Osteoarthritis Flashcards
What is osetoarthritis (OA)?
A condition characterised by damage to the articular cartilage of joints & the underlying bone
What are the functional properties of articular cartilage?
- Joint lubrication
- Stability
- Deformation & congruence
- Loading: Static vs dynamic (cyclic)
What type of loading is good for joints and why?
Dynamic
- Delivers nutrients to the joint
- Improves movement of fluid through the joint
- Improves amount of water in the articular cartilage
What load factors contribute to degree of joint lubrication?
- Manner of loading
- Exercise increases synovial fluid viscosity & lymphatic clearance
- Cartilage deteriorates when unloaded
- Potential for wear increases when joint goes from static to high loads
- Repetitive impulse (sudden) loading is detrimental to HAC & subchondral bone
What are some of the more recently proven facts about OA (former myths)?
- Not wear & tear
- Joints are not worn out
- Not increased by exercise (except in mechanical stress/exceptionally repetitive)
- Cartilage needs movement
- OA is a failure of repair
What are the two types of OA?
Primary
- Genetic
- Bilateral
- Symmetrical
- Inverse to osteoporosis
Secondary
- Mechanical stress (injury, alignment, affects specific joint)
- Metabolic, chemical or inflammatory (affects multiple joints)
What joints are commonly associated with primary OA?
Weight-bearing joints
- Fingers (IPs, not CMCs)
- Knees
- Hips
- Lumbar spine
- 1st MTP
What are examples of diseases that may cause secondary metabolic OA?
- Rheumatoid arthritis
- Haemophilia
- Gout
What are the subjective clinical features of OA?
- Middle-aged or elderly
- Insidious onset or aggravated by an event
- Intermittent, local pain
- Morning stiffness >30 mins
- Stiffness after rest lasts few minutes
- Worse with activity, better with rest
What are the objective clinical features of OA?
- Tenderness
- Limited ROM
- Crepitus
- Occasional effusion
- Bony enlargement
- Narrow joint lines
What are the x-ray clinical features of OA?
- Osteophytes (bony spurs)
- Joint space narrowing
- Flattened condyles
- Subchondral sclerosis
- Malalignment (can be cause or effect, i.e. not diagnostic feature)
How do the articular cartilage cells change as they get deeper into the tissue?
Change from being flat to much more columnar
What does the tide line of articular cartilage divide?
- Uncalcified cartilage (top layer)
- Calcified cartilage (middle layer)
- Subchondral bone (bottom layer)
What is cartilage chemistry made up of?
Proteoglycans (hydrophilic)
What occurs in the very early to moderate stages of OA?
- V early OA: Cartilage swells, superficial layer loss, structural changes
- Early OA: Loss of superficial laminar layer, bone starts growing
- Moderate OA: Loss of organisation & hypertrophy
What occurs in the late to end stages of OA?
- Late OA: Cartilage loss, growth of bone
- End stage OA: Sclerosis
What stages of OA are reversible?
Up to moderate
What are the main differences between the chemical and mechanical pathways of OA?
- Mechanical pathway progresses much slower
- Chemical pathway progresses much faster
- Chemical pathway much more painful (inflammation)
What are the inflammatory markers?
- Interleukin-1 (IL-1)
- Interleukin-6 (IL-6)
- Tumour necrosis factor-alpha (TNF-alpha)
What are the cartilage breakdown biomarkers in OA?
Early OA: Agrecanase (ADAMTS)
Late OA: Matrix metalloproteinase (MMP)
What are the bony changes associated with OA?
- Subchondral bone fractures
- Increased osteoblast activity
- Increased subchondral bone density
- Reduced flexibility
- Osteophytes (bone spurs)
What does the reversibility of OA depend on?
- The number of chondrocytes left
- Stages of damage
- Kinds of healing
- Patient’s QOL
What are the predictors of progression of medial OA?
- Adduction moment (varus thrust/bow legs)
- Gender
- Mechanical axis (varus knee)
- BMI (obesity = cytokines)
- Pain
- Age/presence of OA in other joints
- Not physical activity (joint motion is good for cartilage)
What are the principles of treatment for OA?
- Find cause of mechanical stress
- Relieve extra loading
- Protect joint from shearing damage
- Improve joint nutrition (exercise)
- Relieve pain to enable exercise
What are the core treatments for OA according to the OARSI guidelines?
- Land-based exercise
- Water-based exercise
- Weight management
- Self-management & education
- Strength training