SM_225a: Osteoarthritis Flashcards
Describe osteoarthritis
Osteoarthritis
- Joint failure, pathologic change in all joint structures
- Hyaline articular cartilage loss, initially focal
- Thickening and sclerosis of subchondral bony plate
- Outgrowth of osteophytes at joint margins
- Articular capsule stretching
- Mild synovitis
- Weakness of muscles bridging a joint
Describe the general schema of factors leading to osteoarthritis
Schema of factors leading to osteoarthritis
- Systemic factors lead to OA susceptibility
- OA susceptibility and local factors lead to OA disease
Describe risk factors for incident ostheoarthritis
Risk factors for incident osteoarthritis
- Systemic: age (all joint sites), gender (all sites), genetic factors (many sites, especially hand), excess body weight (especially knee), certain occupations, elite athletic activity
- Local risk factors: major injury (all, even atypical sites), meniscectomy (knee), developmental abnormalities (especially hip), varus alignment (knee), meniscal tear/extrusion (knee)
Describe why there is an increase in osteoarthritis with age
Increase in osteoarthritis with age due to age-related decline in
- Neuromuscular joint protective mechanisms: muscle function, proprioception, soft tissues that stabilize joint
- Biomechanical properties of cartilage matrix
- Joint less able to rebound from injury
- Reduced regenerative potential of joint tissue
Describe excess body weight in osteoarthritis
Excess body weight
- Increases risk of incident and progressive knee OA
- Weight in young adulthood/middle age predicts knee OA risk later in life
- In overweight persons, weight reduction reduces risk of incident knee OA
- Increases risk of hip OA (less than for knee)
Describe occupational risk factors for OA
Occupational risk factors for OA
- Knee: frequent knee bending + heavy lifting, mining
- Hip: farming
- Elbow: jackhammer operation
- Hand: cotton mill work
Describe nonoccupational physical activity as a risk factor for OA
Nonoccupational physical activity as a risk factor for OA
- Recreational - no increase in risk
- Non-elite athletic - no increase in risk, unless injury occurs
- Elite athletic - increase in risk
Describe the effects of physical activity in OA
Effects of physical activity in OA
- Certain amount of regular loading required for cartilage and bone health
- Under experimental conditions, cartilage fibrillation and thinning seen in immobilized limbs and excessively loaded joints
Describe developmental abnormalities in OA
Developmental abnormalities in OA
- Potentially any abnormality that alters joint sirface fit will increase risk of OA
- Especially at hip: acetabular dysplasia
Describe the phases of OA
Phases of OA
- Phase 1: edema of extracellular matrix, microcracks on cartilage surface, focal loss of chondrocytes alternating with areas of chondrocyte proliferation
- Phase 2: microcracks deepen, vertical clefts form in cartilage, clusters of chondrocytes appear arround these clefs and at surface
- Phase 3: fissures cause cartilage fragments to break off (osteocartilaginous loose bodies), subchondral bone uncovered, subchondral cysts, mild synovitis (more focal and milder than RA), subchondral bone sclerosis
Describe Phase 1 of OA
Phase 1 of OA
- Edema of extracellular matrix
- Microcracks appear on cartilage surface
- Focal loss of chondrocytes alternating with areas of chondrocyte proliferation
Describe Phase 2 of OA
Phase 2 of OA
- Microcracks deepen
- Vertical clefts form in cartilage
- Clusters of chondrocytes appear around these clefts and at surface
Describe Phase 3 of OA
Phase 3 of OA
- Fissures cause cartilage fragments to break off: osteocartilaginous loose bodies
- Subchondral bone uncovered
- Subchondral cysts
- Mild synovitis: more focal and milder than RA
- Subchondral bone sclerosis
Describe the joints most commonly affected in OA
Joints most commonly affected in OA
- Primary: hands, cervical and lumbar spine, feet, knees
- Hips: superolateral or inferomedial narrowing
Describe the sites most commonly affected by primary OA
Sites most commonly affected by primary OA
- Hands (DIP, PIP, first CMC)
- Cervical and lumbar spine
- Feet (1st MTP)
- Knees: only tibiofemoral or only patellofemoral but not both, medial or lateral tibiofemoral compartment but not both
- Hips: superolateral or inferomedial narrowing
Joint involvement in OA can be _____, _____, or _____
Joint involvement in OA can be monoarticular, oligoarticular, or polyarticular
When hips are affected by OA, there is _____
When hips are affected by OA, there is superolateral or inferomedial narrowing
Describe the pattern of joint involvement in primary OA
Pattern of joint involvement in primary OA
- Hand
- Cervical and lumbar spine
- Feet
- Knees
- Hips
Pattern of joint involvement in generalized OA is _____ + _____
Pattern of joint involvement in generalized OA is hands + at least one large joint
Secondary OA involves OA in joints ____, such as ____, ____, ____, and ____
Secondary OA involves OA in joints not typically affected, such as MCP, wrist, elbow, shoulder, and ankle
Describe generalized OA
Generalized OA
- Hands + at least one large joint
- Familial predisposition
- More common in women, onset in middle age
- Multiple Heberden’s nodes
- Polyarticular finger interphalangeal joint OA
- Symptoms persist for years but settle down
- Predisposition to OA at other sites such as knee
Describe secondary OA
Secondary OA
- Premature onset
- Atypical site: MCP, wrist, elbow, shoulder, ankle
Describe general clinical characteristics of OA
General clinical characteristics of OA
- Onset tends to be gradual
- Usually only one/few joints problematic at given time
- Evolution of symptoms and structure change slow
- Strong age association: men 40s and older, women peri-menopause and older
Describe symptoms of OA
Symptoms of OA
- Aching
- Early OA: increases with joint use, relieved by rest
- Advanced OA: pain at rest as well as with use, night pain, not relieved easily, sleep interference worsens pain experience
- Pain/structure change closest relationship at hip, weakest at hand and spinal apophyseal joints
- Morning stiffness: ≤ 30 minutes, shorter than RA
- Stiffness after inactivity
- Swelling: less pronounced, less persistent then RA
Morning stiffness duration in OA is _____ than in RA
Morning stiffness duration in OA is shorter than in RA
Swelling in OA is ____ persistent than in RA
Swelling in OA is less persistent than in RA
In OA symptoms occur at ____
In OA symptoms occur at specific sites
Describe symptoms occuring at specific sites in OA
Symptoms occuring at specific sites in OA
- Knee: pain global or compartmental, pain/difficulty with stairs and sitting to standing
- Hip: pain in groin or deep posterolateral, pain/difficulty in/out of car and with putting on shoes and socks
- Spine: pain in region of involvement, radicular symptoms of osteophytes compressing nerve roots
Describe physical exam findings of OA
OA physical exam findings
- Bony enlargement
- Limitation of motion: limited flexion, inability to achieve full extension
- Crepitus
- Malalignment
- Mild inflammation, warmth, effusion (if moderate or severe consider joint infection or crystal process)
______ is a warning sign and symptom of OA
Marked joint inflammation is a warning sign and symptom of OA
- Flares of OA are common and may show mild joint inflammation
- More marked warmth, swelling, or redness warrants urgent investigation for another cause: crystal, septic arthritis (damaged joints are predisposed), coexisting crystal and septic arthritis
Describe laboratory studies in OA
Laboratory studies in OA
- Blood and urine tests have no role
- Synovial fluid analysis reveals non-inflammatory fluid characteristics: low turbidity, low WBC count (<2,000), may show calcium pyrophosphate dihydrate crystals
Describe radiographic findings in OA
Radiographic findings in OA
- Focal joint space narrowing
- Marginal and central osteophytes
- Subchondral sclerosis and cysts
- Osteochondral bodies
- Bony attrition
Role of X-ray in OA is to _____ and _____, which helps _____ and _____
Role of X-ray in OA is to confirm diagnosis/rule other other conditions and assess OA severity, which helps develop a therapeutic plan and understand prognosis/expected course of OA
Describe the role of MRI in OA
Role of MRI in OA
- Large role in research but not in patient care
- MRI in older individuals needs careful interpretation because may reveal incidental lesions
- Low utility in OA joint b/c presence of multiple lesions does not change management
- Useful if arthroscopy under consideration, possible AVN, or unusual pattern or course
Describe key outcomes of OA
Key outcomes of OA
- Disease progression: structural changes at joint level
- Symptoms: pain, stifness
- Function: impaired performance of discrete actions
- Disability: limitation in performance of socially defined tasks expected of individual within typical environment
Prognosis in OA is ____
Prognosis in OA is variable
- Outcome varies between people and within one person from one joint to the next: whether outcome is poor or not, category of poor outcome
- DIsease progression ≠ function decline: separate risk factors
- Worsening not inevitable
Describe factors associated with progression of OA in the knee
Factors associated with progression of OA in the knee
- Excess body weight
- Varus alignment (bow-legged, outward)
- Valgus alignment (knock-kneed, inward)
- Meniscal damage
Describe factors associated with function decline in knee OA
Factors associated with function decline in knee OA
- Pain severity
- Excess body weight
- Inactivity
- Muscle weakness
- Joint laxity
- Low self-efficacy
- Depression/anxiety
- Poor social support
- Other medical conditions
Describe treatment in OA
Treatment in OA
- Patient education: self-management programs (education, self-efficacy enhancement, coping strategies), social support
- Physical and occupational therapy: exercise to preserve ROM/strength/aerobic capacity, assistive devices, improve ambulation and activities of daily life
- Weight loss if overweight
- Systemic: non-narcotic analgesic (acetominophen), anti-inflammatory (NSAIDs, selective cyclooxygenase-2 inhibitors), narcotic analgesics (advanced OA)
- Local: intra-articular, corticosteroid, hyaluronic acid (minimal evidence)
- Surgical: total joint replacement (advanced OA), unclear if helpful in mild/moderate OA w/o response to conservative therapy
