Osteoarthritis Flashcards
NOT a part of normal aging
NOT a “wear & tear” arthritis
A “whole joint disease”
- Cartilage
- Synovial Membrane
- Ligaments
- Bone
Release of inflammatory enzymes + abnormal biomechanical forces -> damage of cartilage -> cartilage loss
Increase in bone turnover & localized density -> osteophytes
Osteoarthritis
Disorder involving movable joints characterized by cell stress & extracellular matrix degradation
- initiated by micro & macro-injury that activates MALADAPTIVE repair responses including pro-inflammatory pathways of innate immunity
Disease manifests first as a MOLECULAR DERANGEMENT (abnormal joint tissue metabolism), followed by ANATOMIC &/or PHYSIOLOGIC DERANGEMENTS (characterized by cartilage degradation, bone remodelling, osteophyte formation, joint inflammation, and loss of normal joint function) that can culminate in illness
OA Definition
Result of bone remodelling
Laid down to help support the joint in OA, but causes the joint to be more rigid and is not usually laid down in the shape of the joint
Osteophytes
- Age
- Sex (45+)
- Genetic (women>men)
- Obesity
- Physical inactivity
- Injury
- Joint stress (occupational)
Risk Factors
Knee OA
- African American > Caucasians
- Medial compartment: Caucasian > Chinese
- Lateral compartment: Chinese > Caucasian
Hip OA
- Caucasian > Chinese
Hand OA
- Asymptomatic: Caucasians > Mexican Americans > African Americans
- Caucasian > Chinese
OA Prevalence in Race/Ethnicity
↓ bone turnover & density
↓ water in cartilage
Fibrillation at WB sites & not progressive
Normal metabolism, no inflammation
↓ lean muscle mass (Type II Fibers)
MSK Changes in Normal Aging
↑ bone turnover & localized density
↑ water in cartilage
Fibrillation focal & progressive
↑ metabolism & inflammatory enzymes
↓ lean muscle mass (Type 1 Fibers)
MSK Changes OA
Localized OA
- Knee: mostly bilateral; tibio-femoral > patellofemoral
- Hip: Unilateral > bilateral
- Spine: Facet joint OA (60% men, 76% women);
- Hand: PIP, DIP, CMC joints
Generalized OA: ≥ 3 joints
Clinical Patterns
1) Radiographic OA
- Kellgren-Lawrence Grading System
2) Symptomatic OA (aka clinical OA)
3) MRI-Defined OA
- Hunter definition
OA Classification
Main radiographic features:
- Loss of joint space
- Osteophytes
- Subchondral sclerosis (↑ periarticular bone density)
- Subcondral cyst formation (typically hyaluronic acid)
Difficult to dx at the early stage (X-Rays are 2D)
Radiographic OA
Grade 0: No radiographic features
Grade 1: Doubtful; minute osteophyte, doubtful significance
- Grade 2: Minimal; definite osteophyte, unimpaired joint space
- Grade 3: Moderate; moderate decrease in joint space
- Grade 4: Severe; joint space greatly impaired w/ sclerosis of subchondral bone
Kellgren-Lawrence Grading System for Radiographic OA
Pain AFTER USING joint
Relieved by rest
Morning stiffness <30mins
Stiffness after a period of inactivity
Only 40% of pts w/ joint damage experience pain (due to deformity/malalignment; when joint is centrated, pt does not usually experience pain)
Clinical Features of OA
Of the knee
‘Yes’ to ALL 4 QUESTIONS: Constant or Intermittent discomfort or pain….
- At any time on most days of the month?
- In the past year?
- Worse w/ activity?
- Relieved w/ rest?
One or more of 3 SIGNS:
- Effusion
- Flexion contracture
- Gait abnormality
Symptomatic OA
55% of people w/ knee pain had MRI-detected OA that was NOT evident on X-Rays
MRI helps to study the pathogenesis of OA
- Bone marrow edema (bone bruise)
- Found in acute traumatic injuries (e.g. ACL tear, patella dislocation)
- MRI shows ↑ in localized blood pooling
- Associated w/ OA
MRI-Defined OA
Myth or Fact?
Arthritis is caused by a wet, cold climate
Myth
