Learning Objectives Degenerative joint disease (Osteoarthritis) Rheumatoid Arthritis Gout Infectious arthritis Ganglion and Synovial Cysts Pigmented Villonodular Tenosynovitis and Giant-Cell Tumor of Tendon Sheath

Most common joint disorder, part of aging Osteoarthritis Most common joint disorder, part of aging Annual economic toll in the United States > $33 billion Degeneration of articular cartilage, structural changes in underlying bone are secondary

Osteoarthritis Primary osteoarthritis: usually oligoarticular, in elderly Secondary osteoarthritis: < 5% cases, in younger patients Previous Traumatic Injury Developmental Deformity Diabetes Ochronosis Hemochromatosis Marked Obesity

Osteoarthritis Knees & hands – more commonly affected in women Hips - more affected in men

Morphology Enlargement, proliferation, and disorganization of chondrocytes in superficial part of articular cartilage Increase in water content of matrix, decrease in proteoglycans Above: normal hip articular cartilage stained with brilliant red showing abundant acid mucopolysaccharide except in superficial zone. Below: degenerative changes (diffuse hypercellularity and extensive loss of acid mucopolysaccharide from matrix, as shown by diminished red dye)

The normal cartilage has smooth articular surface while OA cartilage shows fibrillation, fissuring of articular surface and clustering of cells in superficial zone Fibrillation

Morphology A: Fibrillation of the articular cartilage B: Severe osteoarthritis with (1) Eburnated articular surface exposing subchondral bone, (2) Subchondral cyst and (3) Residual articular cartilage

Eburnation of joint surface Bilateral osteoarthritis of femur with eburnation of anterior joint surface Polished ivory-like appearance of head of femur v/s normal

Loose Bodies Lateral radiographs of 2 knees showing the typical location of symptomatic (left) and asymptomatic (right) loose bodies in the osteoarthritic knee. Symptomatic loose bodies are anterior to the knee in the suprapatellar pouch and are mobile. Asymptomatic loose bodies are posterior to the knee and because they are trapped in a Baker’s cyst they are not mobile and do not cause mechanical symptoms of locking Small fractures can dislodge pieces of cartilage and subchondral bone into the joint, forming loose bodies (joint mice)

Subchondral cysts The fracture gaps allow synovial fluid to be forced into the subchondral regions to form fibrous walled cysts

Osteophyte ("spur") formation Mushroom-shaped osteophytes (bony outgrowths) develop at the margins of the articular surface Osteophytes in Spine Histology of osteophyte in proximal interphalangeal joint

Chondrocyte function affected by Mechanical stress, Aging Imbalance of normal chondrocyte function can lead to osteoarthritis Chondrocyte function affected by Mechanical stress, Aging

Diminished collagen network and increased chondrocyte apoptosis compromises cartilage tensile strength and resilience

Clinical Course Affects patients beginning in their 50s and 60s Pain: is the most common complaint, initially during activity, relieved by rest. Later at rest also Morning stiffness: lasts less than half hour Crepitus: crackling sensation on moving the joint

Heberden nodes in fingers - prominent osteophytes at the distal interphalangeal joints, are characteristically seen in women a b Bony enlargement seen in proximal interphalangeal joints (Bouchard’s nodes - a) distal interphalangeal joints (Heberden’s nodes - b) The x-ray of OA shows "joint space" narrowing (indicating loss of articular cartilage), marginal osteophyte formation, and subchondral bony sclerosis

Clinical Course Osteophyte impinge on spinal foramina - nerve root compression (radicular pain, muscle spasms, muscle atrophy, neurologic deficits)

Clinical Course Can stabilize for years but is slowly progressive No predicted way to prevent/halt progression Although significant joint deformity can occur, unlike rheumatoid arthritis, fusion does not take place Treatment: maintaining healthy weight and exercising regularly, anti-inflammatory drugs, Joint Replacement Surgery

SUMMARY Osteoarthritis - most common form of joint pathology Primary degenerative disorder of articular cartilage with matrix breakdown exceeding synthesis, inflammation is secondary The vast majority of cases - without apparent precipitating cause except increasing age