Chondromalacia of the Patella

What is the role of articular cartilage?

Articular cartilage is a specialized connective tissue located in all movable joints in our body. It is a white, tough material with a unique structure resistant to wear. Articular cartilage serves to protect bones, particularly in the knee, where it facilitates smooth movement and absorbs shocks. Unfortunately, it lacks blood vessels, lymphatic vessels, and nerves, limiting its ability to heal and repair itself spontaneously. It is particularly vulnerable when damaged. The cartilage softens, cracks, and defects appear on its surface. Consequently, these injuries can be accompanied by intense pain, resulting from irritation of the subchondral layer.

What is the function of the patella?

The patella, which is part of the knee joint, is the largest sesamoid bone in the human body, formed through ossification of tendon fragments. It is connected to both the tibia and the femur. Its anterior part forms a smooth surface, easily palpable through the skin. The posterior part of the patella articulates with the distal femoral condyles via its lateral and medial articular surfaces, forming the patellofemoral joint. It is stabilized by the quadriceps tendon and the patellar ligament, allowing it to move in a strictly defined plane within the knee. The primary function of the patella is its role in knee extension movements. As the most forward-protruding part of the knee joint, it protects it from injuries. However, this makes it more susceptible to various types of damage, even though it is covered by a thick layer of articular cartilage. The patella protects the anterior compartment of the knee during both flexion and extension. Its protective function also includes shock absorption during activities that strain the knees, particularly running and jumping.

Anterior Knee Pain Syndrome

Patients suffering from knee pain often visit an orthopedic specialist, believing they have chondromalacia of the patella. However, the pain they describe in the front of the knee does not always correlate with chondromalacia. The correct clinical entity encompassing all pain disorders around the patellofemoral joint and adjacent soft tissues is anterior knee pain syndrome (PFPS). This condition may result from patellar trauma but is more commonly a combination of factors such as patellofemoral joint overload, biomechanical or anatomical abnormalities (e.g., dysplasia, high-riding patella, low-riding patella, or bipartite patella), muscle weakness, or dysfunction of the knee's extensor mechanism. Anterior knee pain syndrome is a chronic condition that tends to worsen during everyday activities such as squatting, sitting, climbing stairs, or running. Various diseases can cause pain in the front of the knee, and one of them may indeed be the previously mentioned chondromalacia of the patella.

What is chondromalacia of the patella?

Chondromalacia of the patella is a term describing damage to the cartilage located beneath the patella. It is one of the conditions within the broader spectrum of chon.dropathies (a general term for various pathologies involving articular cartilage). Chondromalacia of the patella is described as anterior knee pain, also known as patellofemoral pain syndrome, due to physical and biomechanical changes. The term "chondromalacia" derives from the Greek words chondros (cartilage) and malakia (softening). Thus, chondromalacia of the patella refers to the softening of the articular cartilage on the posterior surface of the patella. As a result of chondromalacia, the cartilage, which was once glossy, hard, elastic, and resistant to wear, becomes soft, cracks, and develops defects on its surface. It is a very common cause of anterior knee pain, especially among young individuals. Chondromalacia of the patella also affects older adults, as the cartilage surface is the first area to degenerate in the aging process.

Chondromalacia of the Patella – Causes

Chondromalacia of the patella is typically described as an overuse injury caused by improper alignment of the femur relative to the patella and tibia. Excessive pronation of the ankle joint, resulting from internal rotation of the limb, may also contribute to the improper alignment of the patella. Another anatomical abnormality influencing chondromalacia of the patella is patella alta, a congenital condition where the patella is positioned higher than normal. This occurs when the patellar tendon length exceeds the patella’s height by 20%. Lateral patellar compression syndrome is another example of anatomical irregularities. In this condition, the patella does not move centrally in the groove between the femoral condyles, leading to functional abnormalities in the joint.

Chondromalacia of the patella is linked to both physical activity and lack of movement. Excessive stress on the knee joint and high-intensity physical activity, involving repetitive compression of the patella against the femur, can damage the cartilage structure. Additional risk factors include excess weight, which puts additional strain on the knee joints. Conversely, lack of movement impairs cartilage regeneration. Without adequate activity, insufficient joint usage leads to poor cartilage nourishment and subsequent degeneration.

Chondromalacia of the patella is also indirectly related to gender. All sources agree that women are more prone to the condition than men due to anatomical differences. Women’s wider pelvis results in a greater angle at which the bones of the knee joint converge, making the patella more likely to displace laterally.

Chondromalacia of the Patella – Symptoms

• A typical symptom is pain located at the front of the knee.
• Pain worsens after prolonged sitting.
• Pain is experienced during stair climbing, especially descending.
• Pain is pronounced during sports activities performed with bent knees, such as in a skiing position.
• Swelling of the knee joint may occur.
• Some patients report a feeling of knee joint stiffness.

Chondromalacia of the Patella – Outerbridge Scale

Grade 1: Superficial pathological changes with visible cartilage softening.
Grade 2: Damage to the surface layer, with cartilage losing its smoothness, showing cracks that extend to half its thickness.
Grade 3: Cartilage defects and cracks reaching the subchondral bone, with damage affecting less than 50% of the patellar joint surface.
Grade 4: Severe damage with cartilage defects reaching the subchondral bone.

Chondromalacia of the Patella – Diagnosis

Diagnosis of chondromalacia patella is based on a medical interview and clinical examination. Patients often report pain intensifying during stair climbing. Clinical assessments aim to evaluate the patient's overall condition, considering limb axis disturbances. For this, the orthopedic specialist conducts various tests.

Imaging studies commonly include X-rays (anteroposterior, axial, and lateral views). Although knee X-rays cannot directly assess cartilage changes, they may reveal signs of patellofemoral osteoarthritis in the disease's advanced stages. Magnetic resonance imaging (MRI) is the most accurate imaging method, allowing for the diagnosis of cartilage pathologies and the assessment of the severity of the condition.

Chondromalacia of the Patella – Conservative Treatment

The goals of treating chondromalacia of the patella are: reducing pain and inflammation, regenerating articular cartilage, restoring muscle balance, and regaining the full range of motion in the joint. In the early stages of the condition (grades 1, 2, and 3), conservative treatment is employed.

During the acute phase, rest and unloading the affected limb are crucial, and pain-relieving ointments may be used. Anti-inflammatory pharmacological treatment may also be prescribed.

In the chronic phase, treatment typically involves physiotherapy, manual therapy for the patella, stretching exercises for the quadriceps and iliotibial band, and strengthening exercises for the quadriceps and gluteal muscles. The orthopedist may also recommend intra-articular injections of hyaluronic acid or corticosteroids, and in early degenerative changes, orthokine therapy. Athletes are advised to modify their training regimens to avoid overloading. Low-impact exercises like swimming and stationary cycling are highly recommended.

Chondromalacia of the Patella – Surgical Treatment

If conservative treatment proves ineffective after several months, surgical intervention may be recommended. In such cases, minimally invasive knee arthroscopy is commonly performed. This allows for a more precise diagnosis and determination of whether anatomical knee misalignment exists, which can be surgically corrected, as well as the extent of cartilage damage.

Surgical procedures may include the removal of damaged cartilage layers, debridement and smoothing of the joint surface, and filling cartilage defects with mesenchymal cells or specialized collagen membranes.

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References:

• Physio-pedia - Chondromalacia Patellae - Francky Petit
• National Library of Medicine - Chondromalacia Patella - Steven F. Habusta; Ryan Coffey; Subitchan Ponnarasu; Edward E. Griffin. 2022
• Wiles P, Andrews PS, Devas MB. Chondromalacia of the patella. Bone & Joint Journal. 1956
• Fernández-Cuadros ME, Albaladejo-Florín MJ, Algarra-López R, Pérez-Moro OS. Efficiency of Platelet-rich Plasma (PRP) Compared to Ozone Infiltrations on Patellofemoral Pain Syndrome and Chondromalacia: A Non-Randomized Parallel Controlled Trial. Diversity & Equality in Health and Care. 2017