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
