Prognosis

The natural history of OA is variable:

• It does not necessarily progress to more severe radiographic disease
• The life-time risk of knee joint replacement is 8-11%⁸ ………most people with knee OA will never need an arthroplasty
• A significant number of people will experience no progression, and may even improve, over time.

Major risk factors for knee OA structural progression include⁹:

• Baseline knee pain – associated with a 2.4-fold increase in risk of progression
• Presence of Heberden’s nodes- associated with a 2.7-fold increase in risk of progression
• Knee varus malalignment

There is strong evidence that sex, former knee injury, quadriceps weakness, smoking, running and regular performance of sports are not associated with knee OA structural progression.

Major risk factors for worsening of pain and/or physical function include^10,11:

• Increasing age
• Increasing body mass index
• Increased co-morbidity count
• Higher baseline severity (both radiographic and symptomatic)
• Bilateral knee symptoms
• Depressive symptoms
• Muscle weakness
• Slower walking speed