(msk) management of common orthopaedic conditions Flashcards
name the four types of bone cells
osteogenic cells
osteoblasts
osteoclasts
osteocytes
what are osteogenic cells?
bone ‘stem cells’
what are osteoblasts?
bone-forming cells
- secrete osteoid
- catalyse the mineralisation of osteoid
- become trapped in the mineralised bone matrix
what are osteoclasts?
bone-breaking cells
- dissolve and resorb bone via phagocytosis
- derived from bone marrow
what are osteocytes?
mature bone cells
- form when osteoblasts get trapped in their osteoid secretions and bone mineral matrix
- detect mechanical strain & coordinate osteoblast and osteoclast activity
what do osteocytes do?
- detect mechanical strain
- coordinate osteoblast and osteoclast activity
where are osteoclasts derived from?
bone marrow
unlike other bone cells which come from osteogenic cells
what are the types of bone?
first:
1) weak woven (made first, immature)
2) strong lamellar (replaces woven bone after mineralisation)
second: types of lamellar
1) cortical = compact/dense, useful for weight-bearing
2) cancellous/trabecular = spongy/honeycomb like, not for weight-bearing
describe the structure of cortical bone
made up of osteons
one osteon =
1) Haversian canal of blood vessels, nerves and lymphatics are surrounded by concentric lamallae
2) osteocytes are embedded in the lacunae of the lamellae
3) tiny canaliculi radiate from the lacunae + are filled with ECF to allow movement and migration
4) Volkman’s canal are perpendicular canals formed to connect adjacent Haversian canals
what do Haversian canals contain?
blood vessels, nerves and lymphatics
what are the lacunae of cortical bone?
osteocytes are embedded in the lacunae of the lamellae
what are the tiny canaliculi of cortical bone?
adiate from the lacunae + are filled with ECF to allow movement and migration
what are Volkman’s canals?
perpendicular canals formed to connect adjacent Haversian canals
describe the structure of long bones
1) periosteum = connective tissue covering
2) articular cartilage = on the surface of bone at a joint only
3) outer cortex = compact bone
4) cancellous/spongy bone = ends of long bones (red bone marrow)
5) medullary cavity =contains yellow bone marrow
6) nutrient artery
what are the functions of bone?
support
protection = surrounds major internal organs and vasculature
locomotion = joints to allow flexibility
haematopoiesis = red bone marrow
lipid and mineral storage = adipose tissue in yellow bone marrow & calcium in hydroxyapatite crystals
what are the three mechanisms of bone fracture?
trauma (low or high energy)
stress (abnormal stress on normal bone)
pathological (normal stress on abnormal bone)
what are some possible causes of pathological fractures?
osteoporosis
malignancy (primary or bone mets)
vitamin D deficiency (osteomalacia or rickets)
osteomyelitis
osteogenesis imperfecta
Paget’s
what are open and closed fractures?
open = fractured bone has pierced skin
closed = fractured bone has not pierced skin
what are the local complications of fractures?
urgent
- nerve injury
- vascular injury
- local visceral injury
- compartment syndrome
less urgent
- ligament or tendon injury
late
- non-union
- malunion
- delayed union
- avascular necrosis
what are the three types of joints?
fibrous
cartilagenous
synovial
what are the three types of fibrous joints?
sutures
syndesmosis
interosseous membrane
what are fibrous joints classified as?
synarthroses (allow no movement at the joints)
what are the two types of cartilaginous joints?
synchondroses (e.g. spine) = hyaline cartilage
symphyses (e.g. pubic symphysis) = fibrocartilage
what are cartilaginous joints classified as?
amphiarthrosis (allow limited movement at the joints)
what are the types of synovial joints?
plane pivot hinge condyloid saddle ball & socket
what are synovial joints classified as?
diarthrosis (allow free movement at the joints)
how are synovial joints stabilised?
muscles/tendons
ligaments
bone surface congruity
what are the two components of cartilage?
1) chondrocytes
2) extracellular matrix (water, collagen, proteoglycans)
what is the main proteoglycan present in cartilage?
Aggrecan
what is the blood supply to the cartilage?
cartilage is avascular - it has no blood supply!
describe the structure and function of Aggrecan
made up of many chondroitin sulphate and keratin sulphate chains
= can interact with hyaluronan to form proteoglycan aggregates
what is osteoarthritis?
chronic degradation of articular, chondral cartilage in joint
= bones rubbing together increases friction, creating stiffness, pain, and impaired movement
name the inflammatory mediators involved in osteoarthritis
1) proteinases
- matrix metalloproteinases (MMPs)
- aggrecanase
2) inflammatory cytokines
- TNFa
- IL-1B
name the inflammatory cytokines involved in osteoarthritis
interleukin (IL)-1β
tumor necrosis factor α (TNFα
what is the function of inflammatory cytokines in osteoarthritis?
enhance the synthesis of proteinases and other catabolic factors to degrade the articular cartilage membrane
how does the cartilage appear in early stage and late stage osteoarthritis?
early stage = cartilage oedema
late stage = cartilage damage and loss
what are the risk factors for osteoporosis?
age
hereditary
female gender
excess weight/obesity osteonecrosis mechanical constraints joint injury metabolic disease infectious disease
when do you get pain associated with osteoarthritis?
- exertional
- at rest (joint stiffness can occur, made better on movement)
- at night
what causes osteoarthritis?
mainly joint injury
maybe infection
is osteoarthritis a monoarthritis or a polyarthritis?
develops in a singular joint at first BUT involves other joints as disease progresses
how is osteoarthritis assessed?
look
feel (sweep test)
move (flexion, extension)
special tests (anterior/posterior draw, Lachmann’s)
what key radiographic changes occur in osteoarthritis?
joint space narrowing
osteophytes (bone growths)
subchondral cysts
subchondral sclerosis
how is osteoarthritis managed conservatively?
analgesics
physiotherapy
walking aids
avoidance of exacerbating activity
injections (steroid/viscosupplementation)
= PAWAIN
how is osteoarthritis managed operatively?
replace (knee/hip)
realign (knee/big toe)
excise (toe)
fuse (big toe)
synovectomy (rheumatoid)
denervate (wrist)
what is the term used to describe infection of bone?
osteomyelitis
what is the term used to describe infection of joint?
septic arthritis
how does osteomyelitis present compared to septic arthritis?
osteomyelitis = pain, swelling, discharge, fever, sweats, weight loss
septic arthritis = joint stiffness, swelling, fever, sweats, weight loss
what causes septic arthritis?
bacterial infection of a joint (usually caused by spread from the blood)
what are the risk factors for septic arthritis?
immunosuppressed
pre-existing joint damage
intravenous drug use (IVDU)
what are the long-term effects of septic arthritis?
septic arthritis is a medical emergency!
untreated, septic arthritis can rapidly destroy a joint
how many joints does septic arthritis affect?
monoarthritis usually
how is septic arthritis diagnosed?
joint aspiration
send sample for gram stain, C&S
what are the most common causative organisms for septic arthritis?
Staphylococcus aureus
Streptococci
Gonococcus
how is septic arthritis treated?
intravenous antibiotics
joint lavage
(immobilise joint in acute phase, physiotherapy following acute phase)
what is different about gonococcal septic arthritis?
often affects multiple joints (polyarthritis)
= less likely to cause joint destruction
which investigations are commonly done for septic arthritis?
investigations = plain film, MRI, CT, bone scan
bloods = CRP, ESR, WBCC, TB culture/PCR (detects bacterial DNA in joint)
how is osteomyelitis treated?
intravenous antibiotics
surgical drainage
removal of diseased bone = possible amputation
what shoulder conditions occur most commonly in 15-45 year olds?
dislocations
fractures
what shoulder conditions occur most commonly in 45-60 year olds?
dislocation fractures ACJ osteoarthritis rotator cuff tears impingement
what shoulder conditions occur most commonly in >60 year olds?
fractures
glenohumeral osteoarthritis
rotator cuff tears
impingement
what hip conditions occur most commonly in 15-45 year olds?
developmental dysplasia
leg length discrepancy
impingement
what hip conditions occur most commonly in 45-60 year olds?
osteoarthritis
avascular necrosis
impingement
what hip conditions occur most commonly in >60 year olds?
osteoarthritis
total hip replacement
what knee conditions occur most commonly in 15-45 year olds?
patellofemoral maltracking
ACL/PCL
meniscal tears
fractures
what knee conditions occur most commonly in 45-60 year olds?
osteoarthritis patellofemoral maltracking ACL/PCL meniscal tears fractures
what knee conditions occur most commonly in >60 year olds?
osteoarthritis
