Knee Surgery - Computer Assisted Knee Surgery
Patient Guide
Introduction
Knee Anatomy
Knee Arthritis
Alternatives
Knee Replacement
Computer Assisted Knee Surgery
Surgery Day
Post-op Care
Rehabilitation
After Surgery
Introduction
If your doctor suggests knee surgery as a treatment for your injury or arthritis of the hip, you may feel a little scared and unsure about what’s likely to happen to you. Relax. Getting the right information and knowing the options can help you approach your impending treatment in a calm, unstressed state of mind.
By reading this article, you will be able to gather information about:
Knee anatomy> bones, ligaments, cartilage and tendons
Knee arthritis> causes, symptoms and treatment
Non-surgical alternatives>conservative measures to relieve your pain
Total knee replacement> implant components and procedure
Computer-assisted knee replacement> the new solution, how it works, patient benefits and equipment
Surgery day> pre-operative procedures, preparation for the hospital, day of surgery and recovery
Post-operative care> possible complications and precautions
Rehabilitation> guidelines to help you during your recovery
Life after knee surgery> what to expect in the months and years to come
Knee Anatomy
The knee is a major weight-bearing joint that is held together by muscles, ligaments, and other important soft tissue. Cartilage is the material inside the joint that provides shock absorption to the knee during weight-bearing activities such as walking or stair climbing.
Bones
The bones of the knee are the femur (thigh bone), tibia (shin bone) and patella (kneecap). The femur and tibia meet to form a hinge with the patella in front of these two bones protecting the joint. The patella slides up and down in a groove in the femur (the femoral groove) as the knee is bent and straightened.
Ligaments
Ligaments hold the knee together and give it stability. The medial (inner) collateral ligament (MCL) and outer (lateral) collateral ligament (LCL) limit sideways motion of the knee. The posterior and anterior cruciate ligaments (PCL and ACL) limit forward motion of the knee bones, keeping them stable.
Two structures known as menisci sit between the femur and the tibia and act as cushions or shock absorbers for the knee. A torn meniscus is often referred to as “torn cartilage.” Menisci are one of two types of cartilage in the knee. The other type, articular cartilage, is a smooth and very slick material that covers the end of the femur, the femoral groove, the top of the tibia and the underside of the patella. This articular cartilage allows the bones to move smoothly.
Tendons connect muscle to knee. The quadriceps muscles on the front of the thigh are connected to the top of the patella by the quadriceps tendon, which covers the patella and becomes the patellar tendon. The patellar tendon then attaches to the front of the tibia. The hamstring muscles in the back of the leg attach to the tibia at the back of the knee. The quadriceps muscles straighten the knee and the hamstring muscles bend the knee.
to build a healthy knee.
Knee Arthritis
Osteoarthritis
Osteoarthritis is a progressive, degenerative disease in which the cartilage of the knee slowly wears away. Cartilage serves as insulation between the bones of the joint, and when the cartilage of the knee joint wears away due to osteoarthritis, the resulting pain and inflammation can be debilitating.
Causes
The question of what causes osteoarthritis of the knee has not been answered. Prior knee injuries seem to increase the likelihood of osteoarthritis, but many people with knee arthritis have never had a serious knee injury. Osteoarthritis is the most common form of arthritis, and many people have a genetic predisposition to this chronic disease.
The primary symptoms of osteoarthritis are pain in the knee, swelling and stiffening of the knee joint. In the early stages of osteoarthritis the pain may be mainly associated with activity. As the cartilage wears away and the bones of the joint rub against each other, pain can become more severe and constant, interfering with regular daily activities and disrupting sleep.
In the early stages of osteoarthritis, treatment may involve several techniques. Behavioral and lifestyle changes including losing weight and changing routines to avoid painful situations can be very effective in relieving pain. Non-steroidal anti-inflammatory drugs (NSAIDs) such as naproxen sodium may also provide relief from pain. Cox-2 inhibitors are also effective in providing knee arthritis pain relief. Physical therapy may improve muscle strength and joint mobility, reducing the symptoms of osteoarthritis in the knee. Joint fluid therapy such as SUPARTZ* brand hyaluronic acid may lubricate the knee and reduce the pain and swelling of the joint. Partial or total knee replacement surgery may be necessary as the disease progresses and daily functioning becomes more impaired.
Rheumatoid arthritis
of the over one hundred forms of arthritis. Rheumatoid arthritis usually develops in middle age, but may occur in the 20s and 30s.
The exact cause of rheumatoid arthritis is unknown. It's possible that a virus or bacteria may trigger the disease in people with a genetic predisposition to rheumatoid arthritis. Many doctors think rheumatoid arthritis is an autoimmune disease in which the tissue of the joint's lining is attacked by the body's immune system. It's also possible that rheumatoid arthritis is caused by severe stress. The disease sometimes occurs after a life-changing event such as divorce, loss of a job or a severe injury.
The primary symptoms of rheumatoid arthritis include pain and swelling in the joints and difficulty moving. Other symptoms may include loss of appetite, fever, loss of energy, anemia, and rheumatoid nodules (lumps of tissue under the skin).
Treatment of rheumatoid arthritis usually involves medications such as NSAIDs, aspirin and analgesics. In severe cases, surgery may be indicated to replace the knee joint with an artificial joint.
Alternatives
Lifestyle modification
The first alternative to knee surgery most physicians try is lifestyle modification. This may include weight loss, avoiding activities such as running and twisting which can aggravate the knee injury, modifying exercise to no- and low-impact, and other changes in your daily routine to reduce stress on your knee.
Exercise and physical therapy may be prescribed to improve the strength and flexibility of your hip and other lower extremity muscles. Your exercise program may include riding a stationary bike, light weight training and flexibility exercises. An aquatic therapy program is especially effective for the treatment of arthritis since it allows mild resistance while removing weight bearing stresses. For an appropriate exercise program, contact an experienced physical therapist.
Arthritis pain is caused by inflammation in the knee as the bones rub against each other due to eroded cartilage. Reducing the inflammation of the tissue in the knee can provide temporary relief from pain and delay knee surgery. Anti-inflammatory medications may be prescribed to decrease swelling in the joint. New medications called Cox-2 inhibitors may also be used to reduce inflammation, reducing pain temporarily. A corticosteroid injection may also be used to reduce pain; in this procedure a powerful anti-inflammatory agent is injected directly into the joint.
A dietary supplement called glucosamine/chondroitin may improve the joint's mobility and decrease pain from arthritis of the knee. Glucosamine and chondroitin sulfate can slow the deterioration of cartilage in the joint, reducing the pain of bone on bone. Both are naturally occurring molecules in the body. Glucosamine is thought to promote the growth of new cartilage and repair of damaged cartilage, while chondroitin is believed to promote water retention, improving the elasticity of cartilage, and also to inhibit cartilage-destroying enzymes.
While medications and supplements can be helpful in reducing inflammation and pain and help you delay or avoid knee surgery, there are trade-offs. Drug therapies may have side effects, and there is a limit to how much pain reduction can occur.
Bracing
A brace may be used to provide external stability to the knee joint. Braces are devices made of plastic, metal, leather and/or foam and are designed to stabilize a joint, reduce pain and inflammation and strengthen the muscles of the knee. By putting pressure on the sides of the joint, the brace causes the joint to realign, which in turn decreases the contact between the two rough bone surfaces and reduces the pain while increasing mobility.
Knee Replacement
Your knees work hard during your daily routine, and arthritis of the knee or a knee injury can make it hard for you to perform normal tasks. If your injury or arthritis is severe, you may begin experience pain when you're sitting down or trying to sleep. Sometimes a total knee replacement is the only option for reducing pain and restoring a normal activity level. If your and your doctor decide a total knee replacement is right for you, the following information will give you an understanding about what to expect.
A total knee replacement involves cutting away the damaged bone of the knee joint and replacing it with a prosthesis. This “new joint” prevents the bones from rubbing together and provides a smooth knee joint.
Implant components
In the total knee replacement procedure, each prosthesis
is made up of four parts. The tibial component has two elements and replaces the top of the shin bone or tibia. This prosthesis is made up of a metal tray attached directly to the bone and a plastic spacer that provides the bearing surface. The femoral component replaces the bottom of the thigh bone or femur. This component also replaces the groove where the patella, or kneecap, sits.
Before you are taken to the operating room you'll be given medication to help you relax, and the anesthesiologist will talk with you about the medications he'll be using. In the operating room, you will be placed under full anesthesia. Once you are “under” the surgeon will begin by making an incision in your leg to allow access to the knee joint. He'll then expose the joint and place a cutting jig or template on the end of the femur, or thigh bone. This jig allows the surgeon to cut the bone precisely so that the prosthesis fits exactly. Once the femur is cut, the tibia is cut using another jig for proper alignment of the knee prosthesis. The undersurface of the patella is then removed.
You will be discharged when you can get out of bed on your own and walk with a walker or crutches, walk up and down three steps, bend your knee 90 degrees and straighten your knee.
You'll continue your home exercise program and go to outpatient physical therapy, where you will work on an advanced strengthening program and such programs as stationary cycling, walking, and aquatic therapy.
Your long-term rehabilitation goals are a range of motion from 100-120 degrees of knee flexion, mild or no pain with walking or other functional activities, and independence in all activities of daily living.
Computer Assisted Knee Replacement
Total knee replacement surgery isn't new. It has been practiced worldwide for 40 years, and as might be imagined, the procedure has been refined to the point where hundreds of thousands of people every year are returning to a life of pain-free mobility. However, standard knee replacement surgery has its limitations-the laws of physics being chief among them. A surgeon must implant the orthopedic device in such a manner that its components-a metal and plastic platform atop the tibia and a metal surface on the bottom of the femur-rub together, or "articulate," at precise angles in order to prevent premature or excessive wear of the implant.
As is commonly practiced today, a surgeon achieves proper alignment through "feel." That is, he uses specialized cutting blocks combined with his years of operating room experience to determine where best to remove bone for the implant. Once the cut is made, the natural bone cannot be replaced. Thus, a carpenter's advice to "measure twice, cut once" is especially vital in knee replacement surgery.
Computer-assisted surgery addresses this issue of alignment with an advanced convergence of multiple medical technologies. Using infrared cameras, images and advanced tracking devices, Smith & Nephew's computer-assisted knee replacement procedure achieves precise alignment.
The logic is simple: By combining digital images of the femur and tibia with an implant-specific software package, the computer hardware can track the precise position of the patient's knee and the surgeon's instruments at all times during the procedure. It is as if the patient's leg has a satellite tracking system the computer uses to follow it during surgery.
Patient Benefits
As you might imagine, a surgeon armed with these tools has the potential to achieve better outcomes for the patient. As the computer-assisted procedure evolves, it will become less and less invasive. It has already eliminated the use of an intramedullary (IM) rod; a device inserted up the length of the femur used for determining proper knee implant alignment in relation to the hip joint. Since the data generated by the computer replaces this device, patients undergoing computer-assisted knee surgery may have a reduced risk of fat embolism, caused when the IM rod forces body fat into the patient's blood stream. If fat travels through the blood stream, it could become lodged in the heart or brain and cause heart failure, dementia or stroke. Further, the quality and accuracy of the virtual image provided to the surgeon by the computer enables smaller incisions while achieving the same successful outcomes. Smaller incisions lead to faster surgeries, shorter hospital stays and shorter rehabilitation.
• The elimination of the IM rod reduces the risk of fat embolism.The increased "vision" the procedure provides facilitates minimally invasive surgery. This means a shorter scar, less physical therapy and a faster return to your normal life.
• The accurate alignment and placement of the implant may extend its lifespan and prevent future corrective surgeries.
Since the computer accurately assesses "joint laxity," or soft tissue balance, the surgeon may not need to disrupt as much soft tissue-such as muscle, ligaments and tendons-when determining how tightly the new implant fits in place. This also reduces rehabilitation time and returns you to your active lifestyle more quickly.
The Equipment
The Arrays
"Arrays" are metal prongs with small reflective spheres at their extremities. These devices attach to the surgical instruments and to the patient's tibia and femur.
in relation to the patient's bones, based on where the spheres are at any given second.
The Camera
The camera emits infrared light that reflects off the spheres connected to the arrays. It collects this reflected infrared light, and sends the information about the location of the source of the reflection (the spheres on the arrays)
to the computer.
The Computer
The computer receives information about where the spheres are in space, and combines that data with three-dimensional virtual images of the orthopaedic implants and surgical instruments.
The software displays on the screen the virtual images of the instruments, implants and bones and guides the surgeon through each step of the procedure. The software alerts the surgeon when the instrument is in the most accurate position to make the ideal cut. Also, it helps determine where to best place the knee implant against the bones.
Surgery Day
Pre-operative procedure
Once you and your orthopaedic surgeon have decided to proceed with knee replacement surgery, there are several activities that must occur to help make sure all goes well.
First you will have your initial surgical consultation, which will include preoperative X-rays, a complete past medical history, a complete past surgical history and a complete list of all medications and allergies. This consultation will also include orthopaedic examination and discussion of the knee replacement surgery procedure. Next you will have a complete physical examination. Your internist or family physician will determine if you are in the best possible condition to undergo knee surgery. You may wish to donate blood prior to your knee replacement surgery in the event that a transfusion is required after surgery.
Your doctor may recommend that you see a physical therapist before surgery to learn exercises to begin prior to surgery. You will also get an overview of the rehabilitation process after knee replacement surgery. This will prepare you better for your post-operative care.
You may want to bring the following items to the hospital for your knee replacement surgery:
• Clothing: underwear, socks, t-shirts,
exercise shorts for rehabilitation
• Footwear: walking or tennis shoes for rehab;
slippers for hospital room
• Walking aids: walker, cane, wheelchair, or crutches
if used prior to surgery
• Insurance information
Day of surgery
On the morning of your knee replacement surgery you will be admitted to the hospital. Your vital signs will be taken, you'll be given a clean hospital gown to wear during the procedure, and an IV will be started to give you fluids and medication during and after the procedure.
Recovery
A total knee replacement involves cutting away the damaged bone of the knee joint and replacing it with a prosthesis. You will be under anesthesia during the procedure. After your surgery is completed, you will be transported to the recovery room for close observation of your vital signs, circulation, and sensation in your legs and feet. As soon as you awaken and your condition is stabilized, you will be transferred to your room.
When you wake up you will find a bulky dressing applied to your incision in order to maintain cleanliness and absorb any fluid. There may be a drain placed near your incision in order to record the amount of fluid being lost from the wound.
Your doctor may prescribe a PCA device (patient-controlled analgesia) that is connected to your IV. The unit is set to deliver a small, controlled flow of pain medication and is activated when you firmly press the button on your machine. Press the button anytime you are having pain.
You may have a catheter inserted into your bladder as the side effects of anesthesia may make it difficult to urinate. A continuous passive motion (CPM) unit may be placed on your leg to slowly and gently bend and straighten your knee. This device, if prescribed, is important for quickly regaining your knee range of motion.
Post-Operative Care
Thrombophlebitis
This condition is also known as deep vein thrombosis (DVT), and it occurs when the large veins of the leg form blood clots and, in some instances, become lodged in the capillaries of the lung and cause a pulmonary embolism. The following steps may be taken to avoid knee replacement complications due to blood clots:
2. Elastic stockings (TED hose)
3. Foot and ankle exercises to increase blood flow
and enhance venous return in the lower leg.
IMPORTANT: If you develop swelling, redness, pain and/or tenderness in the calf muscle, report these symptoms to your orthopaedic surgeon or internist immediately.
Infection
Although great precaution is taken before, during, and after surgery, infections do occur in a small percentage of patients following knee replacement surgery. Steps you can take to minimize this knee replacement complication include the following:
2. Take your antibiotics as directed and complete
the recommended dosage duration.
3. Strictly follow the incision care guidelines your surgeon recommends.
Pneumonia
Because your lungs tend to become “lazy” as a result of the anesthesia, secretions may pool at the base of your lungs, which may lead to lung congestion or pneumonia. The following steps may be taken to minimize this complication:
2. Incentive Spirometer: This simple device gives you visual feedback while you perform your deep breathing exercises. Your nurse or respiratory therapist will demonstrate proper technique.
Knee Stiffness
In some cases, the mobility of your knee following surgery may be significantly restricted and you may develop a contracture in the joint that will cause stiffness during walking or other activities of daily living.
The following steps must be taken to maximize your range of motion following surgery:
1. Strict adherence to the CPM protocol as prescribed by your surgeon
2. Early physical therapy (Day 1 or 2) to begin
range of motion exercises and walking program
3. Edema control to reduce swelling (ice, compression
stocking, and elevation)
4. Adequate pain control so you can tolerate the rehabilitation regime
Rehabilitation
Your Orthopedic Surgeon and/or Physical Therapist will most likely assign a specific protocol to you, based on your rehabilitation needs. The following protocol is meant only to give you an idea of the kind of exercises you might do during rehabilitation. When in doubt about an exercise, follow the protocol outlined by your Surgeon and/or Physical Therapist.
Early rehabilitation
Your knee rehabilitation program begins in the hospital after surgery. Early goals of knee rehabilitation in the hospital are to reduce knee stiffness and maximize post-operative range of motion as well as to help you get ready for discharge. The following steps may be taken to help maximize your range of motion following surgery.
2. Early physical therapy (day 1 or 2) to begin
range of motion exercises and walking program
3. Edema control to reduce swelling (ice, compression
stocking, and elevation)
4. Adequate pain control so you can tolerate
the rehabilitation regimen
Outpatient Physical Therapy
Your outpatient knee rehabilitation program will consist of a variety of exercises designed to help you regain range of motion in the knee and build strength in the muscles which support the knee. You will follow an advanced strengthening program, adding weights as tolerated. A stationery cycle and walking program will be used to help increase range of motion and stamina, and an aquatic therapy program may be added as well.
There are several things you can do at home to make your knee rehabilitation more successful. First of all, do the home exercise program as prescribed by your physical therapist. Next, follow these suggestions for daily activities:
• Walking: Do not put weight through the joint
until you've been cleared to do so by your surgeon.
• Lifting: Do not lift more than ten pounds.
• Showering: Showering is preferable to bathing
because of difficulties getting in and out of the tub.
• Exercising: Do the exercises that were recommended
by your doctor and physical therapist. Go to physical therapy
as prescribed and get advice from your therapist as to whether you're doing the exercises correctly.
Long-term rehabilitation goals
Once you've completed your knee rehabilitation therapy, you can expect a range of motion from 100-120 degrees of knee flexion, mild or no pain with walking or other functional activities, and independence with all activities of daily living.
After Surgery
Once you've had knee replacement surgery and completed rehab, your knee should have a range of motion of 100-120 degrees, sufficient for all your daily tasks such as walking and climbing stairs.
Thanks to your new knee, you will be able to do many of the activities you did before your knee surgery, but with little or no pain. Most people with total knees can do recreational walking, swimming, golf, driving, light hiking, recreational biking, ballroom dancing and stair climbing without difficulty.
Activities to Avoid
Even though your activity level is likely to increase, a knee replacement surgery means that high-demand or high-impact activities must be avoided. You should definitely avoid running or jogging, contact sports, jumping sports, and high impact aerobics.
How long will your implant last
The average total knee currently lasts 10-15 years before the components wear out. In some cases, worn components can be easily switched out for new ones, but revision surgery is always an experience doctors and patients want to avoid if at all possible.
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