News Category: Knee

Sometimes surgeons offer other surgeons their knowledge on a particular topic. When published in a journal, this is called a clinical commentary. This commentary on treating articular cartilage defects with the microfracture method comes from orthopedic surgeons at Harvard Medical School.

They review the goals of surgery when treating chondral defects, discuss the two types of defects (partial- or full-thickness), and surgical treatment for both. A chondral defect is a tear or damage of the knee cartilage clear down to the bone. When and how to do the surgery is presented along with results reported from various studies.

Damaged or destroyed cartilage does not heal itself. There is a remodeling system that goes to work after injury but the response is limited. Surgery is needed with the goals of decreasing pain, improving function, and preventing further joint degeneration.

The microfracture technique puts tiny holes in the cartilage down through the bone to the bone marrow. The goal is to stimulate the bone marrow to bring blood to the area. This response starts the healing process.

Some studies show that results are better with smaller defects (less than three millimeters in diameter) with this method of treatment. Others report no difference in results based on size or location of the defect. Microfracture can be used with defects from injury or degeneration.

Some patients may not benefit from microfracture treatment. It is not advised with defects deeper than 10 millimeters or for patients with poor knee alignment. For those patients who do have this treatment, rehab is important. Motion is important but weight-bearing must be limited.

Results of this procedure have been reported. Surgeons use arthroscopy to take a second look. In at least half the knees, defects fill in normally. Other knees show uneven, fragmented, or incomplete healing. Microfracture may fail if tissue repair is more fibrocartilage than hyaline cartilage.

In the mid-1980s, an Australian physical therapist (PT) by the name of Jenny McConnell developed a special way to tape the knee. Patients with patellofemoral pain syndrome (PFPS) seemed to respond well to this treatment.

PFPS is a painful knee condition caused by a misaligned patella (kneecap). The taping helps keep the kneecap in the center where it belongs. This allows better tracking of the patella as it moves up and down along a groove in the bone.

In this study, PTs tried to determine which patients with knee pain would respond best to patellar taping. This is called a clinical prediction rule (CPR). If therapists can tell early on which patients will respond well to treatment with taping, then treatment time and cost can be reduced.

All subjects in this study had PFPS and were given the same tests before treatment started. Some were tests of motion of the knee joint and the patella as it moves over the joint. Muscle strength and flexibility were tested. Ankle motion and alignment were also measured. The authors include a two-page summary of all the tests given.

Pain intensity was also rated on a scale from zero (no pain) to 10 (worst pain). Pain was measured before and after three functional activities. The activities included going up a step, coming down a step, and squatting.

The patients all had the same treatment for PFPS. The patella was shifted to the middle of the knee and taped in place. Each patient repeated the three functional tests and reported pain levels with the tape in place.

Just over half (52 per cent) had an immediate reduction in pain and reported a positive change in their condition. Two of the specific patellar tests (patellar tilt test, tibial varum test) were able to predict who would get better with patellar taping.

The patellar tilt test measures the movement of the kneecap. Too much movement toward the outside of the knee is a sign of patellar mobility that can be helped by taping. The tibial varum test measures the angle of the lower leg bone. More than five degrees of bowing contributes to PFPS and responds to taping.

More testing is needed before these two patient characteristics can be used as CPR for patellar taping. The next step is to repeat the same study with a larger number of patients to make sure the test is valid.

This is the first report of a new suturing method for meniscal tears. The new technique called the cruciate suture is described in detail. The new method provides high fixation strength, which is needed for meniscal tears.

The cruciate suture is recommended for the repair of long tears, complex tears, and degenerative tears. It is especially good for the treatment of elderly patients with meniscal tears.

Surgeons use a variety of methods to repair the torn meniscus. There are four main methods based on whether an open incision is used versus arthroscopic surgery. If arthroscopy is used, then methods are described based on how the needle is inserted. The four main methods of meniscal repair include: 1) open, 2) arthroscopic inside-out, 3) arthroscopic outside-in, and 4) arthroscopic all-inside. The cruciate suture is an arthroscopic outside-in technique.

The cruciate suture was tested on human menisci donated from patients who had a total knee replacement. All donor menisci were from patients with an average age of 75 years. The cartilage was in good condition with no obvious signs of degeneration.

A special testing machine was used to test the ultimate tension load (ULT) of each menisci. The UTL is the maximum load applied to the cartilage before it tears. Once testing was completed, the cruciate suture was made in each meniscus. The strength of the suture was tested using the UTL as the measure. The results were compared with the UTL for repair using a vertical suture.

The authors report greater fixation strength with the new cruciate suture. The UTL for a vertical suture was 67 N compared to 110 N for the cruciate suture. The cruciate suture was 1.6 times stronger than the vertical method, which is currently the gold standard for long, complex, or degenerative meniscal repairs.

In this study, 54 patients with a unicompartmental knee arthroplasty (UKA) were compared with 54 patients who had a total knee replacement (TKR). A UKA replaces just one side of the knee joint. Usually the medial or side closest to the other knee is replaced.

Measures used to compare results included range of motion (ROM), function, and survivorship of the implant. The patients in the two groups were matched (same or similar) in age, body mass index (BMI), and gender. ROM and function before surgery were also about the same in both groups.

All patients were followed for up to five years. Results showed greater motion in the UKA group. Function was the same in both groups. The UKA had a lower survivorship. This means the implant was removed or revised for some reason. In this study, none of the TKAs failed or had to be revised.

The authors report that good results with the UKA has resulted in an increased use of these implants. However, this study showed a high failure rate in the UKA group. They suggest when all things are equal (age, gender, health, severity of arthritis), the TKA was a more reliable choice for knee osteoarthritis.

New treatments for damaged knee cartilage are being developed. Young, active patients are the most likely candidates for this treatment approach. Various cartilage repair techniques are reviewed in this article.

The treatment methods discussed include microfracture, autologous chondrocyte implantation (ACI), and osteochondral grafts. Each of these procedures is used for small areas of damage to the cartilage called focal defects. There are benefits and drawbacks to each treatment method.

Microfracture involves drilling tiny holes through the cartilage to the bone. Cells and growth factors from the bone marrow seep through the holes to form a superclot. The tissue continues to repair itself over the next six to 12 months.

ACI uses a small amount of the patient’s own healthy cartilage. The tissue is harvested from the patient, purified, and expanded. Then it is reimplanted into the damaged area. Success rate with ACI is between 60 to 80 per cent.

Microfracture and ACI treatment to promote regeneration of joint cartilage do not restore the cartilage completely. Osteochondral grafting does restore the hyaline cartilage. In this operation, donor plugs of bone and cartilage are used to fill any area of the recipient’s joint. Problems can occur with tissue rejection and disease transmission anytime donor tissue is used.

Future methods of treating articular cartilage defects are expected to develop. The authors believe full restoration of damaged cartilage in patients with osteoarthritis will someday be possible. New methods of tissue engineering may reduce treatment to a single surgical procedure.

In this study, patients with moderate to severe osteoarthritis (OA) of the knee were treated with electrical stimulation (E-stim). The goal was to delay having a total knee replacement (TKR).

A battery operated E-stim home unit was used everyday for at least eight hours (usually at night while sleeping). Patients used the device for 12-month periods for up to four years.

A second group of patients who had a TKR and no electrical current were used as a comparison (control) group. Patients in both groups were matched by age, gender, and weight. Pain and function were used as measures of results.

Patients in the E-stim group were able to put off (defer) having a knee replacement for up to four years. The first year, 83 per cent deferred TKR. The second year, 75 per cent still had not had a TKR. By the end of the four years, 60 percent had not had the surgery.

The comparison group did not do as well. By the end of the first year, only 67 per cent could put off having a TKR. By the end of the fourth year, this figure was down to only 35 per cent who had not been given a TKR.

The authors conclude E-stim can help patients delay TKR surgery. At the same time, pain and function can be improved. E-stim helps regulate cartilage biochemistry at the cellular level. A strong electrical field influences ion movement in joint fluid and signals the cartilage to repair itself.

The best candidates for this treatment may be adults too young for a TKR, the frail elderly who can’t have surgery at all, and obese patients.

Sometimes patients need both knees replaced because of severe arthritis. If both knees are done at the same time, the operation is called a simultaneous bilateral total knee replacement (TKR). If the patient has one knee done at a time, then it’s called a staged procedure.

The question remains, should both knees be done at the same time (simultaneous)? Or is it better to do the first knee, wait until the patient has recovered, and then do the second knee (staged)?

In this report, the results of 122,385 Medicare patients who had a TKR in 2000 are reviewed. Age, gender, race, and whether the TKR was simultaneous or staged were tallied up. The risk of blood clots to the lung called pulmonary embolism was calculated for both the simultaneous and the staged procedures.

The researchers also looked at where the operations were done and who did them. Total number of TKRs for each geographic area of the U.S., hospital, and surgeon were added up and reported.

The authors report that most of the patients (78.5 per cent) had a unilateral (single) TKR. When a simultaneous or staged TKR was done, it was usually in a high-volume hospital by a high-volume surgeon. Simultaneous TKRs was most likely in white men of higher economic status.

The risk of pulmonary embolism in the first three months after surgery was greatest for patients having a staged operation. However the results must be viewed with caution. If a patient was planning to have both knees replaced in a staged operation but had a clot after the first operation, then the second TKR was cancelled. This factor could make it look like the rate of embolism is higher with unilateral TKRs.

Data from this study may be used to make policy decisions. For example, programs may want to shift patients from low to high-volume centers for simultaneous TKRs. Such a move may lower the overall risk of pulmonary embolism.

Increased sports participation has resulted in more and more anterior cruciate ligament (ACL) injuries. Many athletes return to their former level of activity. This means more people are experiencing a failed ACL repair. In Australia, the number of patients needing an ACL revision has increased 100 per cent over the last 10 years.

In this study, the five- to nine-year results of a revision ACL repair are reported. All 50 patients had a first or primary ACL repair which ruptured and had to be repaired again. The second operation is called a revision reconstruction. All revisions were done using the hamstrings tendon graft method.

Results were measured in terms of pain intensity, level of sports activity, and joint laxity. X-rays were also taken and reviewed. Ten per cent (five patients) of the revision knees failed. The rest of the patients (45 total) had acceptable results at the five-year check-up.

The authors report that overall, results of revision ACL reconstructions are inferior to primary repairs. They found that damage to the surface of the joint was the biggest risk factor for a failed revision.

After the primary ACL repair failed, joint instability led to further joint damage. It is suggested that all primary ACL failures should be revised sooner than later to avoid this type of joint damage and poor outcome.

Is a structured rehab program needed after anterior cruciate ligament (ACL) injury? Would such a program help athletes recover muscle strength to their preinjury strength? How would their strength compare to normal, healthy adults without an ACL tear? These are the questions asked in this study.

Four groups of men were included. Three groups had an ACL injury of differing lengths of time. The time periods included less than six months, six to 18 months, and more than 18 months.

One group of healthy males with no ACL injury was used as the control group for comparison. The control group exercised regularly at high levels making them a good match.

All men were athletes playing regularly in amateur leagues. Cutting and twisting sports such as soccer, basketball, and handball were the most common. After injury they didn’t follow any kind of rehab program. They just did the R.I.C.E. approach with Rest, Ice, Compression, and Elevation.

Quadriceps and hamstring strength were measured for all four groups. A special machine (Biodex) was used to test strength. The Biodex was set at a speed of 60 degrees per second. This setting was chosen because it is less stressful than higher speeds. The 60 degrees per second speed also allows for more comparisons to be made.

The authors report that none of the men in the three ACL groups recovered their full strength. The strength on the injured side slowly improved when compared to the noninjured side. The hamstring muscle was more likely than the quadriceps muscle to come close to normal over time.

The authors conclude that a rehab program is needed after ACL injury. Time and activity will not restore normal strength for the athlete. Supervised training is advised to return to a preinjury level of sports activity.

An organized and guided exercise program may help prevent knee instability during the healing phase. It’s possible this type of structured program could benefit patients who ultimately end up with an ACL repair. Improved knee function before surgery may enhance functional recovery after surgery.

Sometimes people with osteoarthritis (OA) of the knee only need part of the joint replaced. Instead of a total knee replacement (TKR), they get a unicompartmental arthroplasty. Usually the medial side of the joint (closest to the other knee) wears down first and needs to be replaced.

In this report, researchers compared the cost of unicompartmental versus TKR. They used the results of other studies collected in the literature. Out of 345 articles on the topic, nine articles were used for the analysis.

Treatment costs and benefits for each procedure were calculated using a special formula. Utility value, discounting, and hospital costs were calculated as part of the factors. Quality of life, durability of the implant, and improved function were measures used to compare the benefit of these two implants.

The authors report that a unicompartmental implant represents about a 25 per cent cost savings over a TKR. Shorter hospital stay, lower physician cost, and savings on the cost of the unicompartmental implant account for the difference.

The TKR is expected to last at least 15 years. The expected survival rate of the unicompartmental implant is closer to 12 years. The unicompartmental implant has to survive within three or four years of a TKR for equal benefit to occur when comparing costs.

All in all, the authors say the unicompartmental implant is a good choice for some patients with unicompartmental knee arthritis. Durability and function are improved just as much as for patients who get a TKR but at one-fourth less cost.

Women are more likely than men to have arthritis-related disability. They are three times less likely to have a total knee replacement (TKR) compared to men. And when they get a new knee, it’s much later than men.

In this article, researchers investigate the need for an implant designed just for women. Such an implant could be sized down to meet the needs of the female anatomy.

Reviewing results of other studies, the authors found that a gender-specific implant may not be needed. A narrower implant with less overhang on the sides may be all that’s required. Larger women with a higher body mass index (BMI) (30 or more) have a larger thigh so a small implant isn’t always needed.

The goal of a TKR is to decrease pain in order to improve motion and function. The goal of recreating perfect anatomy with a designer implant isn’t cost-effective. Giving the patient a stable joint with balanced soft tissues around the knee is more important than developing a separate system for men and women.

How accurate are MRIs in predicting which meniscal tears can be repaired? Orthopedic surgeons at the University of Paris (France) compare arthroscopic results with prior MRI images to help answer this question.

This type of study uses the final diagnostic results from surgery to look back at MRI findings and see how accurate they were. Knowing what the surgeon found during the operation helps radiologists further refine what to look for on MRI images.

The goal is to recognize on the MRI meniscal tears that can be repaired. Specific MRI observations typical of a reparable lesion are described in detail. Only one type of meniscal tear was studied called a bucket handle meniscal tear (BHMT).

The meniscus is a horseshoe or C-shaped piece of cartilage. When the tear goes from top to bottom of the cartilage, the outer half of the torn meniscus can lift up. The motion resembles a bucket handle being lifted up and away from the rim of the bucket.

The results of this study show good agreement between MRI and arthroscopic findings. Only one case of a BHMT that could be repaired was missed on MRI. The authors say MRI is a good screening tool to identify reparable tears. The surgeon should be aware that new tears can occur after the MRI but before arthroscopic surgery.

Full-thickness cartilage defects in the knee are usually treated with microfracture repair. The two-year results of this treatment for 48 patients are reported in this article.

There are several layers of cartilage and bone in the knee. The outermost layer is called the hyaline cartilage. The next layer is the calcified cartilage. The first layer of bone next to the cartilage is the subchondral bone plate. And finally comes the cancellous bone.

Cancellous bone is spongy bone found at the ends of femur (thighbone), the upper portion of the knee joint. This spongy bone has red bone marrow, which helps with the production of red blood cells. Cancellous bone is where most of the blood vessels of the bone are located.

A full-thickness defect removes the protective cartilage and results in bone rubbing on bone. The microfracture treatment removes the calcified cartilage first. This helps improve bonding between repair tissue and the subchondral bone.

Then a special tool called an awl is used to put holes in the subchondral bone layer. The surgeon must push the awl far enough in to reach the layer of cancellous bone. The authors describe the steps of the microfracture procedure in detail.

Results were measured by increase in activities of daily living and overall function. Factors negatively affecting improvement included obesity, length of time before the operation, and poor fill in of the defect.

Positive factors for a good outcome are just the opposite: low body mass index (BMI) and short time of preoperative symptoms. Good fill in was more likely when the layer of calcified cartilage was scraped away first. The authors say a systematic approach during surgery is important for a good clinical outcome.

Injuries in the military reduce productivity and troop readiness. Finding ways to prevent such injuries is an important goal. The results of this study from Marine Corps basic training at Parris Island (South Carolina) show that the incidence of lower extremity (LE) injuries in female recruits is high. Risk factors were identified.

Out of 824 female recruits, there were 868 overuse injuries to the LE. And injured female Marine Corps recruits were more likely to reinjure themselves after returning to training. A key risk factor for all injuries was low aerobic fitness. This assessment was based on a slower time for these women on the timed run.

Amenorrhea (not having a menstrual cycle) was another significant risk factor. Women who had not had a menstrual cycle in over six months were more likely to get injured during basic training. None of the women included in the study had been pregnant during the previous year.

Stress fractures were more likely to occur in women who had less than seven months of weight-training for the legs. This type of injury is more serious because it takes longer to get back to training activities.

Age, body mass index (BMI), and race or ethnicity did not seem to have any influence on LE injuries. For female recruits with a non-stress fracture overuse injury, fitness rated as fair to poor was a risk factor.

The authors conclude that injuries to the lower leg, especially of the shin and calf occur commonly in female military recruits. The results of this study suggest that exposure to the right kind of training can reduce or even prevent these kinds of injuries. Women starting Marine Corps basic training should also be screened early for menstrual irregularities. Proper medical management is advised for this risk factor.

There remains much debate about what should be done with the patella or kneecap during total knee replacement (TKR). TKR doesn’t always include removing and replacing the patella.

There are three treatment options for the patella. First, the patient’s natural patella can be left alone or unchanged. Second the patella can be removed and replaced with an implant. And third, the patella can be spongialized. It’s unclear if one of these methods is better than the others.

Spongialization is a new way to resurface joints damaged by osteoarthritis. The worn cartilage and layer of bone underneath are removed. A soft layer of bone is left exposed. Blood to the area helps new tissue form.

In this article, surgeons review the benefits and drawbacks of these three treatment methods. They also report on the results of the different treatment options for the patella. They were able to examine the surfaces of 11 patellae during revision surgery years after the primary TKA.

Tissue samples were taken and examined under a microscope. This is called a histologic study. They found the following results:

A good fit between bone and implant is needed to maintain knee range of motion after total knee replacement (TKR). The shape of the bone and thickness of the edges called flanges of the implant are factors affecting motion, too.

Pain and problems after a TKR can be caused by poor alignment of the implant to bone. The wrong size femoral component can change the way the knee works and moves. Any mismatch between the bone and implant can alter the joint biomechanics.

In this study researchers used cadavers models to create a situation called overstuffing. Then they looked to see if overstuffing would decrease knee flexion. Overstuffing occurs when the shape and size of the femoral component of the implant is too large or the wrong shape (often too “boxy” or square).

They found that a small difference where the size of the femoral component (front to back) was only four millimeters larger than the real knee caused a four degree loss of passive knee flexion. This difference may not affect the live human. It’s possible the joint capsule will stretch to make up the difference. Or the muscles around the knee may adjust over time to change the tension on the joint.

The authors say it makes sense to use the correct size implant and place it accurately in the joint even if it does not affect motion. Over time an imbalance in the slope or shape of the bone in more than one place can add up. The result may be uneven wear, pain with movement, and even patellar fracture.

Hip and knee replacements are fairly common for osteoarthritis today. But what about the patient with arthritis of the patellofemoral joint (kneecap)? In this study surgeons report the results of using a custom-made patellofemoral implant for 25 patients with isolated patellofemoral arthritis. All patients were 55 years old or younger.

The anatomy of the patellofemoral joint is very different from patient to patient. Off-the-shelf implants have never worked well for this problem. Custom made implants to fit the patient’s own curves and grooves may be the answer.

In this study a computer program was combined with CT scan to map out a three-dimensional (3-D) model of each patient’s knee. Information about the femoral groove was used to build a custom cobalt-chromium implant. The femoral groove is located on the lower end of the femur (thigh bone). A healthy patella moves smoothly in this groove. Arthritic changes can wear away the smooth surface of this groove.

At the end of three years, all 25 implants were in place and working just fine. The computer technology allowed a custom fit to avoid removing the bone. The implant realigns the knee. It puts the patella in the correct position to improve function of the quadriceps muscle.

The cost of the implant is about 15 to 30 per cent more than the price of a ready made patellofemoral implant. It takes about eight weeks to manufacture.

The authors conclude custom patellofemoral replacement is worth the price for some patients. Young, active adults with isolated and severe patellofemoral arthritis benefit the most. The entire knee joint can be replaced later if necessary. Long-term results of the patellofemoral implant are still being studied.

Scientists are investigating the use of a new platelet sealant to speed up healing after surgery. In this study, the use of platelet-rich plasma to seal the wound after total knee replacement is reported.

Platelet-rich plasma came from the patient’s own blood. A special machine was used to spin the blood until there was a layer of plasma with platelets. This fluid was sprayed onto the cut bone and surrounding soft tissues.

There are many unknowns about this new treatment. Effect on healing, range of motion, and length of hospital stay are measured in 71 patients. The results are compared to 66 patients in the control group.

Patients receiving the platelet-rich plasma left the hospital sooner. They also had greater knee range of motion during the first six weeks after surgery. Fewer blood transfusions were needed in the platelet group. They also used less pain medication. Despite these reported benefits, statistical analysis didn’t show a big difference in pain levels or drug use between the treated and control groups.

The authors conclude this study shows the short-term benefits of using platelet-rich plasma to enhance the body’s natural healing process. This treatment has been reported after dental surgery, cosmetic and plastic surgery, and spinal fusion. This study supports its use after total knee replacement as well.

Since healing and wound remodeling continue for months and even years after surgery, long-term studies are needed.

Surgery can be done for patients with long-term wear and tear from having knock-knees. This condition is called varus deformity. Dr. Frank Noyes, a well-known orthopedic surgeon reports the results of 55 cases treated with an operation called opening wedge osteotomy or high tibial osteotomy (HTO).

This particular procedure is designed to help patients get their motion back quickly and get back on their feet without complications. The surgeon removes a piece of bone from the iliac crest (pelvic bone) to use as a wedge at the knee. The idea is to correct the deformity by changing the angle and slope of the tibia (lower leg bone).

During the HTO, the top of the tibia is sawed almost completely off. The bone is lifted up forming a sideways V-shaped gap. The bone graft is cut into three triangular shapes and carefully inserted into the opening.

A metal plate and screws are used to hold everything together while the bone heals. The goal is to promote healing and prevent nonunion or fracture. A special X-ray called fluoroscopy is used right in the operating room to check the angle of correction.

In this study fifty-five (55) patients who had an HTO were followed for at least six months after surgery. Healing and union at the osteotomy were seen on X-ray by three months for almost all 55 patients. By the end of 10 months all 55 had complete healing.

Quick healing of the osteotomy site allowed patients to get back to full weight-bearing by eight weeks. Many problems were prevented with this fast rehab schedule. Avoiding long weeks of crutch use and providing balanced bone and soft tissue also helped prevent further joint damage.

The authors review the results of other studies using bone graft in an HTO. They offer “technical pearls” to surgeons for avoiding complications in an HTO. Ideas for postoperative rehab program are also outlined.

Patients who have anterior cruciate ligament repair have pain after the operation that can interfere with rehab and recovery. Different narcotics have been used to help control the pain right after surgery.

In this study pain control using a nerve block was compared to results with an injection into the knee joint. For the first 24 hours, group one had continuous ropivacaine femoral block. The drug is delivered directly to the nerve. Group two had a single injection of bupivacaine and morphine into the joint.

The researchers thought the nerve block group would have lower pain. They expected the block patients to be able to do their physical therapy program easier than the injection group.

It turns out there was no difference between the block and injection groups. Patients in both groups had the same amount of pain control with equal amounts of narcotics. Past studies have also shown that combining the two treatments together (block and injection) doesn’t offer any extra pain relief.

The authors report the femoral block fails in some cases due to poor placement of the catheter through which the drug is infused. The needle is usually placed just under the nerve sheath (outer covering of the nerve). They advise surgeons to be prepared to manage pain some other way if this happens.