Chapter 98: Osteoarthritis

PATIENT STORY

A 70-year-old woman presents with pain and swelling in the joints of both hands, which impedes her normal activities. Her pain is better in the morning after resting and worse after she has been working with her hands. She denies stiffness. On examination, you find bony enlargement of some distal interphalangeal (DIP) and proximal interphalangeal (PIP) joints on both hands (Figure 98-1). Radiographs confirm the presence of Heberden and Bouchard nodes. She begins taking 1 g of acetaminophen twice a day and has significant improvement in her pain and function.

INTRODUCTION

Osteoarthritis is the most common type of arthritis. It involves degeneration of the articular cartilage accompanied by osteophytes (hypertrophic bone changes) around the joints. Osteoarthritis leads to pain in the joints with movement and relief with rest. Multiple non-pharmacologic and pharmacologic interventions can improve pain and function.

SYNONYMS

Degenerative joint disease.

EPIDEMIOLOGY

• Osteoarthritis is the most common type of arthritis, affecting 10% of men and 13% of women age 60 years or older.^1,2

• Incidence and prevalence will likely increase given the obesity epidemic and the aging of the population.²

• Hip and knee osteoarthritis was ranked as the 11th highest contributor to global disability.³

• Globally, age-standardized prevalence of knee OA is 3.8% and hip OA is 0.85%. Prevalence of both knee and hip osteoarthritis is higher in females than males.³

• In the Framingham cohort (mean age 71 years at baseline) women and men developed symptomatic knee osteoarthritis at the rate of 1% and 0.7% per year, respectively.¹

• Risk of developing osteoarthritis increases with knee injury in adolescence or adulthood (relative risk [RR] = 2.95) and obesity (RR = 1.51 to 2.07).¹

• Occupational physical activity and abnormal joint loading also increase the risk.^1,2

ETIOLOGY AND PATHOPHYSIOLOGY

• Recent evidence suggests that osteoarthritis should be considered as a systemic rather than focal musculoskeletal disease.⁴

• Biomechanical factors and inflammation upset the balance of articular cartilage biosynthesis and degradation.

• Chondrocytes attempt to repair the damage; eventually, however, enzymes produced by the chondrocytes digest the matrix and accelerate cartilage erosion.

• Inflammation plays a significant role in the progression of osteoarthritis.⁴

RISK FACTORS

• Advanced age.

• Female gender.

• Genetics.

• Obesity.

• Knee injury in adolescence and adulthood.

• Abnormal joint loading.

• Occupational history.

DIAGNOSIS

The American College of Rheumatology uses the following criteria for the most common joints involved in osteoarthritis.