bones and joints pathology Flashcards
What is normal bone?
Outer solid cortical bone
Inner trabecular bone
Outer surface- periosteum
Inner space (medulla)- contains fat/haemopoietic marrow
What is bone for?
Mineral homeostasis- reservoir of calcium phosphate, secreted from kidney, absorbed in gut
Houses haemopoietic system- bone marrow
Mechanical- constantly remodelled
What are bone diseases?
Infections
Tumours
Trauma/degeneration
What are bone matrix formation diseases?
Osteogenesis imperfecta
-mutations in type I collagen
- affects ears/eyes/skin/teeth also
Mucopolysaccharidoses eg. Morquio/Hurler syndromes
What are cartilage matrix formation disorders?
Achondroplasia
-autosomal dominant
-failure of cartilage maturation at growth plate
-mutation of fibroblast growth receptor 3- continually activated
What is disease of mineralisation?
Osteomalacia/rickets
-vit D/calcium deficiency
-dietary/metabolic
-failure of mineralisation of growth plate cartilage
-mature skeleton- bone fragility
What is osteoporosis?
Increased porosity of bone due to reduction in bone mass
Causes- age, hormonal influences, lifestyle, activity, genetics, nutrition
Complications- fragility fractures (vertebrae, femoral neck, instal radius), kyphosis (dowagers hump), loss of height
Tx= bisphosphonates, experimental tx (parathyroid hormone)
What is the difference between osteomalacia and osteoporosis?
Osteoporosis- bone mass is less but ratio is normal
Osteomalacia- ratio of bone mineral to bone is low
What do bisphosphonates do?
Inhibit bone resorption
What are disorders of abnormal turnover?
Paget’s disease aka osteitis deformans
Progressive deformity of individual bones- increased bone resorption and poor controlled bone formation
Genetic component
What are bone infections?
Osteomyelitis
-complication of compound fracture
-blood borne
-necrosis of bone fragments
-new bone formation
-sinuses drain pus
- Staph aureus, M. tuberculosis
- difficult to get rid of due to poor antibiotic penetration of bone
What are bone tumours?
Mostly metastases from lung, breast, prostate
Primary- mostly benign
-malignant can be chondrogenic, osteogenic and others
What are chondrogenic tumours?
60% benign
-osteochondroma (many sites)
-chondroma (mainly fingers)
40% malignant
-chondrosarcoma (femur, pelvis, skull base)
What are osteogenic tumours?
13% benign
-osteoid osteoma (any site)
-osteoblastoma (larger, spinal)
87% malignant
-osteosarcoma (mainly distal femur)
Where do malignant bone tumours usually affect?
Osteosarcoma- 15-30yrs, knee metaphyses
Chondrosarcoma- middle age/elderly, pelvis, ribs, proximal long bones
Ewing’s sarcoma- <20, diaphyses
Undifferentiated sarcoma- middle age/elderly, metaphyses
Start with chemo, then remove to reduce lung metastases
