Description of Patellar Chondromalacia

Patellar chondromalacia refers to pain around the front (anterior) part of the knee.  In the past, it was often a wastebasket term for describing anterior knee pain.  However, patellar chondromalacia refers to a specific diagnosis of the knee.

Injuries, wear and tear, or genetics may play a role in the breakdown of the cartilage under the knee (the patella) and on the distal end of the femur, which is called the trochlea.  In a healthy knee, the cartilage surfaces of the patella and trochlea are extremely smooth.  The joint fluid creates an extremely efficient gliding surface, which is about 1/6 that of ice on ice.  When there is a breakdown of the cartilage, this efficient gliding surface no longer exists.  Any breakdown of the cartilage surface is a form of arthritis, which is commonly classified into grades of chondromalacia.  Thus, chondromalacia occurs when the cartilage surface has broken down and early arthritis has formed.  Unfortunately, the strongest point of the cartilage is the surface, which is called the lamina splendens.  As the cartilage surface of the knee wears down, the deeper cartilage surfaces which are weaker subsequently wear out even faster, leading to a greater development of knee arthritis.

Symptoms of patellar chondromalacia include:

  • Active grinding of the knee with motion
  • Anterior knee pain
  • Swelling with activities

In some cases, patients can have patellar chondromalacia without any of these symptoms.

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(Please keep reading below for more information on this condition.)

Treatment for Patellar Chondromalacia

The first step in treating patellar chondromalacia is to identify its cause.  For patients who have anterior knee pain, a physical exam, x-rays, and possibly an MRI scan are necessary to evaluate the cause of the pain.  The treatments can include rest, activity modification, physical therapy, stretching, bracing, injections, or arthroscopic surgery.

Arthroscopic surgery for patellar chondromalacia involves placing instruments into the knee to shave down any unstable cartilage flaps on the patella and the trochlear groove.  In most circumstances, some surface cartilage will remain present. Physical therapy after surgery will work to strengthen the muscles around the knee and to make sure the patella does not scar in. It is also recommended to avoid any activities that can cause further cartilage wear, breakdown, and swelling in the knee.  In general, except for a very high-level athlete, we recommend avoiding any high-impact activities, and squatting and lunging activities, to try slow down the rate of wear of the cartilage surface.

Post-Op

The postoperative treatment for trimming of the unstable cartilage surfaces of the patella and trochlea involves working on maintenance and regaining of muscle strength, limiting swelling after surgery, and working on patellar mobility with one’s physical therapist.  It is especially important to mainly work on kneecap motion and avoiding knee swelling in patients who has more than relatively small areas that needed to be trimmed.  This is because if one strives to work on aggressive strengthening too soon after this particular surgery, the body may form an increased amount of scar tissue, which is often painful, in response to the increase of activities.  Thus, it is usually recommended to work on light low impact activities for the first 6 weeks after surgery to avoid irritating the knee and causing an aggressive scar tissue healing response.

Related Studies

Anterior Knee Pain Injury FAQ

The following are questions that have presented to our website asking about anterior knee pain. It is important to recognize that “anterior knee pain” is a wastebasket term that is used to clump multiple different conditions into. While in general this is usually due to something involving the kneecap joint, other things in the knee that can cause swelling can also result in anterior knee pain. Therefore, one often needs a very good physical exam and x-rays at a minimum to help localize the etiology of the condition that is causing the pain in the front of the knee.

Will anterior knee pain go away?

It is important to help determine the cause of the anterior knee pain to help determine if it can go away. If it is a relatively moderate problem, such as mild chondromalacia or a muscle imbalance, a well-designed rehabilitation program may be very useful in helping anterior knee pain resolve. However, if one does have anterior knee pain from advanced arthritis of their kneecap joint, or possibly due to advanced arthritis throughout the knee, then it may be difficult to have the anterior knee pain go away for a long period of time.

Is anterior knee pain curable?

It is important to document the cause of the anterior knee pain to help determine if it is treatable and if there is a good chance the symptoms will resolve. If it is due to a muscle imbalance, a proper rehabilitation program will help this significantly. If it is due to advanced arthritis, one can look at nonoperative measures, but the chances of anterior knee pain going away are much less.

What does anterior knee pain mean?

The anterior knee is the front part of the knee. Therefore, any cause of pathology that causes pain in the front part of the knee can be referred to as anterior knee pain. This can include multiple pathologies such as muscle imbalance, patellar tendinopathy, medial plica irritation, patellofemoral chondromalacia, general knee swelling, diffuse arthritis in the knee, quadriceps insertional tendinitis, localized areas of arthritis on the kneecap or on the trochlear groove and other causes.

What causes anterior knee pain when squatting?

When one is squatting, one is putting extra stress on the cartilage in the kneecap joint. Squatting and lunging can increase the force across the kneecap joint by 7 to 9 times one’s body weight or more. Therefore, if one has a cartilage problem of their kneecap joint on the kneecap or the trochlea or both surfaces, then one could have this area of arthritis be overloaded while squatting or lunging and lead to pain in the front of their knee.

What can anterior knee pain lead to?

Pain in the front of one’s knee usually indicates that something is going on that should be evaluated further. Therefore, if one does have anterior knee pain, especially anterior knee pain that does not go away well a well-designed rehabilitation program or time of rest, one should have it evaluated to determine if there is a potentially treatable problem. This can include a course of therapy, therapy with injections, or potentially even surgery. If one has a treatable problem that is ignored, over time, the problem could get worse or become more accelerated so checking it out sooner rather than later would be recommended.

How can one reduce anterior knee pain?

The primary focus of all treatments for anterior knee pain is a well-developed rehabilitation program. This usually involves low-impact exercises to build up one’s core strength so that one has better absorption with activities. Thus, low-impact activities like the use of a stationary bike, an elliptical machine, walking, or swimming are the mainstays of a rehabilitation program.

Other specific exercises can be determined by one’s physician and/or physical therapist. If one does have swelling associated with their anterior knee pain or has significant scarring, the use of a corticosteroid injection may be beneficial to cut down  on the symptoms for anterior knee pain.  If the symptoms are resolved with an injection, one needs to work on a rehabilitation program while the symptoms are minimized to build up their baseline strength. This is because most injections last about 6-8 weeks in terms of their efficacy, so working on one’s general strength is important while the steroid injection is kicking in.

How common is anterior knee pain?

Anterior knee pain is one of the most common presenting symptoms of patients presenting to a sports medicine physician’s office.  It is particularly common in adolescent females who are participating in sports. In younger patients, most anterior knee pain responds well to a program of strengthening and possibly injections. In general, unless there is a well-defined surgical problem, surgery is resolved for those cases that just are nonresponsive to nonoperative means.

What is the cause of anterior knee pain with running?

There could be multiple causes of anterior knee pain with running, including whether one is running on hard surfaces or softer surfaces.  Causes of anterior knee pain with running can include chondromalacia of the kneecap or trochlea, patellar tendinitis (tendinopathy), quadriceps insertion tendinopathy, and knee swelling from other pathology within the knee which can cause anterior fat pat or plical irritation. In addition, previous surgeries which cause scar in the front of the knee could also contribute to anterior knee pain with running.

Why do I have anterior knee pain with prolonged sitting?

Anterior knee pain with prolonged sitting is a fairly common problem. This could include patients having difficulty with long car rides, sitting in a classroom for a long period of time, or sitting in a chair and not moving around at work. This is usually because of some underlying kneecap or trochlear chondromalacia, medial plical irritation, or possibly some scar tissue from previous surgery. Patellar tendinitis can also cause anterior knee pain with sitting, but this is usually a less common cause of anterior knee pain with sitting.

Why do I have anterior knee pain after ACL reconstruction surgery?

Many patients commonly have anterior knee pain after ACL reconstruction surgery, especially for the first 3-4 months after the surgery. This is because the quadriceps muscles are weak and atrophied and this can cause extra stress in the front of the knee leading to plical irritation or irritation of some mild underlying arthritis. In these patients, proceeding with a rehabilitation progress to address the underlying weakness with cause the anterior knee pain to resolve over time. Patients who have anterior knee pain after surgery which does not resolve  can have several different causes. One of these can be some underlying kneecap or trochlear groove arthritis. In addition, patients who may have scar tissue in the anterior compartment of their knee, which most commonly presents as their kneecap getting stuck and not being able to move so well, can also have knee pain in the anterior aspect of the knee after ACL reconstruction surgery.

Why do I have clicking with my anterior knee pain?

One of the most common causes of clicking within the knee, especially if the clicking is not painful, is because one has some underlying swelling in the joint. The normal joint fluid has a very low coefficient to friction, one-sixth that of ice-on-ice, so the tissues that are normally present in the knee glide well. If there is some underlying swelling from arthritis, or a recent surgery, or an injury this will decrease the viscosity and make it harder for one’s knee to move. Therefore, the normal tissues that glide well may catch up a little bit and there may be an audible click. Other sources of clicking inside the joint with anterior knee pain can include scar tissue in the front of the knee or in the sides of the knee, or possibly some cartilage flaps under the kneecap or in the trochlear groove, which are catching when the knee bends back and forth. One should be examined to determine what may be the cause of anterior knee pain when it is painful.

What causes anterior knee pain with knee flexion?

When one flexes their knee, they usually put extra stress on their kneecap joint. Therefore, pain in the front of their knee can be caused from catching scar tissue, putting extra stress on an area of chondromalacia (arthritis) of the kneecap or trochlear groove, or other causes. A good physical exam and x-rays should help to delineate these causes.

What causes anterior knee pain below the patella?

Anterior knee pain below the patella is most commonly due to patellar tendinopathy, which is called patellar tendinitis in the lay literature. This most commonly occurs in court-type sports such as volleyball or basketball where one is jumping and landing on hard surfaces. This can cause an overload of the attachment of the deeper part of the patellar tendon on the patella.  If this happens over a long period of time, the patellar tendon can be swollen at this location and sometimes even partially detached.

What causes anterior knee pain in adolescent females?

Adolescent females are one of the most common age groups to present with anterior knee pain.  Luckily, most of the time the cause of the anterior knee pain is addressable with a nonoperative program. The causes of anterior knee pain can include a muscle imbalance, tight hamstrings placing stress on the front of their knee, Osgood-Schlatter’s syndrome, patellar tendinitis, or medial plical irritation.  In addition, chondromalacia, which is a kind term for arthritis, of the kneecap joint can also cause anterior knee pain in this group. It is important that one has a proper physical exam and plain x-rays to help localize what may be the cause of anterior knee pain in any circumstances.

What x-ray views are good to diagnose anterior knee pain?

The best x-rays to diagnose anterior knee pain would be ones looking at the cartilage space in the kneecap joint. This is usually an x-ray obtained with the knee bent to 45 degrees looking directly down on the kneecap joint. It would help determine if there are any bone spurs (osteophytes) present, or if there is any joint space narrowing. In addition, things like cysts or osteochondritis dissecans could also be diagnosed if it is present in the patellofemoral joint.  Standing AP and lateral x-rays are also useful because they can show patella position and if there are bone spurs present around the kneecap joint, which may indicate some underlying arthritis.

What types of anterior knee pain prevention programs are available?

The usual treatment for anterior knee pain is to work on a lower extremity strengthening program that focuses on low-impact activities initially so one has better absorption with activities. In addition, making sure that one’s hamstrings are appropriately stretched out so there are not any associated bursitis-type symptoms from having tight hamstrings present will be useful. Ensuring that one has appropriate hip strength and balance is also important for anterior knee pain prevention programs.

Can one have anterior knee pain with tight hamstrings?

In the past, patients who had anterior knee pain were often diagnosed as having a “hamstrung knee.”  This is because the hamstrings can commonly become tight when one does have some anterior knee pain. Probably the biggest thing to be concerned about with this is patients that develop pes anserine bursitis due to tight hamstrings. This can also cause one to have functional limitations. I still believe that making sure that one stretches out their hamstrings effectively can help decrease the stress on the front part of the knee, so a hamstring stretching program should be a part of any anterior knee pain treatment program.

What can be the cause of anterior knee pain after tibial nailing?

Tibial nailings are performed for fractures of the tibia. They involve making a hole in the top part of the tibia and inserting a pin down the tibia, reaming over the pin, and then inserting a nail to best stabilize the fracture fragments. In the process of doing this, it can cause some scar tissue in the front of the knee which can lead to anterior knee pain.  In addition, in smaller patients, the insertion of the tibial nail could damage the anterior horn medial meniscus attachment site and this could lead to having the meniscus being nonfunctional anteriorly and it could lead to anterior knee pain. These anterior horn root tears after tibial nailing have been described and validated in biomechanical and clinical models and should be evaluated as a potential source of knee pain in female and smaller patients after a tibial nailing.

What can be the cause of anterior knee pain after a total knee replacement?

Anterior knee after a total knee replacement can be due to several factors.  One of these can include scar tissue, tight kneecap components in the front of the prosthesis, or potentially other causes.  New-onset anterior knee pain may respond to a therapy program, but anterior knee pain that has been present since the start of rehabilitation after a total knee replacement may need further workup to determine its cause.

What is the cause of anterior knee pain at the tibial tubercle?

The most common cause of anterior knee pain at the tibial tubercle is either Osgood-Schlatter’s syndrome in adolescets or the residual of Osgood-Schlatter’s syndrome in adults. Osgood-Schlatter’s syndrome is caused by having tight hamstrings cause one to put extra stress on the growth plate in the front of the knee where the patellar tendon attaches. This can cause the patellar tendon to pull on this growth plate as one tries to straighten their knee and result in a bony bump over time s the growth plate is pulled on. In some people, this can lead to some fragmentation of that bone and a piece of the bone may catch in the front of their knee and lead to anterior knee pain when they are still an adult. In most cases, once the growth plates close in an adolescent, most of the symptoms from Osgood-Schlatter’s syndrome resolve.

What is the cause of anterior knee pain while skiing?

The most common cause that I have seen of anterior knee pain with skiing is in patients who have underlying arthritis of their kneecap and/or trochlear groove that was previously unrecognized. They may ski really hard for a few days and suddenly start having pain and swelling with the same type of activities. This is because of overuse. Having a good physical exam and x-rays may help to determine if this is the cause of anterior knee pain with skiing. Other causes can be patellar tendinitis (tendinopathy), scarring on front of the knee and general knee swelling.

What is the cause of anterior knee pain going up and down stairs?

There can be many causes of anterior knee pain while going up and down stairs. This is because while going up or down stairs, one commonly puts a significant increased amount of stress on the front part of their knee. Thus, scar tissue in the front of the knee, arthritis of the kneecap or trochlear groove, and recent surgery can cause anterior knee pain while going up and down stairs. There can be multiple causes of this pathology and if one does not have relief of their symptoms, a physical exam with x-rays with a physician may be indicated.

What types of operations are available for anterior knee pain?

The operations that are available for anterior knee pain can be dependent upon the underlying cause of the anterior knee pain. For patients who may have cartilage pieces that are catching and grinding when they squat or lunge, a surgery to trim down the cartilage pieces, called a chondroplasty, may be indicated. In patients who have scar tissue that is making their kneecap not move very well, which we call a captured patella, is important to ensure that one has the best diagnosis possible because the results of anterior knee pain surgery for scar tissue are not as successful as those for other causes. Therefore, making sure that one has tried a rehabilitation program and we commonly place numbing medicine in the knee (lidocaine) to see if it takes the knee pain away. If it does take the knee pain away, it helps us to determine that the pain is coming from inside the knee rather than from structures outside the knee (extraarticular). If one does have recalcitrant anterior knee pain with a captured patella whereby the knee pain is completely taken away and one can squat and lunge after a lidocaine injection, the patients could be a candidate for an arthroscopy and release of the scar tissue. However, it is also important to arrange a well-designed therapy program with the surgery to best ensure that when healing occurs, that it does not heal back as tight scar tissue, but rather as loose scar tissue.

Is obesity related to anterior knee pain?

Obesity is related to anterior knee pain because the more that one weighs, the more stress they can place on the front part of their knee. Some studies have calculated that when one loses one pound, it can sometimes equilibrate up to 6 pounds of decreased stress across the front of one’s knee. Therefore. losing 5-6 pounds could be equivalent to losing the effects of a heavy backpack with activities when they stress their knee.

What types of bursitis can cause anterior knee pain?

There are 2 main causes of bursitis which cause pain in the front of the knee. One of these can be associated with Osgood-Schlatter’s syndrome, where the deep infrapatellar bursa that is just in front of the tibial tubercle and below the patellar tendon attachment of the tibia can be irritated. This can be irritated just from having tight hamstrings or possibly because of a bony ossicle located within the bursa. The other type of anterior knee pain associated with bursitis is with the pes anserine tendons, the sartorius, gracilis, and semitendinosus, are tight and cause irritation where they cross the distal aspect of the MCL. Both of these can cause significant limitations in function in some people, and it is generally believed that a well-designed stretching program as well as addressing the cause of why the hamstrings may be tight would be indicated.

Why do I have anterior knee pain with lunges?

The reason that one can have anterior knee pain with lunges is because lunges cause 7-9 times one’s body weight to be present across the kneecap joint. Therefore, any structure which may get extra stress, such as the patellar tendon, quadriceps tendon, cartilage of the kneecap joint or scar tissue or normal structures around the knee, can be irritated with varying degrees and duration of participation with lunges.

Why do I have anterior knee pain after hip surgery?

It is not uncommon for patients to develop anterior knee pain after hip surgery. This is because the whole leg can be deconditioned after a hip replacement or hip arthroscopy, which can cause the muscles around the knee to be affected. If the muscles around the knee are weak, it can cause pain in the front of the knee due to some underlying conditions or just because there is extra stress being placed in the cartilage. In most of these cases, we recommend that the patients participate in a strengthening program, and most of these cases of anterior knee pain will get better. If they don’t get better over time, a further workup may be indicated.

What types of injections may be used for anterior knee pain?

The types of anterior knee injections, most commonly corticosteroids or PRP, depend upon the individual pathology. In general, it is bad to use steroid injections into the patellar tendon for patellar tendinitis.  While the jury is still out on whether leukocyte-rich PRP may be beneficial for patellar tendinitis, it is frequently performed to try to decrease anterior knee pain. In cases of bursitis in the front of the knee, the use of corticosteroid injections into an irritated  bursa may be indicated. In addition, for those patients who have scar tissue or underlying arthritis, the use of corticosteroid injections in the knee joint itself for anterior knee pain may prove useful.

What is the relationship between anterior knee pain and the fat pad?

The retropatellar fat pad is a thick cushion of fat that sits between the distal aspect of the patella and the patellar tendon and the anterior part of the tibia and also somewhat about the trochlear groove.  Its overall function is still being researched, but we do know that when it becomes thickened or fibrotic due to injury or previous surgery that it can be a source of anterior knee pain and also make the kneecap get stuck so it is not as moveable (captured).  Thus, scar tissue in this area can be a frequent source of anterior knee pain. In particular, fat pad fibrosis can contribute to knee pain with prolonged sitting or going up or downstairs.

What can be the cause of anterior knee pain after a fall?

When one falls on a knee that has had no history of previous arthritis or problems, a common cause of anterior knee pain can be a patella fracture, a cartilage injury (chondral fracture) to the kneecap or trochlea, or bruising of the retropatellar fat pad. The retropatellar fat pad has quite a bit of nerve endings, so when it is irritated it can be particularly painful.

How does one examine for anterior knee pain?

The physical examination for anterior knee pain can involve palpation of structures directly as well as assessing for kneecap motion. Palpation of the inferior pole of the patella can help determine if there is patellar tendinopathy present, palpation of the medial or lateral plica can determine if there is any associated plical irritation, and palpation of the edges of the retropatellar fat pad can also determine if there is some scar tissue that may be causing some irritation.

Movement of the patella in the end of the femur, called translation of the patella within the trochlear groove, can help to determine if the patella is captured and not able to move as much due to scar tissue. It also helps to determine  if there is any associated crepitation or crunching with movement of the patella which may indicate there is an area of chondromalacia which is causing the symptoms.  It is usually easier to diagnose patellar chondromalacia because the patella can be rolled on the end of the trochlea, compared to trochlear chondromalacia, because once the knee starts to flex past 15-20 degrees, the amount of patellar mobility is diminished so moving the patella over a trochlear defect may not yield as much movement and the ability to diagnose a cartilage defect of the trochlea is diminished.

How can anterior knee pain develop after a meniscectomy?

There are several causes that can cause anterior knee pain after a meniscectomy. In patients who may have some underlying arthritis (chondromalacia) of their patellofemoral joint, the weakness that one may develop after surgery, which is usually expected, may lead to the development of anterior knee pain.

In addition, the arthroscopic incisions themselves may become thicker than normal in some patients, which is also something that cannot be predicted ahead of time, and the scarring of the surgical incisions for the arthroscopy could also contribute to anterior knee pain. Other sources of anterior knee pain could be due to if the knee keeps swelling, which can cause some irritation of the plica and contribute to anterior knee pain.

What can be the causes of anterior knee pain in a young child?

Anterior knee pain in a child is not uncommon.  Probably the most common cause is Osgood-Schlatter’s syndrome where the tibial tubercle hurts when the growth plate is being pulled during a growth spurt. Other causes include patellar tendinitis, Sinding-Larson-Johansson syndrome, and possibly generalized knee muscle weakness. It is important to recognize if there is any swelling associated with anterior knee pain in a child that a further workup should be done sooner rather than later because children usually do not have intraarticular knee swelling as a rule.  Things that could be present include osteochondritis dissecans, which should be able to be diagnosed on the plain radiographs. While most cases of anterior knee pain in children are benign, those that don’t resolve after a period of time, or those with any associated swelling within the knee should be investigated sooner rather than later.

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