, because they are painful. The knee may swell or “give-way” because the joint is not stable. Other forms of arthritis, such as rheumatoid arthritis and arthritis that results from a knee injury, may also lead to degeneration of the knee joint. In addition, fractures, torn cartilage, and/or torn ligaments may lead to irreversible damage to the knee joint.

If medical treatments are not satisfactory, knee replacement surgery may be an effective treatment. Some medical treatments for degenerative joint disease may include, but are not limited to, the following:

• Anti-inflammatory medications
• Glucosamine and Chondroitin Sulfate
• Pain medications
• Limiting painful activities
• Assistive devices for walking (such as a cane)
• Physical therapy
• Cortisone injections into the knee joint
• Viscosupplementation injections (to add lubrication into the joint to make joint movement less painful)
• Weight loss (for obese persons)

Before the Surgery

• In addition to taking a complete medical history, the doctor may perform a complete physical examination to ensure that the patient is in good health before undergoing the procedure. The patient may undergo blood tests or other diagnostic tests.
• Notify the doctor if the patient is sensitive to or are allergic to any medications, latex, tape, and anaesthetic agents (local and general).
• Inform the doctor of all medications (prescribed and over-the-counter) and herbal supplements that the patient is taking.
• Notify the doctor if the patient has a history of bleeding disorders or if he/she is taking any anticoagulant (blood-thinning) medications, aspirin, or other medications that affect blood clotting. It may be necessary for to stop these medications prior to the procedure.
• If the patient is pregnant or suspect that she is pregnant, the doctor should be notified.
• The patient will be asked to fast for eight hours before the procedure, generally after midnight.
• A sedative is usually given prior to the procedure to help the patient relax.
• A physical therapist may meet the patient prior to surgery to discuss rehabilitation.

During the Surgery

Knee replacement requires a few days’ stay in the hospital. Knee replacement surgery is most often performed under general anaesthesia. The anaesthesiologist will discuss this with the patient in advance. Generally, knee replacement surgery follows this process:

• The patient will be asked to remove clothing and will be given a gown to wear.
• An intravenous (IV) line may be started in the arm or hand.
• The patient will be positioned on the operating table.
• A urinary catheter may be inserted.
• If there is excessive hair at the surgical site, it may be clipped off.
• The anaesthesiologist will continuously monitor heart rate, blood pressure, breathing, and blood oxygen level during the surgery.
• The skin over the surgical site will be cleansed with an antiseptic solution.
• The doctor will make an incision in the knee area.
• The doctor will remove the damaged surfaces of the knee joint and resurface the knee joint with the prosthesis. The knee prosthesis is made up of metal and plastic. The most common type of artificial knee prosthesis is a cemented prosthesis. Uncemented prostheses are not commonly used anymore. A cemented prosthesis attaches to the bone with surgical cement. An uncemented prosthesis attaches to the bone with a porous surface onto which the bone grows to attach to the prosthesis. Sometimes, a combination of the 2 types is used to replace a knee. The prosthesis is generally comprised of 3 components: the tibial component (to resurface the top of the tibia, or shin bone); the femoral [thigh bone] component (to resurface the end of the thighbone; and the patellar component (to resurface the bottom of the kneecap that rubs against the thighbone).
• The incision will be closed with stitches or surgical staples.
• A drain may be placed in the incision site to remove fluid.
• A sterile bandage or dressing will be applied.

After the Surgery

After the surgery the patient will be taken to the recovery room for observation. Once the patient’s blood pressure, pulse, and breathing are stable and he/she is alert, the patient will be taken to the hospital room. Knee replacement surgery usually requires an in-hospital stay of several days.

It is important to begin moving the new joint after surgery. A physical therapist will meet the patient soon after surgery and plan an exercise program. A continuous passive motion (CPM) machine may be used to begin the physical therapy. This machine moves the new knee joint through its range of motion while the patient is resting in bed. Pain will be controlled with medication so that the patient can participate in the exercise. An exercise plan will be given to be followed both in the hospital and after discharge.

The patient will then be discharged home. Physical therapy will continue until the patient regains muscle strength and good range of motion.

Rehabilitation

Once the patient is home, it is important to keep the surgical area clean and dry. Specific bathing instructions will be given. The stitches or surgical staples will be removed during a follow-up visit. To help reduce swelling, the patient may be asked to elevate the leg or apply ice to the knee.

Pain relievers can be taken for soreness as recommended by the doctor. Aspirin or certain other pain medications may increase the chance of bleeding. Hence it is important to take only recommended medications.

The doctor should be notified if any of the following occur:

• Fever
• Redness, swelling, bleeding, or other drainage from the incision site
• Increased pain around the incision site

Normal diet can be resumed unless the doctor advises differently. The patient should not drive until the doctor allows it. Other activity restrictions may apply. Full recovery from the surgery may take several months.

It is important that the avoid falls after knee replacement surgery, because a fall can result in damage to the new joint. The physical therapist may recommend an assistive device (cane or walker) to help the patient walk until his/her strength and balance improve.
Making certain modifications at home may help during the recovery. These modifications include, but are not limited to, the following:

• Proper handrails along all stairs
• Safety handrails in the shower or bath
• Shower bench or chair
• Raised toilet seat
• Long-handled sponge and shower hose
• Dressing stick
• Sock aid
• Long-handled shoe horn
• Reaching stick to grab objects
• Removing loose carpets and electrical cords that may cause the patient to trip
• Avoiding stair-climbing until recommended by the doctor

Complications

As with any surgical procedure, complications can occur. Some possible complications may include, but are not limited to, the following:

• Bleeding
• Infection
• Blood clots in the legs or lungs
• Loosening or wearing out of the prosthesis
• Fracture
• Continued pain or stiffness

The replacement knee joint may become loose, be dislodged, or may not work the way it was intended. The joint may have to be replaced again in the future.
Nerves or blood vessels in the area of surgery may be injured, resulting in weakness or numbness. The joint pain may not be relieved by surgery. There may be other risks depending on the patient’s specific medical condition.

Outlook

With proper care and rehabilitation, a total knee arthroplasty (TKA) may last 20 years or longer. More than 85%-90% of replaced knee joints continue to work 10 years after surgery.