Joints and Joint Disease Flashcards
What does ground substance consist of?
- Proteoglycans
- Glycoproteins
- Water
What is the significance of the ECM?
The composition of the ECM determines the tissues’ physical properties
Name the 2 fibres of connective tissue
- Collagen
- Elastin
Describe collagen and the three types
Good at resisting tensile forces
Type 1 = bone, tendons, ligaments, dermis, organ capsules
Type 2 = Hyaline cartilage, elastic cartilage
Type 3 (reticular fibres) = structural framework of spleen, liver, lymph nodes, smooth muscles and adipose tissue
Describe Elastin
- Major component of elastic fibres
- Enables stretch and recoil of tissues
- Often mixed with collagen to prevent overstretch
- Found in a wide variety of structures e.g. the walls of large arteries, lungs and skin
Describe loose connective tissue
- Contains lots of cells
- Contains nerve fibres and blood vessels
- A loose arrangement of fibres (collagen, reticular and elastic) and abundent ground substance and EC fluid
- Cells contained within the ECM include fibroblasts, adipose cells, macrophages, mast cells and other transient cells responsible for immune and allergic reactions
- Found in a wide variety of places including below epithelial layer of resp and GI tract, below the skin and glands
Describe dense irregular connective tissue
- Contains lots of fibres and fewer cells
- Collagen fibres are arranged randomly and resist stress from all directions
- Can contain network of elastic fibres
- forms the dermis of the skin, capsules of organs including kidneys, testes, ovaries, spleen and lymph nodes, sheaths of nerves
Name 5 different specialised connective tissues
- Dense regular connective tissue (tendons, ligaments, aponeuroses)
- Cartilage
- Adipose tissue
- Haemopoietic tissue (bone marrow, lymphoid tissue)
- Blood
Describe dense regular connective tissue
- colagen fibres are densely packed and arranged in parallel
- Thin sheet-life fibroblasts are located between collagen bundles
- Resistant to axial loaded tension but allows some stretch so forms tendons, ligaments and aponeuroses
Which connective tissue forms tendons, ligaments and aponeuroses?
Dense regular connective tissue
Which conective tissue forms the dermis of the skin, organ capsules and sheaths of nerves?
Dense irregular connective tissue
Which connective tissue sits below the epithelia of the resp and GI tracts and below the pleura, peritoneum and therefore forms part of the serous membrane?
Loose irregular connective tissue
Name 3 important characteristics of cartilage
- Strong, flexible, semi-rigid
- Can withstand compression forces, therefore acts as a shock absorber
- Smooth surface enables friction-free movement
Name 3 functions of cartilage
- Forms articulating surface of bones
- Growth and development of bones (endochondral ossification)
- Supporting framework of some organs, e.g. walls of airway
How is the ECM of cartilage specialised?
- Contains AGGRECAN (a proteoglycan) which has an osmotic effect and so the ECM has a high water content which resists compressive forces
- Contains Collagen and Elastin
Describe the structural appearance of cartilage
Consists of Perichondrium
- Outer fibrous layer
- Inner cellular layer
Describe how cartilage gets its blood supply
Cartilage is avascular, receibes blood supply via diffusion
Describe the development of cartilage cells
- Derived from mesenchyme
Name the 2 steps in cartilage growth and repair
Appositional growth and Interstitial growth
Describe Appositonal growth in cartilage
Surface layers of matrix are added by chondroblasts in the perichondrium
Describe interstitial growth in cartilage
- Chondrocytes grow and divide and lay down new matrix
- Articular cartilage and endochondral ossification
- Occurs in childhood and adolescence
Can cartilage regenerate?
Poor regeneration except in children
–Chondrogenic cells from perichondrium form new cartilage
–Large defects involve replacement with dense connective tissue
Name 3 types of cartilage
- Hyaline
- Fibrocartilage
- Elastic
Describe Hyaline cartilage
- Most common but weakest type of cartilage
- Contains short and dispersed Type II collagen fibres and large amounts of proteoglycans
- Has a perichondrium layer (except on articular surfaces)
Found in
- Articular surfaces of joints
- Costal cartilage
- Epiphyseal growth plates
Describe Fibrocartilage
- Strongest form of cartilage
- Contains thick parallel bundles of type I collagen alternating with hyaline cartilage matrix
- No perichondrium
Found in:
- Insertion points of ligaments and tendons to bone
- IV discs
- Joint capsules
- Knee menisci
- Pubic sympysis
- Temporomandibular joint
Describe Elastic cartilage
- Strong, flexible, resilient
- Present in structures requiring deformation, then rapidly return to original shape
- Contain elastic fibres and Type II collagen fibres
- Has a perichondrium
Found in:
- External ear
- Larynx
- Epiglottis
What is a Synarthrodial joint?
A joint that is fixed and does not allow movement e.g. the cranial sutures
What is a amphiarthrodial joint?
A joint which is only slightly moveable such as the pubic symphysis
What is a Diarthrodial joint?
A joint which is freely moveable such as the shoulder/hip
Name the types of joints
Describe fibrous joints
Name the 2 different types of fibrous joint
Bones connected by dense connective tissue containing mainly collagen and no cartilage.
2 types:
- Sutures = between flat bones of skull, synarthrodial.
- Syndemoses = interossus membrane connecting long bones, amphiarthrodial. E.g. between tibia and fibia & radius and ulna
Describe cartilaginous joints and name the two types
Bones connected entirely by cartilage
Either hyaline and/or fibrocartilage
Can be immoveable or slightly moveable
Allow more movement than a fibrous joint but less than highly mobile synovial joint
Types: Primary and secondary
Describe a primary cartilaginous joint
(Synchodroses)
Hyaline cartilage only
Epiphyseal growth plates, costal cartilage
Describe a secondary cartilaginous joint
(Symphysis)
Hyaline cartilage lines the bones with pad of fibrocartilage in between
IV discs, pubic symphysis, and manubriosternal joint
Describe a synovial joint
Presence of a joint cavity between the bones that contains synovial fluid.
Hyaline Cartilage
Joint is enclosed by a joint capsule
Contains outer fibrous membrane and inner synovial membrane (synovium)
What is a bursa?
Sac made of synovial membrane, containing synovial fluid that reduces friction of one structure moving over another
E.g. in the knee
Name the types of synovial joint and the movements they allow
Movements of synovial joints:-
- Hinge, e.g. elbow joints – flexion and extension
- Ball and socket, e.g. glenohumeral joint – movement in several axes
- Plane, e.g. acromioclavicular joint – gliding or sliding movements
- Saddle, e.g. metatarsophalangeal joint – consists of concave and convex surfaces
- Pivot, e.g. atlantoaxial joint – rotation
- Condyloid, e.g. metacarpophalangeal joint – flexion, extension, adduction, abduction and circumduction
Synovial joints may also be classified as:
- Uniaxial – movement in one plane
- Biaxial – movement in two planes
- Multiaxial – movement in three planes
What is the most common joint disease?
Osteoarthritis
What factors are involved in osteoarthritis development
Complex interaction between genetic, metabolic, biochemical and biomechanical factors
Describe what happens in osteoarthritis
1. Degradation of cartilage
2. Fibrillation of cartillage
3. Chronic synovitis triggered by cartilage fragments (synovial phagocytes release degradative enzymes)
Name some risk factors for osteoarthritis
Risk factors for osteoarthritis include:
- Genetic
- Increasing age
- Female sex
- Trauma
- Mechanical stress on joints
- Obesity
- High bone density – increases the risk of developing osteoarthritis
- Low bone density – increases the risk of progression of knee and hip osteoarthritis
What is the difference between primary and secondary osteoarthritis?
–Primary - due to genetic factors and occurs in the absence of a precipitating insult
–Secondary - occurs as a sequelae of joint pathology, e.g. trauma, infection, joint defects, inflammatory conditions.
Where does osteoarthritis commonly affect?
knees, hips and small joints of the hands
what 3 things happen to the cartilage in osteoarthritis?
Change in composition of cartilage -> reduced shock absorbing abilities
Erosion of cartilage in joints -> fissures (fibrillation)
Ulceration of cartilage -> exposes underlying bone -> microfractures and subchondral cysts
What happens to the joint capsule in osteoarthritis?
Inflammation of synovium
Thickening of joint capsule -> stiffness and restricted movement
What radiographic changes would you see in a patient with osteoarthritis?
Joint space narrowing – characteristically asymmetric
Subchondral cysts and sclerosis
Osteophytes
Malalignment
How might you notice osteophytes in a clinical exam?
Osteophytes are commonly seen on examination in osteoarthritis of the small joints hand where they present as hard swellings around the distal interphalangeal joints (Herberden nodes) and/or proximal interphalangeal joints (Bouchards nodes) and at the base of the thumb.
Name signs and symptoms of osteoarthritis
Joint stiffness – short-lived morning stiffness and post-inactivity stiffness
Joint pain – worse on movement
Functional limitation
Rest/night pain
Examination findings:
–Restricted movement
–Crepitus
–Bony swelling
–Joint effusion
–Joint instability, deformity and muscle wasting
Briefly describe the management of osteoarthritis
Education, advice and information
Non-pharmacological
–Exercise – build muscle strength, loose weight
–Physiotherapy
–Aids and devices
Pharmacology
–Pain management – topical and/or oral
Surgical
–Joint replacement (arthroplasty)
–Joint fusion
–Joint excision
–Realignment surgery
Name 3 types of inflammatory arthritis
- Rheumatoid arthritis
- Spondyloarthritis
- Crystal arthritis e.g. gout
How is osteoarthritis different from rheumatoid?
Rheumatoid arthritis:
- usually begins 25-50yrs
- AI response affecting synovial membrane leads to joint destruction
- develops in weeks/months
- usually symmetrical, affects small joints primarily
- signs of inflammation present
- morning stiffness often >1hr
- more common in females
- no ostephytes
- RF frequently present
- generalised symptoms present e.g. fatigue, weight loss, anaemia
Osteoarthritis:
- Usually begins after 40
- biomechanical - leads to loss of cartilage matrix
- develop slowly over many years
- usually affects weight bearing joints
- pain associated with joint use, less inflammatory signs
- morning stiffness usually <20mins
- no general symptoms
- common in males and females
- osteophytes may be present
- No RF present
What is gout caused by?
which joints are commonly affected?
An inflammatory response to urate crystals deposited in and around joint and synovial fluid
Due to Hyperuricaemia
Crystal formation tends to occur in peripheral areas, e.g. metatarsal-phalangeal joints, especially of big toe
What does gout lead to?
synovitis, cartilage destruction and joint degeneration
What is the difference between primary and secondary gout?
–Primary (95%) - due to an inherited disorder that causes an overproduction or underexcretion of uric acid
–Secondary (5%) – other factors causing overproduction of uric acid (e.g. high dietary purine, drugs, or conditions resulting in increased nucleic acid turnover, e.g. lymphoma, psoriasis, haemolysis etc. etc.) or under-excretion (e.g. chronic renal failure, alcohol, drugs etc.)
What complication can gout cause?
think kidneys
Urate crystals can also be deposited in the renal parenchyma, resulting in renal failure, and urate calculi (kidney stones) can be formed in the urine
Name important risk factors for gout:
Therefore, important risk factors to remember include:
- High serum urate
- Family history
- Excess alcohol
- Renal disease
- Chemotherapy for malignancy
Describe signs and symptoms of acute gout
Acute gout:
–Sudden onset
–May be precipitated by excess food or alcohol, dehydration or diuretics
–Joint inflammation
–Tender, swollen, hot, red joint
–Often affects first metatarsophalangeal joint
Describe signs and symptoms in chronic gout
Chronic tophaceous gout
–Often associated with renal impairment and long-term use of diuretics
–Tophi – deposits of monosodium urate crystals in bursae, tendons, cartilage or periarticular bone. May ulcerate and discharge
–Chronic joint pain
–May have superimposed acute gout attacks
What radiographic changes might you see in a patient with chronic gout?
Joint effusion
“Punched out” bony erosions with sclerotic margins and over-hanging edges
Opacities (tophi) in soft tissue
Soft tissue swelling
Narrowing of joint space in late stages of disease
Briefly describe the management of gout
General measures:
–Reduce alcohol intake
–Avoid purine-rich foods
–Loose weight
–Review medications including diuretics
Acute attack – NSAIDs or colchicine
Chronic gout
–Allopurinol (xanthine oxidase inhibitor – reduces synthesis of uric acid)
–Uricosuric drugs (increases urinary excretion of uric acid)
