News Category: Knee

There are two main graft sources for anterior cruciate ligament (ACL) repairs. The first is a bone-patellar-bone (BPTB) graft. This is a piece of bone and tendon taken from the quadriceps tendon in front of the knee just below the patella (kneecap).

The second graft is taken from the hamstring muscle behind the knee. This graft called the quadruple-strand hamstring tendon graft is folded over to increase its strength.

Many studies have been done comparing these two methods of repair. In this study, 99 patients were divided into two groups by graft type. One surgeon did all the operations.

While using the two different tendon grafts, the method of fixation (bioabsorbable interference screws) was the same for all patients. Results were compared measuring strength, activity level, and range of motion. Follow-up measurements were taken at regular intervals over a period of two years.

The authors report good results with both methods. There were some small differences noted. For example, the BPTB patients were more likely to return to their preinjury level of activity and previous jumping ability. They also had greater flexion strength in the operated leg compared to the nonoperated leg.

The hamstring group had less trouble kneeling and better extension strength in the operated leg compared to the nonoperated leg. The best graft is one that is strong and heals quickly with no problems while providing a stable knee. Choosing the right graft method for each patient should take the small differences reported into consideration.

Physical therapists (PTs) are looking for a few good tests to measure the effectiveness of rehab after anterior cruciate ligament (ACL) repair. In this study, PTs from Canada evaluate the Hop Test as a measure of outcomes after ACL surgery.

The Hop Test may be a good test because it requires neuromuscular control, strength, and confidence that the leg will hold up. It is easy to administer and requires little time or equipment.

Four-hop tests were combined together and given to 42 ACL patients. All patients had surgery at the same center using the same repair and rehab methods. The first test was given 16 weeks after the ACL repair. The test was given three more times. The last test took place 22 weeks after surgery.

Analysis of the results showed that the hop test is both reliable and valid. Change in scores between the first and second tests suggest a fair amount of motor learning took place. Improved scores over the entire six-week period reflect increased strength, coordination, and confidence following recovery and rehab.

The authors conclude the Hop Test is a good way to measure outcomes after ACL repair. It’s a reliable measure of leg strength and stability. The test can be used by therapists to guide treatment decisions. More importantly, it can be used to compare different treatment approaches to see which one works best.

Exercise has been shown to benefit patients with knee osteoarthritis (OA). Different exercise programs have been studied such as quadriceps muscle strengthening and progressive resistive exercises.

At the same time, the use of sodium hyaluronate injected into the joint has also been studied. Given weekly over three to five weeks, these injections work well for patients with moderate-to-severe knee pain.

Perhaps combining exercise with hyaluronate injections (HYL) would work even better. That’s the focus of this study. Researchers asked two questions: how well do these two treatments work when combined together? Is a combined treatment approach safe?

Sixty patients with moderate-to-severe pain from knee OA were divided into three groups. Group one received weekly HYL for three weeks (3-HYL). Group two had three weekly HYL combined with a home exercise program (3-HYL+HEP). Group three received five weekly HYL injections (5-HYL).

Pain was used as the primary measure of results. Pain was measured after each patient walked 50 feet. A baseline test was done before treatment and at regular intervals up to one year after treatment.

There was no difference in baseline scores among the three groups. All patients rated their pain as moderate-to-severe. After treatment, everyone reported improved function and at least 20 per cent improvement in their pain levels.

There was much faster and better pain relief in the 3-HYL+HEP group when compared with the other two groups. The results lasted through the final follow-up visit after 52 weeks. Patients in the 5-HYL group also had better results than the 3-HYL group. At the end of the year, there were no differences between the 3-HYL+HEP group and the 5-HYL group.

This study showed there may be an added benefit of using HYL with exercise in cases of moderate-to-severely painful knee OA. Pain relief was faster, greater, and longer lasting for the HYL+HEP group compared with the other two groups receiving only HYL. The authors suggest it may be possible to use fewer HYL injections when patients participate in a HEP.

In this study, 12 knees with osteochondritis dissecans (OCD) were treated with surgery. OCD is a condition in which a piece of cartilage separates from the bone taking a fragment of bone with it.

OCD occurs most often in young athletes. Boys and girls are both affected. OCD is treated first with conservative or nonoperative care. Nonoperative care includes protected weight bearing and activity modification for at least three months.

When pain persists and activities are limited, surgery may be needed. Surgery is done to enhance the healing process of the osteochondral fragment. In this study, the surgical procedure used plugs of bone harvested from the patient to hold the unstable fragment of bone in place.

This operation is called an osteochondral autograft transfer or OAT. The specific OAT technique used here is called in situ fixation. It means the fragment is fixed or held in place where it separated from the bone. Holes are drilled and the harvested bone plug fits like a peg through the fragment into the bone beneath it.

All patients had six weeks of rehab with a gradual return to athletic activity. High-impact sports such as basketball and gymnastics were not allowed for the first three months. A series of MRIs were taken to show the progress of healing bone. Everyone was followed at least two years. Some patients were seen for up to five years.

Knee symptoms were improved in all patients after the stabilization operation. There were no problems at the donor site. The MRIs showed healed knees for all patients by the end of three months. This is the earliest healing time reported. Other surgical treatment methods take five to eight months to heal.

A rare case of recurring acute compartment syndrome (ACS) is reported in a career athlete. On two separate occasions this football player suffered minor trauma to the lower leg. Both times the result was pain, swelling, and loss of motion because of a fracture and swelling.

The first time it happened, the football player was kicked in the left leg during a training camp scrimmage. X-rays and CT scans showed a fracture in a synostosis.

A synostosis is a bridge of bone between the two bones of the lower leg. It is not a normal part of the bone anatomy. It may be present at birth in a small number of children, but usually occurs as a result of trauma.

Bleeding into the area forms a pocket of blood called a hematoma. The hematoma starts to fill in with bone cells. This abnormal process is called ossification. As the bone heals, stressful activity causes tiny fractures within the synostosis. The patient starts to have the symptoms described leading to ACS.

Surgery is needed to release the connective tissue called fascia. The fascia surrounds the muscles in the lower leg. Fluid from the swelling gets trapped inside the fascia and puts pressure on the blood vessels and nerves. Serious problems can occur without surgery to release the fascia. The procedure is called a fasciotomy.

In this case report, the football player had an injury, developed ACS, and was treated with a fasciotomy. The following year he went back to playing and was kicked in the same leg again. Fracture of the synostosis, hematoma, and ACS recurred. Fasciotomy was performed a second time.

After two years this player was back to normal with running, cutting, and jumping. The authors point out that synostotic fractures can lead to ACS. And compartment syndrome can occur even after the patient has already had a previous fasciotomy. Removing the synostosis is an option but other studies report it often grows back.

Total knee replacements (TKRs) are made of metal and/or plastic parts. Tiny particles called debris can loosen from the implant. As the knee joint rolls, slides, and rotates during motion, the surface of the implant forms pits, cracks, and uneven surfaces.

Over time, the bone around the implant dissolves and the implant loosens. This process is called osteolysis. Implant failure can be the final result.

In this review article, researchers explain three of the major factors known to cause wear debris and osteolysis. These factors are patient activity, implant design, and joint alignment.

There isn’t always much that can be done about patient activity. Active adults with joint replacements often want to remain active. That’s why they had the joint replacement in the first place. Many of these patients do not want to give up or modify their activities.

On the other hand, implant manufacturers are actively searching for ways to improve the implant design to reduce debris wear. For example, methods of sterilizing the implant have changed for the better.

The optimal thickness of the implant has been determined. Stronger materials have been developed. A new process called cross-linking has improved implant resistance to wear. Many other design changes have been made to improve the contact area, load bearing, and shape of the implants.

The surgical procedure is the last factor to consider. Good alignment and proper mechanics are needed to avoid increased forces and uneven load on the joint. Even minor deviations from neutral can result in implant failure.

The authors provide guidelines for management and intervention if osteolysis occurs. No treatment is needed if the patient has no symptoms and the condition is self-limiting (doesn’t get worse). Surgery is advised when the patient has symptoms and the X-ray shows osteolysis is increasing in size quickly.

Early discharge from the hospital is now standard practice after total hip or knee joint replacement. But serious complications can occur, including death. How soon can patients be safely released to go home? Researchers from the Rothman Institute of Orthopedics in Philadelphia may have the answer.

The records of 1,636 total hip and total knee patients during one year at the Rothman Institute were reviewed. Complications in the hospital and for six weeks after were recorded. All patients were followed by an internist during the follow-up.

Complications were put into two groups: systemic and local. Major systemic problems included any life-threatening condition such as heart attack, blood clot, and heart or kidney failure. Minor systemic complications included anemia, urinary tract infection, pneumonia, or change in mental status.

Local complications were also divided into major and minor problems. Nerve or blood vessel injury and bone fracture around the implant were examples of major local complications. Wound drainage or infection, skin blisters, and severe muscle spasm were listed as minor complications.

One patient in the group died and six per cent of the group had major complications. Most of the life-threatening complications happened in the first four days before discharge from the hospital. Some problems could be predicted based on patient’s age, body mass index (BMI), and overall health. But more than half of the patients who ended up with life-threatening complications had no obvious risk factors.

The authors conclude hip and knee replacement continue to be one of the most safe and effective orthopedic surgeries today. Improvements in surgical techniques and anesthesia have reduced the number of deaths following joint replacement.

Even so, based on their results, they advise against current trends toward even shorter hospital stays. Patients who have minimally invasive operations are still at risk for the same major complications as with a standard joint replacement.

Measuring stiffness in arthritic knees is not easy. Most often, doctors rely on the patient’s report of stiffness. The most common way to measure stiffness is through the use of a self-report tool called the WOMAC.

The WOMAC is a survey including 24 questions about pain, function, and stiffness in patients with knee osteoarthritis (KOA). In this study, physical therapists use a three-camera computerized video system to measure stiffness of the knee.

Two groups of adults were tested. The first group had X-ray diagnosis of KOA and reported pain in the last month. The second (control) group were healthy adults matched by age and sex.

One test was performed on each person in both groups. The test was repeated a second time within two weeks of the first test. For each trial, the person sat on an exam table in a relaxed position. The thigh was supported by the table. The knee was bent with the lower leg dangling off the table.

With the person relaxed, the tester straightened the leg and then released it. As the knee fell into flexion, a Motion Analysis system recorded the pendulum motion for five seconds. The angle of knee motion was used to calculate stiffness and damping. Damping reflects how long it takes the knee to stop swinging.

The authors report this pendulum test is a reliable test to measure stiffness in patients with KOA. Their study did not have enough people in it to report valid findings. Further study is needed to confirm these results.

There are many reasons why knee stiffness occurs after joint replacement. In this article, ways to predict and manage such a problem are reported. Computerized records of almost 10,000 patients were reviewed to provide this information.

Stiffness was defined for this study as less than 90-degrees of knee flexion. Two groups of patients were compared. The first group had a total knee replacement (TKR) with stiffness afterwards. The second (control) group had a TKR without stiffness.

Everything about these patients was compared. For example, age, race, sex, and body mass index were compared. Range of motion before the surgery was reported. Details of the operation such as length of time and blood loss were included.

The authors report that more patients with stiff knees after TKR were younger than the control group patients. Women were affected more often than men. They had shorter patellar (kneecap) length and longer patellar tendon. These changes lead to a slightly different position of the patella (lower on the knee) called patellar baja.

Two other predictive factors of knee stiffness after TKR were lower body mass index and increased flexion angle of the femur (thigh bone). Analysis of tissue samples from around the knee showed definite differences in the repair process of the stiff knees.

The authors suggest a genetic tendency to have chemical imbalances during tissue healing may be a key feature in patients with knee stiffness after THR. Treatment to prevent this from happening may be possible in the future. Both pharmacologic and rehab approaches should be studied as potential ways to prevent disabling stiffness.

Patient reports of knee function and activity level are important outcomes after anterior cruciate ligament (ACL) reconstruction. Returning to the same preinjury sports level is an important goal for many athletes after ACL repair.

In this study, patient self-reported outcomes are compared for two groups of patients. Group one was five or more years after ACL repair. Group two was between two and four years out from surgery.

Results were measured using surveys mailed to the former patients. A specific tool called the IKDC Subjective Knee Evaluation was used. It assesses symptoms, function, and sports activity.

All patients in both groups had an ACL reconstruction using allograft (donated) tissue. Both groups were similar in age and level of activity before their ACL injuries.

The results between both groups were the same with the exception of lower scores on the sports activity scales. Both groups had lower scores but moreso for group one. This group (more than five years after surgery) reported more symptoms and greater functional limitations keeping them from engaging in sports.

The authors suggest that most ACL patients naturally decrease sports activity after surgery to protect themselves from further injury. Later, they may decline even more because of aging. It’s also possible patients memory of before and after treatment is faulty.

Further research is needed to compare patient’s perceived function and actual limitations.

Knee bracing is an acceptable solution to off-loading stress on the joint in an effort to control pain and stiffness. Bracing allows the patient to control the position of the knee in order to reduce symptoms. Braces can either be ready to wear off-the-shelf or custom made for each individual patient.

In this study, short-term results are compared between these two types of knee braces. Ten adult patients with a diagnosis of varus gonarthrosis were included.

Varus gonarthrosis means there’s been arthritic wear and tear of the medial (inner side) of the knee joint. The patient has medial knee pain and stiffness. The X-ray shows narrowing of the medial joint space.

Both braces have thigh and leg straps to hold the brace in place. Upright bars on either side frame the leg. Hinge joints on both sides allow full knee motion. The wearer uses a special key to make adjustments of the angle. The custom-fit brace is made based on specific measurements of each individual patient. The off-the-shelf brace is more of a generic one-size-fits-all.

All 10 patients wore both braces an average of eight to nine hours each day. Half the group wore the custom-made brace everyday for four or five weeks. The other half wore the off-the-self brace for the same time period. Then each group took a two-week break before switching to the other brace.

Comparisons were made based on pain, stiffness, and function. A special 3-D computerized system was used to analyze gait and stair-stepping activities. Knee angles were calculated from full-length X-rays taken of the hip, knee, and ankle.

Results showed that the custom brace was more effective in pain relief, reduction of stiffness, and improved function. Speed of walking was no different between the two braces but knee angles were better during stair climbing with the custom brace.

The authors suggest use of a patient-adjustable, valgus-producing unloader brace for patients with varus gonarthrosis. Allowing patients to adjust the custom brace to get the best pain relief is a good idea. Both off-the-shelf and custom-fit bracing have positive benefits. The custom-fit brace is more effective overall.

Sometimes surgery fails. Fortunately, this doesn’t happen very often. In the case of anterior cruciate ligament (ACL) repairs, a second operation is needed when the first one fails.

Studies show that the results of the revision ACL reconstruction (RACLR) aren’t as good as the first operation. The original surgery is referred to as primary ACL reconstruction (PACLR).

In this report, surgeons from the Vanderbilt Sports Medicine Center in Tennessee review how and why PACLR fails. They describe technical and diagnostic errors and offer suggestions for ways to improve outcomes. A very useful flow chart is provided for the surgeon when preparing to do a RACLR.

Loss of motion and scarring are the most common complications after PACLR. Less often, poor surgical technique or too little or too much rehab can lead to poor muscle function or knee instability. Sometimes athletes return to sports too soon. The ACL graft has not healed or rehab has not been completed. The knee isn’t able to respond to stress when there’s still a loss of neuromuscular control. In such cases, traumatic reinjury leads to PACLR failure.

Errors in how the surgery is done are the most common cause of ACL graft failure. For example, the donor graft may be damaged when it is harvested or when it is implanted. The graft may be put in the wrong place or with the wrong amount of tension (too loose or too tight). The surgeon creates a tunnel through which the graft is threaded. Tunnel placement must be just right to prevent problems from the wrong amount of graft tension.

In order to avoid increased loads on the PACLR, the surgeon must make sure all surrounding soft tissues are intact. Any other damage to the ligaments, joint capsule, or cartilage must be repaired during the first operation.

When a revision operation is needed, the surgeon must examine the patient carefully before surgery. The surgeon must decide what to do with fixation devices used in the first operation. Some can be reused. Others must be removed. The size, shape, and placement of the tunnel may need to be changed.

In the future results of both PACLR and RACLR may be improved by identifying risk factors for failure. Knowing the risk factors will help surgeons take steps to avoid problems by choosing the right procedure for each patient.

Scientists continue to look for the cause of patellofemoral pain syndrome (PFPS). Finding the underlying problem could lead to better, more effective treatment.

PFPS is a common cause of knee pain. The patella (kneecap) normally tracks up and down in a groove over the front of the knee. Muscle imbalance may pull the patella away from that groove resulting in PFPS.

Studies so far show mixed findings about the influence of muscle strength, control, and timing. Some researchers report that early activation of the vastus lateralis (VL) may be a key factor.

The quadriceps muscle along the front of the thigh is made up of four sections of muscle. The VL is the section of muscle along the lateral or outside edge of the thigh. When the VL contracts before the vastus medialis oblique (VMO), the patella moves away from the midline and off track. The VMO is the section of the quadriceps muscle located on the inside of the thigh.

This study further investigates neuromuscular control of the hip and knee in patients with PFPS. The effects of weight-bearing exercises on the timing of the VL, VMO, and hip muscle activity are measured. Muscle activity was measured using electromyographic (EMG) readings.

Each subject completed five trials of a stair stepping task. Then they followed a supervised six-week rehab exercise program. At the end of the six weeks, everyone was retested on the stair stepping activity. Changes in EMG readings were recorded and analyzed.

Patients with PFPS had much slower activation of the VMO compared to normal, healthy adults without PFPS (the control group). After training, the VMO contracted sooner int he PFPS group. There was no change in the timing of the VL. The hip muscle tested (gluteus medius) did not change in when it contracted or how long it stayed contracted (duration) during the activity.

The authors say this study supports the use of weight-bearing exercises to decrease pain and improve function for patients with PFPS. A specific rehab program of balance, stretching, and strengthening of hip and knee muscles restored the normal timing of the quadriceps muscle.

Future studies are suggested to test each exercise individually instead of altogether. It’s possible that one exercise is more important than the others.

Many studies report on the results of anterior cruciate ligament (ACL) repairs. In this study from the Sports Injury Center in Rome, Italy, the results of ACL revision are reported.

Thirty patients who had a primary or first ACL repair had to have a second (revision) operation when the ACL repair failed. All revisions were done using a hamstring tendon graft. The surgeon also used a fixation (holding) device. The same surgeon performed all revision operations.

The hamstring muscle is made up of several major muscles and tendons. Two of those tendons (gracilis and semitendinosus) were folded over and used together to replace the primary repair.

The tibial fixation device used to hold the soft tissues in place is made up of three parts. These include a screw, a coil that goes inside a tunnel in the bone, and a washer to hold it against the bone.

There was significant improvement in joint laxity after revision surgery. Patients had full joint motion and all were able to squat fully. Thigh muscle size and strength were still less on the operative side compared to the uninvolved side at the time of testing. Almost all patients had full return of function. Three patients (10 per cent) had a failed revision surgery.

The authors report that not all patients with failed ACL repair need revision surgery. A second operation should be considered when there is knee pain and instability during daily activities or sports.

We can expect to see an increase in ACL injuries as the number of people participating in sports increases. This increase goes along with more failed repairs and failed revisions. The most common cause of failed ACL repair is surgical error.

This study reports on one method to revise the repair. Other surgeons will explore different methods to treat this problem. The authors say that although the patient will have a stable knee, they should be warned that degenerative joint disease is common.

Improvements in joint replacements have made it possible to have a unicompartmental knee replacement (UKR). Instead of replacing the entire joint surface when only one side of the knee is arthritic, just one compartment is replaced. In most patients, the medial or inside half of the knee is removed and replaced.

But there are pros and cons to this idea. UKR costs less than a total knee replacement (TKR). The UKR is less invasive and recovery time is shorter. The TKR may cost more but it lasts longer. If the UKR has to be revised or eventually replaced with a TKR, then the total cost is greater than if the patient just had a TKR to start with.

In this study, the costs of the UKR are compared with a TKR for elderly low-demand patients. Low-demand refers to older adults who are inactive or sedentary. Medicare reimbursement was used to calculate average costs. The researchers took into consideration the risks and benefits of each treatment method.

They used data from a Norwegian national registry with over 9,000 TKRs and 770 UKRs included. Implant survival rates were available up to 10 years after the operation. Using probability rates for infection and revision, they predicted how long each implant would last up until the death of each patient.

The authors report on the basis of their findings that UKR shouldn’t be rejected just because it might not last as long as a TKR. In low-demand patients, a UKR costs less and often outlasts the patient. The model used in this study only accounted for the possibility of a single revision for each UKR or TKR. More studies are needed to compare costs under a variety of conditions.

Athletes who injure the anterior cruciate ligament (ACL) in the knee often have an ACL repair. The surgeon can use a piece of the hamstring tendon to replace the torn ACL. The semitendinosus (ST) tendon is harvested and used as a donor graft.

Studies have shown that the ST does regenerate (grow back). In this study Japanese researchers use MRI and strength testing to see if the athletes regain full function after regeneration.

They found that strength in full knee flexion (squat position) does not always return. It appears that tendons regenerate and reattach in slightly different places. When the tendon reattaches below the knee joint, athletes can perform both shallow and deep knee flexion with strength equal to the other leg.

When the tendon regenerates fully but attaches above the knee joint, then deep knee flexion is compromised. In a few athletes, the tendon did not appear to regenerate at all. They were limited in strength with knee flexion measured at 45- and 90-degrees.

Poor regeneration or altered attachment of the tendon can be a problem for athletes. Those who need greater strength with full knee flexion such as judo athletes, gymnasts, and ballet dancers may be affected most.

The authors conclude there is a need to prevent deficits in knee-flexion torque (force). This is especially important for some athletes. Further studies are needed to find out what will improve tendon regeneration and attachment. It may be that changes in the surgery or the rehab program (or both) could improve the final results.

Various repair systems have been devised for meniscal tears of the knee. Small tears may be repaired with sutures. In some cases, an absorbable implant such as the Stinger, Arrow, or Meniscal Screw is applied. For large tears, surgeons often use both. Sutures are used in places easy to reach. More difficult areas are repaired using the implant.

In this study, German researchers measure the strength of meniscal tears repaired using a vertical suture made out of braided steel wire. Human cadavers were used to test the distraction forces on the suture.

The study was done in a lab where the scientists could make a cut in the meniscus. The incision was designed to mimic a naturally occurring bucket-handle tear. Bucket handle tears divide the meniscus in two pieces horizontally. This leaves the outer portion able to lift up away from the rest of the cartilage. The effect is much like a bucket handle lifts up from the edge of the bucket.

Tiny load sensors were connected to a wire along the edge of the repaired meniscus. The knees were tested at different knee joint angles from zero to 120-degrees of knee flexion.

Weight load and degree of internal or external rotation were also measured. The scientists were looking for the load it would take to pull out the suture. This is called the pull-out strength.

The authors report distraction forces on the meniscus were never enough to cause damage to the repaired meniscus. The average force across the tear was never more than five N (newtons). Five newtons are equal to one pound.
The conclusion of this study was that repair systems for meniscus tears can’t be tested just by relying on distraction forces. It’s likely that shear forces (not measured here) are a major factor in meniscal tears. This study just looked at the medial meniscus. Future studies must measure the forces on a torn lateral meniscus as well.

Many studies have been done comparing the two methods of anterior cruciate ligament (ACL) repair. Good to excellent results are reported with both the patellar tendon graft and the hamstring graft methods.

This five-year study is one of the longest known follow-up periods comparing the results of these two ACL procedures. All operations were done by the same surgeon during this period. Surgical technique for graft fixation used was the same throughout. All patients followed the same prescribed rehab program.

The major finding of this study was the increased number of patients with osteoarthritis (OA). OA was seen five years after ACL repairs using the patellar tendon graft method. A second finding reported was that permanent loss of knee extension can be avoided with an aggressive rehab program.

Other measures of results such as pain, function, and motion were equal between the two groups. But 50 per cent of the patellar tendon group showed X-ray changes. These changes included joint narrowing and bone spurs called osteophytes.

The results of this study confirm that the choice of ACL graft can affect the joint later. The authors say these results were not influenced by meniscectomy (cartilage removal) because the hamstring group had more meniscectomies and less OA than the patellar group.

If you have limited knee motion and cannot straighten the leg fully, you may have what’s called a knee flexion contracture (KFC). This condition occurs when a person avoids motion because it hurts. Total knee replacement (TKR) may help with this problem. The surgeon must release soft tissues and remove bone spurs to help restore full motion.

In this study, surgeons review all cases of KFC treated with TKR. They ask the question, How many steps are needed to correct the KFC? Four steps are evaluated. These include:

Wearing a wedge insole inside the shoe may help patients with early and mild medial knee osteoarthritis. Medial refers to the inside compartment of the joint — the side closest to the opposite knee.

The Researchers at the Gait Analysis Laboratory, Division of Physical Therapy, Fukui University in Japan made a study of patients wearing a lateral wedged insole inside the shoe. The idea is to shift some of the weight off the medial joint by moving the weight slightly to the inside of the foot.

Each patient was fitted with light-emitting diodes from the hip to the thigh. Walking was analyzed using a special computerized system. As the patient walked, a light measuring device and force plates captured walking speed, stride width, and step length. X-rays taken also recorded hip-knee-ankle angles. The same measurements and analysis were made with and without the wedge.

Computer analysis of the results showed decreased step length, stride width, and walking speed in patients with OA but without the wedge. These measurements were compared to healthy normal adults in a control group. After wearing the lateral wedged insoles, the stride width changed but length and speed did not change.

Beneficial changes were only observed in patients with mild (grade 1 or 2) medial knee OA. Dynamic load on the knee while walking is known to be linked with severity of disease. If the knee can be unloaded with a simple wedge insert, the progression of OA may be slowed. Patients may experience less pain and become more active.

The results of this study support the use of a lateral wedged insole for anyone with Grades 1 and 2 medial knee OA. Since measurements were taken right after wearing the wedge insoles, the authors suggest another study to measure the results after several months.