Bones and joints Flashcards
Types of bone and example
Long - femur Short - carpals Flat - scapula Sutural - within a suture in cranium Irregular - vertebra Sesamoid - patella
Structure of short, flat and sesamoid bones
Mainly spongy bone Bone marrow between trabeculae Thin layer compact bone (covered in periosteum) No epiphysis No diaphysis
Blood supply of bones before epiphyseal fusion
Epiphyseal arteries (only blood supply to epiphysis)
Bends of metaphyseal arteries
Periosteal arteries
Nutrient artery
Blood supply of bones after epiphyseal fusion
Anastomoses between epiphyseal and metaphyseal arteries
Periosteal arteries
Nutrient artery
Where do metaphyseal arteries enter bone
Metaphysis at site of attachment of capsule
What does the periosteal artery supply
Periosteum
Outer 1/3 of cortex
Where does the nutrient artery enter bone
Diaphysis via nutrient foramen
How can avascular necrosis be caused
What can it lead to
Fracture Dislocation Steroids Radiation Decompression sickness (N2)
Leads to secondary osteoarthritis
What properties are joints classified by
Structural (tissue between articulating bones)
Functional (amount of movement)
What are the structural joint types
Fibrous
Cartilaginous
Synovial
What are the functional joint types
Synarthrosis - immovable
Amphiarthrosis - slightly moveable
Diarthrosis - freely moveable
Functions of skeleton
Support Protection Movement - attachment site for muscles Mineral and growth factor storage (Ca, PO3, insulin like growth factor, transforming growth factors, bone morphogenetic proteins) Haematopoeisis
Types of fibrous joints
Give a short description of each
Suture -restricted to cranium
Syndesmosis - immovable joint with CT between bones
Gomphosis - peg of bone fits into bone socket
What occurs to suture joints on completion of growth
Synostosis - fusion of adjacent bones
Examples of syndesmosis joint
Inferior tibiofibular joint
Radioulnar interosseus membrane
Posterior sacroiliac joint
Examples of gomphosis joint
Teeth
Types of cartilaginous joints
Primary cartilaginous joint
Secondary cartilaginous joint
Describe primary cartilaginous joints
United by hyaline cartilage
Synarthrosis
Describe secondary cartilaginous joints
Articulating bones covered with hyaline cartilage with fibrocartilage between them
Amphiarthrosis
Examples of primary cartilaginous joints
First sternocostal joint Xiphisternal joint (end of sternum) Epiphyseal growth plate
Examples of secondary cartilaginous joints
Pubic symphysis
Intervertebral disc
Manubriosternal joint (sternal angle)
Describe synovial joints
Diarthrosis
Made up of: Articular cartilage Fibrous capsule Synovial membrane Synovial fluid
What synovial joints don’t have hyaline as the articular cartilage
What do they have instead
Acromioclavicular
Sternoclavicular
Temperomandibular
Fibrocartilage
Describe fibrous capsule of synovial joints
Collagen
Poor blood supply
Encloses joint except at synovial protrusions
Stabilises joint
Describe synovial membrane of synovial joints
Thin Highly vascularised Lines capsule Covers exposed osseus surfaces, tendon sheaths and bursae Doesn't cover articular cartilage Produces synovial fluid
Describe properties of synovial fluid
Clear/pale yellow
Viscous
Slightly alkaline
Composition of synovial fluid
Hyaluronic acid
Lubricin
Proteinase
Collagenase
Functions of synovial fluid
Reduce friction
Shock absorption
Nutrient and waste transportation
Compare bursae and tendon sheaths
Bursa - synovial fluid filled sac lined with synovial membrane
Tendon sheath - elongated bursa around tendon
Blood supply of articular cartilage of synovial joint
Avascular
Blood supply of synovial joints
Periarticular arterial plexus
This contains many vessels so movement doesn’t cut off blood supply
What is hiltons law
Nerves supplying joint capsule also supply:
Muscles moving joint
Skin overlying insertion of these muscles
What are the types of synovial joints
Give examples for each
Planar - sternoclavicular, intercarpal, vertebral facet
Hinge - knee, ankle
Pivot - proximal radioulnar, atlantoaxial
Condyloid/ellipsoidal - MCP, radiocarpal, atlantooccipital
Saddle - CMC
Ball and socket - hip, shoulder
Describe planar joint
Articulating surfaces are flat/slightly curved
Uni axial
Describe hinge joint
Convex surface of one bone fits into concave surface of another
Uni axial
Describe pivot joint
Rounded surface of one bone articulate within a ring formed by:
Concavity of another bone
Fibrous ligament
Uni axial
Describe Condyloid joint
Oval shaped condyle rests on elliptical cavity of another
Biaxial
Describe saddle joint
One bone is concavoconvex (saddle) and the other bone resembles legs of rider
Biaxial
Describe ball and socket joint
Ball like surface of one bone fits into cup-like structure of another
Multi axial
Describe cracking synovial joints
Bones pulled apart at joint so synovial cavity expands
Synovial volume is constant so partial vacuum produced
Gases dissolved in fluid are pulled out of solution making a popping sound
How does aging affect synovial joints
Articular cartilage thins
Ligaments shorten
Decreased flexibility
Decreased production of synovial fluid
Describe Paget’s disease
Increased bone turnover (especially spine and pelvis)
New bone is weaker, less compact and more vascular
Bone pain which is worse lying down
What is arthritis
What is the most common type
Inflammation and stiffness of a joint
Osteoarthritis
Describe rheumatoid arthritis
Autoimmune disorder where rheumatoid factor attacks the synovium causing synovial inflammation
Women affect 2-3x more than men
X-ray features of RA
Narrow joint space Periarticular osteopenia (decreased bone mineral density at joint) Bony erosions near joint Subluxation Gross deformity
What does RA mainly affect
MCP joints Cervical spine Feet Eyes Skin Lungs Heart BVs Kidneys Blood
What local factors affect bone healing
Type of injury (soft tissue)
Type of bone (cortical takes longer)
Treatment - reduction, stabilised by plaster, infection
What regional factors affect bone healing
Blood supply
Muscle cover
What systemic features affect bone healing
Age
Comorbities - e.g cardiac disease reduces blood supply
Bone pathology
Head injury (heals well)
What is malunion
Fracture heals but in wrong position
Causes of malunion
Deformity
Late arthrosis
What’s non-Union
Fracture doesn’t heal
Causes of non-Union
Hypertrophic - bones moving
Atrophic - poor bone quality or blood supply
Local early fracture complications
Neurovascular injury
Compartment syndrome
Avascular necrosis
Infection
Systemic early fracture complications
Hypovolaemia Fat embolism Thromboembolism Acute respiratory distress syndrome Disseminated intravascular coagulation
Local late fracture complications
Delayed Union Non-Union Malunion Myositis ossificans Refracture
Regional late fracture complications
Osteoporosis
Osteoarthrosis
Joint stiffness
Overreaction of SNS leading to increased blood supply and chronic regional pain syndrome
Predispositions to stress fractures
Osteoporosis
Sports
Eating disorders
Diagnosis of osteoporosis
DEXA scan assesses bone mineral density
What are T and Z scores
T is number of SD below mean for sex and race matched with young healthy adult population
Z is number of SD below mean for age, sex and race matched with young healthy adult population
Risk factors for type 2 osteoporosis
Age
Hyperparathyroidism
Ca deficiency
Affects men and women equally
What is type 1 osteoporosis
Affects post menopausal women
Treatment for osteoporosis
Bisphosphonates inactivate osteoclasts:
Decrease bone turnover
Increase bone mineralisation
What is OA
Disorder of synovial joints mostly affecting articular cartilage resulting in decreased joint space
There is sclerosis and formation of osteophytes and bone cysts
There can be mild synovitis
Clinical features of OA
Pain
Stiffness
Deformity
Joint swelling
Treatment for OA
Weight loss
Physiotherapy
Analgesia/NSAIDs
Joint injection
Arthroscopy (endoscope inserted into joint - minimally invasive)
Osteotomies
Arthrodesis (induction of joint ossification)
Arthroplasty (surgical restoration of joint function)
Local complications of hip replacement
Leg length inequality Dislocation Infection Loosening Neurovascular damage
Systemic complications of hip replacements
UTIs
DVT
Pulmonary embolism
Mortality
