The patella, commonly known as the kneecap, is a small bone situated at the front of the knee joint. Housed within the quadriceps tendon, it acts like a pulley to increase the force of the thigh muscles when the leg straightens. The patella moves along a groove in the thigh bone (femur), a motion referred to as tracking. When this movement is consistently misaligned, it causes patellar maltracking, a frequent source of discomfort at the front of the knee.
Defining Normal and Abnormal Patellar Tracking
Normal patellar tracking involves the kneecap gliding smoothly within the trochlear groove of the femur as the knee bends and straightens. Cartilage lines the underside of the patella, allowing it to slide without friction against the femur. This precise movement ensures even distribution of forces across the joint surface during activity.
Patellar maltracking occurs when the kneecap fails to follow this central path, shifting or tilting sideways, usually toward the outer side of the leg. This improper alignment creates uneven pressure and friction between the patella and the trochlear groove. Over time, this mechanical irritation can damage the underlying cartilage and soft tissues, leading to inflammation and pain.
Recognizing the Signs of Maltracking
The most common symptom is anterior knee pain, felt around or under the kneecap. This discomfort is often more pronounced during activities involving significant knee bending, such as squatting, jumping, or climbing stairs. Pain may also increase after prolonged periods of sitting with the knees bent, a phenomenon sometimes called the “theater sign.”
A grating, popping, or clicking sensation, medically termed crepitus, is frequently felt when the knee is flexed or extended. This noise indicates friction or uneven contact within the patellofemoral joint as the kneecap moves improperly. Individuals may also report feeling that the knee is unstable or prone to “giving way.” In severe instances, the patella may partially slip (subluxation) or completely dislocate, which is accompanied by acute pain and visible swelling.
Structural and Muscular Causes
Patellar maltracking rarely stems from a single cause, resulting instead from a combination of anatomical variations and muscular imbalances. Anatomical factors involve the shape and alignment of the bones, which can reduce the natural stability of the kneecap. For instance, a shallow trochlear groove on the femur provides less bony guidance, making the patella more susceptible to lateral movement.
Another structural factor is patella alta, where the kneecap sits higher than normal, reducing the contact area with the femur and limiting stability. The Q-angle, which measures the angle between the thigh bone and the shin bone, is also important; a higher Q-angle (often seen in individuals with knock-knees) can increase the outward pull on the patella.
Muscular imbalances are significant contributors, particularly involving the quadriceps and hip muscles. The vastus medialis oblique (VMO), the inner portion of the quadriceps, pulls the kneecap inwards to keep it centered. Weakness in the VMO relative to the stronger vastus lateralis muscle on the outer thigh results in an abnormal, outward-pulling force on the patella.
Weakness in the hip abductor and external rotator muscles can cause the thigh bone to rotate inward during activities like running or squatting. This inward rotation changes the angle of pull on the patella, forcing it out of the trochlear groove. Acute trauma, such as a direct blow or a sudden twisting motion, can also damage stabilizing ligaments and soft tissues, leading to immediate instability and subsequent maltracking.
Initial Steps in Managing Patellar Tracking Issues
For individuals experiencing mild to moderate symptoms, initial management focuses on conservative, non-surgical methods aimed at reducing irritation and restoring proper mechanics. Activity modification is recommended, involving temporary reduction or avoidance of movements that trigger pain, such as deep squats or running. Applying ice to the front of the knee helps manage pain and swelling resulting from joint irritation.
Physical therapy is the central component of rehabilitation, addressing the underlying muscular causes of maltracking. Exercises are prescribed to strengthen the VMO muscle and the hip abductors and external rotators to stabilize the entire lower limb. Stretching tight structures, such as the lateral retinaculum or the iliotibial band, may also be included to reduce outward tension on the kneecap. Consulting a healthcare professional is necessary for a definitive diagnosis and a customized treatment plan, which may include temporary measures like patellar taping or bracing to assist with alignment during recovery.