Patellofemoral Pain Syndrome

Patellofemoral pain syndrome (PFPS) describes a painful irritation of the cartilage behind your kneecap. Although anyone may be affected, it is often the result of overuse of the knee in sports that require jumping or running so it is sometimes referred to as “Runner’s knee”. PFPS is the most common cause of knee pain in the general population, affecting an estimated 25% of adults.

One of the most common causes of PFPS is an imbalance between the muscles that help to guide your kneecap in its V-shaped groove at the end of your thigh bone. Repeatedly flexing and extending a misaligned kneecap leads to pain, swelling and eventually arthritis. Misalignment of the kneecap (patella) is often secondary to problems in the hip and foot, especially weakness of your gluteal muscles or flat feet.

PFPS produces a dull pain behind the kneecap that is aggravated by prolonged walking, running, squatting, jumping, stair climbing or arising from a seated position. The pain is often worse when walking downhill or down stairs. Longstanding misalignment can cause damage to the cartilage, which results in popping, grinding or giving way.

Conservative care, like the type provided in this office, is generally successful at relieving your symptoms. Initially, it is important for you to minimize activities that provoke your pain, especially running, jumping and activities that stress you into a “knock-kneed” position. Don’t allow your knees to cross in front of your toes when squatting. Some athletes may need to modify their activity to include swimming or bicycling instead of running.

Performing your home exercises consistently is one of the most important things that you can do to help realign the patella, relieve pain and prevent recurrence. The use of home ice or ice massage applied around your kneecap for 10-15 minutes, several times per day may be helpful.

Patellofemoral pain syndrome (PFPS), also called “Runners Knee”, describes the symptom complex of knee discomfort, swelling or crepitus that results from excessive or imbalanced forces acting on the joint. PFPS can be traumatically induced but more commonly results from muscular imbalance and cumulative overload. It is the most common cause of knee pain in the general population, affecting an estimated 25% of adults. (1,5,23) Many PFPS patients are young and athletic. (32) Data suggests the condition may affect nearly 10% of young athletes. (2)

Normal patellar tracking is dependent upon the static and dynamic stabilizers of the lower extremity acting in concert. Imbalances in these stabilizers can alter the distribution of forces to the patellofemoral articular surfaces and related soft tissues. Researchers estimate that patellofemoral forces are between 1/3 and 1/2 of a person’s body weight while walking and can increase almost twenty-fold when squatting. (3) Biomechanical tracking stresses are quickly compounded, causing irritation to the patellofemoral cartilage and eventual patellofemoral degeneration.

PFPS is most commonly related to lateral tracking of the patella. (4) The patella has a natural tendency to migrate laterally due to the pull of the quadriceps and the slight natural valgus of the lower extremity. (5) Compounding this problem is the fact that the patellofemoral orientation is largely determined by the hip and foot. (6,7,40) Pes planus causes internal rotation of the tibia and subsequent deviation of the patella-increasing one’s risk of PFPS. (8,24,40) Gluteus medius weakness is associated with valgocity of the knee and subsequent lateral tracking. (40-44, 54) Current research suggests that patellar movement and tracking is more dependent on global femur and tibia biomechanics than any individual knee muscle strength. (26,40)

Loss of core stability is a risk factor for PFPS. (62) Additional risk factors for the development of PFPS include joint overload/ overuse, trauma, tight lateral knee capsule, patellar hypermobility, and muscular imbalance- particularly quadriceps or iliotibial band hypertonicity, and vastus medialis or quadriceps weakness. (9,28-30)

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