News Category: Knee

This is the first study to report on the results of an all plastic (polyethylene) knee replacement for patients younger than 60 years old.

Total knee implants have gone through major design changes over the years. Metal backing for the lower leg (tibial) portion of the implant was used in the 1980s. Surgeons thought this type of material was stronger with less wear and tear on the bone.

By the 1990s metal backed tibial implants were standard in most total knee replacements. Another 10 years and it’s clear that there’s a downside to this type of implant called backside wear.

This refers to the underside of the tibial plate as it comes in contact with the bone. Severe bone break down called osteolysis from the metal backed implant is a problem. The pendulum has swung back toward using all plastic (polyethylene) implant parts.

The results of this study show good results with the all-poly model in adults ages 47 to 60 years old. All patient were followed up for at least two years. Some were seen for up to 11 years. This shows the all-poly is made to last even in younger, active patients.

There’s a lot of interest in the new mini-incision for knee joint replacement. In this study surgeons compared two groups of patients. One group had the mini-incision done. The second group had the standard length incision. There were 30 patients in each group. They each got the same type of joint implant.

Pain, function, and blood hematocrit (to measure blood loss) were reported for each patient. Other factors related to the surgery were also compared. For example, they looked at surgical time, use of drugs for pain, and problems after surgery.

The authors report the mini-incision group used 15 percent less pain medication. Their range of motion was slightly greater than the standard group. This was only true for the first three days after the operation.

The biggest problem reported was malalignment in the mini-incision group. With this method the surgeon has more trouble seeing inside the joint and finding the landmarks needed.

The authors conclude improvements are still needed. Special surgical tools are needed for the mini-incision method. Better implant designs and the use of computers to guide the surgeon may help reduce problems of alignment.

This is the second study by Dr. Richard Laskin from Cornell University on the use of a new approach to the minimally invasive (MI) total knee replacement (TKR). MI means a small incision is made to complete the operation. With MI, fewer structures are cut or disrupted.

The first study was a pilot study to see the results with a few patients. Dr. Laskin used a mini-midvastus approach. This means the cut was made along the front of the leg from just above the kneecap (patella) and slightly off center, straight down, and a short way below the patella. The patients had an excellent result.

In this follow-up study, 100 TKRs were done with this same method. The purpose of the study was to find out:

Fracture of the kneecap (patella) after a total knee replacement (TKR) is rare. This report of eight such cases offers some insight into the results following removal of the fractured kneecap. The operation is called a patellectomy.

Pain, range of motion, and function were the measures used to assess results. Half the patients didn’t have any pain after the patellectomy. Three had mild pain and one had severe pain. Range of motion and function were not improved. Two of the patients needed more surgery later due to related problems.

The authors hope this information can be used as a baseline since there’s so little known about the results of patellectomy after TKR. It may help others compare their results for this problem in the future.

Cartilage tears in the knee are no longer just removed. Now they are repaired to prevent osteoarthritis later. There are at least a half dozen ways to repair cartilage injuries. This study compares the results for two methods used: debridement versus autologous chondrocyte implantation (ACI). All patients had full-thickness cartilage tears at the end of the femur (thigh bone).

Debridement works well for small cartilage tears. The surgeon carefully scrapes away any loose fragments or flaps of cartilage. The goal is to get back to a smooth, seamless interface between cartilage and bone.

ACI involves removing cartilage cells and growing more of them in a laboratory. The new cells are injected into the defect in the damaged cartilage. Any other repairs needed of nearby ligaments or meniscus were made at the same time.

Results were measured in terms of pain, swelling, and function for three years. Researchers made note if the patients reported the leg giving way either partially or fully. Anyone having a second operation was also reported.

The authors report both groups were better during the follow-up visits. The ACI group had more function and fewer symptoms when compared to the debridement group. They found the type of defect affected the outcomes for the debridement group only. Failure rate was equal between the two groups.

This first study comparing ACI and debridement showed ACI to be the better treatment. It may be the optimal treatment for large or chronic cartilage defects.

New ways to treat cartilage tears in the knee work well for the average person. How well do they hold up for high-level athletes? Researchers take a look at this question and report their results after studying 45 soccer players.

Autologous chondrocyte transplantation (ACT) is a newer method of full-thickness cartilage tears in the knee. Full-thickness means the cartilage is damaged all the way down to the bone. With ACT treatment normal, healthy cartilage cells are taken out and multiplied in a lab then reinjected into the defect.

Results were measured based on activity, function, and return to soccer. Data on the timing of the return and the skill level upon return was collected. Three-fourths of the players reported good to excellent results.

Only one-third of the group returned to soccer. Most of these players were at a high-level and returned to their former level of play. The average amount of time off was 18 months. Very few recreational players went back to the game.

The authors conclude ACT repair of cartilage repairs do hold up under maximum mechanical stress. ACT may work best in younger, high-level athletes. In this study gender didn’t seem to matter — men and women had the same results. Those who had fewer knee surgeries before ACT had the best results.

Doctors from the Aix-Marseille University in France update research they did 15 years ago. The information they gathered looks at the long-term results of patellofemoral arthroplasty (PFA) (kneecap replacement).

All the patients were adults (ages 21 to 82 years). They all had severe osteoarthritis (OA) of the patellofemoral joint. This is where the kneecap moves over the thighbone (femur). The implant was made of plastic (polyethylene), cobalt, and chromium.

About half the group still had the original implant in place 16 years later. One-fourth of this group reported moderate pain. X-rays showed the PFA was stable with no sign of loosening. Most of the other patients had further surgery over the years. Total knee replacement (TKR) was the most common operation. The patients’ with primary osteoarthritis got worse requiring this next step.

The authors point out that patients who develop OA after trauma or patellar instability didn’t need a joint replacement. The arthritis remained stable and didn’t progress. They also found that PFA after patella fracture resulted in severe stiffness after the operation.

They conclude the PFA is a good option for middle-aged patients with good knee alignment. It should be put in place keeping in mind the possible need for future TKR. They prefer a TKR for older patients to avoid a second surgery.

Pain. Pressure. Paresthesia (numbness). Paralysis. Pulselessness. These are the five warning signs of acute compartment syndrome (ACS), a medical emergency. In this article doctors from Duke University review the causes and effects of ACS. They offer orthopedic surgeons ways to watch for this serious complication of lower extremity injury.

ACS is defined by rising pressure between the bone and fascia of the lower leg. The compartment formed by these two structures loses its blood supply. The tissue starts to die. Gangrene is a real danger. That’s why it’s such a serious condition.

ACS occurs after a variety of injuries and medical conditions. Fractures, contusions, bleeding disorders, burns, trauma, and gunshot wounds are a few of the most common causes. Traction for the leg after a fracture, a cast that’s too tight, and ankle position are other risk factors for ACS.

The authors advise doctors to do repeated exams in patients at risk for ACS. The presence of the five Ps and changes over time are red flags. The most common methods of measuring compartment pressures are described. Early measurements are recommended so that early changes can be recognized and treated right away.

Past studies have pointed out the importance of some factors affecting knee motion after total knee replacement (TKR). But it’s been awhile since these have been reviewed.

New implants and surgical techniques may have changed things. The authors of this study take a new look at the things that can affect motion post operatively.

The knee replacements in 192 patients (total knees: 219) were examined. X-rays were used to see the effect of implant position on motion. Other factors tested included age, gender, and body mass index (BMI). Diagnosis and motion before surgery were also tested.

One surgeon did all of the TKRs using a single type of implant. All patients had physical therapy afterward. No one used continuous passive motion. Everyone went home five days after surgery.

The results show that gender doesn’t make a difference on knee motion after TKR. The affect of age is still unclear. BMI was not strongly linked with motion in this study.

Past studies did link knee motion before the operation with motion afterwards. There was some connection in this study between flexion before and after surgery.

The authors found that the use of today’s more modern and up-to-date implants have changed how surgeons view results. This analysis shows that implant size and type no longer influence final knee motion after TKR.

Wanted: An exercise program to speed up recovery after knee injury.
Wanted: Full return to normal activity after knee injury.

Physical therapists help both athletes and nonathletes recover and return to everyday activities and sports after knee injuries. They are actively looking for the best way to do this. They want a program that helps speed up healing and recovery.

The authors of this study say that a full understanding of neuromuscular control of the knee is needed. They studied 15 healthy adult knees (male and female).

Squats on one leg with resistance to movement was the main exercise studied. Different amounts of resistance were used. Both knee flexion and extension were included. Activity of seven leg muscles was measured during the exercise.

The authors report two major findings. 1) Part of the hamstrings muscle (biceps femoris) was active during the entire squat activity. 2) As the resistance increased, the quadriceps was less active. This means with less quadriceps activity, the hamstrings exert greater control over the joint. The hamstrings protect the knee from forces on the joint during single leg squats.

Found: Single-leg squat exercises.
Found: A way to resist both knee flexion and extension to improve neuromuscular control.

Sometimes it happens that a surgical repair fails and has to be done over. The authors of this study report two cases of early problems after a second (revision) ACL repair.

In the first case a 40-year old woman had injured her left ACL in two separate skiing accidents. She fell at home for a third knee injury. The middle third of the right patellar tendon was used as a graft to repair the ACL.

The night after surgery she had an avulsion fracture of the tibia. This means the remaining patellar tendon pulled away from the bone where it normally inserts. Another operation was needed to repair the fracture.

In the second case a 39-year-old woman had a right ACL repair two years ago. She went to the orthopedic surgeon with reports of right knee pain. She had surgery to repair a torn meniscus and revise the previous ACL repair. A piece of her patellar tendon taken from the other leg was used to repair the ACL.

The same day while pivoting to move from a stretcher to a wheelchair, she felt a pop in her knee. An MRI showed the patellar tendon had pulled away from the tibia (lower leg bone). Surgery was done to repair the new damage.

These case studies show that problems can occur after ACL revision surgery using graft tissue from the other knee. The authors warn against overloading the donor knee. Overload can occur while the patient is still under the influence of a local anesthesia. Patients have a tendency to shift too much weight off the repaired knee onto the donor knee.

Doctors know there can be problems without repair of a torn anterior cruciate ligament (ACL). The knee can become unstable. The ACL helps hold the knee joint together and keeps the bones from sliding around.

In this study researchers used MRIs to measure the amount of forward slide of the tibia (lower leg bone) on the femur (thigh bone). In the normal adult, there may be a small amount of this motion. When too much slide is present, this movement is called anterior tibial subluxation or ATS.

The knees of 96 patients with deficient ACLs were measured. The authors found the amount of ATS increases the longer the knee remains unstable. And the more unstable the joint, the greater amounts of ATS were present.

Based on these findings, the authors advise surgeons to use landmarks on the tibia when making tunnels in the bone to repair the ACL. Using landmarks on the femur may not be a good idea. With ATS the femur may shift in relation to the tibia.

They also point out that a patient with ACL deficiency who does not have ATS will develop it over time. This is another reason to repair the torn ACL sooner than later.

With the aging of America the number of adults having joint replacements in the United States is expected to go up. But how much has it increased in the last 10 years? And how much will it go up from there?

Finding out current rates and predicting future rates was the goal of this study. Another goal was to see how often joint replacements have to be revised or replaced. Groups of patients were analyzed based on age. Age groups included less than 45, 45 to 64, 65 to 74, 75 to 84, and 85 and older.

Total number of adults in each group living in the United States was calculated from the 2000 census. Data from the National Hospital Discharge Survey (NHDS) was used to count the number of total hip and knee replacements in the United States. Using these two figures researchers could find percentages of adults having joint replacements and revisions.

The results showed the number of total hip replacements has doubled in the last decade. Total knee replacements have tripled over the same time period. More women and more people over the age of 74 are having joint replacements than ever before. The number of revisions has increased with the overall increase in joint replacements. The relative amount has remained the same.

As expected, the results of this study confirm the fast growth in the number of joint replacements for adults of all ages. Increases are likely explained by the increase in obesity and osteoarthritis. Past guesses about future trends were based on the same number of implants being done each year. This study shows that future numbers are expected to rise at a rapid rate.

Scientists are looking for ways to help patients recover faster from total knee
replacement (TKR). Nutritional supplements may help. In this study creatine was used before and after surgery.

Creatine is made naturally in the body. It’s also present in foods like meat. It’s stored in the muscles and has some important functions in the muscles. Researchers looked to see if it would help with TKR patients. Other studies have shown creatine supplementation builds muscles mass and strength.

It didn’t seem to have that effect on older adults with osteoarthritis having a TKR. There were no measured changes in muscle content or strength. Patients were followed for 30 days after the surgery. In fact there was a major decrease in muscle strength at the knee and ankle at the end of 30 days.

The authors suggest that the lack of physical activity in this older group with arthritis prevented uptake of creatine into the muscles. Other more successful studies included adults of all ages who combined creatine with resistance training. More study is needed to find ways to boost bone healing and recovery of muscle strength.

In this study radiofrequency (RF) (a form of heat) was used to shrink a partially torn anterior cruciate ligament in 19 patients. After one year 86 percent of the patients still had a stable knee. After five years 85 percent had complete failure of the ACL. The results of this study do not support the use of thermal shrinkage to treat ACL laxity.

Doctors are looking for ways to treat a torn ACL without using invasive surgery. One of those methods has been the use of heat to shrink the collagen fibers of the lax ligament. Radiofrequency (RF) has been used in the shoulder with some success. This study supports the findings of other studies that thermal shrinkage isn’t successful for torn knee ligaments.

Three kinds of ligament laxity were included in this report. Some patients
had a recent partial tear of the ACL. Others had an old, chronic injury. A few had ligament laxity from a previously repaired ACL injury. In this last group the graft used to replace the ligament stretched after surgery.

The authors call the failed thermal shrinkage in this study “catastrophic.” They say that RF treatment may work in the short-run, but its effects aren’t worth it in the long-term.

Researchers from several large medical groups did a meta-analysis of anterior cruciate ligament (ACL) tears. They looked to see which treatment method works better: bone-patellar tendon-bone (BPTB) or hamstring tendon (HT) graft.

They found 11 reports that met the standards of this study. Problems and
benefits of each treatment type were reviewed and compared. Both methods work well. Knee pain from the donor-site of BPTB (front of knee) has led to an increased use of the HT graft. The ability to kneel without pain makes the HT graft popular.

On the other hand patients with a chronically unstable knee may prefer the BPTP. This graft has a high amount of strength and stiffness. It seems to be more stable over time. Young athletic patients are able to get back on the field or in play faster with the BPTB.

The authors conclude that each patient must decide which method is best for him or her. Personal goals can be used to decide which method will best help the patient meet those goals.

There seems to be no way to tell who will get better with nonoperative treatment for patellofemoral pain (PFP). Some patients with severe X-ray findings improve. Others with mild changes on X-ray fail to find pain relief with rehab. In this report, Dr. Post from the Mountaineer Orthopaedic Specialists in Morgantown, West Virginia, reviewed the results of nonoperative care for PFP.

PFP includes pain in front of, around, or under the kneecap. Most often sitting for too long, squatting, kneeling, and climbing stairs cause increased pain. Hopping and jumping can also be difficult. Rehab for this problem usually includes exercise, rest, and anti-inflammatory drugs. Taping, biofeedback, and stretching may also be included.

After reviewing the results of many studies and his own patients, Dr. Post concluded that all patients with PFP should start with nonoperative treatment. Activities should be kept below the level that triggers symptoms. Patients should avoid the old saying: “no pain, no gain.” Surgery should only be used when all other efforts fail to help.

The results of any one medical study can offer good information. But comparing the results of many studies is even more helpful. This is called meta-analysis.

In this meta-analysis doctors compared the results of total knee replacements (TKRs) with and without patellar resurfacing. This means the bony kneecap is removed. It’s replaced with a metal or plastic-backed implant.

The authors asked these questions:

Forty patients at the University of Delaware are helping physical therapists find ways to improve the results of total knee replacement (TKR). Research has shown that many adults lose overall function after TKR. Their pain is better but they walk slower. It takes twice as long to go up and down stairs. Many stop doing their favorite leisure activities such as gardening.

Patients in this study did the usual rehab program after TKR. Four weeks after the surgery they started part two of rehab. The program was six-weeks of exercises and activities. The goal was to increase motion and strength. Training to improve function was also included.

Everyone was tested for pain, motion, and strength. Testing was done two weeks before surgery and again two weeks after surgery. Follow-up tests were done at one, two, three, and six months post-operatively. As expected from the results of other studies, patients showed a decrease in motion, strength, and function one month after surgery. Everything improved after that.

The biggest problem was quadriceps muscle weakness. The researchers found that patients had more function as the quadriceps got stronger. This finding is important as many patients gradually decline in function in the years after TKR.

The authors suggest a more rigorous exercise program may be needed after TKR to regain maximal function. Quadriceps strength is more important than joint pain or motion for recovery.

What’s your guess? Is there any long-term difference in results between allograft and autograft repairs of the anterior cruciate ligament (ACL)? An allograft is tissue taken from a donor, not the patient. An autograft is tissue harvested from the patient.

In this study, researchers predicted no difference when results were compared five years later. They did think patients in the autograft group would have more pain and less function early on compared to the allograft group.

They were right on both counts. Using pain, joint motion, muscle strength, and ligament laxity as measures, both groups were about the same after five years. There was a reported difference between the groups during the first three months.

The autograft group had more pain and less function but less laxity than the allograft group. This means the allograft group had less pain and more function but also more joint laxity. At the end of one year, participants in the allograft group were more likely to say their knees were back to “normal.”

The results of this study show that either allograft or autograft reconstructions of ACL tears are acceptable in the long-run. They both provide joint stability. Allografts have fewer problems in the early days and weeks after surgery.