Biochem disorders of bone Flashcards
Give examples of bisphosphonates
Alendronate
Risedronate
Etidronate
What is desunomab
Monoclonal antibody which reduces osteoclastic activity
What does strontium do?
Increases osteoblast replication and reduces resorption
What is Zoledronic acid?
Once yearly IV bisphosphpnate (but v expensive)
Risks of HRT
Inreased breast and endometrial cancer rates
DVT
Risks of Raloxifene (oestrogen receptor modulator)
DVT
Qualitive defect of bone
Osteomalacia
- due to deficient mineralisation of osteoid
- INADEQUATE AMOUNTS OF CALCIUM AND PHOSPHATE
Psuedofractures (Looser’s zones)
Osteomalacia
Patients may complain of bone pain, have deformities of soft bones, sustain pathological fractures easily and have symptoms of hypocalcemia
Osteomalacia
Low calcium
Low phosphate
High serum alk phos
Osteomalacia
Blood biochem in osteoporosis
Normal
Brown tumours
Caused by hyperparathyroidism (lytic lesions in bone)
Osteitis fibrosa cystica
Caused by hyperparathyroidism
Treatment for high serum calcium
EMERGENCY
IV fluids
Bisphosphonates
Calcitonin
Treatment of hyperparathyroidism
Removal of adenomatous glands
Treatment of underlying cause (vitamin D supplementation)
Emergency treatment for very high calcium
What is renal osteodystrophy
Typical bone changes due to CKD
(reduced phosphate excretion and inactive activation of vitamin D –> sclerosis of bones and calcification of soft tissues)
Type 1 osteoporosis
Post menopausal
Colles fracture and vertebral insufficiency fracture most likely
Type 2 osteoporosis
Osteoporosis of old age
Fracture of vertebra and femoral neck most common
Causes of hypophosphatemia
Refeeding syndrome
Alcohol excess
Principal cause of osteomalacia
Insufficienct calcium from the intestine because of lack of dietary calcium or a deficiency of or resistance to the action of vitamin D, or phosphate deficiency caused by increased renal losses
Drugs associated with poor bone quality
Long term anticonvulsant use
Treatment for pagets
Bisphosphonates (inhibit osteoclasts) or calcitonin if extensive lytic disease
Defect of which type of collagen in osteogenesis imperfecta?
Type 1
Osteogenesis imperfecta method of inheritence
Autosomal dominant
Blue sclera and loss of hearing
Osteogenesis imperfecta
Sofield procedure
Multiple osteotomies and intramedullary stabilisation for progressive deformity caused by OSTEOGENESIS IMPERFECTA
Prominent forehead widened nose
Lax joints
Normal mental development
Achondroplasia
Marfan inheritence
Autosomal dominant
Tall stature, disproportionately long limbs and ligamentous laxity
High arched paalte
Scoliosis
Pectus excavatum
Eye problems (lens dislocation, retinal detachment)
Aortic aneurysm
Cardiac valve incompetence
Marfan syndrome
Which dislocation common in Down syndrome?
Patella
Atlanto-axial instability in the C-spine
Profound joint hypermobility, vascular fragility with ease of bruising, joint instability and scoliosis
Ehlers Danlos (autosomal dominant)
Diagnosis is by raised serum creatinine phosphokinase and abnormalities on muscle biopsy
Duchenne muscular dystrophy
Hypoplastic bones
Short
If you have limb malformations caused in gestation, when would they have occurred?
between 4th and 6th week of gestation
What is syndactyly?
COMMONEST congenital malformation
-two digits are fused
(usually separated age 3/4)
Polydactyly
Extra digit
Fibular hemimelia
Absence of fibula
- leads to shortened limb
- bowing of tibia
- ankle deformity
Most common congenital fusion
Tarsal coalition
Erbs palsy
Damage to C5 and C6 during pregnancy
loss of motor innervation of the deltoid, supraspinatus, infraspinatus, biceps and brachialis
What does erbs palsy look like
Humerus is internally rotated (unopposed subscapularis)
“waiter’s tip posture”
Physiotherapy
Prognosis good
What is Klumpe’s palsy?
Lower brachial plexus palsy (C8 and T1)
Paralysis of intrinsic hand muscles +/- wrist flexors an POSSIBLE horner’s syndrome
Fingers typically flexed
(hand looks a bit like spider man but not quite)
No specific treatment
Prognosis poor
Babinski sign
UMN
Drugs which can help reduce spacticity
Baclofen
Botox
Meningocele
This is in spina bifida
–> menignocele not usually associated with neurological sequelae
Myelomeningocele
Usually has neurological deficit
Spina bifida and the feet
Can cause high arched foot!!!
A viral infection affecting motor anterior horn cells in the spinal cord or brainstem resulting in a lower motor neurone deficit
Polio
