osteoarthritis

Last edited 10/2021 and last reviewed 01/2023

Osteoarthritis is a disease of synovial joints which is characterised by loss of articular cartilage and overgrowth of the underlying bone. Unlike rheumatoid arthritis, there is no pannus.

In the past osteoarthritis was considered to be a "degenerative joint disease", implying a passive process associated with old age. This is misleading because osteoarthritis is a multifactorial, active disease which usually begins in middle age.

• osteoarthritis refers to a clinical syndrome of joint pain accompanied by varying degrees of functional limitation and reduced quality of life
  • the most common form of arthritis, and one of the leading causes of pain and disability worldwide
  • most commonly affected peripheral joints are the knees, hips and small hand joints
  • pain, reduced function and effects on a person's ability to carry out their day-to-day activities can be important consequences of osteoarthritis
    • pain in itself is also a complex biopsychosocial issue, related in part to a person's expectations and self-efficacy (that is, their belief in their ability to complete tasks and reach goals), and is associated with changes in mood, sleep and coping abilities
    • often a poor link between changes visible on an X-ray and symptoms of osteoarthritis: minimal changes can be associated with a lot of pain, or modest structural changes to joints can occur with minimal accompanying symptoms
    • contrary to popular belief, osteoarthritis is not caused by ageing and does not necessarily deteriorate

Osteoarthritis is in fact a loosely defined group of diseases which may be triggered by factors such as:

• mechanical damage
• inflammation
• metabolic defects

Osteoarthritis is characterised pathologically by localised loss of cartilage, remodelling of adjacent bone and associated inflammation

• osteoarthritis includes a slow but efficient repair process that often compensates for the initial trauma, resulting in a structurally altered but symptom-free joint
  • in some people, because of either overwhelming trauma or compromised repair, the process cannot compensate, resulting in eventual presentation with symptomatic osteoarthritis; this might be thought of as 'joint failure'

A systematic review and network meta-analysis of randomised trials concluded (2):

• etoricoxib 60 mg/day and diclofenac 150 mg/day seem to be the most effective oral NSAIDs for pain and function in patients with osteoarthritis
  • note that these treatments are probably not appropriate for patients with comorbidities or for long term use because of the slight increase in the risk of adverse events
  • also there was an increased risk of dropping out due to adverse events was found for diclofenac 150 mg/day
• topical diclofenac 70-81 mg/day
  • seems to be effective and generally safer because of reduced systemic exposure and lower dose
  • should be considered as first line pharmacological treatment for knee osteoarthritis
• clinical benefit of opioid treatment, regardless of preparation or dose, does not outweigh the harm it might cause in patients with osteoarthritis

Reference:

• NICE (February 2014). Osteoarthritis Care and management in adults
• de Costa BR et al. Effectiveness and safety of non-steroidal anti-inflammatory drugs and opioid treatment for knee and hip osteoarthritis: network meta-analysis.BMJ 2021; 375 doi: https://doi.org/10.1136/bmj.n2321