FAQ Category: Knee

Research into repair techniques for damage to knee cartilage is moving right along. Surgeons in Europe and Australia are ahead of American surgeons as they have moved from first-generation cartilage repair through second generation methods to the more current third-generation approaches.

As you have discovered, only one type of third-generation cell therapy for cartilage repair is available in the United States: the matrix-induced autologous chondrocyte implantation or MACI. Although it is being used by U.S. surgeons, the U.S. Food and Drug Administration (FDA) has not yet approved this type of cell carrier yet.

But studies from Europe have shown that the MACI method is safe and effective. Over 6000 procedures have been done since 1998. Although most of the published studies are case series or case reports, the results have been consistently the same.

Patients report significant improvements in pain, function, and activity level. Measurable results based on patient report and MRI studies were seen as early as three months after surgery but more often the benefits occurred during the first year.

Post-operative complications were rare and included infection, detachment of the transplant, and overgrowth of the graft. Overgrowth or hypertrophy can require a second surgery to smooth down the surgical area.

Damage to the articular (joint surface) cartilage of the knee is a fairly common problem. For a long time, there was no treatment for this condition. But because so many athletes are affected and given the fact that knee joint (articular) cartilage doesn’t repair itself, researchers started looking for ways to treat cartilage injuries of this type.

At first, they tried scraping the area and smoothing it down, a procedure called debridement. Then they tried drilling tiny holes into the bone marrow to stimulate bone healing. That’s called microfracture. And they tried taking healthy cartilage from one part of the knee and transferring it to the lesion to fill in the hole.

All of these treatment methods had problems. There wasn’t one approach that could work well for all different types and sizes of cartilage defects. That’s when cell therapy was developed. Healthy cartilage cells (chondrocytes) were harvested from the knee but instead of using them directly in the damaged area, they were transferred to a lab.

In the lab, the cells were used to grow more cells. When there were enough cells to fill in the hole, they were reimplanted into the patient and covered with a patch made of periosteal (bone) cells. That procedure was called autologous chondrocyte implantation (ACI).

It was the first cell therapy devised for the problem of full-thickness (down to the bone) cartilage injuries. But there are some problems with this treament. The procedure is invasive and requires a two-step (staged) surgical procedure. That means at least two surgeries with all of the possible costs and risks that go with staged procedures.

Researchers have kept at it and made even more improvements. For the next batch of autologous chondrocyte implants, instead of covering the patched up hole with periosteum (bone cells), they used a collagen covering. The idea was to prevent overgrowth and keep a smooth surface. Overgrowth of bone called hypertrophy was a real problem with the periosteal patch.

Not quite satisfied, scientists continued trying different ways to improve cell therapies. The result was the current attempt to use a three-dimensional scaffold or frame upon which to grow new cartilage cells. This is the procedure that’s called the matrix-induced autologous chondrocyte implantation (MACI).

MACI is still a two-step procedure that starts with the harvesting of healthy chondrocytes that are then taken to the lab to reproduce. Only this time, they are placed directly onto the scaffold that is made of type I and III collagen tissue. When the transplanted cells (taken from the patient’s body) have reproduced enough (in the lab) to fill in the gaps on the collagen scaffold, then the patient returns to the operating room and the MACI implant is cut to fit the defect and glued in place.

Matrix-induced autologous chondrocyte implantation (MACI) is a less invasive treatment technique that has improved on earlier methods of cartilage repair. Surgical time is shorter because there’s no need for a periosteal flap or microsuturing the implant in place (they use glue instead).

Quality of tissue repair is good and the procedure appears to be safe. So far, all we have are short-term results. Future studies will continue to report data that will further reflect the long-term results of MACI. Moderate-to-large cartilage defects can be repaired this way. Affected individuals (especially athletes) are able to get back to an active lifestyle, including full sports participation.

Everyone dreads the call that tells them, Mom (or Dad) fell and broke something. Bone fractures in older adults can be disabling and even life-threatening. The surgeon often has to use metal plates, screws, or nails to hold the bone fragments together while they heal. This treatment approach is called internal fixation.

Most fractures in older adults occur in the upper portion of the femur (thigh bone). Distal femoral fractures (at the bottom end of the femur) present a different type of problem. The bone is much wider at the distal end and more difficult to stabilize. Everything is even more challenging when the fracture is comminuted (broken into many little pieces).

Fixation devices (commonly referred to as hardware) range anywhere from a single nail to a complex series of screws, washers, nuts, and metal plates. The type it sounds like your mother has is a simple bolt down through the bone called a femoral nail with smaller screws sideways through the fracture site and through the bolt.

It’s a fairly straightforward device that doesn’t require any special care or feeding. The surgeon will give you instructions on what to watch for in terms of any complications, which can include observing for any signs or symptoms of implant failure, loosening, or infection. It sounds like you got your mother to the hospital quickly enough after the fall to avoid damaging the bone further.

Fixation devices (commonly referred to as hardware) for fracture repair range anywhere from a single nail to a complex series of screws, washers, nuts, and metal plates. The surgeon must decide which one to use for each patient.

There are many different types of fixation devices available. A recent study from Germany comparing four separate fixation devices with different interlocking patterns offers some helpful information. The researchers tested everything first on synthetic (manmade) bones before trying the same tests on human bones. The natural bone was from cadavers (bones preserved after death).

The four implant types put to the test included 1) a conventional locking bolt referred to as T2, 2) the Distal Femoral Nail or DFN, 3) a plate and screw model called angular stable plate or AxSOS, and 4) a Supracondylar Nail (SCN). Each one has its advantages and disadvantages.

Each fixation device was tested through repeated cycles of load until the bone was observed to deform or give five millimeters or more. Failure was defined as deformation of more than 2.5 mm. The fixation implants were tested using thousands of cycles.

The T2 is a simple bolt with two screws placed through it in. The bolt goes down through the broken bone. The screws go sideways through the bolt from one side of the broken bone to the other. The screws are slightly apart from each other and parallel to one another. The T2 design had the highest failure rate (first to fail).

The Distal Femoral Nail (DFN) is similar to the T2 in structure but one of the screws has a spiral blade design. The DFN was better than the conventional two-screw design (T2) but it had the least stability and the lowest stiffness. Bone fragments could move because there was no compression or force between the fragments.

The angular stable plate (AxSOS) had the greatest torsional stiffness. It was the third of the four implants to fail. This plate and screw design works well for bed bound patients who are not up and putting weight on the leg. The metal plate lengthwise along one side of the broken bone is held to the bone with a series of seven screws placed at different angles through the bone.

The final implant to fail was the Supracondular Nail (SCN). The SCN has a three-plane pattern of interlocking screws meaning the screws are inserted through the central bolt and bone from three different directions. This fixation device had the best strength and stability. The diagonal arrangement of the screws through the bolt gave the best fixation in the dense bone. Its use is advised for patients who are getting up and moving early after surgery for distal comminuted femoral fractures.

Surgeons know what type of fixation devices to use based on type of fracture, biomechanical properties of each implant, rehab schedule, and bone density. Such knowledge can help speed up recovery and prevent complications.

You may be referring to a procedure called autologous chondrocyte implantation or ACI. Autologous means the cells harvested for the implantation come from the patient who needs the repair. In other words, you donate your own chondrocytes (cartilage cells).

This procedure is done when there are full-thickness defects in the articular surface of the joint. Essentially, there has been an injury that has pulled off a piece of the layer of cartilage that lines the joint. Full-thickness means the defect goes all the way down to the first layer of bone.

Autologous chondrocyte implantation isn’t usually done on older adults. The damaged area has often contributed to the development of osteoarthritis. Arthritis is also more likely after age 65 making it less likely that the procedure will be successful.

There may be other safer and more successful methods of treating this problem for you. The best way to find out is to see your orthopedic surgeon for an evaluation. If you’ve had this problem for 10 years, you may have already seen your orthopedic surgeon. But if it’s been a while and you are still experiencing pain (especially if the pain is enough to hamper your activities), it might be worth a follow-up visit to discuss all your treatment options.

Autologous chondrocyte implantation (ACI) involves the use of normal, healthy cartilage cells to fill in a hole (defect or lesion) in the joint surface of the knee. The defect goes clear down to the bone below the cartilage. It’s called a full-thickness cartilage and osteochondral lesion. Osteochondral refers to bone (osteo) and cartilage (chondral).

Autologous chondrocyte implantation is done in two separate steps. First, the surgeon removes the harvested cartilage cells from an area of the knee that doesn’t bear weight. They are taken to a lab where the cells are multiplied until they have enough to fill in and cover over the defect.

A second surgery is done to implant the new healthy cells. If there are any alignment problems or other soft tissue injuries, surgery is done before implantation to correct them. The corrective surgery is a necessary step in order to protect the implanted area. If there are uneven forces within the joint, the load imbalance can reinjure the same spot all over again.

Usually, the realignment process involves rebalancing the muscles around the knee joint so they don’t pull unevenly, reconstruction of the anterior cruciate ligament, or an oosteotomy. The osteotomy involves removing a wedge- or pie-shaped piece of bone from one side of the joint. The effect of an osteotomy is to reduce the uneven forces in a knock-kneed or bow-legged knee.

If you have any doubts about the procedure and what’s needed, ask your regular orthopedic surgeon for his or her thoughts as well as a recommendation for a second opinion.

When it comes to what will happen in the future after a decision of this type, there’s no crystal ball. Surgeons make recommendations like this based on the current available evidence. Right now, there’s enough data to show that arthritic changes occur faster with progressive joint degeneration when the knee is unstable from any kind of injury.

Anterior cruciate ligament (ACL) tears are the most common ligamentous injuries of the knee. Damage to the meniscus is often present as well. And studies of patients who have either avoided knee surgery or who had the meniscus removed have convinced us that surgical repair or reconstruction of many ACL injuries is really the best approach.

What happens 20 to 25+ years after the reconstructive surgery? Well, that’s also being studied right now. The longest research reported comes out of France by a single surgeon who tracked over 100 patients for 24+ years.

Now 20 or more years later, more than half of those patients (57 per cent) rate their results as excellent. Another 27 per cent say they have good results. Only 16 per cent said that they felt their outcomes were poor
(two per cent) to fair (14 per cent).

Patients who had damage to the articular cartilage or meniscus were more likely to have less knee function. And between 10 years post-op and the current study 24 years later, there’s been an increase in the number of these patients with osteoarthritis.

Only 15 per cent of the group with osteoarthritic changes had similar changes in the other knee. So it wasn’t the case that they would have ended up with arthritis anyway. The loss of the meniscus and damage to the joint cartilage were the biggest factors in the development of osteoarthritis.

Surgeons and researchers who study the problems associated with anterior cruciate ligament (ACL) tears are finding that certain factors increase the risk of poorer outcomes. A delay between the date of trauma and the date of surgery does appear to be a risk factor for problems later.

In one ultra long study over a period of 25 years, 100 patients were followed. Throughout those years, risk factors that could affect outcomes were evaluated. For example, data has been analyzed on the effects of age, surgical delay, joint laxity or looseness after surgery, removal of the entire meniscus, and damage to the joint cartilage. Mostly what they were looking at was how much degeneration occurs in the joint and whether any of those risk factors contributed to the problem.

Osteoarthritis was judged based on X-rays by looking at the size of the joint space and presence of bony spurs around the joint. Narrowing of the joint space was seen as a result of degenerative deterioration, especially in those patients who had medial meniscus damage or removal. Patients who waited three or more years to have surgery after injuring the ACL were more likely to develop osteoarthritis later.

So it appears that delay after injury and before surgery can make a difference. But with everything else we’ve learned over the years, every effort is being made to prevent postoperative complications.

A good exercise program to keep the muscles around the knee toned and strengthened is important. Alignment of the foot, ankle, and knee are also important. Sometimes something as simple as a shoe orthotic (insert) can make a big difference.

If you have any reason to suspect there are problems developing, don’t wait to make an appointment with your surgeon. An evaluation five years after surgery isn’t a bad idea and may provide you with the information you need to keep that knee healthy and strong for a very long time.

Probably the biggest reason orthopedics has focused so much in the last 10 years on the repair and healing of cartilage defects is because of athletes like you. Athletes from all disciplines can be affected — these injuries have been reported in wrestlers, soccer players, gymnasts, tennis players, and many others.

A seemingly small thing like a small hole in the knee cartilage can cause significant pain, symptoms, and disability. Left on its own without any surgical intervention, tiny defects in the cartilage might be able to fill in with scar tissue and smooth over with joint movement.

But anything bigger than that can remain a problem — especially if there are alignment issues contributing to the wear and tear of the joint. There are several ways to repair these defects now. All involve making sure the knee has good alignment and balanced joint and muscular biomechanics.

Results from surgery don’t seem to be influenced particularly by whether the athlete is male or female. Other factors such as age and location of the defect may be much more significant.

For example, younger athletes who have smaller (and fewer) lesions seem to do the best.
Smaller defects tended to have less degenerative wear and tear but the plug to fill those holes wasn’t so tough. It’s more difficult to harvest a small amount of cartilage and the smaller grafts are more fragile. The larger graft plugs are more stable making them easier to harvest and insert.

Location of the lesion can be another key risk factor for successful outcomes. Lesions located on the femoral condyles (large round knobs at the end of the femur (thighbone) seem to respond better than damage or defects to the patella (kneecap).

No matter how big the defect or its location, studies show that patient cooperation and compliance with the postoperative treatment is very important. Doing too much too soon and returning to practice and competition before your surgeon approves it can result in less than satisfactory results.

Mosaicplasty is a procedure that involves harvesting plugs of cartilage and bone from one part of the knee joint and transferring it to another. The donor plugs are used to fill in holes and defects that go all the way down to the bone.

The donor tissue is taken from an area that has relatively little weight-bearing and moved to the defect (usually the defect is in a weight-bearing zone). Sometimes only one donor graft is needed but some patients need more than that for larger defects.

Mosaicplasty can help save the joint and protect it from further wear and tear around the defect site. But biomechanics of joint movement that are off or uneven in any way (and not repaired before mosaicplasty) can contribute to uneven forces or load on the joint. Joint degeneration is the result of overuse and uneven weight bearing.

Symptoms of continued pain and swelling may be an indication that the knee alignment is still not balanced. On the other hand, even in high-demand athletes, problems that occur (e.g., pain with weight-bearing) are temporary and seem to go away within the first six weeks up to one year.

You may be someone who will see gradual improvement over time. But a second look through an arthroscopic exam might reveal something that needs attention now before the problem contributes to further degeneration of the joint.

There could be a new injury that wasn’t present at the time of the first surgery. Bleeding into the joint, infection, or stiffness of the healing tissue are other potential reasons for ongoing symptoms. If these have not gone away as expected, then it might be time to take a second look in order to formulate the best plan of care for you.

Conservative care with rest, elevation, ice, and antiinflammatory medication is the standard first-line treatment for muscular problems like this one. It does not sound like there is an undisplaced fracture since you didn’t mention any open wounds or bone sticking out of the skin. The suspicion of a bone fracture might be grounds for a visit to the emergency department.

If the lump you described does not go down (or go away) with conservative care, there may be more going on than just some swelling in response to an injury. An MRI may be needed to identify the tendon or muscle involved and to show the extent of the damage. Full ruptures or tears can be treated conservatively. Physical therapy to help restore motion, strength, and function is usually advised.

Failure to respond to conservative care may point to the need for surgery. But for right now, your decision is a short-term, immediate one. Waiting overnight is usually not a problem. Watch for increasing swelling that might suggest bleeding. When in doubt, it is always a good idea to seek medical care sooner than later.

Nothing is more frustrating for an athlete than an injury — especially one that doesn’t heal. Knowing when to have surgery right away and when to treat the problem conservatively (without surgery) can be a real challenge. That’s the case with tendon ruptures such as the hamstrings.

The semitendinosus is one of three main parts of the hamstring muscle located along the back of the thigh. Distal semitendinosus tells us the tear occurred down by the knee where the semitendinosus inserts (attaches) to the bone.

Hamstring injuries of the muscle belly are fairly common among athletes. But usually, it’s the biceps femoris portion of the muscle that ruptures. This type of distal semitendinosus injury that you have is uncommon but not rare. The decision whether to go to physical therapy or to the operating room can be difficult. There are no known predictive factors to guide patient and surgeon.

Predictive factors are characteristics of the patient or injury that are linked with success or failure. With some injuries, the surgeon knows the chances are good (or bad) for a complete recovery (or failure) if X, Y, or Z factors are present. Predictive factors can be things like the patient’s age, severity of injury, sex (male versus female), body part injured, and so on.

We do have some data that might help based on a study of two orthopedic surgeons involved with 25 professional athletes who had a complete rupture of the distal semitendinosus muscle. They report the treatment results after months of follow-up.

The players who had surgery early on were off the field for about 10 to 12 weeks total. In contrast, the athletes who followed a conservative approach and then needed surgery anyway were out of the game for more than half a year.

The authors suggested based on their findings that athletes with a distal semitendinosus rupture have surgery right away in order to speed recovery and return to competitive play. But their patients were all professional athletes in national league football or major league baseball.

Conservative care is usually advised. When symptoms such as loss of knee motion, tender mass, knee swelling, and inability to walk normally without a limp don’t go away with rehab, then surgery may be advised.

Surgery may provide a faster route to recovery and return to competitive play. Your decision should be made with the surgeon’s help. When needed, MRIs can be used to confirm the diagnosis and severity of injury.

People with knee osteoarthritis are encouraged to maintain an active lifestyle and to exercise those arthritic knees. But as you point out, that seems counter intuitive — if your knees hurt, why would you move and exercise them more?

But study after study confirms that this is good advice. For example, a large study was done by the Osteoarthritis Initiative (OAI) that confirmed this counsel as good advice. The Osteoarthritis Initiative investigators are supported by a combination of public and private funds from around the United States.

These investigators are from the well-known Rehab Institute of Chicago (RIC), Ohio State University, University of California (San Francisco), and Northwestern University School of Medicine. Their report based on over 2200 people with knee arthritis confirmed (again!) the advice to exercise and stay active.

But patients have to be convinced that exercise really makes a difference. And sometimes they need a little extra help getting started. The first step is getting control of the pain, aching, and stiffness that often accompanies knee osteoarthritis. You might want to confer with her physician (with her permission, of course) and review what medications are being used and what might help get her on a more active course.

Then find out what she would like to do if her knees weren’t bothering her. Organizing a plan of action around what would motivate her might help improve compliance. Some seniors seek out group activities with friends or other seniors.

There are walking clubs that meet in malls to walk together. There are pool exercise groups specifically designed for older adults with some physical limitations. Check with the Senior Citizens Center or Adult Aging Services in her area and find out what’s available.

For those who prefer to exercise alone, a home exercise bicycle might be just the ticket. There are also a variety of television shows aimed at the more sedentary population (e.g., Sit and Be Fit) who don’t want to leave home.

Even increasing her physical activity and exercise level a little can make a difference. Of course, it’s possible that she would be a good candidate for knee replacement surgery, so that may be worth looking into.

Whatever approach you take, experts agree the best advice physicians, public health professionals, and physical therapists can give older adults with knee osteoarthritis is to keep moving. Physical activity and exercise are proven to reverse decline and improve function.

There’s no doubt that nutrition and exercise are key factors in maintaining good joint health. Multiple studies on knee osteoarthritis have proven that physical activity and exercise are essential to knee joint health.

According to the Osteoarthritis Initiative investigators who study this problem, participation in sports and exercise has the strongest link to best function. And it doesn’t seem to matter what activities people are engaged in — participation in any and all are beneficial.

Risk factors for poor function are age (65 and older) and being overweight. There’s not much you can do about lowering your age but you can work to keep the weight off. Smoking, a poor diet, and excess alcohol are additional factors that are known to negatively affect patients with knee arthritis.

A knee replacement has become so common any more we tend to forget that it is still major surgery and a fairly complex one at that. With so many aging adults in America, the number of total knee replacements has increased dramatically.

And along with that has come the need to watch out for complications like implant/joint infection. Infection is one of the most common causes of implant failure. Whether infection develops right away (first four to six weeks) after the surgery or much later (even years later), the treatment approach is the same.

First, tests are done to identify what type of organism is growing. The most appropriate antibiotic to combat the infection is selected. If that doesn’t work, then surgery is done to clean out the infection (a procedure called debridement) and possibly replacement of the liner that’s part of the implant.

After debridement, intravenous antibiotics are given for six weeks but patients are warned that the success rate is fairly low. A revision (second) surgery may be required. The implant is removed and replaced but the new implant isn’t put in until the infection is cleared up completely. A temporary spacer is put in the joint instead and the operation becomes a two-part or staged procedure.

But before we jump that far ahead, you are on the right track to see your surgeon and find out what’s going on. Each patient has his or her own unique presentation, problems, and solutions. Having a little idea of the possibilities is good, but wait and see what your physician has to say.

Even though half a million knee replacements are done each year in the United States, there are other treatment options for some patients. If one side of the joint has worn down from problems with alignment, an osteotomy is one possible alternative choice.

What’s an osteotomy? Basically, an osteotomy is a surgical procedure whereby a bone is cut to shorten, lengthen, or change its alignment. Around the knee, it’s the tibia (the lower leg bone) that is involved. The various kinds of osteotomies are often named for their location. The two most basic types are opening wedge and closing wedge osteotomies.

When is an osteotomy a good idea? The purpose of the osteotomy is to shift the patient’s body weight off the damaged area to the other side of the knee. This makes better use of the cartilage that is still healthy.

The surgeon removes a wedge of the tibia from the healthy side of the knee. It might be taken from the inside (medial) of the tibia (meaning the side of the knee closest to the other knee). That’s an opening wedge osteotomy or medial opening wedge HTO. HTO refers to high tibial osteotomy meaning the wedge is removed right at the upper end of the tibia just under the knee joint.

A closing wedge osteotomy (also known as a lateral closing wedge HTO) takes the piece from the lateral tibia and allows the remaining edges of bone to collapse toward each other to close the gap. Once the wedge is removed, the bones are brought together and held in place with a metal plate or pins.

Whether it’s an opening or closing wedge procedure, an osteotomy allows the tibia and femur to bend away from the damaged cartilage. A tibial osteotomy can enable younger, active osteoarthritis patients to continue using the healthy portion of their knee. As you found out, the procedure can delay the need for a total knee replacement for up to ten years.

Degenerative joint disease (osteoarthritis) often causes wear and tear on just one side of a single knee joint. This usually happens when there is a problem with knee joint or lower leg alignment. Because the knee is either in a position more toward knock knees or perhaps the opposite, bow legs, pressure and load are shifted from the midline more toward one side of the joint or the other.

Over time, this uneven weight distribution takes its toll on the joint. But why replace the whole joint when only part of the joint is damaged? Instead, patients can benefit from an osteotomy or a unicompartmental joint arthroplasty (replacement).

With an osteotomy, a wedge or pie-shaped piece of bone is removed from one side of the knee. The goal is to shift the patient’s body weight off the damaged area to the other side of the knee. This makes better use of the cartilage that is still healthy. With a unicompartmental implant, only the side of the joint that’s damaged is removed and replaced with a metal joint implant.

There are some advantages and disadvantages to the osteotomy approach to unilateral (one-side of the joint) arthritis. As mentioned, it can help patients put off joint replacement. And unlike joint implants, with an osteotomy, it’s still possible to engage in high-impact activities like jumping and running. Implants are not as durable and thus limit activities of this type.

The disadvantage of osteotomy is that there is a risk of continued knee pain. It’s a trade-off: with osteotomy, there is a greater activity level but more discomfort. With a unicompartmental (or complete) joint replacement, the pain is gone (or very minimal) but activities are limited.

Most of the time, surgeons recommend osteotomy for younger, more active patients. Unicompartmental knee arthroplasty is a better choice for older, more sedentary adults. As young adults who opt for an osteotomy grow older, they still have the choice of a joint replacement later in life, thus extending the life of the joint for as long as possible.

It sounds like you have a defect or hole in the articular cartilage. This is the cartilage that lines the joint and sits right up against the bone.

We don’t know for sure that if left alone, the articular cartilage would eventually heal on its own. The process of what happens over time without intervention or treatment is called the natural history of a condition.

Right now, it’s assumed that damage to the articular cartilage leads to arthritis sooner than later. But there’s no real evidence to support this view. Most of the studies done so far haven’t been on single (isolated) defects of the articular cartilage. Injuries treated have included additional damage to the joint such as an ACL tear (ACL = anterior cruciate ligament).

The articular cartilage doesn’t have much of a blood supply of its own. It relies on movement of nutrients in fluids that cross the cartilage bringing supplies like a wagon train. But the fluid can’t cross holes in the cartilage and that’s a problem. Without a healthy, intact matrix of bone and cartilage, it’s like the wagon coming to a canyon with no bridge to get across.

Since that time, three different surgical techniques have been developed and tried for this type of injury: 1) microfracture, 2) autologous chondrocyte implantation (ACI), and 3) osteochondral autograft transplantation (OAT). Here’s a brief explanation of each one.

Microfracture involves drilling tiny holes through the cartilage, past the first layer of bone underneath, and into the bone marrow. There’s a rich blood supply there and drops of blood well up through the holes to aid the healing process.

Autologous chondrocyte implantation requires removing some of the healthy cartilage cells, taking them to the lab, growing more healthy cells, and then putting them into the holes or defects in the knee.

And osteochondral autograft transplantation refers to harvesting healthy cartilage cells from a part of the knee that doesn’t bear weight (and isn’t damaged) and using those plugs to repair the damaged area.

Each of these techniques has its own advantages and disadvantages. According to studies done so far, there’s no clear winner. But in a recent report by surgeons revisiting the question of which one has the best results it was suggested that microfracture seems to be the best choice for treating articular cartilage defects.

It is a one-step procedure and less expensive than the other treatment methods. Pain levels, function, ability to return-to-sport, cost, and overall failure rates over time were used to compare results.

But your surgeon is the best one to advise you. Some of the treatment choices depend on how much and what type of damage is present. It’s a whole different picture if there is any knee instability from ligamentous damage. And your age can make a big difference, too. Younger patients seem to respond better to the osteochondral autologous transplantation (OAT) procedure compared with older adults (30 years old or older).

There are several layers of cartilage in the knee. The C-shaped meniscus between the bones is the most commonly known. But your son has damage to the next layer down: the articular cartilage. This is a more pliable, softer cartilage that lines the inside of the joint. It’s between the meniscus and the bone.

Repairing damage to the articular cartilage is a little more complicated than stitching the meniscus back in place. With defects or holes in the cartilage, it’s more a matter of plugging them up and smoothing them over, then letting nature take its course.

The type of surgery you mentioned is called osteochondral autograft transplantation (OAT). The surgeon does, indeed, harvest plugs of good, healthy chondrocytes (cartilage cells). These are taken from a part of the knee joint that doesn’t get used much (non weight-bearing site). The plug (or several plugs) are then used to repair the lesion.

The technique works fairly well (especially in young athletes) but there is some question about durability. Long-term studies just aren’t available yet. The outcomes after two years seem positive. But there are some failures and the reasons for these failures have not been determined.

Studies are ongoing to investigate the results of cartilage repair. Clearly more studies are needed to find out what happens in the long-run and how durable this type of repair really is.

Knee injuries can really lay an athlete low. Those injuries affect the medial side of the knee most often (the side closest to the other knee). The soft tissues involved are first the superficial medial collateral ligament, then the deep medial collateral ligament, and finally, the posterior oblique ligament.

The medial ligament is one continuous structure with these three separate parts that all attach to different places along the knee but all work together to stabilize the medial side of the joint.

Surprisingly, as you have just discovered, treatment is often conservative (nonoperative). The medial collateral ligament has a rich blood supply that makes healing without surgery possible. The torn ligament goes through all the normal stages of healing and eventually fills in with fibrous scar tissue.

The anatomy and biomechanics of these ligaments actually help determine the best treatment approach. Each portion (superficial, deep, or posterior) has its own purpose and function. For example, the superficial and deep portions of this ligament work together to keep the knee joint from sliding into a knock-kneed (valgus) position. At the same time, the posterior aspect of the ligament does the same thing when the knee is in a slightly flexed position (from zero up to 30 degrees of knee flexion).

Understanding the anatomy and function of the separate parts of this medial ligament guides the surgeon in first deciding whether or not surgery is needed and secondly, what kind of repair or reconstruction is needed. Some injuries when left untreated can increase the risk of another injury. All of these factors are taken into consideration when arriving at a plan of care.

Another thing the surgeon pays attention to is the grade of ligament injury. This is a way to classify how severe is the injury. The classification scale goes from grade I (mild joint laxity from a strained but not torn ligament) to grade II (partial tear of one or more portions of the ligament with separation or gapping of the joint with stress testing), and grade III (complete rupture of the ligament and more than 10 millimeters of joint laxity or gapping).

The injury is graded using both clinical tests (stress testing of the joint) and imaging studies such as X-rays and MRIs. Measuring how much the joint gaps (separates) helps determine the grade.

With your MRI results and the surgeon’s exam findings, it sounds like the recommendation for physical therapy to start is right on target. But don’t hesitate to ask your surgeon to help you understand the decision to take the conservative approach. Understanding what the expected outcome is may help you participate fully in the rehab program.