Anterior knee pain is a common problem, frequent in our athletic clients, as well as those in occupations that involve repeated squatting or going up and down stairs. There are numerous causes of anterior knee pain, which makes assessment more challenging. Notably, knee pain can exist in the absence of clearly identifiable tissue damage or structural pathology.

Chondromalacia patellae is one of the primary conditions that can cause anterior knee pain, especially in active individuals. Chondromalacia means “softening” or “degeneration of the cartilage” and can occur in several joints of the body. However, it is most common in the anterior knee region, where the cartilage on the underside of the patella softens and degenerates, resulting in knee pain. This condition is given the unique name of chondromalacia patellae, indicating the bone (patella) and cartilage are most affected. Let’s take a look at how this common condition develops and the potential role massage therapy can play in its treatment.

Anatomy and Biomechanics

The patella is unlike most other bones in the body in that it is a sesamoid or “floating” bone. It is imbedded within the quadriceps (patellar) tendon. There is a common belief that the primary purpose of the patella is to protect the knee, but this is not true. Its primary function is to pull the patellar tendon farther away from the center of the knee joint so the quadriceps can generate greater power during knee extension. As a result, there is a high force load constantly pressing the patella against the femoral condyles (Image 1).

During flexion and extension movements, the patella glides up and down over the femoral condyles. As the knee moves in flexion, the patella moves inferiorly (toward the foot). During extension, the patella moves superiorly (toward the thigh). The patella has a bony ridge on its underside that runs in a superior to inferior direction (Image 2). As the patella glides up and down during flexion and extension, the patellar ridge needs to stay centered in its “track” between the femoral condyles. When the patella does not track straight, it is called a patellofemoral tracking disorder, and tracking disorders are a precursor to chondromalacia.

There are some key structural and mechanical factors that increase the likelihood of a patellar tracking disorder. If you look at the skeletal structure of most people in anatomical position, the femur is not aligned straight up and down. The distal end of the femur deviates toward the midline of the body. This is called a varus alignment of the femur, and some amount is normal for the femur.

Three of the four quadriceps muscles originate on the femur, so their angle of pull is parallel with the angle of the femur. This means these muscles will be pulling in a slight diagonal. Consequently, the patella is also pulled in a slight lateral direction (Image 3). This uneven pull makes the patella susceptible to a lateral tracking disorder.
The medial side of the quadriceps group offsets the pull of the patella in a lateral direction. The distal end of the vastus medialis has a group of fibers angled in an oblique direction and are thus called the vastus medialis obliquus (VMO). A primary function of the VMO fibers is to offset the tendency of the patella to be pulled laterally.

Description of Pathology

Chondromalacia literally means “softening of the cartilage.” However, this problem involves much more than just the cartilage. The cartilage may initially soften, but repeated compressive irritation of the cartilage surface causes cracking, chipping, and degeneration. The continual compressive load on the cartilage can wear away segments of the joint surface and lead to permanent damage.

Activity levels play a big role in the likelihood of developing chondromalacia, simply due to the repeated flexion and extension movements of the knee. The condition is also more likely to occur in certain populations. Young people may be more prone to chondromalacia because growth spurts may cause an imbalance between muscle and bone growth. The discrepancy can lead to abnormal patellar positioning and dysfunctional knee biomechanics.

Postural challenges of the lower extremity frequently play a role in the onset of chondromalacia. Genu valgum (commonly called knock-knee) is the most common postural challenge that may lead to chondromalacia. In this postural disorder, the varus angle of the femur is exaggerated more than usual and that means the patella is even more likely to be pulled in a lateral direction. The increased lateral pull drags the ridge of the patella against the lateral femoral condyle.

Patellofemoral Compression Test

The patellofemoral compression test is one of the most common procedures used to assess the possibility of chondromalacia. In this procedure:
• The client is seated on the edge of the treatment table with the knee in a flexed position.
• The therapist places a hand directly over the top of the patella.
• The therapist then has the client extend the knee while moderate pressure is maintained directly over the top of the patella.
• There may be cartilage degeneration present if the client feels pain, grinding, or grating sensations during the flexion or extension. The practitioner may also feel the grinding or grating sensation during the patellofemoral compression test.

Chondromalacia is difficult to assess with physical examination, so magnetic resonance imaging (MRI) is frequently used to validate the degree of cartilage degeneration on the underside of the patella. One of the challenges with this condition is that the degree of cartilage degeneration does not correlate well with the level of pain or severity of the problem. Cartilage is poorly innervated, so degeneration may be quite advanced before the condition is symptomatic with knee pain.

Despite poor innervation of the cartilage, however, chondromalacia can be quite painful—particularly when the damage has reached the underlying bone. The layer of bone just below the cartilage is called sub-chondral bone and it is richly innervated. Irritation of subchondral bone is likely to be quite painful.

Even in conditions where the cartilage is not seriously damaged, pain can still occur from low-level inflammatory responses to the tissue irritation. Chemical mediators from the inflammatory response can irritate nociceptors around the knee and cause pain. Inflammatory irritation of nociceptors may also help explain why some clients feel knee pain even though the damaged cartilage is poorly innervated.

Assessment

When taking a history, ask your client if there are any particular patterns to the pain they experience. Clients with chondromalacia often report knee pain that occurs after sitting for long periods. This is sometimes called a positive movie sign because it happens after sitting still in a movie theater for a couple of hours.

Clients are also likely to report pain during weight-bearing flexion and extension movements. The pain may not be present during passive flexion or extension because there is not sufficient load on the patellar tendon to press the patella against the femoral condyles. Therefore, having the client attempt to do an activity like squatting is more likely to produce pain than having them on the treatment table and passively flexing or extending the knee.

The client may report crepitus—a sensation of grinding—under the patella during knee movements. Just as with the knee pain, crepitus sensations are much more likely during movement with some load than during passive movement when there is no load on the patella. The practitioner may also feel grinding sensations under the patella during movement by resting the palm on the patella during the movement. It is not necessary to use significant pressure with the palm; even a light contact with the patella may reveal these grinding sensations in many cases.

Sometimes the pain felt in the knee during flexion or extension may be sharp and sudden. An immediate sharp pain can also accompany a sensation of the knee giving way. This knee instability involves a process called reflex muscular inhibition. The brain is trying to cease the mechanical load that caused the pain, so it inhibits the contraction stimulus to the quadriceps muscles. It is the muscular inhibition that produces the sensation of giving way.

If chondromalacia has been present for some time, there may be some atrophy of the quadriceps that is apparent during physical examination. It is not clear why, but some primary antigravity muscles like the quadriceps are prone to relatively quick atrophy from disuse. Pain avoidance and decreased movement are the reasons for disuse. The atrophy is apparent by measuring the circumference of the quadriceps just proximal to the patella and comparing that with the unaffected side.

Assessing Similar Conditions

Several other conditions that cause anterior knee pain can often be confused with chondromalacia. Patellar tendinosis has a similar pain pattern that results from overuse and is also aggravated with resisted knee extension. However, in patellar tendinosis, it is usually easy to reproduce the client’s pain by palpating the infrapatellar tendon. In chondromalacia, pain is generally not reproduced with palpation of the tendon, as the primary problem is on the patella itself and not the associated tendon.

Patellofemoral pain syndrome (PFPS) is a condition that is closely associated with chondromalacia and can have a similar pain presentation. PFPS results from overuse and knee alignment challenges just like chondromalacia, but it is sometimes difficult to identify what is actually causing the pain. In some cases, the pain may be coming from irritated tissues like the patellar retinaculum, which may be exposed to an altered biomechanical load. With PFPS, there is usually increased tenderness in some of the quadriceps retinaculum, superior to the patella. There could also be some low-level inflammatory activity around the anterior knee region that could be producing PFPS pain without the cartilage damage characteristic of chondromalacia.

Other conditions, such as prepatellar bursitis or meniscal damage, may also share some characteristic symptoms with chondromalacia. The accuracy of assessment with the client in this case is important.

Treatment

It is not always clear whether the degenerated cartilage can fully repair, so treatment goals include symptom management and stopping the offending activities. Chondromalacia is most often treated with conservative approaches such as activity modification and appropriately graded exercise. There appear to be some benefits to strengthening exercises that target the VMO, as it is the primary biomechanical opposition to the lateral patellar tracking that is at the root of the problem. In many cases, it would be ideal to change lower extremity postural challenges, such as genu valgum, but it is quite difficult.

Massage therapy can play an important role in the management of chondromalacia. While massage cannot directly repair the cartilage degeneration, it is helpful to reduce and balance the forces that created the problem in the first place. When aiming to achieve muscular balance in the extensor mechanism of the knee, it is not enough to just strengthen the VMO. It is also important to reduce hypertonicity in the vastus lateralis and the lateral patellar retinaculum that are pulling the patella in a lateral direction.

Massage techniques that focus on the quadriceps and distal retinacular tissues appear the most effective for addressing chondromalacia. The goal of our massage treatment is more about helping restore ideal biomechanical balance. Techniques such as active engagement stripping methods and pin and stretch techniques (Image 4 and “Retinaculum Treatment” video) for the patellar retinaculum are valuable to help restore ideal knee biomechanics and appropriately manage symptoms.

In addition to working specifically on the distal retinacular tissues, it is valuable to perform some thorough work on the entire quadriceps group. These are some of the largest muscles in the body, so the tensile forces they transmit to the patellar tendon fibers are significant. Deep longitudinal stripping and active engagement methods are some of the best ways to address those regions as well.

Restoring an Optimal Environment

Chondromalacia pain can be quite debilitating. If the cartilage degeneration is left unchecked, it not only causes an increase of the client’s current pain, but it can also lead to more serious arthritic changes in the knee in the future. If chondromalacia is identified as a likely cause of client knee pain, a conservative treatment approach with massage as a primary focus is a great treatment strategy.

Keep in mind that when treating chondromalacia we are not “fixing damaged tissue.” Instead, we are helping restore an optimal environment to help the client’s body heal, allowing them to get back to activity as soon as possible.

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