20 Musculoskeletal system and pathology Flashcards
Musculoskeletal system and pathology
Aim
Brief outline of normal
Common pathologies
What is the musculoskeletal system?
Provides support and gives us ability to move
Bones
Muscle
Joints, cartilage and tendons
Skeleton
Axial (blue)
Skull, sternum, ribs, vertebral column
Appendicular
Common Pathologies of Bone
Fractures Osteoporosis Arthritis Osteomyelitis Tumours
Fractures
Result of trauma
Can occur in healthy bone or in bone which is otherwise diseased eg. deposit of cancer in bone weakening the bone
Fracture treatment
Aim to realign bone to allow good function after healing.
This can be achieved with a plaster cast +/- surgery depending on the fracture
Fracture Healing
Immediately after fracture rupture of blood vessels causes haematoma which fills the fracture gap
This also provides a fibrin meshwork to allow formation of granulation tissue
Fracture Healing
Inflammatory cells release cytokines to activate osteoblasts and osteoclasts
Development of cartilage cap (callous) ~1week
Bone deposition begins to strengthen callous
Repair tissue reaches maximum girth ~2-3 weeks
Fracture Healing- obstacles
If bones not aligned
If area not immobilised
If fracture site contains dead bone
Infection
Osteoporosis
Decrease in bone mass and density
Can lead to fractures
Very common – 3 million people in UK
Osteoporosis
Imbalance between bone resorption and bone production
Inadequate peak bone mass
Excess bone resorption
Inadequate bone production
Osteoporosis
Hormonal influences- lack of oestrogen (eg. post-menopausal) increases bone resorption and decreases new bone formation
Calcium metabolism and Vitamin D deficiency can also hinder bone formation
Treatment
NICE guidelines
Alendronic acid – bisphosphonate that prevents osteoclast activity
What is arthritis?
Arthritis’ means inflammation of a joint
Characterised by pain, swelling, stiffness
May be redness (erythema) and warmth over the joint
Restricted movement
‘Arthropathy’ means joint disease or disorder
Classification of Arthritis
OSTEOARTHRITIS RHEUMATOID ARTHRITIS Gouty Arthritis Seronegative Spondyloarthropathies - Ankylosing spondylitis - Reactive arthritis - Psoriatic arthritis Infectious arthritis Juvenile Idiopathic Arthritis Arthritis secondary to systemic disease
Osteoarthritis
Most common
Associated with increasing age and obesity
Progressive deterioration
Usually in weight-bearing joints
Most cases primary – no initiating cause
Secondary – at any age with previous joint trauma or congenital abnormality
Risk Factors
Increasing age Female sex, menopause Obesity Pre-existing joint deformity Excess mechanical stress, e.g. professional sportspeople, miners, farmers Genetic susceptibility or family history Hypermobility Other diseases (Secondary OA)
Pathogenesis
wear and tear’
Breakdown of articular cartilage
Underlying bone exposed
Fragments of cartilage can fall into the joint
Bony thickening and outgrowths (osteophytes) develop
Features of Osteoarthritis
Morning stiffness Pain, worse with movement Reduced range of movement Progressive reduction in mobility Joint effusions (fluid) Crepitus
Rheumatoid Arthritis
Affects about 1% of the population
Women affected 3 times more than men
Familial association
Link with HLA (human leukocyte antigen)
Pathogenesis
Rheumatoid factors help form immune complexes in the circulation
Generates inflammation in the synovium
Membranes thicken
Chronic inflammation leads to cartilage and joint destruction
Other tissues involved eg. in lungs and vessels
Features of Rheumatoid Arthritis
Usually affects small joints of hands and feet
Pain
Swelling and deformity
Fever, fatigue, generalised pain
Joints often stiff without prior activity
Most have fluctuating disease
Diagnosis
Need 4 of:
Morning stiffness > 1 hour Arthritis in 3 or more joints Arthritis of typical hand joints Symmetric arthritis Rheumatoid nodules Serum rheumatoid factor Typical radiographic changes
Crystal Arthropathies
Associated with intra-articular crystal
formation
Gout
Pseudogout
Gout
Raised uric acid
Produced by breakdown of purine bases by the enzyme xanthine oxidase
Usually excreted by kidneys
Urate deposited as crystals in the joints
Repeated attacks lead to chronic arthritis
Causes: drugs (aspirin, diuretics), alcohol, renal disease, hypothyroidism, dehydration
Features
Sudden onset excruciating burning joint pain
Redness, warmth, tenderness, stiffness
Usually first attack involved big toe
Subsequent attacks are less severe
Gout Features
Sudden onset excruciating burning joint pain
Redness, warmth, tenderness, stiffness
Usually first attack involved big toe
Subsequent attacks are less severe
Pseudogout (Calcium pyrophosphate crystal deposition disease)
Precipitation of calcium pyrophosphate crystals in connective tissues
Crystals in cartilage can enlarge and rupture causing “crystal shedding” into joint cavity or soft tissues
inflammatory response and synovitis
Usually in knees and ankles
Causes of Pseudogout
Can be hereditary
Associated with osteoarthritis
Trauma or surgery
More common with increasing age
Septic arthritis
Inflammation of a joint caused by bacterial infection
Commonly affects the knee
Causes severe pain, swelling, redness and heat in affected joints. These symptoms tend to develop quickly over a few hours or days.
May also have difficulty moving the affected joint and some people have a high temperature.
Needs treatment with IV antibiotics
May require washout of the joint
Can be very serious and cause sepsis
Osteomyelitis
Bone infection usually caused by bacteria
Trauma, surgery, presence of foreign bodies
Diabetics at increased risk
Haematogenous spread
Bone Tumours
Commonest bone tumour is metastatic disease from a distant cancer eg. prostate, kidney, breast
Primary bone tumours are relatively rare
Benign: osteiod osteoma
Malignant: sarcoma
Muscle
3 types of normal muscle in the body
Striated
Smooth
Cardiac
Striated Muscle
Skeletal muscle
Visible striations on microscopy
Involved in voluntary movements eg. biceps, muscles of arms and legs etc.
Smooth Muscle
Forms muscle layer in walls of GIT, ducts, arteries and internal organs
Involved in involuntary actions such as bowel peristalsis
Controlled by autonomic nervous system
Pathology
Skeletal muscle - muscular dystrophies, neuromuscular disorders
Smooth muscle- leiomyomas
