53: Stress Fractures - Feilmeier Flashcards
define stress fracture
Any fracture or microfracture that occurs as the result of repetitive cyclic insults rather than by one traumatic event (load failure).
pathophysiology of stress fracture
- Increase in osteoclastic activity and micro-fractures of trabecular bone
- Onset of fracture is a function of the amount and duration of stress occurring versus the degree that a bone is able to repair itself
- Day 21 periosteal new bone formation [compensatory reaction to resorption. the body trying to prevent fracture under the stressful environment
fatigue fracture
- Occurs in normal bone when increased stress occurs
- most common
insufficiency/fragility fracture
Occurs in abnormal bone weakened by an underlying disease or condition (arthropathy, metabolic bone disease, osteoporosis), without increase in stress needed
pathologic fracture
Occurs in bone invaded by a tumor/other disease process (ie, aneurysmal bone cyst, osteomyelitis
intrinsic factors etiology
- foot type
- prolong NWB leading to decrease in bone density
- bone mineral density (vit D)
- estrogen/hormone levels (a decline in estrogen triggers an osteoclast production explosion which increases bone turnover and the amount of remodeling)
- decreased testosterone in men
- gender
cavus foot area of fracture
5th met more likely
most common met stress fractured
2nd met
extrinsic etiology factors
- overuse - repeated stress of foot striking the ground (distance running)
- training regimen
- change in surface
- no inciting incident or trauma
- nutritional status/diet
- medications
who is at risk for stress fxs?
- women
- dancers on point
- military recruits
- runners
- chronic medical conditions (RA, metabolic bone disease, neuropathic conditions, diabetes)
female athletic triad ***
- eating disorder
- irregular menstrual cycle
- osteoporosis
what role does estrogen play?
- Estrogen is responsible for suppression of osteoclasts and for keeping osteoblasts alive.
- Decline in estrogen triggers osteoclast production which causes increased bone turnover
most common stress fracture in runners ***
tibia
then tarsals, metatarsals
best independent predictors of stress fracture in women
- smaller calf girth
- age at menarche
dancers on pointe get stress fractues …
base of 2nd met
severly and repetitively hyperplantarflexes the 2nd met base - locks it into position with cuneiform articulation
why might the 5th met (BASE) be injured in stress fracture?
- cavovarus
- limited hindfoot eversion
- metatarsus adductus
- flat foot with metatarsus adductus or prominent 5th met base
where and why stress fx of the navicular?
- Central 1/3rd most common area due to vascular supply
- Shear forces from 1st and 2nd met
- Pressure from talus
- Explosive activities
- Treatment- NWB 6 wks (Grade B)
- Many more likely to consider surgery with screw placement with or without bone grafting (Grade B)
N spot
Small area approximately the size of a nickel
Test sensitivity: 81% in stress fractures
Dorsal tenderness over navicular
which sesamoid is more likely to have stress fx
tibial (b/c largest and rotation causes increased pressure)
s/s fracture
- pain typically very well localized
- Develops gradually, increases with weight-bearing activity, and diminishes with rest
- Pain progressively becomes more severe and occurs during normal, daily activities and then even at rest
- focal swelling
- erythema/rubor
- possible bruising
- recollection of specific traumatic event unlikely
- usually involved in frequent, repetitive work or exercise activities
calcaneal stress fx v PHP
side to side compression/squeeze test for calcaneus on posterior body
pressure to __ of the met will produce
top
if x-ray inconclusive but symptoms are suspicious for stress fracture ..
Bone scan utilizing Te99-MDP
Can be positive within first 24 hours of fracture-highly sensitive, but not specific.
CT scan and MRI can be utilized to help verify extent of fracture seen on bone scan, or help distinguish fracture from infection.
fracture related to weak bone (osteod and mineral less)
fragility/insufficiency fracture
Most common in the metaphyseal areas
Loss of transverse trabecula
History of fragility fracture is more predictive of future fracture than bone density testing
9.5 fold increase risk of second fracture
Hip Ankle** Humerus Radius Vertebral compression
DXA scan is …
measure of bone mineral density
FRAX can help you decide to treat or not by giving risk (treat is 10 yr hip risk greater than 3% of any major fracture risk greater than 20%)
treatment for stress fracture
- rest and cessatiion (reverse destructive phase)
- use of devices
- limit activity 3-4 wks (longer for navicular)
