News Category: Knee

Do patients with total knee replacements (TKRs) have trouble getting around obstacles? Are they more likely to trip and fall when both knees have been replaced? Researchers from the Motion Analysis Lab at the University of Chicago say “Yes” to both questions.

They studied 29 adults with bilateral TKRs and compared them to normal adults. All TKR patients were pain free, able to walk and climb stairs, and rise from a chair. Patients and normal subjects had 20/40 vision or better.

A special walkway was used to test everyone’s ability to avoid obstacles. A band of light was flashed on the floor, and each person was to step over it. Patients with TKRs were 30 percent less likely to avoid the virtual obstacle. Type of joint implant didn’t seem to make any difference on success rates.

Researchers also found success rates went down as body weight went up in both groups. The most important factor in avoiding obstacles was the time each person could stand on one leg.

The authors conclude that older adults with TKRs may be at risk for falling compared to healthy adults of the same age. TKRs are linked with impaired balance. Reduced balance puts patients at risk for falls.

Patients with bilateral TKRs generally have muscle weakness, decreased standing balance, and loss of joint position sense called proprioception. Knowing these risk factors for falls may help in planning a falls prevention program for anyone with a TKR and especially patients with bilateral TKRs.

What’s the best way to control pain and swelling after a unicompartmental knee replacement (UKR)? That’s the focus of this study. UKR only replaces one side of the joint, usually the medial or inside half.

Three groups of patients were compared. Group one used a Cryo/cuff for the first 48 hours. The Cryo/cuff cools the knee while giving compression off and on at the same time. Group 2 had an epidural injection of anesthesia into the space around the spinal cord. Group 3 was the control group. They were given oral pain relievers.

Everyone had the same rehab program for six weeks. Patients were allowed to progress at their own pace. A home program of knee range of motion exercises was given. Full weight-bearing was allowed without a walking aid when the patient was ready for it.

Day 1: No difference between the Cryo group and the EDA group. This surprised the researchers because patients with EDA should be pain free. The control group used more morphine than either the Cryo or the EDA groups.

Day 2: No difference between the Cryo group and the EDA group. The control group used more morphine but the amount wasn’t significant compared to the other two groups.

Day 3: Cryo and EDA was stopped. The Cryo group had a gradual decrease in pain. The EDA group had slightly more pain.

Day 4: No morphine was needed by the Cryo group. Some patients in the EDA group still used Morphine until day 7.

Six weeks later: Patients in all three groups had about the same knee motion as before the operation. Function such as walking and stair climbing was much better.

The authors conclude that the Cryo/cuff works just as well as EDA for UKR in the first 48 hours. There’s no need to use the more invasive spinal injection. Physical therapists should note that motion training shouldn’t be rushed. Failure to increase range of motion should be monitored. Most of the patients regained their motion with a home program of exercise.

This is part two of a previous study on patients with posterior cruciate ligament injuries. Part one reported on the natural history of a PCL tear–what happens to patients years after the injury. Part two looks at long-term results based on how severe the injury was. They asked the question, “Do the results depend on the degree of PCL
laxity?”

The same 271 patients from the first study were part of the second study. Amount of joint laxity (looseness) was measured for each patient. A special test called the posterior drawer test was used to label severity of each injury. Laxity was graded from one to three. The grade depends on how far the lower leg bone (tibia) slides when pulled forward by the examiner. The higher the number, the more severe the injury and laxity.

The patients were asked a series of questions about knee function and activity level. The results showed it didn’t matter how tight or loose the joint was after PCL injury. Patients had varying results from poor to good no matter what grade was given. The
researchers couldn’t find a way to predict which PCL injuries would end up with poor knee function.

Patients sometimes wonder what the effect of a total joint replacement will be on their body weight. This small study from the Insall Scott Kelly Institute in New York City answered that question for 20 patients.

Body weight was measured before and after total knee replacement (TKR). The joint and bone removed was weighed and compared to the weight of the implant replacing the joint. Body weight was measured again one year later.

The authors report a zero percent weight gain. Men who received larger-sized implants had the most weight gain right after surgery. The increase translated to about three-fourths of a pound for men and slightly more than half a pound for women. The increase in weight was directly linked to the size of the implant.

The authors conclude that weight differences before and after TKR are so small as to be negligible.

Whenever possible a torn meniscus in the knee is repaired. When damage is too great then removal and replacement is recommended. In this study 96 patients had more than half the meniscus removed. It was replaced by donor tissue called an allograft. The results of the meniscus transplants are reported here.

One-third of the transplants replaced the medial meniscus on the inside of the knee joint. Two-thirds of the replaced meniscus were from the outer half or lateral side of the joint. In some cases a torn ligament in the knee was repaired at the same time.

Overall knee function after surgery was assessed by measuring joint motion, pain, deformity, and instability. The involved knee was evaluated every year for at least two years and in some cases up to 14 years. Persistent pain and poor knee function were used to define a failed allograft.

The results showed an overall failure rate of 28 percent for the medial allografts and 16 percent for the lateral allografts. This means 70 percent of the patients still had good results 10 years after the transplant.

The group will continue to be studied for long-term results. Efforts are being made to find out what factors might predict failure. So far it looks like the level of pain before surgery may be an indicator of success or failure. Knee function and joint alignment didn’t seem to affect the final result.

When the cartilage in your knee is torn clear down to the bone, it’s called a full-thickness chondral defect. Surgery is the standard treatment for this type of problem. This study examines rehab programs after surgery.

Two rehab programs are compared after arthroscopic surgery to repair the cartilage. Surgery was the same for each patient. The damaged cartilage was trimmed of any loose flaps or pieces. Any nonhealing fibrous cartilage was also removed. Several holes were drilled into the bone where the cartilage attaches to stimulate healing. This procedure is called microfracture.

The first rehab program used minimal weight bearing and continuous passive motion (CPM). Patients were allowed to touch the toe to the floor when walking. CPM is a device that keeps the knee moving slowly and smoothly for hours at at time. CPM may help the cartilage and bone repair faster and better. It does this by applying moving pressure to the cartilage and bone.

The second program allowed patients to put as much weight on the foot as they could tolerate. CPM wasn’t used at all in the second group. Active movement of the leg and knee was encouraged three times a day in this group.

Testing showed no difference between the two groups. Everyone was followed at least two years. Some patients were retested up to nine years later. Measures of change included reported pain, swelling, and motion. Knee function and X-rays were also used to evaluate results.

The authors conclude that the popular use of CPM after cartilage repair doesn’t appear to improve patient results. They suggest using other bone grafting methods to repair cartilage in younger, athletic patients. Studies show higher success rates with bone-cartilage grafting for chondral defects.

Sometimes knee arthritis only affects one side of the joint. In such cases, a unicompartmental knee replacement (UKR) is done. This implant only replaces the affected side of the knee joint. This study looks at knee motion after a UKR and compares it to motion after a total knee replacement (TKR).

Six knees from cadavers were used. The knees chosen were free from defects or deformities. Only left knees were used. The soft tissues around the joint were tested for strength and found to be healthy before the operation. Knee motion and strength were tested before and after the UKR. Then the UKR was taken out and a TKR was inserted and tested in the same way.

Researchers weren’t just looking at how much motion occurred. They were also measuring something called kinematics. Kinematics includes the small rotations, sliding movements, and sideways gliding that occurs during normal flexion and extension of the knee joint.

Since no ligaments are cut with the UKR, it’s thought that the kinematics stay the same as in a normal knee. This study was able to confirm this idea. Knee kinematics didn’t change with the UKR. When a TKR was implanted, the rotation of the tibia (lower leg bone) was altered during knee flexion.

The authors conclude that near normal function can be expected after UKR. Healthy ligaments aren’t as important as the surface geometry of the knee. TKR changes the way the joint matches up and moves. Even the muscles work differently with the TKR compared to the UKR. Young, active adults who have arthritis on one side of the joint but need normal motion to join in sports may be the best candidates for a UKR.

How well does the knee work in a healthy aging adult? How does this compare to patients who have a total knee replacement (TKR)? These are the questions investigated in this study by doctors at Baylor College of Medicine (Houston, Texas).

Two groups of people were included in the study. One group (243 adults) had a TKR at least one year ago. The control group (257 adults of the same ages and gender) had no previous knee problems of any kind.

Everyone filled out a survey. Questions were asked about common activities, walking, and exercise. The answers were used to compare activity level and function between the two groups. They found some big differences between the two groups.

About half of the TKR group reported limits on their activities. Only 22 percent of the control group had problems with similar activities such as kneeling, turning, dancing, and gardening. Subjects in both groups could do activities such as swimming and biking equally well. These activities aren’t as demanding on the knee as squatting and kneeling.

The authors conclude that adults with no previous knee problems do have limits in what they can do. Even so, it’s clear that TKR doesn’t completely restore normal knee function. It reduces pain and allows patients to do many routine activities. Patients with TKR generally can’t do more demanding activities compared to the control group.

There are two ways to reconstruct a torn anterior cruciate ligament (ACL) in the knee. One is with a graft from the patellar (knee) tendon. The other is from the hamstring tendon. There is ongoing debate about which graft type is better.

This study looks at the effects of each graft type on walking after recovery. Studies show that most of the time walking patterns after ACL reconstruction return to normal. There may be a few changes that persist. Changes in knee function may be caused by problems at the graft site.

Three groups of patients were included in this study. The first group had a patellar tendon graft, the second group had a hamstring tendon graft, and the third group was a control group. The control group had no history of knee problems and shared similar activity levels with groups one and two. One surgeon did all the ACL procedures using the same surgical technique in each patient.

Walking and gait patterns were recorded using infrared-sensitive cameras. A force plate in the floor measured force through the foot and leg from the ground up. The authors report the results of comparing gait patterns of patients with these two different ACL graft types.

Walking speed was the same for all three groups. Hip and ankle joint movement was similar among the three groups. The big difference was seen at the knee joint. The group with a patellar tendon graft had less knee flexion when standing on the leg. In contrast the hamstring tendon group had less knee extension just before lifting the leg off the floor for the next step.

Decreased knee flexion (patellar tendon graft) reduces the knee’s ability to absorb shock. This could lead to early arthritic changes in the joint. If this is true, then the hamstring graft is a better choice. More studies are needed to show what happens seven to 10 years after ACL reconstruction surgery.

Researchers from the Harvard Medical School reviewed 25 studies of arthroscopic partial meniscectomy (APM). The studies were done on adult patients of all ages. The goal of the review was to find ways to predict the outcome of APM. X-ray findings and function were the two main measures of results.

Here’s a summary of what they found:

The results of this study challenge current thinking on follow-up treatment after microfracture. Microfracture is an arthroscopic operation for cartilage tears in the knee. The surgeon makes several holes in the layer of bone underneath the damaged cartilage. This brings blood to the injured cartilage and speeds up healing.

Right now doctors are following a standard rehab program. The patient puts no weight on the leg and uses continuous passive motion (CPM). CPM is done with a device that slowly bends and straightens the knee over and over. The idea is to use CPM to put “dynamic” (moving) pressure but no weight through the joint to enhance healing.

In this study two groups of patients were compared. Group one was treated with the standard rehab (non-weight bearing and CPM). CPM was done for at least six to eight hours each day for six weeks. Group two was allowed to walk on the leg and didn’t use CPM. Patient results were followed for up to six years.

The researchers report no differences between the two groups. X-rays, activity levels, and number of infections or blood clots were used as measures of results. They concluded the use of CPM and a nonweight-bearing status aren’t needed after microfracture.

However, based on the results of this study (only 60 percent had good results), the authors suggested microfracture as a treatment for damaged cartilage should be re-evaluated. Perhaps this method isn’t the best way to stimulate healing after all.

This is a review article on the nonoperative treatment of knee osteoarthritis (OA). It was written by physicians for physicians. The value of patient education is number one. Since there’s no cure for OA, learning how to manage the symptoms is important.

Controlling pain and improving function are the two most common goals in treating patients with OA. Self-help starts with exercise and weight control. It’s been proven that adults who exercise and lose weight have 50 percent less risk of developing OA.

Bracing and shoe inserts to unload the knee may be advised for some patients. Even using a cane can help slow the progression of this disease. Less load means less pain, which means improved activity level.

Tylenol remains the top choice in pain relievers. It is safe when used as directed, and it’s not habit forming or addictive. Drugs such as ibuprofen and other nonsteroidal anti-inflammatories (NSAIDs) may be a better choice for patients with severe pain. Topical (rub on) creams such as Capsaicin have been shown to help, too.

Besides over-the-counter and prescription drugs, nutritional supplements can help. Glucosamine and chondroitin sulfate work to protect the joint cartilage and reduce pain. What about steroid injections? They can be used up to three times in a year when a joint is painful and swollen.

Finally, the authors review the use of acupuncture and lubricants injected into the knee. All of these treatments can be tried before patients turn to surgery. Sometimes several nonoperative treatments are used. Relieving symptoms helps patients stay active and improves their quality of life.

This report is the second in a two-part study on patellofemoral pain syndrome (PFPS). In the first study it was found that patients with PFPS use less knee flexion when going up and down stairs compared to healthy adults. In this study physical therapy was used to see if reducing pain would increase knee flexion while climbing stairs. The same group of PFPS patients was in both studies.

PFPS is a common cause of knee pain, especially when going up and down stairs. Normally the patella (kneecap) slides within a slot on the femur (thigh bone) called the trochlear groove. Sometimes the patella tracks improperly and doesn’t stay in the groove. When this happens during movement pain occurs around the kneecap.

Patients were divided into two groups. One group received physical therapy to decrease knee pain and improve muscle control. These patients were given exercises, mobilization of the patella, and corrective taping of the patella. The goal was to retrain quadriceps muscle function. This would improve knee flexion during stair climbing.

The second group was the placebo group. They received a placebo taping and fake ultrasound (deep heat that wasn’t turned on) along with a fake gel. Both groups were treated once a week for six weeks. Results were measured by overall pain levels and the number of steps the patient could make going up or down without pain. A special camera recorded how much knee flexion occurred while using stairs.

The authors report that patients had less pain and more knee flexion while walking after physical therapy. There was no change in the physical therapy group going up stairs. This same group had less knee flexion when coming down stairs. The placebo group had no change of any kind at any time.

Physical therapy to improve motor control of the quadriceps muscle can help patients with PFPS. Changes may not be seen with the naked eye but can be recorded on video. Pain levels and angle of knee motion are reliable measures of change.

Rehab is the answer to preventing problems after knee surgery. Activities and exercise prevent muscle wasting and scar tissue from forming. Rehab helps keep the heart and lungs in shape. The bottom-line in rehab is: restore function in the shortest time possible. This study looks at another way to speed up rehab and meet that goal: lower body positive-pressure exercise.

A special device called the lower body positive pressure (LBPP) chamber was used. The LBPP is a waist high box with a treadmill inside. It’s been used by NASA for astronaut training. Pressure inside the chamber can be reduced to decrease the effects of gravity. This means less load on the bones and joints while walking on the treadmill.

Fifteen knee patients were included. Nine patients had part of the meniscus taken out via arthroscopy. The rest had an anterior cruciate ligament (ACL) repair.

Pressure inside the chamber was increased to unload the joints by 40 percent and then by 80 percent. Each patient walked for two minutes under three different conditions: normal body weight, then 40, and 80 percent unloaded. Ground reaction force (GFR) is the amount of force from the ground up through the leg when walking. GFR was measured along with knee range of motion and pain levels.

This was the first study to use LBPP with patients who had knee surgery. The goal was to see if LBPP could decrease GFR comfortably during walking after knee surgery. The results showed LBPP not only decreased bone and joint loads, but also decreased muscle activity further unloading the knee joint.

The authors suggest that the LBPP exercise chamber may be a good device to rehab patients. It could be used with anyone who needs to get up and walking but can’t put weight on the leg. This could include strokes, spinal cord injuries, amputees, and orthopedic patients after surgery.

Tripping on an object is the most common cause of falls for people 65 years old and older. Hip fractures and even death are the result of such falls. How well can adults with knee osteoarthritis (OA) avoid suddenly appearing obstacles?

In this study from the Motion Analysis Laboratory at the University of Chicago adults with and without knee arthritis were tested to answer this question. As the researchers expected, people with painful knee arthritis were less able to avoid the obstacle. The greater the pain level, the less chance they had of missing the obstacle.

Tests of single-leg balance also showed the arthritic group had a harder time missing obstacles. The results of the study showed that as pain increased the ability to stand on the painful leg decreased. Patients in pain couldn’t balance on the arthritic leg long enough to avoid tripping over the object. Pain affects gait and balance and increases the risk of falling.

The authors report that patients with knee OA often can’t react fast enough to avoid a suddenly appearing obstacle. They have less knee and hip range of motion. Their movements are impaired. Their focus is on avoiding the pain, not avoiding the obstacle.

The solution? Pain relief and balance training. This type of program may help reduce the risk for tripping in patients with painful knee arthritis.

Improved technology is expanding the role of computers in the operating room. In this study surgeons report on the use of computers to help put in knee joint replacements.

Fifteen unilateral knee arthroplasties (UKAs) were done using computers to help the surgeon. Fifteen UKAs were done “the old fashioned way” without the use of a computer. All UKAs were done using very small incisions called minimally invasive surgery (MIS).

Only the inside half of the knee joint was replaced, which is why it’s called a unilateral joint replacement. The navigation system uses an infrared camera to find and keep track of joint position and angles. In this way the implant can be put in while keeping the hip, knee, and ankle all lined up.

The idea is to prevent overcorrecting the knee joint. Getting as close to normal will help restore function. It will also prevent breakdown of the new joint. In this study, the 15 UKAs done with computer-assisted navigation had better alignment than those done without computers.

The author’s conclude that with today’s smaller incisions, surgeons aided by computer navigation get more accurate joint alignment when doing UKAs.

If you had an anterior cruciate ligament (ACL) reconstruction 20 years ago, your leg would have been immobilized for six weeks or more after surgery. Today patients begin moving the knee and putting weight on the leg right away. But how much movement can be allowed without stretching out the repair graft or damaging the knee cartilage? That’s
the topic of this study.

Researchers in the United States, Canada, and Sweden worked together to complete this study. Two groups of patients were included. All had an ACL repair using the same kind of tendon graft. Everyone exercised under the supervision of a licensed physical therapist three times a week. A home program was done on other days. Both groups followed the same exercise program.

The main difference between the two groups was how fast the patients progressed. In the first (accelerated) group, patients went through the whole program in 19 weeks. There was more strain on the healing ACL graft with this exercise program. The second
(nonaccelerated) group completed the program in 32 weeks. Exercises that strained the healing graft weren’t started until later in the second group.

Results were measured using joint laxity, patient satisfaction, and function. Patients were evaluated before surgery and again three, six, 12, and 24 months after surgery. Synovial fluid from the joint was also tested for biomarkers of cartilage metabolism.

The authors report no difference in results between the two groups. This was true early on after the surgery and as much as two years later. The most surprising discovery was that the joint cartilage showed signs of healing even two years after the repair. Researchers aren’t sure what to make of this finding. It means that the joint is still remodeling after patients have returned to full activities.

Patellofemoral pain syndrome (PFPS) of the knee has been treated successfully with foot orthotics. These shoe inserts correct the foot position. They help the quadriceps (thigh) muscle work better. In this study three groups of adults were studied. Muscle activity was measured while using orthotics.

Each group had a different natural foot position. Some of the subjects had a flat foot. Others had a high arch. The effects of four orthotic postings were measured on three upper leg muscles. Changing the tilt of the insert is called posting.

Electrical activity of each muscle was measured. Activities included a single-leg squat, lateral step-down, and vertical jump. In one set of exercises, no orthotic was used. Three other trials were done using different orthotic postings. There are very few studies on the effects of orthotic postings on leg muscle activity.

The authors report natural foot position doesn’t seem to have any effect on muscle activity during the exercises described. Muscle activity increased with any orthotic used. The results were the same for all postings. Changes in muscle activity were seen in the squat and step down activities, but not during the vertical jump.

Increasing the right muscle activity helps patients with PFPS. The muscles keep the kneecap tracking normally. More research is needed on the effects of orthotics on muscle activity. This information may be helpful in treating PFPS.

There are three ways to replace both knee joints when pain and disability of arthritis make life difficult. These are: staggered, sequential, and staged

Looking at the results of many studies can offer answers to a single question. In this study the question of interest was: Should the kneecap (patella) be replaced during a total knee replacement (TKR)? Looking at studies one at a time can’t always give the information needed to answer the question.

Researchers reviewed the results of 15 studies done between 1996 and 2003. The studies were all randomized control trials (RCT). This means patients were put in one of two groups randomly: the experimental group and the control group. RCT allows scientists to tell when the results are directly from the experiment. A blinded RCT means no one (subjects or researchers) knows which group the subjects are in.

All patients had arthritis, either osteoarthritis or rheumatoid arthritis. Half the group had the patella replaced. Ten different types of joint implants were used. This is called patellar resurfacing. The other half didn’t have the patella replaced (nonresurfaced). For patients who kept their own patella, the surgeon smoothed any rough edges and removed any torn cartilage or bone spurs.

More patients with nonresurfaced patellas had problems later. Reoperation was much higher for this group. The nonresurfaced group also had more knee pain and especially pain when climbing stairs. Overall results seemed to point to patellar resurfacing as the better way to go when replacing the knee joint.

The authors say that this is just a general opinion. Follow-up in most studies wasn’t long enough to give a complete picture of results. The broad range of implant types and level of surgeon experience were factors in the outcome. The type of patient and the methods of operating affect results too.