Osteoarthritis is a disorder arising from different pathophysiological causes with manifestations of joint damage, mechanical stress, and loss of articular cartilage resulting in functional and mechanical joint failure.1-3
As the most common degenerative joint disease, it affects 12% of the population between the ages of 25 to 74, and up to 85% of those over the age of 75.4-6 Women over 50 years experience increased hand, knee, and foot osteoarthritis while older men are more affected with hip pain. Risk factors associated with osteoarthritis include advanced age, female gender, genetics, obesity, history of joint trauma, repetitive movement, malalignment, and quadriceps weakness.4-8
A normal joint is composed of subchondral bone covered by a thin layer of articular cartilage on one end.7,9,10 The interarticular space separates the adjoining subchondral bone and is cushioned with synovial fluid.7,9,10 Articular cartilage allows frictionless movement and uniform load distribution.7,9,10 Muscles, ligaments, and tendons surround the joint providing strength, maintaining stability, and absorbing load.7,9,10 Weight-bearing joints such as the knee and hip are mainly affected in osteoarthritis; however, joints of the hand, foot, lumbar and cervical spine may also be involved.7,9,10 Certain features, common to joint degeneration, lead to development of pain and decreased mobility.7,9,10 Changes within the articular cartilage cells or chondrocytes result from increased synthesis of proteoglycans and the collagen matrix accompanied by increased destruction from metalloproteinases (MMPs) secondary to inflammation from release of cytokines within the synovium and bone.7,9,10 Chondrocyte destruction exceeds formation resulting in interarticular joint space narrowing and development of fibrillations (cartilage clefts). Subchondral bone sclerosis occurs when cartilage is destroyed.7,9,10 Bone remodeling results in osteophyte development and cyst formation (cavities within the bone).9,10 The result is a weakened joint susceptible to instability with loss of dexterity.7,9,10
Patients with osteoarthritis may present clinically with history of pain and tenderness of the joint, limited joint mobility, joint instability, and crepitus with joint movement.3,11 First signs of osteoarthritis may occur on radiographs with absence of clinical symptoms. Symptoms may progress from absence of pain, to joint pain upon movement relieved by rest, to ultimately pain with rest. Loss of functional ability displays as stiffness with inactivity, limited range of motion, and gait instability. Bony or cartilaginous enlargement of the joint, such as the Heberden (located on distal interphalangeal joint) and Bouchard (present on proximal interphalangeal joint) nodes, is an outward physical sign of osteoarthritis. Advanced disease will manifest with joint space narrowing, formation of new bone at joint margins (osteophytosis), and subchondral sclerosis on radiographs.
Diagnosis of osteoarthritis is commonly based on patient history and physical examination. Radiographic evidence and laboratory testing may be useful ...