Joints & Joint Disease Flashcards
What are the 2 fibres of connective tissue?
Collagen - resists tensile forces
Elastin - enables stretch and recoil
What are 3 types of connective tissue?
Loose irregular connective tissue
Dense irregular connective tissue
Specialised connective tissue (dense regular connective tissue, cartilage, adipose tissue, blood)
What are characteristics of cartilage?
Strong, flexible, semi rigid
Withstand compression forces
Shock absorber
Smooth surface for friction-free movement
What are 3 functions of cartilage?
Articulating surfaces of bones
Growth and development of bone (endochondral ossification)
Supporting framework
What are features of cartilage ECM that determine its properties?
Contains aggrecan (proteoglycan) which has high water content/osmotic effect and can resist compressive forces Fibres: collagen and elastin
Outline cartilage cell development
Mesenchymal stem cells -> Chondroblast -> Chrondrocyte
Outline appositional and interstitial growth of cartilage
Appositional: surface layers of matrix added by chrondroblasts in perichondrium (fibrous layers)
Interstitial: chondrocytes grow and divide to lay down new matrix, articular cartilage and endochondral ossification
Cartilage is avascular so relies on diffusion
What are 3 common types of cartilage?
Hyaline
Fibrocartilage
Elastic
What’re the difference between hyaline, fibrocartilage and elastic cartilage?
Hyaline is most common but weakest, contains type II collagen and proteoglycans
Fibrocartilage is strongest but has no perichondrium (contains type I collagen)
Elastic cartilage composed of elastic fibres and type II collagen and present in structures that require some degree of deformation
Where are hyaline, fibrocartilage and elastic cartilage found?
Hyaline: articular surfaces of joints, costal cartilages and epiphyseal growth plates
Fibrocartilage: insertion points of ligaments and tendons, IV discs, joint capsules, knee menisci, TMJ, pubic symphysis
Elastic cartilage: external ear, larynx, epiglottis
What are the 3 main groups of joints?
Fibrous, Cartilaginous, Synovial
In fibrous joints how are the bones connected? What are types of fibrous joint?
Bones connected by dense connective tissue containing mainly collagen - no cartilage
Sutures (between flat bones ie skull)
Syndesmoses (interosseous membrane connecting long bones)
How are cartilaginous joints connected? What types are there?
Bones connected by cartilage (either fibrocartilage +/- hyaline)
Primary joints (only hyaline cartilage) eg synchondroses like epiphyseal growth plates Secondary joints (fibro + hyaline) eg IV disc, manubriosternal joint
Outline characteristics of synovial joints
Joint cavity between the bones containing synovial fluid (hyaline cartilage)
Joint enclosed by a joint capsule: outer fibrous membrane and inner synovial membrane
Bursa surround the joint to further reduce friction
Fibroelastic ligaments cross the joint to reinforce
Menisci in the knee are made of fibrocartilage
What are types of synovial joint?
Hinge (elbow) Ball & socket (glenohumeral - shoulder) Plane (AC) Saddle (MTP) Pivot (radioulnar) Codylar (MCP)
Briefly what is osteoarthritis?
Joint disease - loss of articular cartilage +/- bone leading to synovitis; inflammation affects parts of the joint and leads to reduced shock absorbing abilities of cartilage
What are risk factors for osteoarthritis?
Genetic, increasing age, female, trauma, obesity, mechanical stress
What’s the difference between primary and secondary osteoarthritis?
Primary - occurs due to genetic factors in the absence of precipitating insult
Secondary - occurs as sequelae of joint pathology (trauma, infection, inflammatory conditions)
What are radiographic changes seen in osteoarthritis?
Joint space narrowing
Osteophytes
Subchondral cysts and sclerosis
Malalignment
What are the signs and symptoms of osteoarthritis?
Joint stiffness (short lived in the morning)
Joint pain (worse on movement)
Functional limitation
Pain on rest/night
Signs: Restricted movement Crepitus Bony swelling Joint effusion Herbenden's nodes
How is osteoarthritis managed?
Education
Non-pharmacological: exercise, physio, aids
Pharmacological: pain (topical/oral)
Surgical: joint replacement, joint fusion, joint excision, realignment surgery
What’s the pathophysiology of osteoarthritis?
Chondrocytes trigger release of cytokines, which produce and release protease enzymes to degrade cartilage/joint structures
Fibrilation of cartilage: as smooth surface lost and cracks develop
Chronic synovitis: triggered by cartilage fragments/osteophyte formation
What are 3 types of inflammatory arthritis?
Rheumatoid
Spondyloarthritis
Crystal (gout)
What’s Rheumatoid arthritis?
Autoimmune multi-system inflammatory disease
Inflammation of synovial membrane and articular surfaces = joint destruction
Also associated with extra-articular features affecting eyes, skin, respiratory system, cardiovascular system
What are articular characteristics of Rheumatoid arthritis?
Warm, tender and swollen joints
Morning stiffness lasts >1 hours (longer than osteoarthritis)
Joint deformities
What are some key differences between osteoarthritis and rheumatoid?
RA onset between 25-50 years OA 40yrs + OA biomechanical; RA autoimmune inflammatory RA affects symmetrical smaller joints OA affects weight bearing joints Osteophytes present in OA only RF present in RA only RA: morning stiffness >1hr ; OA morning stiffness <20mins
Primary vs Secondary gout?
Primary (95% cases): inherited disorder overproducing, or under excreting, uric acid
Secondary: high dietary purine, drugs/conditions causing high nucleic acid turnover, lymphoma, psoriasis
Why is gout associated sometimes with renal failure?
Crystals can be deposited in renal parenchyma = urate calculi (stones) formed in urine
What are signs and symptoms of acute gout?
Sudden onset, my be precipitated by alcohol, excess food, dehydration Joint inflammation (typically in the periphery and big toe) Tender swollen hot red joint (metatarsophalangeal joint)
What are signs and symptoms of chronic gout?
Often associated with renal impairment and long term diuretic use Tophi formation (deposits of monosodium urate crystals in bursa, tendons, cartilage) Chronic joint pain
What are radiographic changes seen with gout?
Joint effusion
Tophi in soft tissue/soft tissue swelling
Punched out bony erosions
Joint space narrowing
How is gout managed?
Reduce alcohol intake, reduce purine-rich foods, lose weight, review diuretic medication
NSAIDs in acute attack
Allopurinol in chronic gout
