Knee replacement, also called arthroplasty, is a surgical procedure to resurface a knee damaged by arthritis. Metal and plastic parts are used to cap the ends of the bones that form the knee joint, along with the kneecap. This surgery may be considered for someone who has severe arthritis or a severe knee injury.
Various types of arthritis may affect the knee joint. Osteoarthritis, a degenerative joint disease that affects mostly middle-aged and older adults, may cause the breakdown of joint cartilage and adjacent bone in the knees. Rheumatoid arthritis, which causes inflammation of the synovial membrane and results in excessive synovial fluid, can lead to pain and stiffness. Traumatic arthritis, arthritis due to injury, may cause damage to the cartilage of the knee.
The goal of knee replacement surgery is to resurface the parts of the knee joint that have been damaged and to relieve knee pain that cannot be controlled by other treatments.
Joints are the areas where two or more bones meet. Most joints are mobile, allowing the bones to move. Basically, the knee is two 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 two 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.
When is Knee Replacement Surgery recommended?
You and your doctor may consider knee replacement surgery if you have a stiff, painful knee that makes it difficult to perform even the simplest of activities and other treatments are no longer working. This surgery is generally reserved for people over the age of 50 with severe osteoarthritis.
What are the causes?
Sequele to inflammatory arthritis or trauma
In an Arthritic Knee:
The cartilage lining is thinner than normal or completely absent. The degree of cartilage damage and inflammation varies with the type and stage of arthritis
The capsule of the arthritic knee is swollen
The joint space is narrowed and irregular in outline; this can be seen in an X-ray image
Bone spurs or excessive bone can also build up around the edges of the joint
The combinations of these factors make the arthritic knee stiff and limit activities due to pain or fatigue.
How is Knee Replacement Surgery diagnosed?
The first part of a diagnostic interview for knee pain is the careful taking of the patient's history. The doctor will ask not only for a general medical history, but also about the patient's occupation, exercise habits, past injuries to the knee, and any gait-related problems. The doctor will also ask detailed questions about the patient's ability to move or flex the knee; whether specific movements or activities make the pain worse; whether the pain is sharp or dull; its location in the knee; whether the knee ever buckles or catches; and whether there are clicking or popping sounds inside the joint.
PHYSICAL EXAMINATION OF THE KNEE. Following the history, the doctor will examine the knee itself. The knee will be checked for swelling, reddening, bruises, breaks in the skin, lumps, or other unusual features while the patient is standing. The doctor will also make note of the patient's posture, including whether the patient is bowlegged or knock-kneed. The patient may be asked to walk back and forth so that the doctor can check for gait abnormalities.
In the second part of the physical examination, the patient lies on an examining table while the doctor palpates (feels) the structures of the knee and evaluates the strength or tightness of the tendons and ligaments. The patient may be asked to flex one knee and straighten the leg or turn the knee inward and outward so that the doctor can measure the range of motion in the joint. The doctor will also ask the patient to lie still while he or she moves the knee in different directions.
IMAGING STUDIES. The doctor will order one or more imaging studies in order to narrow the diagnosis. A radiograph or x ray is the most common, but is chiefly useful in showing fractures or other damage to bony structures. X-ray studies are usually supplemented by other imaging techniques in diagnosing knee disorders. A computed tomography, or CAT scan, which is a specialized type of x ray that uses computers to generate three-dimensional images of the knee joint, is often helpful in evaluating malformations of the joint. Magnetic resonance imaging (MRI) uses a large magnet, radio waves, and a computer to generate images of the knee joint. The advantage of an MRI is that it reveals injuries to ligaments, tendons, and menisci as well as damage to bony structures.
ASPIRATION. Aspiration is a procedure in which fluid is withdrawn from the knee joint by a needle and sent to a laboratory for analysis. It is done to check for infection in the joint and to draw off fluid that is causing pain. Aspiration is most commonly done when the knee has swelled up suddenly, but may be performed at any time. Blood in the fluid usually indicates a fracture or torn ligament; the presence of bacteria indicates infection; the presence of uric acid crystals indicates gout. Clear, straw-colored fluid suggests osteoarthritis.
ARTHROSCOPY. Arthroscopy can be used to treat knee problems as well as diagnose them. An arthroscope consists of a miniature camera and light source mounted on a flexible fiberoptic tube. It allows the surgeon to look into the knee joint. To perform an arthroscopy, the surgeon will make two to four small incisions known as ports. One port is used to insert the arthroscope; the second port allows insertion of miniaturized surgical instruments; the other ports drain fluid from the knee. Sterile saline fluid is pumped into the knee to enlarge the joint space and make it easier for the surgeon to view the knee structures and to cut, smooth, or repair damaged tissue.
What are the treatment options for Knee Replacement Surgery?
The decision to proceed with TKR surgery is a cooperative one between you, your surgeon, family and your local doctor.
The benefits following surgery are relief of symptoms of arthritis. These include
Severe pain that limits your everyday activities including walking, shopping, visiting friends, getting in and out of chair, gardening, etc.
Pain waking you at night
Deformity- either bowleg or knock knees
Prior to surgery you will usually have tried some conservative treatments such as simple analgesics, weight loss, anti-inflammatory medications, modification of your activities, canes, or physical therapy.
Once these have failed it is time to consider surgery. Most patients who have TKR are between 60 to 80 years, but each patient is assessed individually and patients as young as 20 or old as 90 are occasionally operated on with good results.
Your surgeon will send you for routine blood tests and any other investigations required prior to your surgery
You will be asked to undertake a general medical check-up with a physician
You should have any other medical, surgical or dental problems attended to prior to your surgery
Make arrangements for help around the house prior to surgery
Cease aspirin or anti-inflammatory medications 10 days prior to surgery as they can cause bleeding
Cease any naturopathic or herbal medications 10 days before surgery
Stop smoking as long as possible prior to surgery
Day of your surgery
You will be admitted to the hospital, usually on the day of your surgery
Further tests may be required on admission
You will meet the nurses and answer some questions for the hospital records
You will meet your Anesthetist, who will ask you a few questions
You will be given hospital clothes to change into and have a shower prior to surgery
The operation site will be shaved and cleaned
Approximately 30 minutes prior to surgery
you will betransferred to the operating room
Each knee is individual and knee replacements take this into account by having different sizes for your knee. If there is more than the usual amount of bone loss, sometimes extra pieces of metal or bone are added.
Surgery is performed under sterile conditions in the operating room under spinal or general anesthesia. You will be on your back and a tourniquet applied to your upper thigh to reduce blood loss. Surgery takes approximately two hours.
The surgeon cuts down to the bone to expose the bones of the knee joint.
The damaged portions of the femur and tibia are then cut at the appropriate angles using specialized jigs. Trial components are then inserted to check the accuracy of these cuts and determine the thickness of plastic required to place in between these two components. The patella (knee cap) may be replaced depending on a number of factors and depending on the surgeon's choice.
The real components are then inserted with or without cement and the knee is again checked to make sure things are working properly. The knee is then carefully closed and drains usually inserted, and the knee dressed and bandaged.
What are the risk factors for Knee Replacement Surgery?
As with any surgical procedure, complications can occur. Some possible complications may include, but are not limited to, the following:
Blood clots in the legs or lungs
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 your specific medical condition. Be sure to discuss any concerns with your doctor prior to the procedure.
Can Knee Replacement Surgery be prevented?
The following tips may prevent knee problems.
General prevention tips
Wear your seat belt in a motor vehicle.
Don't carry objects that are too heavy. Use a step stool. Do not stand on chairs or other unsteady objects.
Wear knee guards during sports or recreational activities, such as roller-skating or soccer.
Stretch before and after physical exercise, sports, or recreational activities to warm up your muscles.
Use the correct techniques or positions during activities so that you do not strain your muscles.
Use equipment appropriate to your size, strength, and ability. Avoid repeated movements that can cause injury. In daily routines or hobbies, look at activities in which you make repeated knee movements.
Consider taking lessons to learn the proper technique for sports. Have a trainer or person who is familiar with sports equipment check your equipment to see if it is well suited for your level of ability, body size, and body strength.
If you feel that certain activities at your workplace are causing pain or soreness from overuse, call your human resources department for information on other ways of doing your job or to talk about using different equipment.
Tips specific to the knee
Keep your knees and the muscles that support them strong and flexible. Warm up before activities. Try the following stretches:
- Hamstring stretch
- Knee-to-chest exercise
- Calf stretch
- Straight-leg raises
Avoid activities that stress your knees, such as deep knee bends or downhill running.
Wear shoes with good arch supports.
Do not wear high-heeled shoes.
When playing contact sports, wear the right shoes that are made for the surface you are playing or running on, such as a track or tennis court.
Replace running shoes every 300 to 500 miles (480 to 800 kilometers). Experts recommend getting new athletic shoes every 3 months or after 500 miles of wear.
Tips specific to female athletes
Sports trainers recommend training programs that help women learn to run, jump, and pivot with knees bent to avoid knee injuries. In sports such as soccer, basketball, and volleyball, women who bend their knees and play low to the ground have fewer knee injuries than women who run and pivot with stiff legs.
Knee brace use
Some people use knee braces to prevent knee injuries or after a knee injury. There are many types of knee braces, from soft fabric sleeves to rigid, metal hinged braces, that support and protect the knee. If your doctor has recommended the use of a knee brace, follow his or her instructions. If you are using a knee brace to help prevent problems, follow the manufacturer's instructions for use.
Keep bones strong
Eat a nutritious diet with enough calcium and vitamin D, which helps your body absorb calcium. Calcium is found in dairy products, such as milk, cheese, and yogurt; dark green, leafy vegetables, such as broccoli; and other foods. For more information, see the topic Healthy Eating.
Exercise and stay active. It is best to do weight-bearing exercise for at least 2 hours a week. One way to do this is to be active 30 minutes a day, at least 5 days a week. In addition to weight-bearing exercise, experts recommend that you do resistance exercises at least 2 days a week. Exercises that are not weight-bearing, such as swimming, are good for your general health. But they do not work your muscles and bones against gravity and so they do not stimulate new bone growth. Starting these exercises at any age will help prevent bone loss. But if you stop exercising, your bones will begin to thin. Talk to your doctor about an exercise program that is right for you. Begin slowly, especially if you have been inactive. For more information, see the topic Fitness.
Don't drink more than 2 alcoholic drinks a day if you are a man, or 1 alcoholic drink a day if you are a woman. People who drink more than this may be at higher risk for weakening bones (osteoporosis). Alcohol use also increases your risk of falling and breaking a bone.
Stop or do not begin smoking. Smoking puts you at a much higher risk for developing osteoporosis. It also interferes with blood supply and healing. For more information, see the topic Quitting Smoking.
How fast can you recover?
After the surgery you will be taken to the recovery room for observation. Once your blood pressure, pulse, and breathing are stable and you are alert, you will be taken to your 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 with you soon after your surgery and plan an exercise program for you. A continuous passive motion (CPM) machine may be used to begin the physical therapy. This machine moves your new knee joint through its range of motion while you are resting in bed. Your pain will be controlled with medication so that you can participate in the exercise. You will be given an exercise plan to follow both in the hospital and after discharge.
You will be discharged home or to a rehabilitation center. In either case, your doctor will arrange for continuation of physical therapy until you regain muscle strength and good range of motion.
Once you are home, it is important to keep the surgical area clean and dry. Your doctor will give you specific bathing instructions. The stitches or surgical staples will be removed during a follow-up office visit.
To help reduce swelling, you may be asked to elevate your leg or apply ice to the knee.
Take a pain reliever for soreness as recommended by your doctor. Aspirin or certain other pain medications may increase the chance of bleeding. Be sure to take only recommended medications.
Notify your doctor to report any of the following:
Redness, swelling, bleeding, or other drainage from the incision site
Increased pain around the incision site
You may resume your normal diet unless your doctor advises you differently.
You should not drive until your doctor tells you to. Other activity restrictions may apply. Full recovery from the surgery may take several months.
It is important that you avoid falls after your knee replacement surgery, because a fall can result in damage to the new joint. Your therapist may recommend an assistive device (cane or walker) to help you walk until your strength and balance improve.
Making certain modifications to your home may help you during your 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
Long-handled shoe horn
Reaching stick to grab objects
Removing loose carpets and electrical cords that may cause you to trip
Avoiding stair-climbing until recommended by your physician
Your doctor may give you additional or alternate instructions after the procedure, depending on your particular situation.
What are the results of the surgery?
Most people who have a knee replacement experience significant pain relief, improved mobility and a better overall quality of life. Talk with your doctor about what you can expect from knee replacement surgery.
Four to six weeks after knee replacement surgery, you generally can resume most normal daily activities such as shopping and light housekeeping. Driving is also possible at around four weeks if you can bend your knee far enough to sit in a car and you have enough muscle control to properly operate the brakes and accelerator.
After you've recovered, you can enjoy a variety of low-impact activities, such as walking, swimming, golfing or biking. But you should avoid higher impact activities — such as jogging, skiing, tennis, and sports that involve contact or jumping. Talk to your doctor about your limitations.
What are the complications?
Complications can be medical (general) or local complications specific to the Knee
Medical complications include those of the anesthetic and your general well being. Almost any medical condition can occur so this list is not complete. Complications include:
Allergic reactions to medications
Blood loss requiring transfusion with its low risk of disease transmission
Heart attacks, strokes, kidney failure, pneumonia, bladder infections Complications from nerve blocks such as infection or nerve damage Serious medical problems can lead to ongoing health concerns, prolonged hospitalization or rarely death
Infection can occur with any operation. In the knee this can be superficial or deep. Infection rates vary. If it occurs, it can be treated with antibiotics but may require further surgery. Very rarely your new knee may need to be removed to eradicate infection.
Blood Clots (Deep Venous Thrombosis)
These can form in the calf muscles and can travel to the lung (Pulmonary embolism). These can occasionally be serious and even life threatening. If you get calf pain or shortness of breath at any stage, you should notify your doctor.
Stiffness in the Knee
Ideally your knee should bend beyond 100 degrees but on occasion, the knee may not bend as well as expected. Sometimes manipulations are required. This means going to the operating room where the knee is bent for you and under anesthetic.
The plastic liner eventually wears out over time, usually 10 to 15 years and may need to be changed.
Wound Irritation or Breakdown
The operation will always cut some skin nerves, so you will inevitably have some numbness around the wound. This does not affect the function of your joint. You can also get some aching around the scar. Vitamin E cream and massaging can help reduce this.
Occasionally, you can get reactions to the sutures or a wound breakdown that may require antibiotics or rarely, further surgery.
The knee may look different than it was because it is put into the correct alignment to allow proper function.
Leg length inequality
This is also due to the fact that a corrected knee is more straight and is unavoidable.
An extremely rare condition where the ends of the knee joint lose contact with each other or the plastic insert can lose contact with the tibia (shinbone) or the femur (thigh bone).
Patella (knee cap) can dislocate. This means it moves out of place and it can break or loosen.
There are a number of ligaments surrounding the knee. These ligaments can be torn during surgery or break or stretch out any time afterwards. Surgery may be required to correct this problem.
Damage to Nerves and Blood Vessels
Rarely these can be damaged at the time of surgery. If recognized they are repaired, but a second operation may be required. Nerve damage can cause a loss of feeling or movement below the knee and can be permanent.
Fractures or breaks in the bone can occur during surgery or afterwards if you fall. To repair these, you may require surgery.
Discuss your concerns thoroughly with your Orthopaedic Surgeon prior to surgery.
Cost of Surgery?
The cost of surgery for Knee Replacement depends on many factors. They include the cost of being in the hospital for several days. Unexpected events that result in an extended hospital stay will also increase the overall cost.
Costs also vary depending on the type of insurance coverage you have. Many insurance companies cover the cost of the surgery, the hospital stay, and the instruments to straighten the spine. You may owe a co-payment or you may be billed the balance of what your insurance does not cover.
Be sure to contact your insurance provider prior to surgery to discuss the extent of your coverage. Discuss with your surgeon, as well as the hospital billing department to make sure you understand all the costs involved.
- Amjad Khan