Which muscle is primarily involved in weakness contributing to patellofemoral pain syndrome?

Patellofemoral pain syndrome is often associated with weakness of the quadriceps muscle, particularly the vastus medialis oblique (VMO) component. The quadriceps plays a crucial role in stabilizing the patella during knee movement and is responsible for extending the knee. When the quadriceps are weak, it can lead to inadequate support and alignment of the patella as it moves across the femoral groove during activities such as walking, running, or squatting. This misalignment can increase stress on the patellofemoral joint and contribute to pain and dysfunction.

While other muscles are important for overall knee and lower limb function, they do not have the same primary role in causing the type of instability and pain associated with patellofemoral pain syndrome. For example, the hamstrings assist in knee flexion and can affect overall knee dynamics, but they do not primarily contribute to patellar tracking. The gastrocnemius is more involved in plantarflexion of the foot and maintaining gait, whereas hip flexors primarily influence hip movement rather than direct knee stability. Thus, weakness in the quadriceps is a key factor leading to the symptoms experienced in patellofemoral pain syndrome.