News Category: Knee

A torn knee ligament, such as the anterior cruciate ligament (ACL), often requires surgical reconstruction. Exercise is important after the operation to keep the muscles from wasting and weakening. The challenge is to exercise the muscles without straining the healing graft.

In this study, researchers try to find out how much strain four commonly prescribed exercises put on the ACL. The exercises are: (1) the step up, (2) the step down, (3) the lunge, and (4) a one- legged sit to stand. A small probe was put inside the joint and used to measure joint movement. The measurements were converted to tell how much strain is put on the ACL. Each subject did the four exercises while the researchers recorded the position of the knee joint and the strain on the ligament.

The authors report no difference in strain from one exercise to the next. The four exercises used in this study didn’t produce any greater strain than the two-legged squat used most often in rehab. The flexion angle of the joint didn’t seem to make a difference either. If anything, having the knee straight put more strain on the ACL.

Exercises chosen to rehab a reconstructed ACL should be based on how much strain is placed on the healing graft. The results of this study suggest working with the joint flexed during the early phase of rehab. Working with the joint in a fully extended position may cause damage to the healing graft. Lunges and parallel squats are safe. Step-up, step-down, and mini-squats are usually done with the knee close to full extension and put more strain on the ACL. Physical therapists may want to wait to add these exercises until later in the rehab process.

Doctors use several tests to measure knee instability after an anterior cruciate ligament (ACL) tear. A special machine can measure the amount of knee laxity. Two other tests are often used: the Lachman test and the pivot-shift test. These same tests are used after an operation to repair the torn ligament. It helps doctors see how stable the knee is after surgery.

How do patients’ symptoms compare to these findings? If the knee is stable, does the patient still have pain and swelling? If the knee isn’t stable, will patients know it by how limited they are in function?

The purpose of this study was to see if there’s any link between objective test results and patient’s reported symptoms. Any connection between these two has never been reported. Two hundred patients having an ACL reconstruction were studied. All patients were followed at least two years.

Two sets of data were collected: the doctor’s report and the patient’s report. Patients informed their doctors about the following symptoms:

Workers compensation (WC) insurance can be vital for people who are injured on the job. But WC patients more often have chronic pain and problems after surgery. No one is exactly sure why.

These authors looked at how 21 WC patients did after total knee replacement (TKR) surgery. The WC patients were compared to a control group of 16 TKR patients who did not have WC. The average follow-up time was 4.5 years.

Both groups had much better knee function after TKR. Both groups were very satisfied with the results of surgery. However, the WC group had worse function and pain scores than the control group. Only five of the 21 patients in the WC group went back to the job they had before their injuries.

No one is sure exactly what this means. Were the jobs too physically demanding for TKR patients? Were patients using injury as an excuse to change jobs? Were accommodations made in the workplace to help the WC group return to their jobs? A larger, more in-depth study is needed to understand why WC workers don’t always return to their jobs after TKR. The authors say that returning WC patients to their previous jobs might not be a realistic goal. They also remind doctors that they should be sure not to overlook the mental state of injured workers after TKR surgery.

Do patients get better faster with an exercise program after a total knee replacement (TKR)? When should the rehab program be done? Two months after the operation? Four months later? Physical therapy researchers from Canada teamed up to answer these questions in this report.

Seventy-seven TKR patients were divided into two groups. All patients had their first TKR for knee osteoarthritis. Group one was the intensive functional rehabilitation (IFR) group. They had 12 rehab sessions with a physical therapist (PT) along with a home program of exercises. Group two had standard care with just the home program. Both groups were treated between months two and four after the TKR.

Everyone was tested for pain and function right after the TKR, right after the treatment, and eight months later. The six-minute walk test was used, which measures the distance walked in six minutes. Patients can use a walker, cane, or other helping device. They can stop and rest whenever needed.

The authors report that the IFR group walked farther than the control group each time they were tested after treatment. The IFR group also had less pain and stiffness right after the IFR program and again two months later (four months after the TKR). Performing daily activities was also easier for the IFR group. Patients in the IFR group reported only positive changes in their quality of life right after the intense rehab ended.

The results of this study suggest that more intense rehab is needed two to four months after TKR. Waiting two months gets the patient past the first phase of pain, swelling, and stiffness. Intense therapy wouldn’t be possible during the early recovery time. An IFR program at the right time promotes better function even up to eight months later.

Osteoarthritis (OA) is a common problem in aging adults. The hip and the knee are affected most often. Women are more likely to have knee OA than men. When the knee is involved, it’s often just on one side of the joint. Doctors report the medial (inside) compartment of the knee is affected 10 times more often than the lateral (outside) edge of the knee joint.

One way to treat this problem is with surgery to realign the knee. But problems can occur, such as injury to the nerves or blood vessels. A more conservative approach uses a wedged insole in the shoe. The insole is commonly made of sponge rubber. It’s built up under the outside edge of the heel. The wedge is attached to the foot with strapping tape. This approach changes the position of the ankle bones, which helps line up the knee joint.

The authors report that the insole with strapping works better than just using the insole alone. Patients are able to walk farther with less pain by realigning the ankle and the knee.

The authors also report on the best size of insole for the most relief from painful symptoms. Patients got a better correction with a 16 mm wedge, but it was too uncomfortable. Therefore, the researchers suggest using an eight or 12 mm wedge instead.

Physical therapists have been using a special method of taping the kneecap (patella) to control pain since 1986. It’s called McConnell taping. Studies of this taping technique don’t all agree. Does the tape hold the patella in place during exercise? Is it the taping that reduces knee pain?

Researchers at Boise State University are using a special MRI tests to take a look. They studied 18 healthy women with no history of knee problems. First they took MRIs of the knee in various positions. Then they taped the patella to hold it in the middle of the knee. The MRIs were repeated. The women completed an exercise course and had a final MRI done after exercise.

The results show that McConnell taping does put the patella in the right place before exercise. However, it doesn’t keep it there during exercise. The MRIs showed that the patella had moved a significant amount at every knee angle.

The authors suggest McConnell taping may work by some other means than position. Perhaps increasing the surface contact between the bones is the key. Or maybe the muscles work better when the patella is taped no matter what position it’s in. More studies are needed to answer these questions.

Preventing injuries in athletes is a major goal of sports medicine research. In this study researchers look at the effect of muscle fatigue on knee ligament injuries. Fatigue leads to a loss of joint position sense called proprioception.

We know that reduced joint position sense leads to injury. We don’t know what causes decreased joint proprioception. Is it a change in the receptors in the muscle? Receptors in the joint? Or is some other part of the proprioceptive pathway affected?

This study had two goals. The first was to measure the effects of two kinds of fatigue on knee joint proprioception. The second goal was to find out what part of the muscle control pathway changes with fatigue. The hope was to find ways to prevent knee ligament injuries caused by decreased proprioception from fatigue.

Twenty-seven healthy men ages 19 to 31 were studied. Local and general loads were applied. Local load was given by a device that resists knee motion. Local fatigue was measured using the speed of resisted knee motion. Running five minutes on a treadmill gave each man a general load. Heart rate was used to measure general fatigue.

The authors say results show that only general fatigue affects knee proprioception. Decreased proprioception occurred without a loss of muscle strength. This means that the cause of injury was some other factor besides local fatigue.

The authors suggest adding a new exercise element to endurance training. Neuromuscular training must be a part of a knee injury prevention program. This type of training works on muscle control in order to effect the nerves and the nerve sensors of the knee. The next step is to measure how long it takes to recover from general fatigue during exercise. This information may help decrease knee injuries in athletes.

There’s a new trend in treating meniscus tears of the knee: repair it or leave it, but, whenever possible, don’t remove it. Taking the cartilage out of the knee leads to higher rates of future knee damage and more surgery.

In this study 332 patients had an anterior cruciate ligament (ACL) tear along with damage to the lateral meniscus. The lateral meniscus is the cartilage along the outside edge of the knee joint. Only the ACL was repaired. The surgeons left the lateral meniscus alone. In some cases the meniscus was shaved or smoothed out, but it was not removed.

Every year after the operation, doctors sent the patients a survey to fill out. Patients came back to the clinic at two, five, and 10 years after surgery for examination and X-rays. How did these patients do years later?

They had excellent results! Only three percent had to go back for surgery to repair the torn meniscus. Almost all (96 percent) had normal knee function. Only a little over five percent had any joint changes. Even so, in these cases, the joint space was only narrowed mildly.

This study shows that a damaged lateral meniscus doesn’t always have to be dealt with at the time of knee surgery for a torn ACL tear. Not all lateral meniscus tears have to be stitched up during surgery for the ACL. Some do fine either being left alone or by simply roughing up the damaged spot. This is true for a variety of small tears in the lateral meniscus. The long-term results show that the these types of tears have at least some ability to heal.

Hamstring strains are a common sports injury. (The hamstrings are the muscles in the back of the thigh.) Most of the time the hamstrings are hurt while sprinting. Runners, soccer players, or football players are moving at high speeds and suddenly pull up lame. Hamstring injuries are especially annoying to athletes because recovery can take a long time, and the risk or re-injury is high.

Athletic trainers and physical therapists have developed hamstring rehabilitation programs for athletes. However, these programs are not based on much medical research. These authors wanted to help develop evidence for hamstring rehab programs. This small-scale study compared two methods of treating athletes after hamstring injuries.

Twenty-four athletes with injured hamstrings were divided into two groups. All the athletes started their rehab programs within 10 days of injury. None of them used any other treatments, including medications, during the rehab program. Group one did a program of static stretching, resistance exercises that were focused on specific muscles, and icing. Group two did agility and trunk exercises and icing.

The athletes had weekly meetings with the physical therapist. They did their exercises at home every day. Before the athletes could go back to sports, they had to do jumping and sprinting tests to prove that their hamstring was better. They were told to continue the exercises at least three days a week for the next two months. Neither group went back to sports significantly faster. Both groups performed about the same on the function tests.

But the re-injury rates were much different. Within two weeks, six athletes in group one had re-injured their hamstrings, compared to none in group two. Within the first year, a total of 70 percent of group one had re-injured their hamstrings. This compared to only eight percent in group two.

The agility and trunk exercises obviously seem to be a better way to rehabilitate hamstring injuries. Still, larger studies are needed to find out exactly why and how the exercises work. The authors note that they are studying how these exercises affect the hip and trunk muscles.

A popular way to treat osteoarthritis (OA) of the knee is injections with hyaluronic acid (HA). HA is an important part of the normal synovial fluid in the joint. It helps lubricate the joint for smooth, gliding action.

How well do HA injections work? Is HA safe to use? Researchers in Taiwan compared the results of 20 other studies to find out. By combining the results of the studies, the authors were able to compare a large number of patients in each group. There were more than 800 in each group, for a total of 1,647 subjects.

All the studies had two groups of patients. One group received injections of HA into the joint. The second group also had injections, but they were placebos that didn’t contain any HA. Researchers used three categories of results to measure success. The categories were: 1) pain with activities; 2) pain without activities; and 3) function.

The authors found that HA may not work as well for patients over 65 years of age. Patients with severe OA didn’t do as well as those who still had some of the joint surface left. The authors conclude that doctors should consider patient age and status of OA before using hyaluronic acid to treat patients. Choosing the right patients for HA treatment will improve results.

Doctors in Norway report on the use of two methods to treat knee cartilage defects. All patients had injured the knee and damaged the cartilage. They later developed knee osteoarthritis. There were 40 patients in each group.

Group one was treated with autologous chondrocyte implantation (ACI). Normal, healthy cartilage cells were taken from the joint and used to grow more in a lab. The new cells were put back into the joint four weeks later.

The second group had microfracture, a method of increasing bone marrow cells to help repair the damage. Surgeons use a blunt awl (a tool for making small holes) to poke a few tiny holes in the bone under the damaged cartilage. The goal in either treatment method is to restore normal knee function by attempting to replace the damaged cartilage with new tissue.

Patients were followed for two years. Doctors took a small piece of tissue from the repaired site. The amount of actual tissue repair seen during the biopsy was the same between the two groups. Repair tissue after microfracture isn’t really normal cartilage. Studies so far report the patient gets a mixture of two kinds of cartilage: fibrocartilage (scar tissue) and hyaline cartilage. Patients with smaller defects had better clinical results with microfracture than those with a bigger defect. The size of the cartilage injury didn’t seem to matter in the ACI group.

Overall results showed much more improvement in the microfracture group compared to the ACI group. Microfracture patients had less pain and better physical function. Younger, more active patients had the best overall results in both groups.

The authors report this is the first study to compare ACI and microfracture in repair of knee cartilage. Patient outcome and quality of repair tissue were measured. Researchers think the better physical function after microfracture may be because the operation is much simpler than the ACI procedure. Rehab is easier, too.

A larger, longer study is needed to show what happens years later. It’s not clear if one method is better than the other over the long term.

The formation of blood clots is a fairly common problem. Most of the time it isn’t dangerous. However, sometimes a blood clot can lodge in the lungs causing death. People are at higher risk for blood clots after certain types of surgeries, such as knee or hip surgery. Blood clots commonly form in the legs. This condition is called deep venous thrombosis (DVT). Sometimes the clots break loose and make their way to the lungs. But DVT rarely causes problems after knee arthroscopy. (Arthroscopy is a procedure using a tiny TV camera and requires only small incisions.)

This article reports on a rare case of a man who died of a blood clot after knee arthroscopy. The man was 46 years old. He had arthroscopy to remove part of the meniscus in his knee. One week later he collapsed and died. Doctors couldn’t find anything else to blame for his death besides the knee arthroscopy a week earlier.

Remember, complications of DVT are very rare after arthroscopy. Studies show that about three to eight percent of arthroscopy patients have DVT after surgery. But it almost never causes any symptoms. The authors could find only one other report of a death due to DVT after knee arthroscopy.

The authors conclude that, even if it is rare, surgeons should make sure to take steps to prevent deaths due to DVT after knee arthroscopy. Patients should begin exercises early, and maybe even take a blood thinner if they have other risk factors. Future research will be needed to be sure these methods work to prevent deaths from DVT after arthroscopy.

In this study, the anatomy and function of injuries affecting the inside back corner (the posteromedial corner) of the knee are reported. The authors of this article took the time to look closely and carefully at injuries to this part of the knee.

The knee can be divided many ways. Some doctors look at it as four separate corners. Others discuss it in terms of its two sides: medial (inside half) and lateral (outside half). Yet another view is to look at the knee joint in thirds: front, middle, and back. In this study a single surgeon used the corner method. Ninety-three cases of posteromedial knee injuries were reviewed.

The anatomy of the inside back corner is described. How each structure works is also discussed. The author calls the work of the posteromedial corner dynamizing action. The soft tissue and ligaments work together. They pull tissue out of the way, lengthen structures to prevent pinching, and help us keep our balance. Ligaments and cartilage give us just the right amount of bone rotation.

The action of each structure is very important. The authors show how often injury to the posteromedial corner is more than first seen. Often the main ligament is torn, along with a piece of capsule or tendon in that corner. They point out that final results may not be good unless the surgeon repairs all damage present.

Restoring dynamic action to the knee requires all parts to be in good working order. These authors show how structures in the posteromedial corner work to give us normal knee motion. Surgeons must look at each injury carefully, find any hidden damage, and repair it.

Engineers at Massachusetts General Hospital are using robots to get some answers about knee joint replacements. The role of the anterior cruciate ligament (ACL) is the focus of this study. How important is the ACL after unicompartmental knee arthroplasty (UKA)?

UKA replaces just half of the knee joint. UKA is becoming a popular solution because arthritis wears down a joint unevenly. UKA leaves the normal side of the joint intact. The patient doesn’t need a total knee joint replacement. Usually the inside edge (the medial side) of the joint is replaced. This is called a medial UKA.

The ACL keeps the tibia (lower leg bone) from sliding too far forward during knee flexion. This ligament is often torn before the joint replacement. Sometimes it’s cut during knee replacement. In this study, engineers measured the effect of UKA on the stability of the knee with and without the ACL.

Researchers used seven human knees saved for study after death. A robotic testing system measured knee motion before and after a UKA was implanted. The same system applied repeated loads to the knee before and after the ACL was cut. A computer recorded the forces transmitted through the knee.

As the engineers suspected, the tibia moved forward more when the ACL was cut than in either the normal knee or the knee with an UKA and intact ACL. The motion was like an ACL-deficient knee with or without UKA.

The authors don’t think a medial UKA changes the forward stability of the knee. The results of this study show the importance of the ACL after UKA. A normal, working ACL is needed for the success of the UKA. In general the knee with an UKA does best when the soft tissues are left in place.

This is the first study to look at the validity of a special test for balance used in patients with osteoarthritis (OA) of the knee. The Get Up and Go Test (GUG) is a way to measure a person’s ability to get up from a chair, walk, and maintain balance. The person is timed while getting up from a chair and walking up and back 50 feet (12.2 meters).

Physical therapists at the University of Pittsburgh compared how long it took 80 patients with knee OA to complete the GUG test. They compared the results with 25 adults who don’t have OA. The purpose of the study was to find out how useful the GUG test is as a measure of physical function for patients with knee OA. Is it reliable for these patients? Can it predict function?

The authors report the GUG test is reliable. They found that adults with OA take longer to perform the GUG than those with healthy knees. Average time to rise from the chair and walk the distance was 11 seconds for the patients with OA and eight seconds for the healthy subjects.

The researchers say the GUG test can’t be used alone as a single measure of physical function. It’s too narrow and doesn’t look at activities patients with OA find hard to do. For example, it doesn’t measure ability to go up and down stairs or get in and out of a car. These skills are often problems for patients with OA.

These therapists suggest more research is needed to find useful tests and measures of physical function for patients with knee OA. It’s better to have a specific test than to rely on the patient’s report. Patients tend to report what they think they can do rather than what they can really accomplish. They may not see their own decline in physical function. A test to show early decline in strength and balance may help prevent further problems in patients with knee arthritis.

Damage to the ligaments of the knee are fairly common injuries. The anterior cruciate ligament (ACL) is affected most often. Many studies have been done to find the best treatment for this injury. Tears to the posterior cruciate ligament (PCL) are not as common. Researchers report PCL injury occurs between 3.4 and 20 percent of the time.

Treatment for PCL tears isn’t standard. This means there isn’t one best way to repair the damage. Doctors in Taiwan report on their success using a tendon graft from the knee. They took a piece of the quadriceps tendon above the kneecap and used it as a graft to replace the torn PCL. The quadriceps tendon is wider and thicker than the patellar tendon, which is located below the kneecap. The quadriceps tendon is also 1.36 times stronger than the patellar tendon.

Measures of success included patient satisfaction, motion, function, and strength. The amount of knee looseness or laxity was measured. Patients also reported any symptoms. Each patient was examined before the operation and again at one year, two years, and three years (or more) after the operation.

The authors report that 83 percent of the patients had good or excellent results. More than half could return to activities at a moderate to strenuous level. Only 14 percent had too much joint laxity. Strength returned to 80 percent of normal for most patients. However, only about half could regain up to 90 percent of their full strength. Flexion was stronger than extension in all patients.

There are many reasons to use a quadriceps tendon graft to repair a torn PCL. The authors of this study review the pros and cons of this treatment method. They suggest this graft is a reasonably good choice. Rehab afterwards is still very important for all patients. This includes athletes and patients who aren’t involved in sports or strenuous activities.

Anyone who has injured the hamstring muscle is more likely to injure it again compared to others without injury. Athletes have the highest number of hamstring injuries. Soccer and track and field athletes miss more playing time because of hamstring strains than other athletes. These sports involve sprinting and sudden bursts of speed.

Researchers in Australia set out to study the link between damage to the muscle fibers and actual muscle tear in hamstring injuries. Do tiny tears in the muscles lead to a muscle strain with continued use of the muscle? The hope is to find ways of preventing such injuries.

Twenty-seven athletes were included in this study. Two groups were formed: one group without a previous history of hamstring injury, and a second group with an old hamstring injury on one side only. Some of the previously injured athletes had re-injured the same side more than once.

Each athlete was tested for hamstring strength. The angle at which the muscle was strongest in flexion and extension was recorded. For the injured athletes, the injured leg was compared to the uninjured leg. Researchers found that the previously injured muscles reached their peak sooner than uninjured muscles. This means the injured muscles worked best at a shorter length than uninjured muscles.

Strength differences between the hamstrings and quadriceps muscles didn’t predict hamstring strain. In this study, type of sport didn’t seem to make a difference, either. It all boiled down to the optimum length of the muscle. After injury, this length is shorter. Since muscles with shorter optimum angles are at greater risk of injury, repeat strains and tears are common.

The authors explain that, when a muscle gets stretched beyond its optimum length, small tears are likely. When the athlete uses the muscle to slow down or brake motion it’s called an eccentric contraction. Repeated eccentric contractions cause more damage, and the size of the tear gets larger.

The authors suggest including eccentric exercise during rehab as soon as the athlete is pain-free after the injury. This will shift the optimum angle from shorter to longer, so injury is less likely.

A new study shows seniors over age 90 are helped by a total knee replacement (TKR). The pain relief and increased mobility these patients get makes it worth the effort. Most patients live more than five years after receiving the new knee joint.

Doctors at the Mayo Clinic in Rochester, Minnesota, followed 51 TKRs in adults ages 90 to 102 years old. Most were getting their first knee replacement. A few were having a second surgery to revise a failed first TKR. It’s likely that as more and more people live longer, TKRs put in at age 70 will need revision or replacement by the time the patient reaches 90.

Problems during and after the operation are a concern in this group. In this study, the rate of complications was 41 percent for first-time TKRs. Many problems were linked to medical conditions already present. The most common problems were high blood pressure, diabetes, or bleeding ulcers. Patients getting a previous TKR repaired or replaced didn’t have any complications.

Results from the operation are also important. The authors report a high rate of patient satisfaction. Everyone reported relief from pain. Three-fourths of the patients could walk without a limp or only a slight limp. This was compared to 71 percent who walked with a marked limp or who couldn’t walk at all before the operation. In addition, many more patients were able to go up and down stairs again after TKR.

This study shows total knee revision or replacement can be done safely in patients over 90 years of age. The TKR is durable and reliable. The authors advise a careful exam before the operation. Patients with medical problems can be watched carefully to avoid problems.

These doctors report cases of locking knees in two women during pregnancy. Joints are often looser during pregnancy. Increased weight on the joint can cause problems, especially if the woman has a history of previous knee injury.

Both of these women had knee injuries and a knee operation years before their pregnancies. They had no further knee problems until the pregnancy. The locked knee in the first woman turned out to be a tiny piece of cartilage and bone floating freely inside the joint. The second patient had a torn meniscus (cartilage) in the knee joint.

Surgery to remove the loose body and repair the torn meniscus was done. There were concerns about the unborn children. For this reason, a spinal anesthetic was used instead of a general anesthesia or local knee block. This means the patient was numb from the waist down instead of being asleep (as in general anesthesia) or having sensation to the knee blocked.

The authors also report the reasons why a spinal anesthetic was used. Not as much anesthetic is needed with a spinal anesthetic. Greater muscle relaxation is possible. If high stress must be placed on the knee, the patient won’t feel pain during the operation. Sometimes a local block to the knee is incomplete. If a pregnant woman feels any pain or discomfort, her blood pressure might go up. Doctors try to avoid this during pregnancy for the sake of the unborn child.

Surgery is usually avoided during pregnancy. Emergencies do come up, however. A locked and painful knee is one such emergency. Surgery can usually be done safely in these cases. Surgeons are advised to use a spinal anesthetic and fetal monitoring.

With a team approach, no harm is done to the baby. There’s only a one to two percent chance the woman will have a miscarriage.

Different running styles put stress on different joints in different ways. Medical professionals would like to understand exactly how different running styles affect the knee, ankle, and hip. This knowledge could help runners and other athletes recover from injuries. It could also help prevent injuries.

Researchers know that running backwards is easier on the knee. The calf muscles absorb most of the stress. Obviously, athletes can’t start running backward to avoid knee problems! So these authors studied the way three different running styles affect the leg joints.

Twenty runners took part in the study. All of them were heel-toe runners. In a heel-toe running stride, the heel hits first. The runner then rolls the weight forward through the foot. The authors taught all the runners two new running styles. Midfoot running is much like heel-toe running, but the middle part of the foot hits the ground first. The runners learned midfoot running within 15 minutes.

It was a much different story for the third running style. The authors call it pose running. Runners took about 7.5 hours to learn pose running. Pose running involves keeping the body more upright. The shoulders, hips, and ankles stay aligned. Runners don’t push off the ground as in the other running styles. Instead, they lean forward a bit, bend the knee, and avoid pushing off the running surface. In pose running, the ball of the foot hits the ground first. Pose running was designed to have leg movements that are similar to backward running.

The authors analyzed stride, speed, and ground forces for each of the three running styles. Ankle, knee, and hip movements were also studied. Pose running was slower than the other two styles. Pose running also had shorter strides and lower forces. The joints handled the load differently in pose running. The ankles worked harder, and the knees worked less.

The authors think that the different body posture may have had a lot to do with redirecting the force in pose running. They suggest that research needs to consider body position to fully understand the way the joints work while running.