Chapter 70 - Knee Osteoarthritis

Abstract

Osteoarthritis (OA) is becoming the most common cause of disability for the middle-aged and the knee joint is the most frequently involved lower extremity site. It is estimated that nearly half of all adults will have symptomatic knee arthritis in their lifetimes. Younger populations are not immune to knee OA, as an increasing number of athletes with prior knee injuries may experience post-traumatic knee OA, with a particular risk to participants of ice hockey, soccer, and football. Knee OA is also common in those performing heavy physical work, especially if this involves repetitive knee flexion such as bending, squatting, kneeling, or lifting. OA can affect any or all of the three major knee compartments, but the medial compartment is most often involved, leading to medial joint space narrowing and subsequent genu varum (bowleg) deformity. Physical therapy and exercise remain the mainstay of nonsurgical, non-pharmacologic therapy with an increased focus on the benefits of resistance exercise to improve function and reduce pain. New technologies include musculoskeletal ultrasound for imaging and platelet-rich plasma for pain relief. The role of obesity as a risk factor for knee OA has been well documented, and more recently, metabolic factors are thought to play a role as well. Recent studies demonstrate short-term relief from corticosteroids injections, with less dramatic but slightly more durable relief from injections of viscosupplements.