Bone Flashcards
which Bone Cells are of the macrophage family?
osteoclasts
what. is the process allowing bone resorption?
osteoblasts with RANK-L bind to RANK on surface of osteoclast precursors
osteoblasts also release macrophage colony-stimulating factor (M-CSF) which binds to MCSF receptor. on surface of osteoclasts p
these 2 together induce activation into osteoclasts
what is the process stopping bone resorption?
stromal cells / osteoblasts release Osteoprotegrin
OPG acts as a “decoy” receptor for RANKL, preventing it from binding the RANK receptor
Consequently, OPG prevents bone resorption by inhibiting osteoclast differentiation.
what is the downstream factor activated by RANK-RANK-L. binding?
NFKB
90% cases of osteoporosis is due to ??
insufficient Ca intake and post-menopausal oestrogen deficiency
what are the mechanisms. of. Glucocorticoid-Induced Bone Disease ?
excess steroids can lead to osteonecrosis and fractures through;
- Osteocytes - increased apoptosis
- Osteoblasts - less made = less bone formed
- Osteoclasts - less made, but temporary increased in bone breakdown
how. does. Osteoporosis typically present?
back pain and #
> 60% vertebral # are asymptomatic
compression sx
what are the 2 types of osteomalacia?
- Deficiency of vitamin D
2. Deficiency of PO4
Looser’s zone fracturesare seen in?
osteomalacia
what are the sx of Hyperparathyroidism?
Stones (Ca oxalate renal stones)
Bones (osteitis fibrosa cystica*, bone resorption)
Abdominal groans (acute pancreatitis)
Psychic moans (psychosis & depression)
- Browns tumours - fibrovascular tissue and giant cells with abundant deposits hemorrhage and hemosiderin.
what does Renal Osteodystrophy involve?
Comprises all the skeletal changes of chronic renal disease
name. a disorder of bone turnover?
Pagets disease
what is the aetiology of Pagets disease?
Familial cases show autosomal pattern of inheritance with incomplete penetrance (mutation 5q35-qter - sequestosome 1 gene)
what is the. presentation of pagets?
pain
microfractures
nerve compression (incl. Spinal N and cord)
+/- haemodynamic changes, cardiac failure
Development of sarcoma in area of involvement 1%
what are the histological features of pagets?
cortex - thickened
trabeculae - coarse, irregular, thick
what are the stages of fracture repair?
- Organisation of haematoma at # site (pro-callus)
- Formation of fibrocartilaginous callus
- Mineralisation of fibrocartilaginous callus
- Remodelling of bone along weight-bearing lines
what are the presenting sx of osteomyelitis?
General - malaise, fever , chills , leucocytosis
Local - pain, swelling and redness
what are. common sites for osteomyelitis?
Vertebrae
Jaw (2º to dental abscess)
Toe (2º to diabetic skin ulcer) (>3mm)
Long bones (usually metaphysis)
how might we ivx osteomyelitis?
60% positive blood cultures
X-ray - mixed picture; eventually lytic
what is the most common organism in osteomyelitis?
Staph Aureus(90%)
name some xray changes for osteomyelitis?
exam purpose only
Usually appear 10 days or so post onset
Mottled rarefaction and lifting of periosteum
>1week - irregular sub-periosteal new bone formation called involucrum
Later - irregular lytic destruction (takes 10-14days)
Some areas of necrotic cortex may become detached called sequestra (takes 3-6 weeks)
psoas abscess and severe skeletal deformity (Pott’s disease) may present in the skeletal manifestation of which condition?
Tuberculosis
TB Osteomyelitis
since osteomyelitis only means infection n inflammation of bone
list some rarer causes of Osteomyelitis?
TB
Syphilis
name the most prevalent vector bone disease
Lyme disease
