News Category: Knee

Female athletes have many more injuries to the anterior cruciate ligament (ACL) of the knee than male athletes. Studies have shown that women college soccer and basketball players have two to four times as many ACL injuries as men. And among professional basketball players, women have 10 times more ACL injuries than men. ACL injuries are especially serious. They often require surgery and intense rehabilitation. And they force many injured athletes to give up their sports.

No one is exactly sure why women suffer so many ACL injuries. It is known that the thigh muscles help stabilize the knee joint during start-and-stop sports like basketball and soccer. These researchers tested the muscle activity of male and female college athletes during exercise. They wanted to see if the thigh muscles worked differently when doing intense extension and flexion exercises.

The results showed that the men’s quadriceps muscles (in the front of the thigh) produced much more force than the women’s. But the women’s quadriceps muscles showed greater activity during knee bending actions, which the authors think could be a factor in putting added strain on the ACL. Women also seemed to have less “fast-twitch” muscle in the hamstrings. Less fast-twitch muscle could make this muscle slower to react in cutting and quick-stop situations, putting more demand on the ACL.

Taken together, all these differences suggest that female athletes need to pay special attention to their hamstring muscles in their strength training. The hope is that stronger and quicker hamstring muscles would decrease women athletes’ risk of ACL injury.

Total knee replacement (TKR) surgery has become a safe and commonplace procedure. However, any surgery has risks–including the risk of death. These researchers studied the death rate after TKR in more than 3,000 patients who had surgery over a period of 20 years. All the patients had TKR done by the same surgeon at the same hospital.

More than 90 percent of the patients had TKR surgery because of knee osteoarthritis. The rest of the patients had rheumatoid arthritis. Patients averaged 70 years of age. All the new knee joints were implanted using cement.

The records showed that 14 patients (0.46 percent) died within 90 days of having surgery. This equals one death for every 217 TKR surgeries. No one died in the operating room. Heart problems were the cause of death in at least six patients.

The researchers found that the death rate was much higher for older patients and those with heart problems. No differences were noted between men and women. And death rates were not changed for those who had TKR on both knees. (The doctors in this study explain that they do TKR on both knees only in younger patients and patients with lower risk factors.)

The results of this study support the current thinking that TKR is a relatively safe surgery. This type of data can help doctors decide if and when to recommend TKR for their patients.

Blood clots can be a major problem after a total knee joint replacement (TKR). Without prevention, up to 84 percent of all patients develop blood clots, medically known as deep venous thrombosis (DVT). Developing a clot increases the risk of pulmonary embolism, a life-threatening condition in which the clot breaks free and travels to the lung.

There are several ways to prevent DVT. Drugs such as aspirin, warfarin, and low-molecular weight heparin are used to thin the blood. This keeps the blood platelets from clumping together and forming a clot.

The authors of this study looked at the use of compression pumps as a prevention tool. The pumping action of a compression device gets blood moving through the veins and keeps it from pooling in one place. Drugs have side effects and complications for many patients. Compression pumps, applied to the legs, prevent clots and other problems. However, they only work if they are used.

In this study, 100 patients used the PlexiPulse® compression device after TKR. Nurses kept track of how often these were worn. This is called patient compliance. Patients and nurses were asked about ease of use, comfort, and how well the device worked.

Patient compliance was 90 percent, meaning patients wore the device 90 percent of the time. Pumps have to be removed when walking, and they can be uncomfortable at times. Nurses and patients both liked the PlexiPulse® and rate it highly.

Compression pumps to prevent blood clots are known to work well when used by patients. The PlexiPulse® improved comfort and ease of use over other types of devices. Patients are more likely to use it and put it back on after walking. Doctors, nurses, and patients involved in this study recommended its use after TKR.

In all medical studies, there are patients who are “lost to follow-up.” They stop taking part in the ongoing appointments, surveys, or tests. In other words, they drop out. In long-term studies, as many as 25 percent of patients end up dropping out. That’s a significant number, which could skew the results. Researchers often assume that these dropouts had worse outcomes than the rest of the patients in the study.

These authors put this theory to the test. They tracked down patients who had a total knee replacement (TKR) as part of a study and who later dropped out. It took two years and a private detective, but all 123 dropouts were found. Each person completed surveys about their knee function, which were compared to the other 440 patients who stayed in the study.

The authors ran separate comparisons for the two different types of artificial joints that were used in the study. Results showed no significant differences in rates of implant failure, overall outcomes, or survival between the dropouts and those still in the study. The main differences were in gender (more dropouts were women) and knee score (dropouts had slightly worse knee function and pain).

This study suggests that dropouts don’t necessarily skew research results, at least not in this case. The authors stress that it is still important to keep patients from leaving the study, but that it may not be worth the cost or effort to track them down.

Traditionally, orthopedic surgeons wait until patients’ knee osteoarthritis (OA) is unbearable before doing a knee replacement. (The surgery is also called a total knee arthroplasty, or TKA.) But this situation is changing. There is still no clear best time for doing TKA.

These researchers compared results for 130 patients who underwent TKA. X-rays were used to rate the severity of OA. The patients were divided into two groups. One group had moderate OA based on the X-ray results. The second group had severe OA.

All the patients answered questions about knee pain and function before surgery and one year after surgery. Both groups reported roughly the same knee pain before and after surgery. Over 90 percent of patients in both groups showed improved knee function and pain after surgery, and both groups showed improvement to about the same levels. Notably, the patients with the least severe OA regained more ability to use their knees than those with more severe OA.

The researchers also noted that X-ray changes of OA were not that closely linked to OA symptoms described by patients. Other research has shown this as well.

The results suggest that surgeons need to rethink the idea of the best timing for TKA in patients with knee OA. The authors recommend more research to help find the best timing for the best possible results from surgery. The good news for patients with knee OA is that they may not need to wait until their knees are terribly painful and nonfunctional before getting a new joint.

Doctors agree that blood clots after knee surgery are a serious problem. This is a real concern with total knee replacements. Preventing blood clot formation, medically known as deep vein thrombosis (DVT), is paramount. Blood clots can break off and travel to the lungs or brain causing death or stroke. The best way to prevent DVT remains uncertain.

DVT can occur right away, so drugs to prevent clotting are used during and after the operation. Other measures are also taken. For example, leg pumps placed over the legs apply pressure on and off after surgery. This keeps the blood moving through the veins back to the heart. Early physical therapy to get the patient up and moving is also advised.

This study looked at the effectiveness of using every way possible to prevent DVT. Should prevention begin before the operation or only after a clot occurs? Do all clots have to be treated? These researchers believe that DVT can occur at the time of the operation, confirming that measures to prevent DVT should begin during surgery.

Only four percent of the patients developed blood clots when using drugs, leg pumps, and activity as preventive measures. This is much lower than the usual 50 percent when steps are not taken to prevent DVT. Future studies may be able to tell us which one or two measures work best. Perhaps a certain combination will prevent problems of DVT.

More and more Americans are benefiting from knee joint replacements for severe arthritis. Problems sometimes occur after the operation to reduce knee motion. Deep vein thrombosis (DVT) or blood clots is one of these problems.

DVTs can be prevented in patients receiving a knee joint. Drugs, leg pumps, and exercise are used in this effort. Without these measures, 50 to 70 percent of patients having this operation will develop DVT. With preventive steps, the number of patients affected drops to 30 percent or less.

There are several drugs that can be used to prevent blood clotting. Aspirin is a commonly known choice. Others include enoxaparin and warfarin. This study looked at two drugs used to prevent blood clots and how they affected knee range of motion after knee replacement surgery.

One group of patients received aspirin after the operation. The second group got enoxaparin. Both are blood thinners with advantages and disadvantages. Enoxaparin can cause major and minor cases of bleeding, and there may be more wound drainage and leg swelling with this drug. Aspirin can cause bleeding ulcers.

Patients receiving aspirin regained knee motion faster than those on enoxaparin. With aspirin, there was less pain and faster recovery. These results are only present in the short-term. Fifteen months after the operation, both groups had the same range of motion.

The authors emphasize that the type of drug used to prevent blood clots is important in knee joint replacements. When aspirin is used, patients have less pain and less swelling, resulting in more motion. Early motion is a big measure of success after knee joint replacement surgery. Aspirin appears to give this edge for patients receiving a new knee joint.

The anterior cruciate ligament (ACL) is an important stabilizer of the knee. The ACL is often injured in sports while jumping, cutting, and sidestepping. A torn ACL often requires surgery, and can sometimes end an athlete’s career. For some reason, women athletes have two to four times more ACL injuries than men. Much research has been done to try to figure out why.

This study analyzed the way high-level male and female athletes used their knees and muscles when landing jumps. Men and women basketball players from the University of Iowa were tested doing three different types of jumps: jumping as high as possible from the floor, jumping off a box about one foot high, and jumping off a box about two feet high. The athletes were tested both fresh and fatigued. In all jumps they landed on their dominant leg (the leg they would use to kick a ball).

The authors expected to find that women landed with less bend in their knees and with less activity in the hamstring muscles (the muscle on the back side of the thigh). These are known risk factors for ACL injuries. However, the results showed that women had about the same activity in their hamstring muscles, and they tended to have more bend in their knees. The results actually suggested that women should be less likely to injure the ACL when landing.

The significance of this study is unclear. The authors point out that this study had many limitations. It was small, and it only analyzed simple, planned jumps, rather than the unplanned jumps and continuous movement of real competitive play. However, the study does seem to suggest that physical differences in landing jumps is likely not the reason for the higher rate of ACL injuries in women athletes.

The authors of this study attempted to find out how many people develop ganglion cysts in their leg. A ganglion cyst forms when fluid builds up inside the lining of a joint. The joint studied by these authors is the upper tibiofibular joint, which sits on the outer edge the knee. It is the upper connecting point of the thin fibula bone that runs down the lower leg next to the larger shin bone, the tibia.

Prevalence is the term for how many people in a given place have this condition if we counted today. These researchers found that the prevalence of tibiofibular joint ganglion cysts in patients sent to an orthopedic doctor for a knee MRI is less than one percent.

How can these details be found? Doctors who take the time to review MRIs gather this information. In fact, this study is the first to report prevalence of tibiofibular ganglion cysts. Only a few other studies have described the cysts.

The authors of this study reviewed 654 knee-MRI scans over a six-month period of time. A total of five scans had a tibiofibular ganglion cyst. Before the MRI was done, doctors thought these patients had a tear of the meniscus (cartilage) in the knee.

Studying MRIs helps doctors find MRI patterns that match patient problems. For example, in this review, the authors found out what ganglion cysts look like using different signal intensities. By reporting this information, other doctors will be able to more easily recognize a tibiofibular ganglion cyst on MRI.

Doctors in Florida have reported an injury rarely seen. A professional basketball player hit his knee on a tray table during an airplane landing. He still played basketball, but he had discomfort on and off that became constant pain. A year later, he was unable to play basketball.

Doctors were puzzled at first. The usual tests in the office didn’t show anything. The kneecap (patella) was moving normally and the knee was stable with full motion. X-rays and MRIs showed some dense bone tissue that looked like chronic knee (patellar) tendonitis.

After trying various treatments, the athlete chose to have surgery. Doctors used a device called an arthroscope to look inside the knee. They found a bipartite patella. The kneecap was in two parts that had never fully fused together.

Only about two to six percent of the American population has this condition. At birth, the patella is normally a thick piece of cartilage. By age four to six, it has hardened into bone and has become one piece. If this doesn’t happen, a direct force to the kneecap can cause it to separate.

Bipartite patella can be treated with drugs, changes in activity level, and local steroid injections. A cast to keep it immobile may work. In other cases, surgery is needed to remove small pieces of the patella. Since it doesn’t happen very happen, doctors haven’t been able to study this condition enough to know if there’s a “best” treatment for everyone.

More and more people are enjoying the ski slopes. Fifteen million people of all ages in the United States ski every year. Along with this increased ski activity, there are increases in ski injuries. Fewer ankle injuries occur now with the newer and better ski equipment. However, the equipment improvements haven’t stopped knee injuries.

Damage to the knee occurs in one-third of all ski-related injuries. Many injuries affect more than one structure in the knee. For example, the number of ski injuries involving more than two knee ligaments tripled between 1980 and 1995. The cause and treatment of these “combined ligament injuries” is the subject of this study.

The authors review many ways a skier can lose control and injure the knee. For example, a twisting motion along with force against the outside of the joint is most likely to cause damage to both the anterior cruciate ligament (ACL) and the meniscus (knee cartilage).

The skier is at greater risk for injury if he or she shifts weight too far forward or back over the skis. The ski can become a lever arm that puts too much force on the ligaments. If the boot bindings don’t release or the ski doesn’t fall off, serious injury can occur. One or more ligaments may be damaged.

The best treatment for combined knee ligament injuries is something of a puzzle for doctors. What to do and when to do it are the subjects of this report when the ACL and the medial collateral ligament (MCL) are both torn.

Nonsurgical treatment for a partial MCL tear is first. These doctors suggest keeping the knee from moving for two weeks by using a splint or brace to hold it in place. Immobilization is followed by early range-of-motion exercises with a protective knee brace. When the patient has full motion and good strength without swelling, the ACL can be repaired. These decisions are based on the severity of the tear. A partial tear may be treated differently than a full tear.

Tears in the anterior cruciate ligament (ACL) of the knee are common sports injuries. Athletes with torn ACLs may end up wearing a brace to help support the injured knee. Research has shown that knee braces can help prevent too much movement in knees with a torn ACL. Braces seem to help in situations when weight is borne on the foot (weightbearing) and also when it’s not (nonweightbearing). Still, even braced knees are often injured again.

These researchers studied what happens during the transition between nonweightbearing and weightbearing–for example, landing after a jump. They used a special machine to measure the movement of the knee joint in nine people with ACL tears. The results were compared for each person’s healthy knee and injured knee.

The results showed that bracing definitely helped keep the knee joint from moving too much during weightbearing and nonweightbearing. But in the transition, all the injured knees showed much more movement. This part of the testing showed an average of 3.5 times more laxity (looseness) in the injured knees than the healthy knees.

These results help explain why athletes with braced knees after ACL tears often experience injuries when quickly changing directions or landing from a jump. What researchers would like to know is how much joint movement is too much. That knowledge would help them develop a better knee brace for ACL tears.

The knee is a sturdy joint, but it can dislocate as a result of injury. When this happens, there’s a risk of injury to the nerves around the knee. Two nerves that may be injured are the peroneal and tibial nerves. The peroneal nerve has two main parts: one is close to the skin and the other deep in the muscles. Together, they are all called peripheral nerves.

Each nerve has two jobs. It receives and sends information about sensation. This is the sensory component of the nerve. It also controls the movement of the leg by giving the muscle messages to contract. This is the motor component.

The force of a knee dislocation may be enough to stretch or disrupt nearby nerves. This can result in pain, numbness, loss of motion, and a condition called foot drop. Nerve damage to the muscles that hold or pull the foot up is a cause of foot drop.

If a nerve isn’t completely destroyed, it can grow back. Nerves regrow at a rate of one millimeter each day or three centimeters each month (about one-half of an inch). If severe nerve injury has taken place, then surgery may be needed.

Surgery can repair the nerve or release it from scar tissue. The timing of the operation is important. If the nerve repair is delayed by nine to 12 months, then the chance of success is much lower. After nine months, muscle wasting and scarring may be permanent.

Studies show that incomplete nerve paralysis after knee dislocation can can heal if given enough time. Patients with complete nerve paralysis will likely need surgery. An operation at the right time improves the chances for a good recovery.

Fractures of the lower leg bone (the tibia) can lead to arthritis of the knee later in life. This is especially true when the break occurs at the upper end of the bone near the knee joint. This area is called the tibial plateau.

Fractures of the tibial plateau can cause problems. If the fracture extends inside the joint, there is a greater risk of early arthritis. A tibial plateau fracture can also cause bone malunion. In a malunion, the bones don’t line up exactly during the healing process. The way the patient accepts weight through the leg changes. Arthritis develops faster in such cases.

Many patients with arthritis after tibial plateau fractures end up needing a total knee replacement (TKR). These patients are younger than usual when they get TKR. This situation has its challenges. The authors discuss some of the difficulties during a TKR in a patient with a prior tibial plateau fracture. They point out that the surgeon must use skills, implants, and methods usually needed for complex cases.

Doctors at the Mayo Clinic know that the results of TKR after tibial plateau fractures aren’t as good as for TKR patients without a prior fracture. Their study was in agreement with similar studies. Specifically, patients with a previous tibial plateau fracture have more problems after a TKR than those who don’t have a prior fracture. The authors list the most common problems: poor healing, joint stiffness, and changes in the way the muscles move the joint.

Do healthy knees work the same way as knees that have had ACL (anterior cruciate ligament) reconstruction? The answer may help doctors and physical therapists plan the best rehabilitation exercises for their patients.

This study focused on recreational athletes who had earlier ACL surgery using a graft from the hamstring muscle. Their knees seemed to be fully recovered. However, researchers found that these athletes actually use their legs differently than athletes who have never had knee surgery.

All the athletes were tested by stepping off a box that was about two feet tall. The athletes who had ACL surgery absorbed the impact of landing differently than the control group. They absorbed less impact in their hips and more in their ankles. The researchers think the differences may be due to an unconscious effort to protect the hamstring that provided the tendon for surgery. The researchers suggest that athletes needs to build strength in the whole leg after ACL surgery, not just around the knee.

Most patients who have a total knee replacement (TKR) report a good outcome. This can be directly linked to the skill of the surgeon. Stiffness and pain after TKR are mostly due to the way the operation was done. For example, painful symptoms occur if one ligament is too tight or if the implant is too large and hangs over the edge of the bone.

Other causes of problems after TKR may be infection, failure of the implant to work properly, or psychological effects. These aren’t usually under the control of the doctor.

Doctors who replace knee joints try to restore the natural joint connection as much as possible. They also work to regain a balance of the soft tissues, such as the muscles, ligaments, and tendons. One ligament can’t be tighter than another, and the new joint mustn’t rub the wrong way against ligaments and tendons.

If problems occur after TKR, the doctor should try to find out what’s causing the problems. Surgery to revise the new joint shouldn’t be done until the source of the pain and stiffness is found. This improves the odds of success. Even so, most patients who need surgery to revise a TKR shouldn’t expect to get full motion back. They commonly do, however, improve their range of motion enough to make the knee more functional.

Osteoarthritis (OA) of the knee can cause lots of pain and disability. Most patients with OA of the knee get magnetic resonance imaging (MRI) scans at some point in their treatment. Often, the MRI shows tears in the meniscus. The meniscus is a crescent pad of cartilage in the knee joint.

Doctors commonly suggest repairing the meniscal tear. The goal is to decrease pain and increase knee function. But does repairing meniscal tears found by MRIs really help patients with knee OA? It is not even known how common meniscal tears are in the general population, or how tears relate to the pain of knee OA.

These researchers wanted answers. They compared 154 patients over age 45 with painful knee OA to 49 people of the same age with healthy knees. All patients had X-rays, MRI scans, and pain and function measurements. The results of the two groups were then compared. The researchers found that 91 percent of the OA group had meniscal tears, compared to 76 percent of the group with healthy knees. More men than women had tears. And the people with the most severe OA all had meniscal tears.

However, there was no relationship between meniscal tears and higher levels of pain. There was also no relationship between tears and lower levels of function. The authors conclude that surgery to repair the meniscus is probably not warranted based on an MRI scan alone. There may be some patients with knee OA who need to have meniscal tears repaired. But an MRI alone shouldn’t be used to determine the need for meniscal repair in patients with OA. Other measures, such as the how well a patient’s knee functions, also need to be considered.

The authors note one shortcoming in their data: the OA group was significantly heavier than the healthy group. They suggest that meniscal tears are possibly related to body weight. If this is true, it could mean there is even less relationship between meniscal tears and the pain of OA.

A new knee joint is not without its problems. The kneecap can dislocate or even break. And sometimes there can be knee pain long after the operation.

There are many possible causes for these problems. Sometimes, the new parts aren’t lined up properly. For other patients, the muscles, ligaments, and other soft tissues are out of balance.

The kneecap moves up and down over the knee as the leg bends and straightens. This is called patellar tracking. Patellar tracking might change after a knee joint replacement. This happens because of implant wear, muscle weakness, or stretching of the nearby soft tissues.

A new study reports that similar problems can occur because of the joint implant. The design of the implant changes how the patella tracks. It may also cause wear and tear on the kneecap and changes in tissue tension.

New knees with patellar tracking problems are being reported. Some problems don’t happen right away. Doctors are watching for these problems and looking for an implant that won’t cause a patellar tracking problem.

Knee pain from osteoarthritis (OA) is becoming more common every day. It is now the leading cause of disability in older adults. OA makes walking and stair climbing the most difficult tasks. Many studies have been done on the forces placed on the arthritic knee during walking. Researchers are now turning their attention to stair climbing.

Going up and down stairs is more demanding than level walking. Greater muscle strength and control are needed. OA is often linked with weak muscles. Pain causes the affected person to move less often. This sets up a cycle of pain, loss of motion, weakness, and more pain–and ultimately less activity. Weak muscles get tired easily. Weak and tired muscles don’t contract quickly or on time. All of these factors make stair climbing difficult.

The knee joint takes a greater force going down stairs. Patients with OA bend the knee less when going down stairs. This loads the joint because the muscles are slow to contract to protect the joint. If the thigh muscle doesn’t contract in time during stair descent, the knee doesn’t absorb shock as well. The puts a much bigger load on the joint and can make arthritis worse.

Having good control of the muscles is important in knee OA. It gives full motion to the joint and reduces the load. Finding out when the muscles aren’t contracting properly may help prevent arthritic changes. This is the focus of research by physical therapists, so they can better prescribe exercises to keep knee arthritis from getting worse.

Osteoarthritis of the knee often causes a loss of motion. This is often because bone spurs form along the front of the joint and block movement. This causes pain in the front of the knee and an inability to fully straighten the knee.

If the loss of motion is less than 10 degrees, a simple surgery to remove the bone spurs may be all that’s needed. This operation is called arthroscopic debridement. The doctor inserts a slender device, called an arthroscope, into the joint. It has a tiny TV camera on the end that displays a view of the joint on a TV screen.

During the debridement procedure, the doctor scrapes away bone spurs and smooths the joint surface. The goal is to increase motion, decrease pain, and increase function. It may also prevent the need for more extensive surgery later.

Debridement should be done sooner rather than later. Patients who wait more than five years and who have lost more than 10 degrees of knee extension are poor candidates for this operation. Often, the result isn’t as good, and more surgery is needed. Those with early symptoms (less than one year) and minimal loss of motion (less than 10 degrees) generally regain full knee extension and keep it.