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What Causes Knee (Patellofemoral) Pain?

Knee pain is one of the most common conditions prompting patients to present to my office. Although there are many causes of knee pain, many people have pain around the front of the knee, or what we call “patellofemoral pain.” The patella is the kneecap. It is a focal area of the extensor mechanism of the knee where many vital structures attach, such as the thigh muscles (the quads), patellar tendon, and the supporting shrouds on either side (retinacula), which function as checkreins to keep the patella centered.

What Causes Knee (Patellofemoral) Pain?

The patella glides on a groove on the femur, also known as the “thigh bone.” The patella provides the surrounding muscles a significant mechanical advantage to straighten the knee from a bent position, but also to prevent the knee from collapsing and folding over when weight is applied. It allows us to jump, land, squat, climb and descend stairs. It requires tremendous coordination with hip and ankle muscles for it to work in a chain effect in the lower extremity. Any deviation from the fine coordination in the lower extremity chain can lead to patellofemoral pain.

Patients with Knee Pain

Many patients that I see with patellofemoral pain present without any specific injury, with gradual onset, while others present after a twisting incident, a fall, a collision, or other traumatic event. The alignment of the extensor mechanism is critical for function, stability, and efficiency. Any minor alteration in tracking of the patella can result in pain, dysfunction and potentially arthritis. Some people are born with abnormal alignment and the patella glides off track. Others may have an imbalance in strength of their thigh or their hip, thigh muscles that are too tight, ligaments that are too loose, or even problems with their feet. There are some that overload their knee with excess sports, overuse with lifting, and very importantly, overload with weight! Any amount of injury, whether from acute trauma or chronic overload can alter the patellofemoral balance and result in patellofemoral pain.

Knee Pain Symptoms

Patellofemoral pain can present in many ways, either in front of the knee, on the inside, or the outside of the knee. Pain can manifest with stairs, prolonged sitting (theater pain), getting up from a chair (startup pain), a sense of catching, partial collapse (give way), and even pain with prolonged standing. It can present as sharp pain, achy pain, a sense of shifting or a sense of coming out of joint. There may be swelling, grinding, or even an occasional locking sensation.

Most patients do not need surgery for patellofemoral pain. A thorough evaluation is critical to identify the cause of patellofemoral pain. Physical therapy is the mainstay of treatment to restore the proper tracking of the patella. The therapist will work on many techniques to ease the pain, including taping or bracing, while restoring balance with strength, flexibility, and proper muscle control. They will include hip and lower leg balance, strength and endurance, as they contribute to the chain of lower extremity function. Your therapist will also provide a home exercise program to enhance your treatment plan.

Although success of treating patellofemoral pain is very high with therapy, with medications, and sometimes with injections, some patients will require surgery. Surgery can help realign the patella in its groove. It may require reconstruction of loose or stretched structures. Conversely, it may also require loosening tight structures. Surgery can help smooth out or replace worn cartilage with transplant cartilage. Of course, knee replacement surgery is usually not necessary, except in very chronic or severe cases. Ultimately, with or without surgery, with good communication between physician and therapist working together, the outcome of patellofemoral pain is very favorable.

Etienne (“E.T.”) Mejia, MD

Sports Medicine Center, SC, Appleton, since 1999

(920) 993-1643

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