Runner's Knee

Estimates indicate that as many as 15% of U.S. adults take part in a regular running or jogging exercise program. The majority of these individuals remain healthy, and will have no significant problems relating to their knees or other musculoskeletal joints. However, some individuals who run regularly do develop a painful condition known as “Runner’s Knee,” also called Patello-femoral Pain Syndrome. Simply stated, this malady can be described as pain under the kneecap. This condition is not the result of just one traumatic injury or episode, but it is most commonly due to the long-term, repetitive motion stresses of running.

The patella (or kneecap) is the disc-shaped bone located on the anterior or front aspect of the knee joint, and is connected to a large muscle group in the thigh (the quadriceps) by a very thick tendon. In addition, it also is attached to the lower leg bone (the tibia) by way of a strong ligament called the patellar ligament. The peculiar shape of the underside of the patella allows it to fit snugly into the groove between the condyles in the end of the femur. During flexion and extension of the knee joint, the patella glides smoothly in this groove throughout the knee’s arc of motion, The leg’s quadriceps mechanism is described as the extension or straightening motion of the lower leg in response to the contraction of the quadriceps muscles in the thigh. Kicking a ball is a perfect example of this mechanism. The patella is located within the tendon/ligament interface of this mechanism, and serves as a fulcrum at the knee joint.

Lateral x-ray of the knee showing early degenerative changes under the patella.

The repetitive motion of the patella sliding over the condyles of the femur in such fitness activities such as running, jogging, and even walking, may result in a painful inflammation or irritation of the underside of the kneecap. Many conditions with names such as overuse synovitis, patellar tendonitis, and tenosynovitis all are associated with the repeated stresses incurred from running. This syndrome may also be caused by the way the kneecap aligns itself on the anterior knee during flexion and extension. Alignment problems of the patella at the knee may be caused by anatomical relationships in other parts of the body such as the hips, thighs, or even feet. In most cases of patellar malalignment, the patella subluxes (slips laterally), and may actually dislocate in some individuals. A special x-ray view of the knee called a merchant's view will help identify this lateral displacement. Treatment for Runner’s Knee may include rest, anti-inflammatory medication, physical therapy and strengthening exercises, knee bracing, orthotics (shoe inserts), or use of an infra-patellar sleeve or strap. Chronic, long-term problems such as continued pain, patellar tendonitis, malalignment, and degenerative changes in the knee joint may require arthroscopic or more traditional surgery.

Lateral view of the knee showing inflammation and degenerative changes both to the underside of the patella and to the articular cartilage of the femur.