week 26 bone lesions (metabolic (osteoporosis (Age related, post…
week 26 bone lesions
uncommon metabolic disease of the elderely. characterised by excessive uncontrolled destruction of bone by abnormally large and active osteoclasts, with concurrent inadequate attempts at haphazard new bone formation by osteoblasts, producing physically weak woven bone. unknown cause, genetic and environmental perhaps paramyxo virus.
insidious presentation with random ALP. Pain, deformity, erythema, bowing, arthralgia, warmth over the area.
chalkstick fracture, vertebral collapse, deafness, CCF (high output), osteosarcoma, osteoarthritis.
phase 1) osteolytic 2) mised lytic and blastic 3) sclerotic quiescent.
reduced physical activity
slowly progressive increase in bone erosion which is not adequately countered by new bone formation. thus the cortical bone is thinned and the bone trabeculae are thinned and reduced in number leading to general reduction in bone mass but without distortion in architecture.
Osteomalacia (and rickets )
osteoblastic production of bone is normal by calcification mineralisation is inadequate. this leads to trabecular bone which is only partly mineralised and therefore soft and weak. can be from vitamin D deficiency.
excessive secretion of PTH produces increased osteoclast activity. there is excessive destruction of cortical and trabecular bone with inadequate compensatory osteoblastic activity.
skeletal disorder associated with chronic renal failure. two important parts. osteomalacia of renal origin, lack of conversaion of 25-hydroxyvitamin D to 1-25 dihydroxyvitamin D because of tubular damage leads to less ca absorption int he gut, the htubular damage also increases PO4 which increases PHT because of low serum calcium and phosphate retention.
clinically: the bone shows a combination of changes = excessive bone erosion by osteoclasts and failure of mineralisation of osteoid collagen.
remember in haemo and peritoneal haemodyalysis. increases aluminium.
osteoid osteoma MOST COMMON
anurysmal bone cyst
Tumour like lesion
Giant cell tumour of bone
bone and cartilage
Malignant fiberous histiocytoma
bone marrow tumours
Esinophilic granuloma (tumour like lesion)
: carcinoma, melanoma, lymohoma. prostate, thyroid, breast, lung kidney.
defects in hormonal signalling
inhibition of cartilage at growth plate.
Defects in extracellular structural proteins
type 1 collages diseases.
metabolic enzymes and transporters
osteoclast differentiation or function.
osteopetrosis and osteoporosis
osteoclast dysfunction, results in stony brittle bones which fracture easily. bones lack medullar canal and hence are impaired haemoatpoetic zones.
avascular necrosis of bone
trauma/ fracture. e.g. femoral head NOF interruption to blood supply, thrombosis and/ or embolism (the bends), vessel injury (vasclitis or radiation), venous hypertension, sickle cell disease, SLE, alcohol, dyslipidaemia.
mainly subchondrial region of bone.
ischaemia, necrosis, breaks down, becomes cystic, falls apart, results in severe arthritis
coumpound or closed
comminuted, complete or incomplete.
infection and inflammation of bone, haematogenous spread, S. Aureus, TB, syphilis, biofilms,
sequestrum and involucrum.
: pain at site or diffuse, systemic features of infection, vertebrae and long bones affected.
Xray, MRI and Bonescan better. WCC, ESR and CRP
Antibiotics, surgical drainage, bone debriedment