Bone Clinical Conditions Flashcards
osteoporosis - defined
*decrease in bone mineral density or mass, resulting in decrease in bone strength and increased risk of fractures
*1 in 2 postmenopausal women will have a fracture; mortality 1 year after hip fracture ~20%
osteoporotic (fragility) fracture - defined
*fractures occurring in a setting of low-level or low-energy trauma, defined as falling from standing height or less
*hip, vertebral, forearm are most common
*pts with hip and vertebral fractures often never regain the same level of function, can lose independence, and can experience chronic pain (esp. with vertebral fractures)
pathogenesis of osteoporosis
*most common factor contributing to osteoporosis = estrogen deficiency
*other factors include: medications (STEROIDS), hyperparathyroidism, hyperthyroidism, tobacco/alcohol, no weight-bearing activity
note - peak bone mass is achieved around age 30 (due to nutrition, exercise, environment, and lifestyle factors)
osteoporosis - diagnosis/screening
*dx can be made based on imaging or clinical presentation (pt sustaining a fragility fracture)
*screening recommended for postmenopausal women > 65yo, or if postmenopausal with other risk factors
*DEXA scan is best imaging modality for diagnosis/screening
screening for osteoporosis: DEXA scan
*DEXA = dual energy x-ray absorptiometry, aka “bone density scan”
*reports T-scores at the lumbar spine, total hip, and femoral neck
*T-score: where you lie within the standard deviation of bone density for young, healthy patients of same gender
*Z-score: where you lie within the standard deviation of age-matched patients of the same gender
*osteopenia (low bone density) = T score: -1.0 to -2.5
*osteoporosis (porous bone that can lead to fractures) = T score: < -2.5
osteoporosis - treatment (general)
*goal = not to fracture
1. lifestyle modifications:
-vitamin D and calcium through diet/supplements
-weight bearing exercise: causes microfractures that then repair stronger
-balance training: PT trained in fall prevention/osteoporosis
-safe practices: remove slippery rugs, avoid high pile carpet, hand rails, nightlights, walker or cane if necessary, no dogs
2. pharmacotherapy
osteoporosis - pharmacotherapy (general)
- anti-resorptives: stop bone loss, freeze bones where they’re at
ex: bisphosphonates, RANK ligand inhibitors - anabolics: promote bone building
ex: PTH analogues - other: estrogen replacement, selective estrogen receptor modifiers
bisphosphonates - drug class, MOA, examples, uses
*drug class: anti-resorptive (prevent bone loss)
*MOA: bind to hydroxyapatite in the bone; inhibit osteoclasts from attaching to bone and from secreting protons; ultimately leads to apoptosis
*ex: aledronate, risedronate, zoledronate
*used for treatment of osteoporosis
RANK ligand inhibitor: denosumab - drug class, MOA, examples, uses
*drug class: anti-resorptive (prevent bone loss)
*MOA: binds to RANK-L (mimics osteoprotegerin)
*ex: denosumab
*used for treatment of osteoporosis
anti-resorptives for osteoporosis - ADEs
*prolonged use can result in ADEs:
-osteonecrosis of the jaw following dental procedures
-atypical femur fractures
-esophagitis (oral bisphosphonates)
recall: bisphosphonates (“-dronates”) and RANK-L inhibitors are examples of anti-resorptives
PTH analogues - drug class, MOA, examples, uses, ADEs
*drug class: anabolic agents (promote bone building)
*MOA: when bone is exposed to PTH in a pulsatile fashion, it can increase osteoblast activity
*ex: teriparatide, abaloparatide
*used for treatment of osteoporosis
*ADEs: orthostatic hypotension, transient hypercalcemia
osteoporosis vs. osteomalacia/rickets
1. osteoporosis = not enough bone; matrix and mass are lost but there is still mineralization
2. osteomalacia = undermineralized bone matrix; matrix is maintained but there is not enough mineralization
*both have low bone mineral density on DEXA but underlying cause (and treatment) differs
osteomalacia/rickets - defined
*defective mineralization of osteoid (osteomalacia) or cartilaginous growth plates (rickets, only in children)
*most commonly due to vitamin D deficiency; other causes include:
-X linked hypophosphatemia
-hypophosphatasia
note - osteomalacia is referred to as rickets in children; it is more severe; associated with bone deformity
rickets - physical exam findings
*pathologic bow legs (genu varum)
*beadlike costochondral junctions / swelling of rib cage at costochondral junctions (rachitic rosary)
*craniotabes (soft skull)
risk factors for vitamin D deficiency
*lack of sun exposure - dark skin, climate
*premature baby - not enough Vit D from mother
*mother with severe Vit D deficiency during pregnancy
*exclusive breastfeeding without supplementation (breast milk does not contain enough Vit D)
