News Category: Knee

Total knee replacements (TKR) are fairly common these days. Doctors use many different types of implants. Each new joint implant has several parts: the top half (femoral component), the bottom half (tibial component), and the kneecap (patellar component).

Sometimes one or more of these parts will fail, resulting in a second operation to correct the problem. Often only the patellar component fails. Not much is known about why this happens. Some doctors think it’s a combination of the way the implant is made and the way the operation is done.

Doctors at a leading medical center in Chicago are studying this problem. They found that even after replacing it, the patellar portion doesn’t work well. In fact, almost 40 percent of the knees that had patellar revision failed a second time. The patients had painless squeaking, swelling, and trouble walking long distances.

Many changes have already been made in the design of these implants. For example, the metal backing on the patellar piece is now made of plastic. The surgeons have also changed the way the bone is turned during the operation.

Unsuccessful revision can be disappointing to the patient and the doctor. The authors of this study advise doctors to look at the problem carefully before operating a second time. More studies are needed to increase the success of this operation.

Injury of the anterior cruciate ligament (ACL) in the knee is more than just a tear in the ligament. Sensation changes, too. The patient no longer has a normal sense of the joint’s position. Signals that tell the joint and nearby tissues what position they’re in is called proprioception.

The link between the ACL and proprioception is important. Normally, the signals tell the knee muscles to contract. This steadies the knee against outside forces. Without it, the knee has less protection.

Researchers at the University of Chicago are looking at proprioception in the knee with a torn ACL. Does it get better faster after surgery depending on the type of operation? Does proprioception come back slower if the meniscus or bone is damaged? How soon after surgery does this sense of position return?

Studies are being done to answer these and other questions. Special equipment is used to help with this. Physical therapists use a special device to measure two types of proprioception. In a recent study, 26 patients were measured after an ACL repair. No difference in proprioception was seen until six months after surgery.

The authors of this study aren’t sure if this is the result of the operation or the rehab program after surgery. Proprioception improved in both the injured knee and the opposite knee six months after the surgery. Improvement is more likely to occur when surgery is done soon after the original injury.

There are still many questions about the knee after ACL repair. Are some patients more likely to recover faster because of their genetic makeup? Does a lack of training lead to slower return of proprioception? Is it the surgery or the rehab afterwards that makes a difference? More studies are needed before we’ll have the answers to these questions.

Many studies have shown that smoking is bad for your health. Lung cancer, heart disease, poor circulation, and delayed skin healing are only a few of the effects of tobacco. Other studies have looked at the effect of tobacco use on bone healing. Broken bones or fractures that poke through the skin are called open or compound fractures. Resesarchers have studied open fractures of the main lower leg bone (the tibia). Doctors wanted to know the effect of smoking on healing of open tibia fractures. They also wanted to see if using one kind of operation to repair the break was better than another.

Open tibial fractures must be closed and held together until healing has occurred. This means an operation using either pins through the bone or a long pin down the inside of the bone, called a nail.

Even with proper care, these fractures often develop problems. The problems include infection, failure to heal, or inability to heal correctly. Smoking can create even more problems for the patient. Tobacco (even just one cigarette) can slow the blood flow to the healing area. Toxins from tobacco stay in the body at least one week. These toxins and the lack of oxygen delay wound and fracture healing.

Smokers with open tibial fractures heal slower than nonsmokers. This is true no matter what kind of implant is used to hold the bone together. In terms of bone healing, it’s not yet clear whether light use of tobacco is different from heavy use of tobacco. Future studies are needed to determine this.

It can happen in almost any sport. A player is running hard. No one hits her. But she suddenly stops or falls down, grabbing a leg. These noncontact leg injuries usually involve ligaments. Noncontact knee ligament injuries are especially common. But exactly why and how they happen is not well understood.

It is known that muscles surrounding the knee can absorb a lot of the stress and strain of running and cutting. In this way the muscles protect the ligaments from being overloaded. Much of this ability depends on the nervous system to control the muscles in the right way.

It is this muscle action that these authors studied. They tested the muscles around the knee in 11 male soccer players while running, cutting, and sidestepping. The soccer players had electrodes placed around the knee before going through two series of drills. In one series, they knew exactly when and where they needed to run, cut, and sidestep. This was called the “preplanned” series. In the second series, they had to react quickly during the test to change movements. This was called the “unexpected” series. Knee movement was also studied during both series.

The authors found that the muscles worked much differently in the two series. In the preplanned series, specific muscles contracted together to help protect the knee. In the unexpected series, the muscles contracted more randomly. The knee also went through much more rotation and stress during the unexpected series. The muscle contractions in the unexpected series were less efficient and less able to protect the ligaments of the knee. The nervous system simply didn’t have enough time to activate the muscles to provide optimum protection for the knee.

Obviously, the unexpected tests were more like playing in a real soccer game. The authors wonder if training could be geared toward “preprogramming” the muscles to contract more effectively under unexpected conditions.

The lower leg bone (tibia) is at risk for fractures from overuse. This can happen in both sports and military training. Any kind of walking, marching, or running can put high stress and strain on the bone. Tiny fractures can develop. These are called stress reactions or stress fractures. They are very painful and keep the athlete or recruit from running or even walking.

Studies are being done around the world to find a way to prevent such stress fractures from happening. In Sweden a group of doctors are using shoe inserts to help lower the strain on the bone. With today’s advanced technology, researchers can measure the force on the bones with and without shoe inserts. These measurements are taken in military boots and athletic shoes. Volunteers from a highly-trained police force are involved.

The results of a small study (nine officers) have been reported. The authors of this study report that specially designed shoe inserts can make a difference. Stress fractures may be prevented during military training. This is true for walking activities in boots. However, inserts don’t seem to make a difference for running in boots or walking or running in shoes.

Shoe inserts may be used to prevent tibial stress fractures. They work best when worn with military boots for walking or marching. These inserts are not as effective with running shoes for any activity or for military boots during running. In fact, inserts inside shoes have been shown in some cases to actually increase strain during running.

After a knee injury, exercise is very important. This is especially true when there’s a torn or damaged anterior cruciate ligament (ACL). Knowing which muscles to work on is a major part of a successful rehabilitation process.

Rehab specialists are teaming up with engineers to study muscle actions after injury. New technology makes it possible to measure joint movement and muscle strength. The dynamometer measures muscle strength in various positions and at different speeds.

The arthrometer is used to measure joint laxity, a gauge of how “loose” a joint is. Joint laxity occurs when one bone slides too far over another. In the case of a torn ACL, laxity increases and can result in an unstable knee joint. Using measures of strength and laxity, researchers can compare people with normal knees to patients with ACL damage. These studies are ongoing.

Patients with ACL deficiency have less strength in the quadriceps muscle on the front of the thigh. The hamstrings behind the thigh aren’t usually affected. It is thought that the loss of quadriceps strength leads to a loss of muscle and knee function. The loss of strength is most obvious during strenuous activities.

In this study, joint laxity, didn’t seem to cause a change in muscle function. This was true whether the patient was walking, jogging, or going up and down stairs. According to this study, restoring quadriceps muscle strength and function after ACL injury seems to be the most important goal for rehab.

Often in orthopedic surgery, there’s more than one way to do an operation. In the case of a tear in the anterior cruciate ligament (ACL), there are two main ways to repair the damage.

In both cases, the doctor uses tendon from some other part of the knee (the graft) to replace the damaged knee ligament. The graft may come from the front of the knee (patellar tendon) or from along the inside of the knee (hamstring tendon).

Does it make a difference which way the surgery is done? Is one method better than another? Only a few studies have compared the two methods. Doctors in a recent study from Finland give us an update. The results of their study show that there is no difference between the two methods.

One hundred patients were divided into two groups. One group had the ACL repair with the patellar tendon graft. The other group received a hamstring tendon graft. Knee function, stability, and results of X-rays were all equal between the two groups. There weren’t any differences seen between men and women, either.

There are some other kinds of differences reported between these two methods. The patellar tendon graft is stiffer, perhaps making the knee more stable. However, kneeling commonly causes knee pain in this group. All studies agree that ACL repair should be done as soon as possible after injury. This tends to give the best result overall.

The body adapts well to injury. One example is how the motion of the knee changes after the anterior cruciate ligament (ACL) is torn. Walking patterns during the gait cycle are the subject of this new study. The gait cycle is used to describe movements of the body and limbs beginning when one foot hits the ground and ending when that foot lands again.

Researchers at the University of Athens Medical School in Greece teamed up with scientists University of Nebraska in the United States. They used a three-dimensional (3-D) optoelectric system to film, record, and measure the gait cycle.

There were three groups in the study: people with normal knees, patients with a torn and unrepaired ACL, and patients with a torn ACL that had been repaired. The researchers studied bending and straightening, side-to-side motion, and rotation.

Only one movement was affected by damage to the unrepaired ACL. It was rotation of the lower leg bone (tibia) during walking. The tibia in the knees with an unrepaired ACL rotated inward when the leg swung forward. Normal knees without ACL damage and knees with repaired ligaments rotated outward.

The authors of this study don’t know if this is a long-term problem. If it is, then even a simple activity such as walking increases the risk of more knee damage. However, there may be other ways the body compensates for the lost ACL. For example, the hamstring muscle behind the knee may contract when the leg is straight. This would protect the knee by keeping the tibia from moving forward and rotating abnormally.

New 3-D technology is making it possible to revisit some issues, such as knee motion in all planes and movements after ACL injury. Changes in walking patterns after the ACL is torn may lead to further damage to the joint and bone. Specialized equipment can now be used to study the effects of exercise programs on knee motion and the gait cycle.

The knee joint is formed where the thigh bone (femur) meets the shin bone (tibia). The top of the tibia forms a shelf called the tibial plateau. This is also the bottom half of the knee joint. Various muscles and ligaments hold these bones together.

These bones can be fractured during an injury. A high-energy fracture to the tibial plateau can occur when the knee is injured in a car accident, during a fall, from the impact of a bat or other object, or during sports activity.

When the tibial plateau is fractured, the joint is damaged. There is usually severe soft tissue injury. The knee becomes unsteady or unstable. Surgery is commonly needed to repair the damage. Screws and wire are used to hold the bones together while healing takes place. Torn ligaments and muscles are also repaired.

Most of these surgeries have a good outcome. The bottom surface of the knee along the tibial plateau seems to heal well. This is true even when there has been a severe injury. Two to five years later, patients typically have good range of motion and have returned to work without problems. Even workers with jobs that involve hard labor have good results. Generally, no additional surgery is needed. Only a few patients have any long lasting knee joint problems.

A new treatment for osteoarthritis of the knee is gaining in popularity. It is the injection of a liquid called hyaluronate. This is also known as Hyalgan or Hylan G-F 20. It is made from chicken combs and works by coating the joint lining to protect it during motion.

Once a new treatment has been used for awhile, doctors start studying its success or failure. Since the hyaluronate must be injected into the joint to work, it is important to know how often it gets directly into the joint.

There are three different places the doctor can insert the needle for the injection. The knee is either straight or bent depending on which site the doctor chooses. It is much easier to inject the knee when there is swelling present. However, the hyaluronate treatment works better when no swelling is present.

One doctor tested his results to see how accurate the injections were and which injection site worked best. Using an X-ray imaging method called fluoroscopy, the doctor was able to see right away if the needle went into the joint.

Two of the injection sites were only 75 percent correct. The knee was bent and the injection went in either side of the knee from the front. The doctor found the best results by keeping the knee straight and injecting just under the outside edge of the kneecap. There is less fat and soft tissue in this area.

These results are based on one doctor and should be repeated by other doctors. Comparing the results for different doctors will show if this one method is the best for everyone.

Injecting a lubricating fluid made from chicken combs has proven helpful for some people with knee osteoarthritis. An injectable drug called Hylan GF-20 is now on the market. A series of three to five weekly injections is given directly into the joint. The injections can give pain relief and increased knee mobility for up to six months. But if symptoms return, can the injections be used again?

Doctors are looking into this question. There is some concern that a local reaction may occur with more than one series of injections. There have been reports of pain, swelling, and loss of motion with this drug. Sometimes, patients can’t put weight on their leg because of severe pain.

Research at the William Beaumont Army Medical Center in Texas is being done in this area. Two groups of adults with knee osteoarthritis received Hylan GF-20. One group had a single series of three injections. The other group had two or three more sets of injections. The group with the extra injections had eight times more local reactions than those who only had one set of injections.

Some patients who initially get relief from the injections may want to use them again. However, they should be aware that a reaction to the drug may occur. Repeated injections that cause joint pain, and swelling can otherwise be treated with steroid medication. At this point, there isn’t enough research to tell patients not to try the injections a second or third time. They must be alerted, however, about possible problems when making this decision.

One single ligament has more to say about function and activity than any other. The anterior cruciate ligament (ACL) is one of two major ligaments in the knee. If you can walk, squat, and climb stairs easily and without pain, thank your ACL. On the other hand, if your knee locks, makes noises, and gives out from under you without notice, your ACL might be to blame.

People of all ages injure the ACL. Surgery is often needed to repair the ligament. New ways to repair the ACL have been developed with better overall results. Doctors are measuring these results long after the surgery is over.

A group of doctors in Vail, Colorado, measured outcomes for over 200 of their patients. The group ranged in age from 14 to 60 years old. All had surgery to repair a torn ACL. Results were measured in three ways: symptoms, function, and patient satisfaction. Patients were followed for two years after the operation.

Patients were most often unhappy with their result if there was loss of motion, pain with activity, and giving way of the knee when standing or walking. Other symptoms, such as the knee joint locking or making noise, swelling, and tenderness along the joint were also reported as a poor result.

Patients are generally not satisfied after surgery to repair an ACL tear if they can’t return to work or sports activities. Being able to perform daily activities at home, work, and play are important to patients. Doctors are paying attention to this and measuring results after surgery even years later.

Pain under the kneecap is the most common knee problem in children and young adults. This condition is called patellofemoral pain syndrome (PFPS). The exact cause is unknown. For some reason, the kneecap is pulled slightly to the outside of the knee. This makes it move up and down unevenly over the leg bone and can cause pain.

Scientists are looking for a muscular cause of this problem. The quadriceps muscle in front of the thigh attaches around the kneecap. This muscle is made up of four parts divided into two main sections. These two sections are called the vastus medialis oblique (VMO) and the vastus lateralis (VL).

The VMO pulls the kneecap in, while the VL pulls it out. A balance between these two muscles keeps the kneecap in the middle. When there is a problem with the kneecap tracking properly, it is usually being pulled toward the outside. Exercise to strengthen the VMO and pull the kneecap more toward the inside has been tried.

However, there hasn’t been enough proof to show that this really works. Researchers are using computers to help study this problem. With a custom interactive graphics program, it is possible to find out which part of the quadriceps muscle fires first. Computer analysis also shows how strongly each section of the quadriceps muscle is contracting. The results from normal knees are compared to knees with PFPS.

It looks like the timing of the muscles firing is the same between the two groups. The difference is the number of muscle fibers that fire at one time. For people without PFPS, an equal number of VMO and VL fibers contract at the same time.

For patients with PFPS, both sides of the quadriceps muscle contract more than in the normal group. There is also a difference in how these two muscles fire in the patients with PFPS. More of the vastus lateralis muscle is activated. This pulls the kneecap out to the side.

These findings give proof that patellofemoral pain is linked to a control problem within the quadriceps muscle. The next question to answer is: Can rehabilitation or exercise make a difference in the way the muscles are activated?

Knee joint replacement has become common in many places around the world. Usually, the entire joint is replaced with an implant in both bones making up the joint. Sometimes, only one half of the joint is replaced. This is called a unicompartmental knee arthroplasty (UKA).

The first case of a cyst in a knee with a UKA has been reported in Japan. The top surface of the knee joint was replaced in a 78-year-old woman. Eight years later, she started having calf pain, swelling behind the knee, and trouble walking. Tests showed that it was a popliteal, or Baker’s, cyst.

Doctors were able to see from X-rays and imaging studies the cause of the problem. Part of the implant for the new joint had been inserted at a slight angle. This caused increased pressure and loading on the inside edge of the joint. A cyst formed behind the knee with fluid from inside the joint.

The patient didn’t want a total knee replacement. The doctors were able to remove the cyst and revise the joint implant. The doctors reported that removing the cyst without correcting the problem would likely result in formation of a similar cyst.

One year after surgery, the patient was still pain-free, and there was no sign of the cyst. Full knee range of motion was present. The patient will need periodic follow-up to make sure the implant stays intact.

It’s well known that removing the meniscus from the knee causes joint damage. This pad of thick cartilage between the main bones of the knee has many important jobs. It acts as a shock absorber, helps lubricate the joint, and gives added stability to the knee.

Knowing all this about the meniscus, doctors are looking for ways to save a damaged meniscus. Efforts to preserve or replace a torn meniscus are underway. One new method is to implant replacement tissue to the area of damage. This is an important discovery for patients who have lost most or all of the entire meniscus.

It’s not clear whether these grafts can prevent or delay arthritic changes in the joint. According to researchers, the graft does help the area heal and replace the cartilage. The patient gets pain relief and improved function. However, scientists think this may not be the same as having normal function of the meniscus for the rest of life.

Doctors advise careful selection of patients for this treatment. The ideal patient is under 45 years of age. The patient has normal bone and joint position. Patients with some joint cartilage have a better result than those with injury to the underlying bone when the graft is done.

Knee injuries with a torn meniscus can result in arthritis later. To avoid this, doctors are trying to save the meniscus by repairing it. When that’s not possible, a graft can be transplanted to the area. The short-term results are pain relief and improved function. Because this is a new treatment, the long-term benefits are not yet known.

Total joint replacements have been used for over 30 years now. New hip and knee joints are the most common. Nearly a quarter of a million hip and knee joint replacements are done every year in the United States. This number is expected to continue going up. This is because adults in the United States are living longer and are more active.

Researchers tell us that everyone, including older adults, should exercise and increase their daily activity. This is the new way to have good health and to prevent disease. However, today’s new joints may not be able to hold up under the new activity levels. New and better materials for these joints are being studied to take care of this problem.

In the meantime, some guidelines for activity after joint replacement are needed. Doctors from the Mayo Clinic and other centers are trying to provide these. They know that patients can have 10 to 20 years of good function from a new hip or knee joint. Doctors say that patients should be told that wearing of the joint surface is linked to activity level.

Until more is known, doctors generally tell patients that low impact and low contact activities are the best. Athletic activities should be avoided until the muscles are strong enough. It is recommended that adults with a new joint not join in competitive sports.

Doctors usually tell patients with a new joint to follow some careful guidelines. This is especially true for younger, middle-aged patients. The patient must be careful during the first 10 years after replacement. Problems don’t usually occur until then, but over doing it during that time is directly linked to joint failure.

Patellofemoral arthritis strikes the joint between the kneecap (the patella) and the femur (the thigh bone). When this condition becomes severe, doctors are not always sure how to treat it. Treatment is even more unclear when patients are older and less active.

These authors studied how well total knee replacement worked for older patients with patellofemoral arthritis. They followed 27 patients who had a total of 30 knee replacement surgeries for patellofemoral arthritis. The patients ranged from 59 to 88 years old. They all had pain with walking, rising from sitting to standing, and going up and down stairs. Many patients had knee instability, weakness, and pain at night.

To find out how the patients were doing after total knee replacement, the authors followed them for at least four years. All patients were interviewed and filled out a survey about their knee function and activities. They also had X-rays and physical exams.

The results were positive. The authors rated the function of 28 of the knees as excellent, one good, and one poor. The patient with a poor result had later fallen and torn a tendon in the knee. Aside from this patient, most of the patients were pain-free and could do many of their daily activities without support. The authors conclude that total knee replacement can be a good way to treat patellofemoral arthritis in older patients.

Injury to the anterior cruciate ligament (ACL) in the knee is really more than just a torn ligament. Along with damage to the ligament comes weakness of the quadriceps muscle. The quadriceps is the large muscle that comes down over the front of the thigh from the hip to the knee.

Scientists are trying to unlock the puzzle of this muscle weakness. The muscle isn’t wasting away, a condition called atrophy. So what could be causing this weakness? Is there some way that the ligament signals the muscle to contract in a normal knee? What other changes occur after a ligament is torn or damaged that could affect the muscle?

Researchers at the University of Tokyo in Japan set out to answer these questions. They found signals that form a complete loop from knee joint to ligament to muscle. This is called afferent feedback. Before the experiment, scientists thought that damage to the ACL alters this loop. Decreased signals to the muscle cause the weakness.

To prove this, they used vibration to the tendon of the quadriceps muscle. After vibrating the tendon, they measured muscle strength in patients with a torn ACL and compared this to people with a normal ACL. By looking at the muscle response to vibration, the scientists could measure differences in signal loops with and without a torn ACL.

Sure enough, they found that damage to the ACL leads to weakened signals from the joint to the muscle. This confirms the scientists’ belief that there is a complete loop of communication between these structures. Damage to the ligament disrupts the loop and leads to muscle weakness.

The use of electrical stimulation (ES) as a treatment for muscular problems has been questioned. Some researchers claim it doesn’t work, while others aren’t so quick to throw in the towel. When any treatment comes into question, scientists must review the findings. New studies must be done to confirm or deny the information.

The first step is to study single cases. When enough information is gathered, a larger study is done. At the present time, a case has been reported using ES for the knee. The patient had surgery to cut the fibrous band along the outer edge of the kneecap. This is done when this band of tissue called the retinaculum pulls the kneecap too far off center.

Five months after the operation, the patient still had stiffness and was unable to walk without a cane or climb stairs normally. The usual physical therapy program wasn’t enough. This program usually includes strength exercises and taping.

A new physical therapy program was started using ES. ES was used to contract one part of the quadriceps (thigh) muscle many times each day. This was done for 33 days. The patient had quick relief from the stiffness with a more gradual return of function. Walking and going up or down stairs returned to normal by the end of the treatment five weeks later.

Despite previous reports, the uses and limits of electrical stimulation aren’t fully known. Researchers are reviewing single cases to take a second look at ES. In this case, it worked quite well after surgery for a knee that wasn’t responding normally.

It is well known now that the cartilage in the knee called the meniscus is very important to knee function. When torn or damaged, it is best to repair (instead of remove) the meniscus whenever possible. This is even more so for people under 20 years of age. Taking the meniscus out in a young athlete leaves the surfaces of the knee joint unprotected for many more years than in older adults.

Doctors are looking for ways to save the inner (central) part of the meniscus. This is an area where there is no blood supply to help with the healing process. Using animals and then humans, studies are being done to find ways to repair the meniscus and aid healing.

Dr. Frank Noyes from the Cincinnati Sports Medicine and Orthopaedic Center and his co-workers are studying this problem in a group of young athletes. Meniscal repairs in 71 knees of patients under 20 years old were followed for over four years. A special method of repairing the inner part of the meniscus was tried.

The results were good with 75 percent success. Only one in four patients (25 percent) had return of symptoms and a second operation. Some of these cases occurred because of a reinjury during sports activity. Before this study, the central meniscus would typically have been removed. With this new operation, surgeons are beginning to repair meniscal tears in young, active patients. This will help save knee function for many years to come.