Health

There are many types of surgical procedures for the knee, but the main ones involving knee arthritis are arthroscopy, osteotomy, unicompartmental (partial) knee arthroplasty, and total knee arthroplasty.

Arthroscopy

Arthroscopy is a surgical procedure which can be performed through tiny (1/4 inch) incisions using small instruments and a special camera to look inside the joint. This procedure can be performed to remove loose or torn cartilage, smooth roughened arthritic articular cartilage surfaces, trim or repair a torn meniscus, and reconstruct torn ligaments. Knee arthroscopy is usually performed in an outpatient setting, meaning surgery can be performed and you can go home on the same day.

The benefits of knee arthroscopy is that it is the least invasive of all the surgical procedures, the recovery is relatively fast, the procedure may provide some pain relief from the arthritis, and the procedure can be performed as an outpatient surgery. The disadvantage to knee arthroscopy is that it does not “cure” the arthritis, and the pain relief may only be temporary.

The surgery is performed under an anesthetic which is selected by you and your anesthesiologist. Through several small incisions the surgeon introduces thin instruments and a camera called an “arthroscope” which is skinnier than a pencil. The arthroscope is connected to a TV screen so that the surgeon is able to see the inside of the knee joint and the surgical instruments. The arthroscope also pumps sterile fluid into the knee to distend the joint capsule and to allow the surgeon to see. There are a variety of different instruments that are available to the surgeon to cut, trim, shave, or grab torn cartilage or loose bone pieces. It is common within an arthritic knee joint is to see cracked or worn articular cartilage. Worn cartilage often looks like crab meat hanging off the ends of the bone which can be gently trimmed. Sometimes there are loose pieces of cartilage or bone floating around inside the knee which can be removed by the surgeon to prevent the knee from locking. Loose bodies in the knee can act like a door stop and prevent the knee from bending or straightening if it gets caught in the joint. Another common treatment is to trim away a torn meniscus. If the meniscus is torn it can catch between the femur and the tibia. Just like a hangnail that gets caught and becomes painful, if the torn meniscus edge is trimmed back, the catching disappears and the pain is eliminated. In certain circumstances when the meniscus is completely detached at the outer rim, it can be repaired using special techniques. Ligaments like the anterior and posterior cruciate ligaments can also be reconstructed arthroscopically but this is usually not performed in a knee joint that already has a lot of arthritis. At the end of the surgical procedure, the arthroscopic instruments are removed, the fluid is drained, and the incisions are closed with a couple stitches.

Recovery from arthroscopic surgery is generally fast. Most patients can expect to have some degree of soreness and pain medications are typically prescribed for a short period after surgery. You can usually bear as much weight as tolerated unless your surgeon specifically gives you instructions otherwise. Most patients use a cane or crutches for a short period of time, and are able to wean from these gait aids after a few days. It is important to work on bending and straightening the knee after the arthroscopic surgical procedure and some patients see a physical therapist to instruct and assist them with their exercises. Sutures are typically removed 10 to 14 days after surgery. Most patients feel that they have recovered from surgery and resume normal activities about six weeks after the operation.

Osteotomy

Osteotomy is a procedure that realigns the tibia (shin bone) or femur (thigh bone) in order to redistribute the weight that passes through the knee joint. In a normal leg, if you dropped a plumb line down from the center of the hip down to the center of the ankle, the line should pass through the center of the knee. This line is what orthopedic surgeons refer to as the “mechanical axis”. Often in an arthritic joint, one side of the knee wears out quicker than the other. The compartment on the inner side of the knee, or what we call the “medial compartment”, more commonly wears out leading to a bow-legged or varus deformity. This results in the mechanical axis passing to the inner side of the knee which results in even more of the body’s weight passing through the part of the knee that is worn away. If the outer compartment of the knee, called the “lateral compartment”, wears out, this leads to the plumb line falling to the outer part of the knee which leads to more weight passing through the already arthritic portion of the knee. During an osteotomy, the bone is cut and the leg is realigned so that the mechanical axis is shifted to unload the part of the knee that is arthritic.

The osteotomy procedure has historically been indicated for younger, active patients with isolated arthritis in just one side of the knee. Contraindications for this procedure are inflammatory disorders such as rheumatoid arthritis, arthritis in other areas of the same knee, and the presence of unstable ligaments. The benefits of an osteotomy are that it unloads the arthritic portion of the knee to relieve pain, your own native bone and cartilage are retained, and patients can typically return to a higher level of activity if the operation is successful. The disadvantages are that the results may only be temporary, the leg may look funny because of the new alignment, and a fairly long recovery period as it typically takes 2-3 months for the bone to heal. Lastly, if the arthritis in the knee progresses to need a knee replacement, that surgery is slightly more complicated because of the previous osteotomy. Because of the high success rate of knee replacements, osteotomies are becoming less common.

This procedure is performed under a general or regional anesthetic which will be decided by you and your anesthesiologist. Depending on the pattern of the arthritis and which part of the knee is involved, the surgeon will determine which bones need to be cut and realigned. The surgeon usually plans out where the cuts will be made and the overall angle of the leg, just like a carpenter would make plans for construction. The bone cuts are made with the aid of fluoroscopy, which is a live x-ray machine. With this machine, the surgeon is able to visualize the bones and the instruments that are used to cut the bones. To realign the bones, either a “closing wedge” or “opening wedge” osteotomy is performed. A “closing wedge” is when a wedge of bone is removed and the gap between the bones is closed together. An “opening wedge” is when a bone cut is made and the space is wedged open and filled with bone graft. Once the bone cuts are made and the leg is realigned, the position of the bones is held in place with special plates and screws.

After surgery, most patients are placed in a special brace or a custom cast that protects the osteotomy, yet allows for motion of the knee. The hospital stay is usually several days. Just like a broken bone, an osteotomy takes several months to heal. Crutches are used to help you walk while the bones heal. Your surgeon will determine how quickly you can advance your activities and exercises after the procedure. A physical therapist is often used to help work on knee flexibility exercises after surgery. Follow-up includes serial x-rays to check how the osteotomy is healing. Since the procedure is considered a joint salvage procedure for younger, more active patients, once the osteotomy is healed, most surgeons allow those patients to return to activities as tolerated.

Unicompartmental Knee Arthroplasty

A unicompartmental knee arthroplasty is a partial knee replacement. Unlike a total knee arthroplasty where all the joint surfaces of the knee are replaced, a unicompartmental arthroplasty only resurfaces the one part of the joint that is arthritic. The advantage of this procedure is that it is less surgery than a total knee arthroplasty and the recovery is quicker.

Similar to candidates for an osteotomy procedure, patients considering a unicompartmental arthroplasty are typically younger patients with isolated arthritis in just one part of the knee that are not ready for a total knee arthroplasty or more elderly patients in which a less involved surgical procedure may be of benefit. This procedure is not good for those that have arthritis in multiple areas of the knee, patients with inflammatory arthritic diseases, unstable ligaments, and severe deformity of the knee.

This surgery requires either a general or regional anesthetic. During surgery, an incision is made on the front of the knee. Once the joint is opened, the arthritic surfaces of the knee can then be seen. Using specialized tools and jigs, the ends of the bone on the side of the knee that is arthritic are prepared in a carpentry-like fashion to accommodate the new metal and plastic implants.

The implants are then cemented into place. Instead of raw bone grating against raw bone in that part of your knee, the finished result allows you to have metal articulating with plastic.

The recovery for a partial knee replacement is typically faster than a total knee replacement or an osteotomy. The hospital stay is usually only 2-3 days. Physical therapy is started in the hospital and continued once you go home. Crutches or a walker are typically used while you recover. Most patients return to normal activities after two to three months. Lower impact activities are preferred (cycling, walking, swimming) over high impact activities (running, jumping, cutting and pivoting sports) to preserve the lifespan of the implant. If a unicompartmental knee fails either because of implant failure or arthritis developing in other areas of the knee, this requires an additional operation to convert the knee to a total knee replacement.

Total Knee Arthroplasty

Total knee arthroplasty is a successful procedure that been performed for nearly forty years. At the present time, over 400,000 knees are replaced every year in the United States. This procedure is indicated for end-stage arthritis associated with pain and dysfunction when non-operative treatment measures have failed. Prior to considering knee replacement, most patients have tried medications, undergone injections, modified their lifestyle, and have even had other surgeries such as an arthroscopy.

Surgery

The surgical procedure involves replacing the arthritic surfaces of the knee with metal and plastic implants (Click here to view video). This is performed under a regional (spinal or epidural nerve blocks) or general anesthetic as determined by you and your anesthesiologist. An incision is placed on the front of the knee. Once the knee joint is opened, the arthritic ends of the bone are visualized. Using specialized instruments and jigs, the surgeon is able to precisely remove the ends of the arthritic cartilage and bone. The entire knee joint is not removed. Typically, only 10mm or less of bone is removed from the end of the femur (thigh bone) and top of the tibia (shin bone). Special measuring devices are used to determine what size implants are needed for your knee. Similar to if you have a size 8 foot; you get a size 8 shoe. Similarly in the knee, a variety of implant sizes are available and your surgeon is able to select the appropriate size implants for your knee. After all the bone cuts have been made, trial implants (dummy versions of the actual implants) are placed in the knee. A cap is placed on the end of the thigh bone (the femoral component), a tray is placed on the top of the shin bone (the tibial component), a plastic spacer is placed in between (the tibial insert), and a plastic button is placed onto the back of the knee cap.

With the trial implants in place, the surgeon is able to perform a final check to determine if the sizes of the implants are appropriate, if the knee is stable, and how the knee bends and straightens (Click here to view video). Once the surgeon is happy with the test run, the trial components are removed and the knee is washed. The final components are fixed in place with special bone cement that cures in a matter of minutes. The knee is then closed with sutures and staples.

The disabling pain of advanced knee arthritis stems from the fact that after the articular cartilage is worn away, raw bone is rubbing against raw bone. This bare bone is heavily penetrated with nerve endings which transmit pain impulses to the brain when irritated. the reason knee replacement is very successful in relief of pain is due to the fact that the worn bone surfaces are now covered with artificial surfaces (metal and plastic) which have no nerve endings embedded within them and therefore cannot transmit painful nerve stimuli to the brain.

Recovery

Your doctors will make sure that you are healthy enough to go home and your pain is under control before they discharge you from the hospital. Most patients are in the hospital for 2-4 days. a physical therapist will work closely with you to teach you how to walk with a walker or crutches, get in and out of bed, go up and down stairs, how to bend and straighten your knee, and how to appropriately strengthen your muscles. therapy is extremely important after a knee replacement. Even if you have a perfect knee replacement, if you do not work hard on your physical therapy, you will not have a good functional result. Therapy typically continues for a number of weeks after you leave the hospital. Most patients use a walker for several weeks followed by a single cane. Most patients feel like they have “recovered” from surgery at about the three month mark. Even though most patients feel pretty good at three months, your body will continue to heal even a year after surgery. In that time period, you will still make gains in terms of your motion, your strength, and improvement in pain and swelling.

Activities after a Knee Replacement

Perhaps one of the most common concerns about knee replacements revolve around the activities permitted after surgery. Most surgeons recommend avoiding high impact activities such as running, jumping, or sports that require cutting and pivoting, or any activity that places you at risk for falling or getting injured. Reasonable activities are walking, hiking, swimming, cycling, and golfing.

Complications

Just like with any surgery, complications are infrequent but do occur. Bleeding, nerve damage, infection, blood clots, and complications with anesthesia are all possible. Specific to knee replacement surgery is the possibility of scarring which results in stiffness after surgery. Stiffness is usually avoided if the patient aggressively participates in the recommended physical therapy exercise program following their operation. Precautions are taken to minimize risks but the risk is never completely eliminated.

Minimally Invasive Total Knee Arthroplasty

New techniques have been recently developed to perform knee replacements through smaller incisions and with lesser trauma to the soft tissues within the knee.

Updated instruments have also been developed to allow the surgeon to perform the surgery through those smaller incisions. Through these less invasive techniques, some studies are reporting a faster short term recovery and less pain, while other studies reveal little difference in the overall outcome and higher complication rates.

Computer Assisted Total Knee Arthroplasty

Recent technology has been created to assist the surgeon in performing total knee replacements. Computers have been developed which are able to map the three-dimensional shape of your knee during surgery and to help with the precision of the bone cuts and your knee alignment. Currently, although the use of the computer has been shown to improve the precision of procedure, it does add more time to the operation. With continued improvements in the computers and the software programs, computer assisted knee replacements may become an increasing trend in the future.