The knee joint complex is the largest in the human body and very elaborate in design. The knee is composed of two distinct joints located inside one joint capsule: the patellofemoral and tibiofemoral joint. The patellofemoral joint involves the movement of the knee cap. The tibiofemoral joint involves articulation between the larger bones of the leg: the femur and the tibia. With so many bony and soft tissue structures inside the knee, there can be numerous amounts of problems that could lead to non-traumatic knee pain.
Osteoarthritis
Osteoarthritis is the most common cause of disability in the Unites States, according to the Framingham osteoarthritis study. OA is characterized by onset at a later age, motion loss, aching pain with weight bearing and swelling, according to Dutton. OA is also associated with occupations with repetitive kneeling, older age, female gender, obesity and previous knee surgery. Dutton states that regular physical activity, particularly strengthening the quadriceps, is often the best treatment for OA. For severe OA, surgery may be indicated.
Congenital Abnormalities
It is common for individuals to be born with conditions called genu varum and genu valgus. These terms simply refer to being bow-legged or pigeon-toed. This is essentially an abnormal alignment of the major bones that connect at the knee. The result of this alignment is often cartilage or ligament wear and tear that results in pain. The main factor in these conditions is genetics. Several conservative options are available, including physical therapy or bracing.
Patellar Tendonitis
This condition, also referred to as jumper's knee, is caused by overuse during activities such as running, basketball or plyometrics. Diagnosis of jumper's knee can easily be made by pressing on the tendon directly below the knee cap to elicit a pain response. Jumper's knee typically resolves with rest and gentle exercise. Physical therapists treat this condition with modalities to decrease inflammation followed by gradual return to activity.
Bursitis
A bursa is a fluid-filled sac that provides lubrication to joints.The knee joint consists of several bursae so there are several types of bursitis. Bursitis is characterized by a large amount of swelling and pain in a small, localized ares. The most common is superficial and deep infrapatellar bursitis which results from mechanical irritation to the front of the knee. Superficial pes anserinus bursitis results in pain on the inside of the knee. This type is common in novice swimmers and long-distance runners, according to Dutton.
Baker's Cyst
Baker's cysts are the result of irritation to the synovial lining of the knee joint. This condition is characterized by swelling and pain behind the pain. Pain is usually made worse while weight bearing, flexing the knee all the way or extending the knee all the way. Medical treatment consists of aspiration or surgical resection.
References
- Felson DT, Naimark A, Anderson JJ, et al.: The prevalence of knee osteoarthritis in the elderly. The Framingham study. Sem Arthritis Rheum 20:42-50, 1990.
- Dutton, M. Orthopaedic Examination, Evaluation, and Intervention, 2nd Edition. McGraw-Hill Companies, Inc., 2008.
