MSK & Rheumatology Flashcards
What is bone structure made up of?
1) Cortical bone outside (arranged in osteon functional units) 2) Trabecular bone inside
Structure of osteons?
Made up of concentric lemellae (like a tree trunk) and central Haversian canal - Haversian canal supplies a single longitudinal osteon - horizontal communication between osteons = volkmann canals
Component of bone? (Inorganic and organic)
Inorganic component = hydroxyapatite (Ca2(PO4)3) - stiffness Origanum component = collagen T1 - elasticity
Purpose of trabecular bone?
Bone marrow structural meshwork Low in mass but high in strength
Three types of joints?
1) Fibrous (synarthrosis, unmovable) - skull sutures 2) Cartilaginous (amphiarthrosis, partially moveable) - IV disc, pubic symphysis 4) Synovial (diarthrosis, freely moveable) - most joints of body (knee, hip, shoulder etc)
Synovial joint components?
- articular cartilage - joint capsule (inner lining = synovial membrane) - synovial cavity filled with little synovial fluid
Attachment from bone to bone?
Ligaments
Attachment from muscle to bone?
Tendons
Most common type of arthritis?
Osteoarthritis
What is osteoarthritis?
- Traditionally a “non-inflammatory” age-related “degenerative” joint disorder characterised by joint pain and functional limitation. - No longer thought to be the case as it is shown to be inflammatory too. - Metabolically active and dynamic process that is mediated by cytokines. - Often symmetrical and bilateral
What joints does osteoarthritis typically affect?
Knees Hips Hands Spine (cervical and lumbar) Base of thumb pain pain almost ALWAYS osteoarthritis
Non modifiable risk factors for osteoarthritis?
- Age (50+) - uncommon in those under 45 - Females (hip OA is twice as common in women than men) - Genetics (COL2A1= predisposition) - more common when it presents bilaterally - High bone density - but actually protective against osteoporosis - abnormal biomechanics - joint hypermobility or congenital hip dysplasia
Modifiable risk factors for osteoarthritis?
- obesity (3x increased risk) as it is a low grade inflammatory state with release of cytokines - joint injury and damage (history of inflammation can increase risk) - Exercise stresses (occupation with lots of standing or professional athletes) footballers more likely to have osteoarthritis of knees and those with lots of manual labour more likely to have osteoarthritis in the hands
Aetiology of osteoarthritis?
Imbalance between extracellular matrix synthesis vs degradation regulated by chondrocytes within the cartilage => loss of cartilage, remodelling of adjacent bone and subsequent inflammation
Pathophysiology of osteoarthritis?
Increased metalloproteinase secretion by chrondocytes which degrades T2 collagen and causes cysts - bone attempts to overcome this with T1 collagen leading to abnormal bony growths (osteophytes) + remodelling
Symptoms of osteoarthritis?
- Transient morning pain (<30min) - joint pain exacerbated by movement and gets worse as the day goes on - swelling - joint locking (particularly common at the knee) - functional impairment such as walking or activities of daily living
Signs of osteoarthritis in the hands?
Haberden’s nodes: asymmetrical bony swelling at the distal interphalangeal joint -Bouchard’s nodes: asymmetrical bony swelling at proximal interpharangeal joint (also seen in RA) -Thenar wasting -First carpometacarpal joint: most typically affected as most stressed
Sign of osteoarthritis in the knee?
Crepitus: crackeling or grating sensation when moving a joint
Signs of osteoarthritis in the hips?
Antalgic gait: patients may walk with a limp Restricted internal rotation: when hip flexed
Investigations to diagnose osteoarthritis?
joint x-rays: LOSS LOSS of joint space osteophytes Subchondral cysts Subchondral sclerosis -bloods will be normal with no inflammatory markers
Treatment of osteoarthritis?
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Complications of Osteoarthritis?
Biopsychosocial: NSAID complications Low mood Chronic pain Fictional decline in activities of daily living
What is rheumatoid arthritis?
Chronic, systemic inflammatory disease => deforming, symmetrical inflammatory arthritis of the small joints and progresses to involve larger joints and other organs
Genetic risk factors for rheumatoid arthritis?
HLA-DR1 and DR4 are crucial in activating t-cells -PTPN22 also implicated