Osteoarthritis Flashcards
What’s the most common arthropathy? What does the primary path involve? Inflammatory or non-inflamm process?
Osteoarthritis - most common arthropathy
¨Primary pathology involves cartilage, subchondral bone, and synovium
Non – inflammatory joint fluid, Involves active cytokines
¨Multi - factorial etiology
What is the progression of OA?
Progressive deterioration & loss of articular cartilage, leading to loss of normal joint structure & function
What causes primary OA? What joints are affected?
- Aging or Idiopathic.
- Hands: DIP, PIP, first CMC.
What causes secondary OA? What is it frequently comorbid with?
- Due to disorders* that damage articular cartilage, subchondral bone, or synovium.
- May have had congenital or developmental defects of the hips.
Name some causes of OA.
¨Vascular
¨Infectious, Inflammatory, or Infiltrative
¨Neoplastic/Neuromuscular
¨Degenerative, Deficiency
¨Idiopathic, Intoxication (Drugs)
¨Congenital
¨Autoimmune, Allergic
¨Traumatic
¨Endocrine/metabolic, Environmental
¨Depression (Anxiety)
What are some vascular causes of OA?
¨Vascular (sickle Cell, thalassemia, avascular necrosis)
What are some infectious, inflamm, and infiltrative causes of OA?
¨Infectious (Staph), Inflammatory (RA) Infiltrative (sarcoid, hemophilia)
What are some neoplastic or neuromuscular causes of OA?
¨Neoplastic (acromegaly, Pagets)/Neuromuscular (muscle weakness, tabes, diabetes/Charcot joint)
What are some congenital causes of OA?
(hip dislocation, slipped femoral epiphysis; genetics - differentially methylated genes; BMP and WNT signaling pathways)
What are some endocrine/metabolic causes of OA?
(obesity, alcaptonuria, gout, pseudogout, hemochromatosis, Wilsons)
What are some path characteristics of OA?
- Altered chondrocyte function
- Loss of cartilage - thinning
- Subchondral bone thickening - sclerosis
- Remodeling of bone
- Marginal spurs - osteophytes
- Cystic changes in subchondral bone
- Mild reactive synovitis
Describe the pathophysiology of OA.
external events and forces alter the synovium, articular cartilage, and/or subchondral bone resulting in cytokines (especially IL 17) and metalloproteases being released into the joint
Cartilage matrix degeneration follows.
This results in synovial cell stimulation and chondrocyte cloning in an attempt to repair the cartilage by increased proteoglycan (hyaluronic acid) production.
In turn, the cartilage swells. (IL1 is also a key mediator of cartilage damage and is produced in response to calcium and UA crystals that often accompany OA.
Eventually proteoglycans become exhausted and as a result numerous vertical slits occur in the articular surface cartilage. This change in the cartilage is known as flaking or “fibrillation” with cartilage thinning, and eosinophilia of the remaining cartilage.
What is ‘flaking’ in the context of OA?
exhausted proteoglycan stores leading to flaking on articular cartilage surface
What does loss of cartilage in OA lead to?
leads to narrowed joint spaces and further trauma from adjoining bone with more destruction in the high load areas.
As subchondral bone is subjected to vascular invasion with cellular proliferation, eburnation, and spur formation occur
What are bone spurs?
Vascularization with osseous metaplasia eventually produces ossifying cartilagenous protrusion referred to as spurs or osteophytes.
What leads to subchondral cysts?
Chronic impaction and intrusion of synovial fluid leads to subchondral cysts and osseous necrosis.
What are some common sites of OA presentations?
Cervical spine
Lumbar spine
1st CMC
PIP
DIP
Hip
Knee
1st MTP
What are some uncommon sites of OA?
Shoulder
Thoracic spine
Elbow
Wrist
MCP
Ankle
Subtalar
What are the sxs of OA?
¨Insidious onset
¨Deep, achy joint pain associated with movement*
¨Minimal stiffness – usually lasting < 30 minutes
Subchondral vascular congestion, osteophytic periosteal elevation, muscle fatigue, synovitis, effusion, stretched capsule, etc.
What are the physical signs of OA?
¨Limited ROM and crepitus
¨Joint line tenderness
¨Cool effusions
¨Spasm or atrophy of adjacent muscles
What are the diagnostic test appropriate for OA?
No specific diagnostic tests
•Synovial Fluid - class 1
(non-inflammatory – clear, yellow, WBC < 2000; < 25% neutrophils)
Does have citrullinated protein but no antibodies