FAQ Category: Knee

An orthopedic doctor can best answer this question. The removal of the kneecap or patella is called patellectomy. Replacing the patella is optional and not always advised. There can be problems with the plastic implant interfacing with bone. No one really knows how long these replacement parts last.

However, newer and better implants and improved surgery makes a patellar implant possible. See your doctor for an exam to answer this question.

Joint replacements are wonderful when they work. However, in a small number of patients, complications can occur. Besides the ones you mentioned, there is also infection, knee pain, and osteonecrosis (death of bone). These can cause severe problems.

Joint replacements are used knowing that they don’t last forever. Most doctors tell their patients to expect 10 to 15 years of life from a joint implant. This, of course, depends on how active the patient is and whether any accidents or trauma occur.

Your experience is unusual, but it does happen.

Several studies have reviewed this question. There’s strong agreement that implant parts can come from different manufacturers without causing problems.

Small mismatches in shape and the way the implant parts connect aren’t the cause of implant failure. Of greater importance is the method used to sterilize the parts. This takes place at the time of manufacturing and packaging. Implants that come loose or wear out early have been linked to gamma irradiation in the air.

Researchers and implant manufacturers are looking at this problem more closely.

Heterotopic ossification (HO) takes place when something triggers basic cells in the muscle to start forming bone cells. This becomes calcified and forms a hard mass in the muscle. HO can be painful and limit motion, but over time, the problem can go away. The body slowly breaks down and absorbs the bone.

Rarely, surgery is done to remove the mass. If recognized early, radiation can be done. This prevents cells from making more cells. If your husband has a joint replacement in the future, radiation may be advised before the operation. This will help prevent the problem from occurring again.

With heterotopic ossification (HO) bone cells form inside soft tissues, such as muscles. This occurs shortly after some other operation. It’s also more likely after a knee joint manipulation.

Patients who’ve had HO are at greater risk of having it again after other surgeries. The doctor can give you treatment before the next operation to prevent HO. This includes radiation and drugs to slow down bone growth. Even with preventive treatment, HO can occur a second time.

The anterior cruciate ligament is one of the most commonly injured parts of the knee. Doctors have been studying this injury for many years now. They’ve seen that one-third of the patients with an ACL tear heal well and return to full activities.

One-third of the injured patients will heal, but they’ll give up many activities. One-third will do poorly and need surgery to repair the tear. For the patient and physician, the trick is to tell which patients will heal and who will need surgery.

Researchers still don’t know why or how the top third heal and the middle third compensate while the last third require surgery.

The normal knee is a very tight structure with very little “give.” Movement of one bone against another is called joint play. Every person has a certain amount of joint play in the knee. Some people have more than others.

Tests for joint laxity (looseness) give the doctor an indication of possible injury. When a ligament is damaged or torn, there is increased joint laxity. Often, when the ACL is torn, there is also damage to the cartilage.

The pop you heard may have been a flap of torn cartilage unfolding. It’s also possible that the torn ligament ruptured completely with the maneuver. It’s actually better to have a partially torn ligament rupture in the doctor’s office than when you step off a curb or on the playing field. It was bound to happen sooner or later. In this way, you have a “controlled injury” that can be managed right away.

You’re not alone. Many studies show that some patients continue to report these kinds of sensations. The leg doesn’t give way or fail to hold you up, but you feel as though it could.

Researchers can’t find any problem in the repaired tissue to account for this. The joint is just as strong and stable as before the injury. It may be caused by a loss of proprioception. This is the joint’s sense of its own position.

Proprioception is damaged or lost when the ACL is torn or injured. After surgery, it’s a full six months before the sense of joint position returns. There may be a permanent loss of proprioception if the surgery is delayed too long.

Not much is really known about this problem. Studies are ongoing to find some answers.

Proprioception is joint’s sense of position and joint motion. For example, imagine you are blindfolded. The therapist moves your left big toe upwards 10 degrees. You could match that position with your right big toe without looking. You do this using proprioception.

The sense of joint position is important to protect the joint. Once the joint senses motion, the muscles contract to hold it steady. Scientists think that once the ACL is torn or damaged, the joint loses this protective sense.

Researchers at the University of Chicago found that proprioception improves gradually after ACL repair. This change can be measured around six months after the operation.

You are! Newer and better repair methods help make the difference. Doctors can now repair a torn or damaged ACL using other tendon grafted from the patient. The operation can be done using an arthroscope to avoid cutting the knee open. These two things alone have cut down on problems after surgery.

Research has also shown the importance of rehab after surgery. Improving motion and strength is a major part of the exercise program. Restoring proprioception has also been added. Proprioception is the sense of joint position. Is my knee bent or straight? Exactly what position is the joint in? Messengers in the ACL help give the joint this information.

Physical therapists are finding new and better ways to help restore proprioception. Today’s technology has provided equipment that wasn’t available even 10 years ago.

Tissue engineering is a new area of science. It includes growing living human tissue for transplantation and other uses. Tissue engineering combines biology and engineering. It looks for ways to restore, maintain, or improve tissue function.

One example of this is the use of cartilage cells to replace damaged or destroyed cartilage. Normal, healthy cartilage cells called chondrocytes are removed from the knee. These are grown and multiplied in a lab and then reinjected into the knee.

The new cells are injected into the area of damaged cartilage. This allows the patient to regrow a smooth joint surface. The new, smooth weight-bearing surface is less likely to become arthritic.

Many different types of tissue can be grown this way. This includes skin, bone, ligaments, and tendons. In the future, labs may be able to make donor tissue and organs for anyone who needs them. Living tissue and electronics may be combined to form new joints. These are only a few of the many possible uses for tissue engineering.

Using a patient’s own cartilage to replace torn or missing cartilage was first tried in 1994. Actually, researchers tried this method on animals and human cadavers first before using it on live humans.

Since that time, there have been reports on more than 5,000 cases. No doubt, there are many more that have been done but haven’t been reported on. The reported results have been very good. The operation has been improved in the years since it was first done.

Doctors no longer cut the knee open to place the new cartilage in place. A tool called an arthroscope is used to insert the new patch of cartilage right into the joint. It’s stitched in place with sutures that will dissolve and don’t have to be removed.

Implanting cartilage cells to replace cartilage defects is a relatively new operation. It’s been used in humans since 1994. At first, doctors opened the joint to insert the new cartilage, but now they can do this through a closed method.

This is done with an arthroscope, a long needle with a TV camera on the end. The arthroscope is inserted into the joint, which allows the doctor to see inside the joint. The joint is prepared for the new tissue. The implanted cartilage is inserted through the arthroscope and stitched in place.

The open method had many problems. More than a quarter of all patients had serious problems afterwards. Today, with arthroscopy, there are fewer adhesions, less scar tissue, and less pain. After the operation, the patient also has more motion.

Early rehab is important to the success of this operation. Some doctors advise early motion. The patient must limit how much weight is placed on the joint. Crutches are used during the early post-operative phase.

Doctors will use measurements of muscle size, muscle strength, and symptoms as a guide. Each nerve provides information about sensation and controls muscle contraction. Change in either of these functions can signal nerve damage.

Electromyography (EMG) studies can give good information about the condition of the nerve. Serial EMGs (doing more than one) help track recovery over time. Nerve tissue regenerates at a rate of about 1 millimeter each day. This is equal to approximately one-half an inch in a month’s time. If there is no sign of nerve recovery three months after the injury, surgery may be advised.

The most common use of tendon graft is to repair the anterior cruciate ligament (ACL) in the knee. Donor tissue can come from the hamstrings tendon behind the knee or from the patellar tendon just below the kneecap.

In either case, the doctor uses a special tool to harvest the tissue. This is called a tendon stripper. This device helps the doctor remove just the right amount and shape of tissue. The gap in the donor tendon is closed using absorbable stitches.

The patient must be careful not to overstress this site during healing. This usually takes around six weeks. It’s about the same amount of time needed to heal the graft site. After that, strength returns to normal as the patient rehabs the knees from the original injury.

A neuroma is a benign tumor made up of nerve cells. Benign means it’s not cancerous and not dangerous. It can be, however, quite painful. The most common cause of this type of neuroma is direct injury to the nerve.

When the tendon was harvested from your knee, the nerve was most likely cut. This is a common problem with this operation. Knee pain prevents the patient from kneeling or moving around on the knees. Once it happens, there isn’t much that can be done. Prevention is now possible with an alternate method of operation. This uses the tendon from behind the knee instead of the front.

The first line of treatment is an antibiotic. A sample of the infected tissue is sent to the lab to identify the cause. In this way, treatment can be as specific as possible.

The doctor may also wash the joint out with a saline solution. This process is also called irrigation. It’s done under anesthetic using an arthroscope. The arthroscope is a tool that allows the doctor to see inside the joint while working on the joint.

A long needle with a tiny TV camera on the end is inserted into the joint. After cleansing the joint, the doctor may scrape away any extra tissue or deposits left by the bacteria. The joint will be irrigated again one fine time. Antibiotics can be put right in the joint as well as taken orally.

The anterior cruciate ligament (ACL) in the knee helps hold the knee together and keeps the lower leg bone (tibia) from sliding too far forward. This forward movement of the tibia is called anterior tibial translation.

After injury, the body tries to make up for the weak or missing ACL. One way to prevent tibial translation is to avoid contracting the quadriceps muscle. This large muscle over the front of the thigh straightens the knee. It pulls the tibia forward.

During walking (gait), the patient with a weak ACL tends to keep the hip extended longer. This keeps the knee in a flexed position, once again avoiding contraction of the quadriceps.

Some studies show that patients may not be avoiding the use of the quadriceps at all. They may be contracting the quadriceps (front of thigh) and the hamstrings (back of the thigh) at the same time. This is called co-contraction.

Measuring the electrical impulses of the muscles shows that the hamstrings are just contracting more than the quadriceps. The hamstrings bend the knee … yet another way the body finds to prevent tibial translation when the ACL is weak or absent.

Doctors may advise a wait-and-see approach for some patients. If the knee is stable and the ligament isn’t ruptured, a rehab program works well. The patient must be motivated and stick to the program during and after the healing process for it to work.

There is always the risk of reinjury without surgery to repair the torn ligament. Studies from the University of Omaha offer some new information on this. A three-dimensional (3-D) system to study walking (gait) patterns was used. Three groups were included: people with normal knees and patients with a torn ACL with or without repair.

They found changes only for those patients who didn’t have the torn ligament repaired. The muscles on either side of the knee change how and when they contract in order to protect the knee. The lower leg bone (tibia) rotates in instead of out during part of the gait cycle. Changes in simple activities such as walking with an unrepaired ACL can result in more damage to the joint and bone.

These researchers will carry out more studies with this updated technology. Studies to look at exercise and rehab programs are next.

The anterior cruciate ligament (ACL) is one of the major ligaments in the knee. It criss-crosses with the posterior cruciate ligament to help hold the two bones of the knee together.

If the ACL is torn or damaged it becomes deficient or weak. One of its important functions is to keep the lower leg bone (tibia) from sliding too far forward as the knee bends. An ACL-deficient knee doesn’t hold the tibia in place during movement as it should.

The ACL also keeps the knee from rotating or twisting the wrong way. A recent study at the University of Nebraska showed that ACL-deficient knees tend to rotate inward during walking. A normal knee rotates outward or externally.

An ACL-deficient knee can be returned to near normal status. This can be done with surgery to repair the damage. If the ligament has a minor tear, a rehab program may be able to restore the function of the knee without surgery.

Without repair, the ligament remains weak and at risk for reinjury. ACL-deficiency leads to other damage to the joint. There can be tears in the meniscus or injury to the bone. Osteoarthritis of the knee is common in patients with unrepaired (deficient) ACL ligaments.