Chondromalacia Patellae, often called “Runner’s Knee,” is a common source of anterior knee pain. The condition involves the softening and breakdown of the cartilage on the underside of the kneecap (patella). This specialized cartilage normally acts as a smooth, protective layer, allowing the patella to glide effortlessly over the thigh bone. When this surface deteriorates, it causes friction and irritation, resulting in a persistent ache felt deep within the knee joint.
The Specific Sensations of Chondromalacia
The primary sensation is a dull, aching pain localized behind or directly around the kneecap. This discomfort is consistently felt in the front of the knee. The intensity of this ache can fluctuate, often worsening after periods of rest or activities that compress the joint.
A characteristic symptom is crepitus, a mechanical noise or sensation that occurs when the knee moves. It is frequently described as a grating, grinding, clicking, or crunching feeling. This grating indicates that the roughened undersurface of the patella is rubbing against the groove of the femur.
In more severe cases, the knee may feel like it is catching, locking momentarily, or “giving way.” Swelling (effusion) may also occur around the joint, leading to stiffness and reduced mobility. The pain usually has an insidious onset, meaning it develops gradually over time rather than from a sudden injury.
Activities That Increase Discomfort
The pain is aggravated by specific movements and positions that increase pressure between the kneecap and the thigh bone. One common aggravation is prolonged sitting with the knees bent, known as the “movie theater sign.” This position significantly increases the compressive force on the patellofemoral joint.
Activities that involve moving the body’s weight vertically place substantial stress on the damaged cartilage. Ascending or, more frequently, descending stairs causes a noticeable spike in pain. The force exerted on the kneecap when descending stairs can be up to five times the body’s weight.
Movements that require a deep bend in the knee also provoke discomfort. Squatting, kneeling, and deep knee bends are particularly painful because they maximize the contact pressure between the joint surfaces. High-impact exercises, such as running, jumping, and activities requiring quick stops and starts, also cause the pain to flare up.
Why the Cartilage Causes This Feeling
The pain felt in Chondromalacia Patellae is not generated by the cartilage itself, as articular cartilage lacks nerve endings. Instead, the discomfort originates from the surrounding structures that become irritated and inflamed. The softening and erosion of the cartilage disrupt the smooth motion of the kneecap within the femoral groove.
When the patella tracks improperly, the resulting friction irritates the underlying bone and the sensitive soft tissues around the joint. The primary pain generators are the anterior fat pad and the joint capsule, both containing many pain-sensing nerves. This abnormal rubbing causes inflammation in the joint lining (synovium), which releases chemical irritants that trigger the pain response.
This friction also increases pressure on the subchondral bone, the layer just beneath the cartilage, which can generate pain signals. The grinding sensations are the direct result of the irregular, damaged cartilage surfaces physically catching and rubbing against each other during knee flexion and extension.
Initial Steps for Managing the Pain
Management focuses on reducing inflammation and avoiding further irritation. Immediately avoiding painful activities is essential, especially deep knee bending, jumping, or prolonged sitting. Allowing the knee relative rest from aggravating activities helps the joint settle down and reduces mechanical stress.
The R.I.C.E. protocol is a helpful initial strategy for controlling symptoms. Applying ice packs to the front of the knee for about 15 to 20 minutes several times a day can help dull the pain and reduce swelling. An elastic bandage or brace can be used to provide gentle compression and support to the joint.
Over-the-counter Non-Steroidal Anti-Inflammatory Drugs (NSAIDs), such as ibuprofen, may be used temporarily to reduce inflammation and discomfort. It is important to switch to low-impact exercises to maintain activity without stressing the patellofemoral joint. Swimming, especially using a flutter kick, and walking on level ground are often tolerated well.
Seeking a professional diagnosis is important for a definitive long-term treatment plan. While self-care provides immediate relief, addressing underlying issues like muscle imbalances or patellar tracking problems requires guidance. A clinician can confirm the condition and recommend a comprehensive approach to manage symptoms.