The kneecap, or patella, is absolutely supposed to move, and this movement is fundamental for healthy knee function. It is a complex, moving part of the knee joint’s extension mechanism, allowing the powerful thigh muscles to work efficiently. Its ability to glide smoothly during bending and straightening movements is crucial for recognizing and addressing knee pain.
The Patella’s Role in Knee Mechanics
The patella is the largest sesamoid bone, embedded within the quadriceps tendon. Positioned between the quadriceps muscle and the shinbone (tibia), it functions like a pulley or fulcrum. By holding the quadriceps tendon away from the knee joint center, the patella dramatically increases the leverage and efficiency of the quadriceps muscle during leg extension.
The back surface of the patella is covered in thick articular cartilage and glides within the trochlear groove, a deep channel on the end of the thigh bone (femur). This precise sliding motion is known as patellar tracking. As the knee bends, the patella glides downward, and as the knee straightens, it glides upward. The path involves small amounts of tilt and rotation to accommodate the groove’s shape.
When Patellar Movement Goes Wrong
When the patella deviates from its normal path within the trochlear groove, it is called patellar maltracking or patellar tracking disorder. This misalignment causes uneven pressure on the cartilage, leading to pain and instability. A common result is Patellofemoral Pain Syndrome, characterized by a dull ache under or around the kneecap, often worsened by climbing stairs, squatting, or prolonged sitting.
Maltracking often stems from a combination of factors, including muscle imbalances. Weakness in the hip abductors and the vastus medialis obliquus (VMO) allows stronger, outer thigh muscles to pull the patella laterally from its groove. Structural abnormalities can also contribute, such as a shallow trochlear groove or patella alta (a high-riding kneecap), which delays the kneecap’s stabilizing engagement with the groove.
More severe issues include patellar subluxation, where the kneecap partially slips out of the groove, and patellar dislocation, where it completely moves out, usually to the outside of the knee. Dislocation causes significant pain and often involves damage to stabilizing soft tissues, most commonly the medial patellofemoral ligament (MPFL). Symptoms of instability include a feeling that the knee is going to “give way,” a catching or locking sensation, or an audible popping or grinding sound (crepitus) when bending the knee.
Treatment Options for Patellar Instability
Treatment for most cases of painful patellar maltracking and instability begins with conservative management aimed at restoring proper mechanics. Physical therapy focuses on strengthening the muscles that control kneecap movement, especially the VMO muscle and hip muscles like the abductors and external rotators. Therapists also employ techniques to stretch tight lateral structures that may be pulling the kneecap outward.
Other non-surgical methods include wearing a flexible knee brace or using specialized athletic taping to help guide the patella into its correct alignment during activity. Acute symptoms like pain and swelling are managed with rest, ice, and nonsteroidal anti-inflammatory drugs (NSAIDs). These conservative treatments are often highly effective, especially for patellofemoral pain syndrome and first-time dislocations without significant damage.
Surgical intervention is typically reserved for chronic instability, recurrent dislocations, or cases involving significant cartilage or bone damage. Options vary depending on the underlying cause. Soft tissue procedures, such as MPFL reconstruction, restore the primary passive restraint against lateral movement. Bony realignment procedures, like a tibial tubercle transfer, change the angle of the quadriceps pull to reduce lateral stress on the patella in cases of severe anatomical malalignment.
Maintaining Optimal Knee Health
Preventative strategies focus on maintaining a balanced musculoskeletal system to ensure the kneecap tracks correctly. Consistently strengthening the muscles surrounding the knee, including the quadriceps, hamstrings, and especially the gluteal muscles and hip stabilizers, provides the necessary dynamic support. Exercises that focus on proper form, such as squats and lunges, are important to avoid excessive stress or twisting motions on the knee joint.
Incorporating regular stretching helps maintain flexibility, particularly in the hamstrings and lateral thigh structures that can contribute to maltracking if they become too tight. Appropriate footwear that supports proper foot and ankle alignment is also beneficial, as foot movements influence the entire leg’s mechanics, affecting the kneecap. Maintaining a healthy body weight reduces the overall load and compressive forces placed on the knee joint, minimizing cartilage wear and tear.