FAQ Category: Knee

All indications are from studies reported that infection after total knee replacement is a problem that is on the rise. With “bugs” (bacteria) more resistant than ever to antibiotics, it can be a challenging problem to treat. It may require removal of the implant and revision surgery to put in a second implant.

Treatment depends somewhat on the type of knee infection present. These are classified as one of four types: 1) infection present at the time of the primary total knee arthroplasty, 2) infection develops within the first 30-days after surgery, 3) infection goes into the blood but symptoms only last four-weeks, and 4) a chronic infection lasting more than 30-days.

Treatment is based on the infection type and condition of the patient. Treatment choices include: antibiotics, irrigation and debridement, removal and replacement of the implant, arthrodesis (fusion), and (worse case scenario): amputation. Who gets what treatment?

Antibiotics alone (called antibiotic suppression) is very ineffective (20 per cent success rate) and only used for a small number of patients. These are folks who are too sick for surgery, who have a stable implant (not loose), and a bacteria that is considered “low virulence” (in other words, not terribly strong or destructive).

The preferred treatment is actually more of a combined management approach. Open incision with irrigation and debridement works best for acute infections. But the surgeon must take into consideration several factors when using just this approach. For example, your health, the type of bacteria present, the length of time since the primary surgery, and other patient risk factors must be reviewed and assessed before choosing the best treatment option for each patient.

More often, it is necessary to remove the infected implant, clean out the joint, and replace some of the component parts of the implant. The replacement procedure is referred to as an exchange arthroplasty. The exchange arthroplasty can be a one-step or two-step process (also known as one-stage or two-stage exchange arthroplasty).

As the names suggest, in a one-stage procedure, everything is done in one surgery. In a two-stage exchange, the implant is removed but not replaced just yet. Instead a spacer that contains high-dose antibiotics is put in place instead.

Once the infection is under control, then the spacer is removed and the replacement implant installed. Usually the antibiotics are used for at least six weeks with another four to six weeks time period off antibiotics before reimplantation can take place. Once the lab tests show the infection is cleared up, then the exchange can take place.

The more extreme options of joint fusion or even amputation are only considered when all other treatment methods have failed. Amputation may be necessary when the infection cannot be stopped and the patient is either in terrible pain or their life is threatened by the infection spreading throughout the body. In all cases, every effort is made to save the leg, save the joint, save the implant. Fusion and/or amputation are only considered when all else has failed.

Since your infection has been identified early, you are in a good position to receive the medical care necessary to prevent any of these more extreme measures. Once the surgeon assesses your situation, he or she can give you a better idea of your choices. What we presented here is a range of possibilities.

Fear of reinjury is a natural reaction after an anterior cruciate ligament (ACL) injury in many high school and college athletes. In fact, a recent survey of over 150 football players showed that about one-third to one-half of players at both these levels of play don’t return to the field.

And when asked why not, fear or reinjury was the number one reason followed by knee symptoms such as pain, stiffness, and swelling; perception that strength and/or speed were not enough for competitive play, and advice from others.

Emotional and psychologic factors for not returning to play after injury aren’t discussed much in the sports world — especially at the high school level. Knowing that this is a potential issue might make it easier to bring up in a conversation with your son. Sometimes it is the case that high school athletes develop other interests or just weren’t settled enough on football to make it a high priority after injury. It’s easier to make the decision to move on to other things when an injury gives the player the freedom to do so.

A proactive approach to potential sports injuries (especially the all-too-common knee injuries) is a good idea. Studies show that up to 15 per cent of all high school football players suffer some type of knee injury — anterior cruciate ligament (ACL) tears and ruptures being a major type. But other knee ligaments and the cartilage inside the knee (meniscus) are also often involved as well.

College-level programs and professional football players have started paying closer attention to this type of prevention program, too. There are certain positions that seem to put players at increased risk for knee injuries. Any sport or position that requires speed, quick changes in direction, and planting the foot and pivoting over it are red flags for injury prevention.

This type of description certainly fits many basketball players. In football, it’s the running backs and wide receivers who have to be quick on their feet, change directions often, and use pivoting motions that can put more load and stress on the anterior cruciate ligament (ACL) than it can withstand. There is the same concern for other players (e.g., lineman) who are more likely to take hits directly to the knees. A strengthening and conditioning program can be very helpful in reducing knee injuries for all players, but especially these groups.

There haven’t been a lot of studies comparing long-term results following ACL injuries and in particular, what happens to the other leg. Comparing results of dominant versus non-dominant leg is another added dimension. And there are many other factors and variables to consider (e.g., age, gender, sport, type of treatment) that can make it difficult to tell cause and effect.

When the treatment approach is surgery, there are two different types of graft material that can be used. Results may vary depending on which leg is affected and which graft material is used.

There was a study done recently where surgeons from three large medical centers combined their efforts to investigate the rates of return-to-play and need for further surgery among just soccer players. Part of their research did report on the effects of injury based on whether the injury affected the dominant versus nondominant leg.

One-hundred (100) active soccer players (males and females) between the ages of 11 and 53 were included in the study. This was a retrospective study, which means the athletes were contacted after their surgery and rehab to see what kind of results they had. Two-thirds had a bone-patellar-bone graft to reconstruct the anterior cruciate ligament (ACL). The other one-third had a hamstring graft. Information about the type of graft used is always important in these studies to see if it makes a difference in results.

Final, long-term results were measured by looking at number of patients who went back to full sports participation, how many were still actively playing soccer years later, and how many people had to have another knee surgery (either on the injured side or the opposite side).

They found some interesting patterns. First, the graft type (hamstring versus patellar) did NOT make a measurable difference. Second, female soccer players were more likely to experience reinjury or future injuries. Any athlete who injured the nondominant leg was at increased risk for recurrent ACL injuries. That’s because after the injury, they put even more stress and strain on the dominant side — eventually leading to an overuse injury. Slightly more than half of all injuries (57 per cent) affected the dominant leg in these 100 patients.

The fact that women are actually more likely to experience future injuries (compared with men) may have to do with differences in muscular strength and joint laxity between the sexes. Women tend to have greater joint laxity or looseness. Men tend to have tighter and stronger muscles on either side of the joint to support and protect it.

The authors suggested greater emphasis on injury prevention for all soccer players (young and old, male and female). Studies reporting results of ACL injury prevention programs are favorable at this point. Future programs need to pay attention to those athletes at increased risk for ACL reinjuries or opposite leg ACL injuries. Females and athletes injuring the nondominant leg are the first groups to target with a prevention plan.

Well, of course, most studies focus on only one sport at a time and don’t usually compare athletes across the disciplines. So you may be on to something with your record keeping. Past studies do support your observations that in the U.S. and in Europe, women athletes tend to injure their anterior cruciate ligaments (ACLs) more often than men.

The main reasons for this are probably already well-known to you: women tend to have a larger Q-angle (altering joint biomechanics), greater joint laxity (looseness), and weaker musculature. Combined together, these factors can contribute to an increased risk of ACL tear or rupture.

Your question about return rates to sports is an intriguing one. There was a recent study looking into this just for soccer players (males and females). One-hundred (100) active soccer players (males and females) between the ages of 11 and 53 were included in the study.

This was a retrospective study, which means the athletes were contacted after their surgery and rehab to see what kind of results they had. Two-thirds had a bone-patellar-bone graft to reconstruct the anterior cruciate ligament (ACL). The other one-third had a hamstring graft. Information about the type of graft used is always important in these studies to see if it makes a difference in results.

Final, long-term results were measured by looking at number of patients who went back to full sports participation, how many were still actively playing soccer years later, and how many people had to have another knee surgery (either on the injured side or the opposite side).

They found some interesting patterns. First, the graft type (hamstring versus patellar) did NOT make a measurable difference. Second, female soccer players were more likely to experience reinjury or future injuries. Any athlete who injured the nondominant leg was at increased risk for recurrent ACL injuries. That’s because after the injury, they put even more stress and strain on the dominant side — eventually leading to an overuse injury. Slightly more than half of all injuries (57 per cent) affected the dominant leg in these 100 patients.

There was a general trend among all players but especially for the females of declining sports participation over time. In other words, more patients returned to the game and played during the first couple of years after surgery. But by the end of five to seven years, far fewer were engaged in sports play. This may be similar to what you are seeing in your study.

The reason(s) for this trend are unknown. The authors suggest that maybe women who finish college and go on to a career and/or family gradually give up sports. Men were more likely to say that fear of reinjury and the trauma and pain of the injury and surgery were the reasons why they did not stick with sports.

The fact that women are actually more likely to experience future injuries (compared with men) may have to do with differences in muscular strength and joint laxity between the sexes. Women tend to have greater joint laxity or looseness. Men tend to have tighter and stronger muscles on either side of the joint to support and protect it.

The authors summarize by suggesting greater emphasis on injury prevention for all soccer players (young and old, male and female). Studies reporting results of ACL injury prevention programs are favorable at this point. Future programs need to pay attention to those athletes at increased risk for ACL reinjuries or opposite leg ACL injuries. Females and athletes injuring the nondominant leg are the first groups to target with a prevention plan.

The first order of business is to find an orthopedic surgeon who can follow up on your care. If you have a primary care physician, he or she will help guide you through the referral process. If you are a university student with student health coverage, then the clinic there will be your first stop.

The type of procedure you had done is called cartilage meniscus implantation or (CMI). CMI is designed to regenerate damaged cartilage instead of just removing it. This is important because studies show that meniscectomy (surgical removal of any part of the meniscus) can lead to early degenerative changes and osteoarthritis of the knee joint.

A mesh of tissue from bovine (cow) tendon) has been developed for this purpose. The mesh or “scaffold” as it is called is used to fill partial defects (holes or lesions) in the meniscus. After removing the flapped over or torn piece of meniscus, the remaining meniscus is smoothed and shaped carefully to accept the graft. Tiny holes are drilled around the edges of the defect. This step helps create some bleeding that will aid healing and recovery. Once the implant is placed in the hole, the edges are stitched down to hold it in place.

After surgery, a knee brace is used to hold your knee in full extension (completely straight) for six weeks. The idea of such a brace is to prevent load or compressive force through the joint that could disrupt the healing process.

Most of the time, patients take the brace off three to four times each day (every four to six hours during the waking day) and use a device called a continuous passive motion (CPM) machine. The machine is set to gently but passively (no effort on your part is required) bend the knee up to about 60-degrees of flexion. After two weeks, the machine is reset to move your knee up to 90-degrees. In the final two weeks, full passive motion is allowed.

At first, patients are placed on crutches and all weight must be kept off the surgical leg. Isometric exercises to contract and relax the leg muscle are allowed (actually required) from day one. Two weeks post-op, you will be instructed to start putting partial weight through that leg. And you will probably be progressed to start some cycling on a stationary bike.

All of this is usually done under the supervision of a physical therapist. The rehab program is gradually moved along from a passive to very active approach. Strengthening exercises and other activities are part of the program until you are able to return to full motion, strength, and function. The entire rehab process can take four to six months or more.

Every surgeon has his or her own preferences for their patients after surgery. The protocol described here may not be exactly the way it is done where you go for follow-up. But it gives you a general idea of what to expect.

A complete tear or avulsion of the proximal hamstring tendon often requires surgery to heal. (Proximal means the tear occurred where the tendon attaches to the pelvis). How well patients recover from this type of surgery was actually the topic of a recent study.

Strength, satisfaction with results, return-to-sports participation, and function were the key areas measured. The number of patients involved was small (13) but the follow-up was good (from two up to five years). Each patient tore the hamstring as a result of a traumatic injury during a sporting event.

Surgery was done within two months of the injury for all but one of those athletes. Ages ranged from 26 to 58 years old, so you can see these weren’t just young sports participants. And that makes the findings of this study unique and important. More middle-aged adults are involved in sports and remaining physically active. There are more of these kinds of injuries.

Tools used to assess results included MRI images (a way to visualize tendon healing), leg circumference (assessing muscle atrophy), goniometer (measuring range of motion), Lower Extremity Functional Scale (LEFS; function), Tegner Activity Scale (physical function and activity), and isokinetic machine (strength). Pain and other symptoms such as numbness or nerve palsy were also evaluated.

The goal of the study was to use these clinical, radiological, and functional means of evaluating patient results after surgery to repair proximal hamstring ruptures. It is a retrospective study meaning the authors took a look back after the treatment had been completed to see how everyone fared. Like you, they wanted to know: does the tendon heal?

Here’s what they observed. There were no differences in side-to-side muscle circumference measurements but they found strength was not equal. The surgical side was still only 78 per cent as strong as the normal, uninjured leg. The really unusual finding was that these patients thought the surgical leg was at least 90 per cent as strong as the other leg.

All but one patient was completely satisfied with the results. But the authors knew there were four of the 13 who had poor outcomes so they wondered how this could be. A closer look revealed that perhaps the tests used really didn’t adequately evaluate patient satisfaction — the questions asked might not have given the patients the opportunity needed to express dissatisfaction with their particular results. That is something they intend to investigate more fully in future studies.

Almost half of the group (45 per cent) reported a significant decrease in activity level and sports participation after surgery compared with before the injury. Other studies report a much higher return-to-sports (80 per cent or more). So this is another area where closer study is suggested. In future studies, it will be important to find the right tools to accurately measure satisfaction and function after surgical repair of this type of injury.

And finally, MRIs are one way to look for tendon healing. In the study mentioned here, there was a 100 per cent rate of hamstring tendon healing. There were no signs of tendon tears or fraying. In some cases the healing tendon was filling in with a small amount of fat instead of normal collagen tissue. This finding might account for the lower rates of strength and function observed.

The authors concluded that surgical repair of a complete proximal hamstring tendon rupture in athletes of all ages does yield good results. But there were some lingering questions because hamstring function was not completely restored in this group of patients. As noted, this group of researchers intends to continue studying ways to adequately measure outcomes and improve patient results.

More and more adults are remaining active through mid-life and on into their senior years. Record numbers are participating in Senior Olympics. And even those who don’t compete are finding ways to exercise routinely.

For anyone involved in physical activity, exercise, and sports — whether alone or with a group — the risk of injury goes up. Hamstring strains are the most common muscle injuries in all age groups. There may be a partial tear (considered more of a “strain”) or complete rupture known as an avulsion.

Treatment can be conservative (without surgery) for minor tears. But most of the time, when an athlete of any age experiences a complete tear of the proximal hamstring tendon, surgery to reattach the tendon to the bone is indicated.

Studies show that return-to-sports is possible. It is even possible for the older athlete to return at a level equal to their pre-injury participation. But that kind of full recovery isn’t guaranteed. Anywhere between 45 and 80 per cent of active adults who experience a proximal muscle hamstring avulsion and who have surgery to repair it regain full function.

Experts are trying to understand why there is a wide range of outcomes. Some of the spread in results may have more to do with how the studies are conducted. Different tools to measure outcomes may be used from study to study. So it is more like comparing apples to oranges. And some researchers have suggested the differences may be more likely due to the type of test being used. It’s possible that some of the tests of function don’t really assess this problem accurately.

There are different clinical ways to measure results including strength, muscle atrophy, range of motion, patient satisfaction, and level of function. MRIs provide an alternate way to view results. With this type of advanced imaging, it is possible to visibly see physical evidence of healing.

But to come back to your question: what to expect? Your surgeon will probably be the one to give you the best range of expectations (and potential surprises). This type of counsel is based on the severity of injury, type of surgery needed, and your general health. In the end, your goals and expectations may be just as important in identifying and achieving final outcomes.

It has been known for many years now that bracing after surgery to reconstruct a ruptured anterior cruciate ligament (ACL) just isn’t needed. Study after study have shown there isn’t any benefit to bracing no matter what type of brace is used, when it is used, or how it is used.

This message was repeated once again in a recent systematic review of the literature conducted by orthopedic surgeons at Washington University School of Medicine in St. Louis. They searched for all articles on the rehabilitation after ACL reconstruction from 2006 to 2010. There were 29 high-quality studies that could be included for the review and analysis.

Patients who used braces to limit knee motion and protect against too much movement from side to side did not have any different results compared with patients who did not use a brace. Recovery was not statistically improved in either group (with brace, without brace). Measures used to judge differences between the two groups included level of pain, number of reinjuries, joint range-of-motion, or knee stability.

Many surgeons still do provide their patients with a brace after ACL reconstructive surgery. But the experts in this field keep trying to get the word out that bracing just isn’t effective and shouldn’t be part of the postoperative protocol. This is an area where clinical practice has not fully caught up to the research yet.

There are many different ways to approach the rehabilitation of ACL injuries. Sometimes it is possible to complete a conservative plan of exercise without surgery. This approach is most likely for the less active individual or the patient who did not completely rupture the ligament.

Most of the time, when there is a complete rupture, then surgery to reconstruct the knee is necessary. Active participants in sports and especially those players with a complete ACL rupture will definitely require surgery to reconstruct the ligament.

Graft tissue taken from the patellar or hamstring tendons is used to replace the destroyed ligament. Rigorous rehab is always important after surgery. The goals are to regain motion, strength, and balance. Athletes have the additional goal of eventually returning to full level of sports play.

Studies show that early, aggressive rehab can be started right away during the recovery process. This is referred to as accelerated rehabilitation. Early, aggressive therapy is safe and may restore strength faster. This type of approach includes immediate post-op weight-bearing (standing and walking) and range-of-motion exercises.

Muscle strengthening is an essential part of the post-operative rehab program. Eccentric quadriceps strengthening and isokinetic hamstring strengthening can be started three weeks after surgery. So you have that to look forward to next week. The more you do at home following the physical therapist’s instructions, the faster your recovery will be.

Even with early, aggressive rehab, you can expect a six-month recovery time minimum. Most people who are consistent with their program actually need up to a year to fully recover. You may not be an athlete in need of a quick turn around time. But anyone who has had ACL surgery is at risk for reinjury if the knee is not retrained.

Collagen Meniscus Implantation (CMI) is a new treatment for people with damaged, destroyed, or removed knee meniscus. The implant is actually a scaffold (mesh) made from bovine (cow) Achilles tendons. As you have found from your search, it has been tried with medial meniscal problems. A group of surgeons from Italy recently published their results using collagen meniscus implantation for lateral meniscus injuries. They say theirs is the first published report of results using CMI for lateral meniscal.

In this study, 24 patients with irreparable lateral meniscus tears received the CMI treatment. Their ages ranged from 16 years old to 53 years old. Without the CMI treatment, these partial tears would have required removal of the damaged cartilage. The risk of early, degenerative arthritis in this age group is a major reason for the use of this new surgical technique. And the results?

All but one patient experienced significant improvements with decreased pain, better knee joint motion, and improved function. Although the knees were stable, not everyone was able to return to their preinjury level of sports or athletic participation. Clinical measurements and repeat MRIs taken over a two-year period of time showed gradual, progressive improvements right up until the end of the study period.

The MRIs showed a partial (not complete) filling effect with collagen meniscus implantation (CMI) therapy. The reason(s) for this remain unknown. It’s possible that chronic injuries that are not treated soon enough just can’t recover as well as acute (early) meniscal injuries. There may be just too much meniscal damage and degeneration at the cellular level to respond in a robust fashion.

Even so, the authors concluded there’s no doubt the use of collagen meniscus implantation you asked about is safe and effective for partial lateral meniscal tears. Patients can expect a decrease in their painful symptoms accompanied by an increase in motion and function. Rehab is started right after surgery and continues for a full six-months until full unrestricted activity is resumed.

In each human knee, there are two menisci. One is the lateral meniscus (on the outside of your knee) and the other is the medial meniscus (on the inside of the knee). The menisci are attached to the tibia (lower leg bone) by ligaments. The menisci are important because they act as shock absorbers. They stabilize the knee and allow your body weight to be evenly distributed across the joint. The menisci protect and lubricate the articular cartilage (a separate layer of cartilage right next to the joint).

In the past, damaged menisci causing pain and other joint problems would have just been removed surgically. But when we realized joint degeneration leading to early osteoarthritis develops without the meniscus, surgeons started to repair rather than remove this protective cartilage. Eventually, efforts to replace (not just repair) the cartilage were developed. Collagen meniscus implantation (CMI) is an example of this type of regenerative treatment technique.

The scaffold of bovine tissue developed for this purpose is used to fill partial defects (holes or lesions) in the meniscus. The procedure for lateral meniscus implantation is the same as the one used for medial meniscus implantation. After removing the flapped over or torn piece of meniscus, the remaining meniscus is smoothed and shaped carefully to accept the graft. Tiny holes are drilled around the edges of the defect. This step helps create some bleeding that will aid healing and recovery. Once the implant is placed in the hole, the edges are stitched down to hold it in place.

As you know, osteochondritis dissecans (OCD) is a problem that affects the knee, mostly at the end of the big bone of the thigh (the femur). A joint surface damaged by OCD doesn’t heal naturally. Even with surgery, OCD can lead to future joint problems, including degenerative arthritis and osteoarthritis.

There are many different ways to treat this problem. The choice often depends on several factors: your age at the time of diagnosis (children and teens who are still growing are treated differently than adults), severity of the lesion(s), patient choice, and surgeon’s expertise in this area.

Some patients with minor defects can be treated with conservative (nonoperative) care. Rest, activity modification, and specific exercises may be prescribed. Surgery (when it is advised) can consist of reattaching the fragments that have pulled away from the bone or removing them. Reattachment is called reduction and internal fixation; removal is called debridement.

Other treatment choices also include a procedure called microfracture (drilling tiny holes into the joint surface to stimulate healing), osteochondral grafts (donor tissue used to fill the hole), and autologous chondrocyte implantation (ACI). Since we don’t know what type of first procedure you had, we cannot say what the next step may be. But a visit with your surgeon is the first order of events.

Your surgeon will re-evaluate your situation. Reasons for treatment failure may help direct the next treatment choice. For severe and chronic osteochondritis dissecans (OCD) lesions, autologous chondrocyte implantation (ACI) has been reported as a good option. In this procedure, healthy chondrocytes are removed from an area or normal tissue in your knee. They are sent to a lab where more chondrocytes are grown until there is enough graft tissue to fill in the defects.

Knowing what some of the treatment options are will aid you in talking with your surgeon and making the best decision for you. It’s a fact that OCD can be a challenging condition to treat successfully. But studies also show that with surgery, the majority of patients with severe lesions do get satisfactory results. With the right treatment for you, you can expect reduced pain and improved function. Sometimes it takes more than one treatment to achieve these results so be patient with the process until you find what works best for you.

ACL ruptures are surgically reconstructed by using a piece of graft material to replace the torn ligament. The graft is taken from the patient’s own patellar or hamstring tendon. Studies show that the majority (75 to 80 per cent) of patients return to their preinjury level of activity.

But like you, many patients wonder what will happen down the road after this surgery? How long will the ACL graft last? What are the chances of the graft rupturing? Why does it rupture? Knowing the risk factors might help patients prevent such an event. And what about the other knee? Does having an ACL rupture on one side increase the risk of an ACL tear on the other side?

Studies show that the risk of rupture of the ACL on the other side is less than one per cent per year. If it’s going to happen, it will most likely occur between year one and year four after the primary (first) ACL surgery. You are well past that now.

Patients who have patellar tendon grafts may be more likely to have an ACL rupture in the opposite leg compared with those patients who have the hamstring graft. ACL grafts survive intact in the first two years for 90 per cent or more of patients studied.

But the risk of rupture increases as time goes by. Rupture of the surgical graft affects about 10 per cent of patients studied. When rupture does occur, it will most likely to happen in the first year after the primary surgery. Again, you have moved well past this bench mark.

All the risk factors for rerupture of the injured side and rupture of the opposite side probably haven’t been identified yet. But graft type (patellar tendon) and age (younger patients) may be two of the main risk factors.

Younger age is linked with higher activity level and therefore increased risk of injury. Unless you are an extremely active retiree, this doesn’t describe you either. Two other possible risk factors that have not been proven yet are: 1) graft size on the surgical side is larger than ACL on the opposite side creating some differences in tension and 2) there is greater load placed on the opposite leg as that leg works harder to protect the injured leg.

If you are experiencing any symptoms that would make you think either knee is unstable or changing in function or strength, then see your surgeon for a follow-up evaluation. You may want to do this anyway to relieve your mind of any further worry.

Rupture of the anterior cruciate ligament (ACL) is a fairly common injury these days — especially among young athletes. Surgery to reconstruct the ACL has improved over the years. It is still done with one of the two graft choices you mentioned (patellar tendon or hamstring tendon) but the procedure is far less invasive now. Arthroscopic surgery with minimally invasive techniques are standard.

Surgeons have been following patients over the years to see how well the graft holds up. They are interested in improving results and long-term outcomes can help guide them in that quest. Studies are being done to address many unknowns such as:

We can help you right here! ACI or autologous chondrocyte implantation is a surgical procedure used in the knee for a condition known as osteochondritis dissecans (OCD). With OCD the surface of the knee joint surface is damaged and doesn’t heal naturally. OCD mostly affects the femoral condyles of the knee. The femoral condyle is the rounded end of the lower thighbone, or femur.

Like most joint surfaces, the femoral condyles are covered in articular cartilage. Articular cartilage is a smooth, rubbery covering that allows the bones of a joint to slide smoothly against one another.

The problem occurs where the cartilage of the knee attaches to the bone underneath. The area of bone just under the cartilage surface is injured, leading to damage to the blood vessels of the bone. Without blood flow, the area of damaged bone actually dies. This area of dead bone can be seen on an X-ray and is sometimes referred to as the osteochondritis lesion.

Autologous chondrocyte implantation (ACI) is a fairly new treatment approach developed in the last 10 years. It is currently being studied closely. It involves using the patient’s own cartilage cells (chondrocytes) to help regenerate articular cartilage. The laboratory where the chondrocytes are grown for the ACI procedure is conducting a study they call STAR: Study of the Treatment of Articular Repair.

In the STAR study, patients who have severe lesions and one failed surgery were treated with autologous chondrocyte implantation (ACI) and then followed for the next four years. The results of treatment and analysis of factors that might improve treatment are periodically reported on as more people enter the study.

Outcomes of treatment are measured based on patient report of pain and other symptoms (swelling, tenderness) as well as activity and function. Activities include return to sports or physical recreation. Function is measured by patients’ perception of their quality of life and ability to perform activities of daily living (walking, climbing stairs, getting up and down, returning to work).

The majority of patients in the STAR study have a successful repair of their severe osteochondritis lesion using autologous chondrocyte implantation (ACI). Although it is two years before the repair tissue is mature enough to mimic normal tissue, patients report pain relief and functional improvement early on.

Factors identified so far that affect outcomes include 1) chronicity of the disease (i.e., how long it has been present), 2) severity (how deep and wide are the lesions), 3) delays in treatment, and 4) age (adults versus teens).

As you might expect from the listed factors, the larger the defect and the longer it is present, the greater the risk of a poor outcome. Likewise, a long delay between diagnosis and treatment is an added predictive factor of worse results. And the timing of treatment is linked with age. Patients who develop OCD in their teen years but aren’t treated until they are adults tend to have a lower success rate than those patients who are treated during their adolescent years.

One of the other positive features of this procedure is the fact that it can be used when other surgeries fail to produce the desired results (pain relief, improved knee function). There are some side effects of the procedure that may be undesirable. These include cartilage injury and graft overgrowth.

About one-third of the patients in the STAR studies have developed these adverse events but they are not considered a treatment “failure”. A follow-up surgery may be needed to remove the extra tissue in the case of overgrowth or to attempt another cartilage repair.

The majority of patients (85 per cent or more) who have an ACI procedure for osteochondritis dissecans (OCD) have good results with high rates of patient satisfaction. OCD is a complex and challenging problem but successful treatment is possible.

We are assuming from what you wrote that perhaps you had an avulsion injury to the hamstring muscle with either a partial or complete tearing of the tendon where it attaches to the bone.

Since you mentioned painful sitting, it’s probably safe for us to also assume the tendon pulled away from the bone where it normally attaches to the ischial tuberosity. The ischial tuberosity is the bump on the bottom of the pelvic bone where your bottom rests when sitting. Some people refer to this area as their “sit bones.”

From the description of your symptoms, you may be experiencing sciatic neuralgia. The sciatic nerve is a large nerve that starts in the low back and goes down the back of the leg from hip to foot. It can be irritated or injured when it is pulled out of the way to repair the torn hamstring tendon. In the normal process of healing, scar tissue can form around the sciatic, too. Either (and often both) of these situations contribute to sciatic neuralgia.

The incision made over the ischial tuberosity to perform a hamstring repair is a common cause of painful sitting. Over half of all patients who have this repair procedure still report these kinds of symptoms a full year after the surgery.

There are some ways to approach this problem. You will want to consult with your surgeon for the best treatment for your situation. Treatment may start with analgesics (pain relievers) and physical therapy.

The therapist can help you change your posture as malalignment might be contributing to the problem. Stretching the piriformis muscle around the sciatic nerve often helps. The therapist can also take you through a series of movements that will mobilize (move, slide, and glide) the sciatic nerve.

The therapist guides you through these steps, but in some cases, the painful symptoms persist. Other more invasive procedures can be tried. For example, the surgeon may try injecting a numbing agent around the nerve. Sometimes even a short period without pain helps “reset” the nervous system.

In order to determine the best treatment for you, see your surgeon. This may be something that just requires more time for healing to take place. But at least you can get some help with the painful symptoms and keep the problem from getting worse while you wait for completion of the recovery process.

Most hamstring injuries occur in the musculotendinous complex. This is the area where the muscles and tendons join. (Tendons are bands of tissue that connect muscles to bones.) The hamstring has a large musculotendinous complex, which partly explains why hamstring injuries are so common.

When the hamstring is injured, the fibers of the muscles or tendon are actually torn. The body responds to the damage by producing enzymes and other body chemicals at the site of the injury. These chemicals produce the symptoms of swelling and pain.

In a severe injury, the small blood vessels in the muscle can be torn as well. This results in bleeding into the muscle tissue. Until these small blood vessels can repair themselves, less blood can flow to the area. With this reduced blood flow, the muscles cannot begin to heal.

The chemicals that are produced and the blood clotting are your body’s way of healing itself. Your body heals the muscle by rebuilding the muscle tissue and by forming scar tissue. Carefully stretching and exercising your injured muscle helps maximize the building of muscle tissue as you heal.

If the force of the injury is severe enough, the muscle and tendons can tear away from the bone. This happens most often where the hamstring tendons attach to the ischial tuberosity (what you call your “sit bones”). These tears, called avulsions, sometimes require surgery. An incision is made over the back of the thigh where the hamstring muscle is torn. The muscle repair involves reattaching the two torn ends and sewing them together.

If surgery is delayed after an avulsion, the tendon may begin to retract further down the leg, and scar tissue may form around the torn end of the tendon. Both of these factors make it more difficult to do the surgery. With or without surgery, the recovery time can be quite long.

As your hamstrings begin to heal, it is critical that you follow an exercise program to regain your strength and mobility. Specially designed exercises encourage your body to rebuild muscle instead of scar tissue. The exercises also help prevent reinjury. Rehabilitation can be slow, so you will need to be patient and not push yourself too hard or too fast. Returning to active sports like skiing (with the potential for reinjury) must be done only with your surgeon’s approval and after proper rehabilitation.

When testing for a torn meniscus, a C- or horseshoe-shaped piece of cartilage in the knee, the McMurray test is used most often to diagnose posterior (along the back of the knee joint) meniscal tears. This is most likely the test your surgeon used on you.

There are two McMurray tests: the standard or conventional McMurray and the paradoxical McMurray. Both tests are performed in the same way. The knee is bent; the examiner holds the heel and twists the lower leg in and out. If there is a torn or loose meniscus, there will be a painful, snapping or clicking sensation as the movement shifts or traps the meniscal flap or fragment between the tibia (lower leg bone) and the femur (thigh bone).

The results are what make the test conventional or paradoxical. For example, the test is considered “paradoxical” when the leg is rotated internally (inward) and the medial side of the knee (side closest to the other leg) clicks. There can also be a paradoxical McMurray when the leg is rotated externally (outward) and the clicking occurs in the lateral compartment (or side) of the knee. Lateral refers to the side of the knee away from the other knee.

The results just described are considered paradoxical, meaning the opposite of what is expected. In the conventional test, the clicking occurs on the opposite side of the knee from the rotation. When the leg is rotated inward, the clicking occurs on the outside of the knee. When the knee is rotated outward, the clicking occurs on the inside of the knee.

When there is a positive McMurray test (conventional or paradoxical), it is an indication that there is a torn fragment or loose piece of meniscus. The clicking sound can occur when the meniscal piece flaps over on itself and gets stuck between the two bones. The same clicking can also occur when a torn meniscus is flapped over on itself and the test movement smoothes it back out where it belongs.

This second scenario is probably what happened to you during the test. The torn meniscus is now in place but it is likely not stable. A sudden or unexpected movement can cause the flap to come up and rub between the bones, possibly even getting torn even more. An arthroscopic exam can help confirm the diagnosis.

If there is any indication that the area is healing on its own (unlikely given what we know about this type of cartilage injury) the surgeon can leave it alone. But if the surgeon is able to see a badly frayed or damaged meniscus, she can repair it right then and protect the joint from further injury.

In the case of the meniscus, a C- or horseshoe-shaped piece of cartilage in the knee, the McMurray test is used most often to diagnose posterior (along the back of the knee joint) meniscal tears. There are other meniscal tests that can be done for tears in other parts of the joint but the posterior tears are the most common.

There are two McMurray tests: the standard or conventional McMurray and the paradoxical McMurray. Both tests are performed in the same way. The knee is bent; the examiner holds the heel and twists the lower leg in and out. If there is a torn or loose meniscus, there will be a painful, snapping or clicking sensation as the movement shifts or traps the meniscal flap or fragment between the tibia (lower leg bone) and the femur (thigh bone).

The results are what make the test conventional or paradoxical. For example, the test is considered “paradoxical” when the leg is rotated internally (inward) and the medial side of the knee (side closest to the other leg) clicks. There can also be a paradoxical McMurray when the leg is rotated externally (outward) and the clicking occurs in the lateral compartment (or side) of the knee. Lateral refers to the side of the knee away from the other knee.

The results just described are considered paradoxical, meaning the opposite of what is expected. In the conventional test, the clicking occurs on the opposite side of the knee from the rotation. When the leg is rotated inward, the clicking occurs on the outside of the knee. When the knee is rotated outward, the clicking occurs on the inside of the knee.

An MRI should be ordered when the paradoxical McMurray test is negative but the patient has pain and other clues pointing to a meniscus problem. A positive paradoxical test is a sign that there is a large meniscal tear — long enough to shift the loose or torn meniscus during the test. But a positive paradoxical McMurray test does not mean the patient should have surgery immediately. The surgeon must evaluate the patient history and clinical findings and find out the patient’s goals and activity level.

If you are having doubts about the proposed treatment, it may be a good idea to either get a second opinion or go back to your surgeon with your questions and concerns. Some people do both and there’s nothing wrong with that plan of action. You must be satisfied that the diagnosis is accurate and the planned treatment is the best option for your specific situation.

It is possible that you have injured some of the soft tissues around the patella (knee cap). A little bit of anatomy will help explain this injury. The patella moves up and down in front of the knee joint along a built-in track called the patellofemoral groove.

The kneecap is held in place by several ligaments on either side and by the patellar tendon (attached to the quadriceps muscle). The quadriceps muscle is the large, four-part muscle along the front of the thigh.

Although you can take your hands and passively move the kneecap from side to side, this is not an active movement you can make your patella do without assistance. We call that side-to-side (medial-to-lateral) movement accessory motion. The up-and-down and side-to-side accessory motions are referred to as patellar glide.

As part of the patellar tendon, there are slips of ligamentous fibers that help hold the patella in place and keep it from moving too far to one side or the other. On the inside of the kneecap is the medial patellofemoral ligament. On the outside is the lateral patellofemoral ligament.

Without the medial patellofemoral ligament, the kneecap dislocates laterally (in a direction sideways away from the other knee). Because the medial patellofemoral ligament is connected with other ligamentous structures, complete rupture will likely damage other areas as well. The medial patellofemoral ligament attaches above to the femur (thigh bone) and below to the tibia (lower leg bone).

A medial patellofemoral ligament injury can be treated conservatively without surgery. The knee may have to be immobilized in a splint for a number of weeks to allow for healing. Physical therapy, taping, and a home program of exercises prescribed by the therapist begin after the period of immobilization. The rehab program must be given the good old college try: in other words, for more than a few days or weeks. It can take months to rehab this injury.

But if nonoperative care fails and the patella dislocates again, then surgery may be the next step. The surgical approach that works best depends on the underlying damage and specific patient factors. The surgeon will decide if the torn ligament can be reattached to its original insertion on the bone. This is a repair procedure.

More complex injuries with damage to the surrounding tissues may require reconstructive surgery (taking graft material and using it to replace the ruptured ligament). Overall results for repair or reconstructive surgery are good to excellent. Many active patients (teens to adults) are able to resume full physical activities, including sports participation.