Bone Remodelling
Normal Bone remodelling system
Osteoporosis
Key Players
Osteoclasts: Resposible for bone resorption
Osteoblasts: Resposible for synthesis and mineralization of bone
Osteocytes: Bone cells formed with osteoblasts become embedded in matrix
Remodelling Process
Resting Stage -> Resorption -> Reversal phase with osteoblasts -> Formation -> remodelling complete
Definition
Characterized by compromised bone strength leading to enhance bone fragility and increase risk in fracture
Tests for Osteoporosis
low eight (<51 kg), tooth count <20, rib-pelvis <2 finger breadths, wall-occiput distance >0 cm, humped back
Dexa can measure bone mineral density
Risk factors
Previous fracture, glucocorticoids, >2 falls iin last year, fractured him, low BMI, smoking, alcohol, vertebral fracture
Indications for testing
70 years of age, 65-69 with 1 risk factor, 50-64 with previous fracture or >2 risk fractures
Previous hip/spine fracutre, >2 fracture events
BMD test Interpretation
T score # of SDs from average person at peak bone mass
Z score: # of SDs compared to average person of same gender, age, race
Diagnostic Critea
Normal: T score >-1
Osteopenia: T score between -1 and -2.5
Osteroporotos T score <-2.5
Severe Osteoporosis: T score <-2.5 with Hx of fragility fractures
Types
Priamry Osteoporosis
Type 1: Loss of trabecular bone
Type 2: Predominantly cortical bone loss
Secondary Osteoporosis
Specific clinical disorders that cause low bone mineal ensity
Idiopathic juvenille osteoporosis
Transient that affects previously healthy 87-14 year olds
Tests
Calcium, albumin, CBC, creatinine, ALP, TSH, SPEP, 25-OH
Fracture Risk Assessment
CAROC
Age, Sex, Femoral neck T-Score
Increase to higher category if: Fragility fracture after 40 or >3 mos of high dose glucocorticoid
FRAX
2nd osteoporosis
Type 1 diabetes, untreated hyperthyroidism, hypogonadism, chornic malnutrition, malabsotrption, chronic liver disease
Typical Osteoporotic Fractures
Clkinical vertebral fractures, hip fracture, wrist fractures, proximal humerus fracture
Pharmacotherapy
Indications
Suggest: 10 yr fracture risk 15-19.99%, T score <2.5 and age <70, and if not started reassess in 5 year if 10 year fracture is 10-15 or in 3 year if >15%
Recommend if: Previous hip/spine fracture, >2 fracture events, 10 yre fracture risk >20, T score <2.5 and >70
Biphosphonates
Common 1st line treatment which inhibits osteocalsts
Pros: reduces fracture, increased benefit/safety
Cons: Esophagitis, soteonecrosis, atypical subtrochanteric fractures
Rank Ligand inhibitor (Denosumab)
Pros: Reduces fracture vertebral and non-vertebral fractures
Cons: osteonecrosis, atypical subtrochanteric fracture,s rebound bone lsos
Selective Esttrogen Receptor Modulator
Pros: Decrease in Breast cancer
Cons: Increase in hot flashes,. thromboembolic disease, and no evidence in reduction in non-vertebral fractures
Hormone Replacement therapy
Pro: Decrease osteoblastic activity, increases bone density, treat symtpoms of estrogen deficiency
Cons: Increase CVD and PE risk, increase breast cnacer risk, adverse effect on cognition