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Ortho/Rheum Wk1
Question | Answer |
---|---|
Describe the structure of a normal long bone | Collagen matrix impregnated with calcium carbonate, calcium phosphate and osteocytes. Periosteum, compact bone (with Haversian systems), spongy bone (with trabeculae and marrow). Diaphysis, metaphyses, epiphyses. |
What vessels are found within a Haversian canal? | Vein, artery, lymphatic vessel |
Describe the process of bone remodelling | Osteoclasts resorb old bone, osteoblasts secrete a surrounding collagen matrix which is then mineralised. A surrounded osteoblast is an osteocyte. |
What is osteoid? | The collagen matrix of bone |
How might osteoporosis present? | Fracture, kyphosis due to vertebral collapse |
Describe the presentation of Paget's disease | Pain at site (usually pelvis, lumbar spine, femur), hearing loss due to VIIIth nerve compression, tibial bowing, abnormal modelling, eczematous nipple |
How may multiple myeloma present? | Bone pain, pathelogical fracture, lassitude, pyogenic infection, amyloidosis, bleeding |
What are the laboratory findings associated with osteoporosis? | DEXA scan. Ca, phos, and alk phos normal. |
What do investigations show in Paget's disease? | ^ALP, normal Ca, x-rays show expansion, deformity, and osteolytic and sclerotic areas |
How do investigations suggest multiple myeloma? | ^ESR, (^urea, creatinine, urate, and Ca in 40%), bone biopsy, urine contains Bence-Jones protein, x-rays show lytic lesions |
List the bone imaging techniques | Plain film, nuclear medicine, ultrasound, CT, MRI |
Describe the pros and cons of plain film | Cheap, available, easy, quick, transportable BUT radiation, limited contrast (insensitivity to early pathology and soft tissue) |
Describe the pros and cons of nuclear medicine | Physiological, sensitive to early pathology, covers whole body BUT radiation, limited spatial resolution |
Describe the pros and cons of ultrasound | No radiation, cheap, portable, available, soft tissue detail BUT can't see through bone, user dependent |
Describe the pros and cons of CT | Exquisite bone detail, multiple planes BUT very high radiation, limited soft tissue contrast |
Describe the pros and cons of MRI | Exquisite soft tissue detail, multiple planes, no radiation BUT not widely available, expensive, claustrophobic, pacemaker hazard |
Describe the pharmacology of NSAIDs | Inhibit COX enzymes which control formation of prostaglandins (inflammatory mediators) |
Describe and explain the side-effects of NSAIDs | Peptic ulceration (irritation of mucosa, lack of prostaglandin protection), worsens renal impairement causing salt + fluid retention, hypertension (lack of PG mediation in haemodynamics) |
How do patients with osteomalacia present? | Bone pain, fracture (often NoF), waddling gait (proximal myopathy) |
What would investigations show in osteomalacia? | Mildly lowered Ca, phos, vit D; ^alk phos |
How does bone infection present? | Pain, reluctance to move, may be swelling, heat, oedema over pus formation in later stages |
What are the common causative agents in bone infection? | Staph aureus, pseudomonas, E. coli, M. tuberculosis |