Patellofemoral Syndrome (PFS) is a common condition that causes discomfort centered around the kneecap. Although the pain is felt at the knee joint, the source of the problem often lies elsewhere in the leg. This knee issue can be linked to pain felt in the hip region, but typically not because the knee condition directly causes hip damage. Instead, the two pain sites are generally symptoms of a shared, underlying biomechanical problem affecting the entire lower limb.
Understanding Patellofemoral Syndrome
Patellofemoral Syndrome is characterized by pain located at the front of the knee, either behind or around the patella. This discomfort arises from the abnormal way the patella tracks or moves within the groove of the thigh bone (femur) when the knee bends and straightens. Poor alignment can cause irritation to the surrounding soft tissues and cartilage.
The symptoms of PFS worsen with activities that increase pressure on the kneecap. Common triggers include walking up or down stairs, squatting, kneeling, or sitting for extended periods with the knees bent. It is considered a syndrome because the exact cause is often multifactorial rather than a single injury.
The Role of the Kinetic Chain
To understand the connection between knee and hip pain, the leg must be viewed as a kinetic chain, where the ankle, knee, and hip joints function as a linked system. Movement in one joint influences the mechanics of the joints above and below it. A problem originating at the hip or foot can transmit rotational forces up or down the leg, affecting the knee’s stability.
When the patella tracks incorrectly in PFS, it is frequently a consequence of faulty motion originating higher up the chain. For instance, if the femur rotates inward excessively during activities like running or squatting, it forces the patella out of its normal groove, leading to pain. This abnormal rotation at the thigh bone is directly controlled by the muscles surrounding the hip joint. This mechanical misalignment required to compensate for the knee issue can place excessive strain on the hip joint and its surrounding musculature, resulting in discomfort that is felt in the hip region.
Common Underlying Causes of Both Pains
PFS and hip pain share a common root cause: weakness in the muscles that stabilize the hip and pelvis. Weakness in the gluteal muscles, particularly the gluteus medius and gluteus maximus, is a frequent culprit. When these muscles fail to adequately stabilize the hip, the thigh bone tends to rotate inward and move toward the midline of the body (adduction) during weight-bearing activities.
This excessive internal rotation and adduction of the femur directly disrupts the patellar tracking mechanism at the knee, leading to PFS. Simultaneously, the instability and increased strain on the hip joint from the lack of proper muscular control can cause pain in the hip itself. Evidence suggests that individuals with PFS often exhibit significantly weaker hip abductor and external rotator strength compared to those without the condition.
Core instability is another factor that impacts the entire lower extremity kinetic chain. Poor strength in the abdominal and lower back muscles affects the tilt and stability of the pelvis, providing a poor foundation for the hip and leg muscles to function efficiently. Finally, excessive foot pronation can also contribute by causing a compensatory internal rotation that travels up the leg, affecting both the knee and the hip.
Addressing the Combined Symptoms
Management of co-occurring PFS and hip pain requires treating the underlying mechanical faults, not just the pain symptoms at each joint. Physical therapy is the accepted primary intervention, focusing heavily on strengthening the weak links in the kinetic chain. Specific exercises target the gluteus medius and core musculature to improve pelvic and hip stability.
Research indicates that strengthening the hip muscles alongside the knee muscles provides superior results than focusing on the knee in isolation. Temporary pain relief strategies include the use of nonsteroidal anti-inflammatory drugs (NSAIDs) and ice application. Other interventions may include patellar taping or bracing to improve kneecap alignment, and the use of orthotics to address foot pronation. Resolving the problem depends on identifying the source of the mechanical imbalance and consistently strengthening the hip and core.