Arthritis - OA Flashcards
___ is the most common form of arthritis
OA
1 in 4 people in US
Leading cause of disability in older adults:
OA
Most commonly affected joints (but can impact ANY synovial joint):
Hips
Knees
Hands
*shoulder, ankle,
OA: Clinical Features
Loss of Articular Cartilage
Synovitis
Boney Changes
Ligamentous Changes
Meniscal Changes
OA: Patient Impact
Pain
Swelling
Stiffness
Loss of Function
Bone responds by laying down more bone:
*osteophyte is one way
*sclerosis is the other way (bright white new layer)
Ligamentous changes = what the osteophyte is responding to
ligaments become more lax (take away some of the stretch they are under)
*osteophytic lipping occurs
*LCL and MCL more lax - lipping happens to make deeper bowl
OA Pathophysiology
Degenerative process of the whole joint with different phenotypes emerging
Primary OA:
Idiopathic
Secondary OA:
Underlying cause or event (trauma)
Risk factors for primary OA:
Age
Obesity/Metabolic Disease
Sex (60% female)
Cartilage Major Components:
Water
Extracellular Matrix (ECM) & Proteoglycans
Chondrocytes (Responsible for both catabolism and anabolism)
Cartilage Function:
Withstand highly repetitive compressive and shear loads, maintain a near frictionless joint surface environment, allow force transmission between articulating bones
collagen arrangement of articular cartilage:
articular surface
superficial tangetial zone: 10-20%
middle transitional zone: 40-60%
deep zone: 30%
calcified cartilage
subchondral bone
cancellous bone
Review of normal cartilage physiology and biomechanics:
Uses hydrodynamics- water flows out in response to compression
Proteoglycans are hydrophilic, attract water to flow back into cartilage following water loss
Combination of hydrodynamics and ECM structure allow compressive forces to be converted to shear at the calcified cartilage/bone interface
Cartilage Regeneration:
Chondrocytes repair ECM (very slow process) -> poor healing potential
Chondrocytes are mechanosensitive, regenerative process is stimulated in response to loading
What’s happening with OA - Impairment of cartilage regeneration
Regeneration is too slow to keep up with damage repair AND/OR regeneration pathway is altered
Presence of inflammation impacts chondrocyte function
Produce more pro-inflammatory markers and matrix degrading enzymes
Early chondrocyte senescence
Proteoglycan loss occurs first, followed by ___
eventual ECM breakdown
Loses ability to handle loads via hydrodynamics (less water), placing more stress on ECM
Articular Cartilage Breakdown:
This process is going on for YEARS/DECADES before we can see cartilage breakdown
Translation: By the time we start to see cartilage breakdown its far too late
Cartilage response to loading in controls vs OA:
More ECM deformation and more water loss in OA
Primary OA Phenotypes:
1) overweight/obesity
*poor diet indirectly impacts
2) ageing
3) lifestyle choices
all 3 lead to inflammaging ->chondrosenescene -> OA
Secondary OA:
OA due to associated event
The normal joint structure and biomechanics are impacted resulting in both inflammatory environment and changes to loading environment
Slow cartilage metabolism does not adapt quickly enough to joint changes
Joint Injury: PTOA
Knee injury: 6x risk increase
Abnormal Alignment or Geometry (Congenital, tumor, etc)
Malalignment of the knee is an independent risk factor of OA progression
___ is an independent risk factor of OA progression
Malalignment of the knee
PTOA: The major issue:
Huge cohort of young individuals with old knees
Lots of years left in the medical system
Downstream healthcare impacts of physical inactivity and/or disability
Joint arthroplasty only lasts~ 20 yrs
* These people may need multiple arthroplasties in their lifetime = $$$$$
post ACL: ~50% will have radiographic OA within ___
10-20 yrs
Much more complex than originally thought (not just wear and tear)
Cartilage regeneration is unable to keep up with microdamage
Impacted by biomechanics and/or inflammatory environment
Impacts the whole joint (not just articular cartilage)
We don’t fully understand what causes symptoms - OA Pathophysiology
Worse radiographic OA more likely to have symptoms
Primary OA: Intersection between ____
aging, genetics, metabolic syndrome/obesity, lifestyle choices
Secondary OA: Intersection between _____
joint biomechanics and inflammation
Common Imaging Features:
Loss of joint space width
Osteophyte formation
Sclerosis of subchondral bone
Imaging Modality:
Radiographs (gold std)
MRI
CT
OA Grading System:
0-4
OA: grade 0
no OA
no osteophytes
no JSN
OA: grade 1
doubtful OA
possible osteophytes
doubtful JSN
OA: grade 2
mild OA
definite osteophytes
possible JSN
OA: grade 3
moderate OA
moderate osteophytes
definite JSN
OA: grade 4
severe OA
large osteophytes
great JSN
Curveball:
Up to 50% of people with radiographic OA have no associated symptoms
We do not currently understand why some are symptomatic and others are asymptomatic
Advanced Imaging Techniques:
New promising imaging sequences that allow us to assess cartilage physiology before cartilage damage is evident
MRI T1rho
MRI T2*
MRI T1rho:
Associated proteoglycan content/concentration
MRI T2*:
Associated with ECM orientation and free vs bound water
We currently have ___ treatments that have been proven effective at reversing OA or stopping its progression
zero
The treatments we do have:
Treat the symptoms (reduce pain)
Promote function
Prevent OA from happening in the first place
Prevent OA from happening in the first place:
Injury prevention (Secondary OA)
Lifestyle (Primary OA)
* Moderate Activity
* Weight Management
Pharm interventions:
NSAIDs
Corticosteroids
Hyaluronic Acid
Biologics
Surgery interventions:
Debridement
Cartilage Repair
Joint Replacement
Common NSAIDs:
Ibuprofen
Naproxen
Diclofenac
NSAIDs Treatment:
Effective at reducing pain and targeting synovitis
Cheap
Cons: Some with comorbidities unable to use
Some have topical versions available
Con: Treats symptoms, no impact on disease
Common Corticosteroids:
Cortisone Injection
Corticosteroid Treatment:
Effective at reducing short-term pain and inflammation
Intended to be an adjunct
More localized treatment
Cons: Some with comorbidities unable to use
Con: Treats symptoms, no impact on disease
Con: Limited dosage schedule, infection risk
Hyaluronic Acid
Common: (Viscosupplementation)
Synvisc
Hyalgen
Euflexxa
Hyaluronic Acid Treatment:
Can improve symptoms and function in mild/moderate OA (high bias evidence)
“lubricates” the joint
Cons: Expensive (limited insurance coverage)
Con: Treats symptoms, no impact on disease
Con: Limited dosage schedule
Common Biologics:
Stem Cell Therapy
Platelet Rich Plasma (PRP)
Biologics treatment:
Promising basic science results
Some mixed results but mostly poor findings of effectiveness in vivo
No Standardization
Cons: Expensive (not covered by insurance)
Cons: Travel to special clinic
Disease-Modifying Osteoarthritis Drugs (DMOADs)
Corticosteroids have short-term symptomatic benefits and should be adjuncts
Placebo effect from injections
Surgery:
Joint replacement is highly effective but still considered a salvage procedure
Reduces pain, reduces disability, improves QOL
Viscosupplementation studies that show benefit have ___
high risk of bias
Recommendation: try it if the patient had little to no effect from steroid or can’t have steroid
Rehab Interventions:
Weight Management
Exercise
Bracing
Weight Management:
9-76% reduction in pain following gastric bypass
Pain scores reduced, functional scores improve
Improved joint space associated with weight loss
Con: Poor adherence to interventions
Dose response exists (More weight loss more symptomatic improvement)
Physical Activity and OA:
Maintain and/or improve functional capacity
Supplement diet for weight loss
No specific recommendations:
*No evidence to support a hierarchy of types of exercise
*Whatever the patient likes to do will improve adherence
Rehab programs:
Decrease pain, improve function, improve QOL
Quad strength/power = Function
PT had better outcomes through 1 year follow up vs corticosteroid injection
Bracing:
Unloader braces have some symptomatic benefit
Other braces: Likely placebo/tactile
Braces are generally bulky, uncomfortable, and/or not aesthetically pleasing
In general, running was not associated with OA
Running at a recreational level was associated with lower odds of hip/knee OA compared to those running competitively and more sedentary, non running individuals
Recreational runners have the lowest incidence of OA
The Debate:
Don’t Unnecessarily Load
Don’t Change Activity
swinging pendulum
Not all OA is the same:
Primary vs secondary with phenotypes of each
It is unlikely there will be one blanket recommendation, each subset will need its own specific recommendations that is also adjusted to the individual patient
The most basic principle of treatment is the ___
risk reward benefit to the patient
Promote physical activity for weight management, joint health maintenance, pain/mental health
Weigh the risk reward for whether higher loading activity is appropriate
Use irritability as a guide
Quad strength and power to maintain function
Combination of open and closed chain depending on joint irritability and compensations
OA PT Management
Assistive device use for significant gait deviations
Self-management focus
Booster visits currently being explored, watch for evidence
The future:
Harness mechanosensitivity of chondrocytes to promote regeneration
Can we identify specific loading inputs to optimize cartilage health after injury and surgery
Likely in combination with pharm
Use of biologics to regenerate damaged cartilage
Our current post-injury and post-op treatments are focused on short term goals of ___ and have little focus on ___
return to sport and function
long-term joint health
