53: Stress Fractures - Feilmeier

Question 1

define stress fracture

Answer 1

Any fracture or microfracture that occurs as the result of repetitive cyclic insults rather than by one traumatic event (load failure).

Question 2

pathophysiology of stress fracture

Answer 2

• 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

Question 3

fatigue fracture

Answer 3

• Occurs in normal bone when increased stress occurs

- most common

Question 4

insufficiency/fragility fracture

Answer 4

Occurs in abnormal bone weakened by an underlying disease or condition (arthropathy, metabolic bone disease, osteoporosis), without increase in stress needed

Question 5

pathologic fracture

Answer 5

Occurs in bone invaded by a tumor/other disease process (ie, aneurysmal bone cyst, osteomyelitis

Question 6

intrinsic factors etiology

Answer 6

• 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

Question 7

cavus foot area of fracture

Answer 7

5th met more likely

Question 8

most common met stress fractured

Answer 8

2nd met

Question 9

extrinsic etiology factors

Answer 9

• overuse - repeated stress of foot striking the ground (distance running)
• training regimen
• change in surface
• no inciting incident or trauma
• nutritional status/diet
• medications

Question 10

who is at risk for stress fxs?

Answer 10

• women
• dancers on point
• military recruits
• runners
• chronic medical conditions (RA, metabolic bone disease, neuropathic conditions, diabetes)

Question 11

female athletic triad ***

Answer 11

• eating disorder
• irregular menstrual cycle
• osteoporosis

Question 12

what role does estrogen play?

Answer 12

• Estrogen is responsible for suppression of osteoclasts and for keeping osteoblasts alive.
• Decline in estrogen triggers osteoclast production which causes increased bone turnover

Question 13

most common stress fracture in runners ***

Answer 13

tibia

then tarsals, metatarsals

Question 14

best independent predictors of stress fracture in women

Answer 14

• smaller calf girth

- age at menarche

Question 15

dancers on pointe get stress fractues …

Answer 15

base of 2nd met

severly and repetitively hyperplantarflexes the 2nd met base - locks it into position with cuneiform articulation

Question 16

why might the 5th met (BASE) be injured in stress fracture?

Answer 16

• cavovarus
• limited hindfoot eversion
• metatarsus adductus
• flat foot with metatarsus adductus or prominent 5th met base

Question 17

where and why stress fx of the navicular?

Answer 17

• 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)

Question 18

N spot

Answer 18

Small area approximately the size of a nickel
Test sensitivity: 81% in stress fractures

Dorsal tenderness over navicular

Question 19

which sesamoid is more likely to have stress fx

Answer 19

tibial (b/c largest and rotation causes increased pressure)

Question 20

s/s fracture

Answer 20

• 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

Question 21

calcaneal stress fx v PHP

Answer 21

side to side compression/squeeze test for calcaneus on posterior body

Question 22

pressure to __ of the met will produce

Answer 22

top

Question 23

if x-ray inconclusive but symptoms are suspicious for stress fracture ..

Answer 23

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.

Question 24

fracture related to weak bone (osteod and mineral less)

Answer 24

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

Question 25

DXA scan is …

Answer 25

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%)

Question 26

treatment for stress fracture

Answer 26

• rest and cessatiion (reverse destructive phase)
• use of devices
• limit activity 3-4 wks (longer for navicular)