Classic Tibial Stress Fracture

Transcription

Classic Tibial Stress Fracture
Karl B. Fields, MD
Moses H Cone Sports Medicine
Fellowship
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A stress fracture is an overuse injury resulting
in structural damage to bone from repetitive
weight bearing or increasing stressful muscular
activity too quickly
Stress fractures should be differentiated from
insufficiency fractures which are bone injury in
weakened bone from normal activity
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Olympic victors are those who did not
squander their powers by early and over
training. Aristotle 200 BC
Identified by Breithaupt in Prussian soldiers
in 1855
1897 first x-rays of metatarsal stress
fractures
1958 Devas associates these injuries with
athletes
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Prospective trial of collegiate athletes showed
6.9% F and 2%M over 2 years
Rates in intense training reported much higher
in 20% to 30% range for 1 year
Military recruits range from 1 to 5% in basic
training of 8 to 14 weeks with much higher
rates in special forces and groups who train >
15 hours per week
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White males and females have 2.3 relative
risk of stress fracture versus blacks
relative risk in women ranges from 1.3 to 3.5
times as high as men
Previous Stress fracture > 5x higher rate
Low BMD (each SD decrease, 2x higher rate)
– based on prospective trial AJSM
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Now most common site in men
primary sports are distance running,
basketball, soccer and ballet
Sxs of MTSS that localize
Differential Dx includes MTSS, compartment
syndrome, muscular strains
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Localized tenderness that usually starts along
posterior medial border of tibia
Most commonly at junction of distal and
medial third of tibia but can be anywhere
localized swelling
+ hop test
+ tuning fork
Video of Fracture Site
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Distal third of tibia and medial third along
medial and posterior border heal well
Anterior tibia - middle third classic problems
with “dreaded black line”
Complicated healing high tibia/ anterior tibia,
tibial plateau
Adolescents more typically have injury to the
proximal metaphysis
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RICE
long air splints and padded lower extremity
appliances – Cochrane rates these as speeding
healing by ~ 42 days
No medications have proven benefit although
calcium and Vit D did lessen risk preventively
in studies of naval recruits
Substituted training schedules and cross
training
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Proximal 1/3 : 43% one to two mos; 57% >
2mos.
Middle 1/3 : 48% one to two mos.; 52% > 2
mos.
Distal 1/3 : 53% one to two mos. ; 47% > 2 mos.
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“Dreaded anterior black line”
Higher grade stress fractures that extend across
more than 50% of diameter
Tibial plateau
Medial Malleolus
Individuals with significant anatomical or
biomechanical problems
Medial Malleolus
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21 year old hurdler
History of metatarsal stress fracture last season
Insidious onset of pain left tibia since this fall,
now with pain with every step, night pain
Thought this was “shin splints”
Nl periods, wt, eating habits
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Probably most common stress fracture in
women
2nd, 3rd and 4th metatarsals all common
First and fifth metatarsals are uncommon stress
fractures and often difficult to heal
Standard Xrays are of limited value
MSK US may emerge as preferred dx test
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Avulsion fractures are not typically stress
fractures
Jones fractures generally heal faster with
pinning
Stress fracture is in the diaphysis and not in the
articulation
These can be treated conservatively
Trend has been to pin these as well
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Scaphoid
Navicular
Femoral Neck
Pars intra-articularis
Talar Dome
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Usually present with groin pain
Commonly missed for several months and
considered groin strains
Differential diagnosis includes AVN, SCFE,
DJD, Idiopathic Osteoporosis of the Hip
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Back pain in adolescents is usually organic in
nature
These commonly occur in several sports in
which back extension is repetitive
One leg hyperextension test – “flamingo”
Bilateral stress fractures can slip and lead to
spondylolithesis
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Often are “ankle sprains” that will not heal or
result in persistent pain
OCD lesions can occur and may require
arthroscopy to remove
Healing may not take place without putting
ankle to rest for 6 weeks and sometimes NWB
Talar Dome Fracture Lateral Corner
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14-35% of all stress fractures
59% of Navicular fractures are in track athletes
No significant risk factors
Diagnosis averages 4 months
Delay is bad as this can cause non-union
Limitation of activity has only a 26% cure rate
Calcaneus
Talu
s
Navicu
lar
Cuneifor
ms
During foot strike, the Navicular becomes impinged, mostly in
the central 1/3, a relatively avascular area.
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Aching pain in the
dorsal midfoot
Radiates along the
medial arch
Pain increases with
activity such as
running, jumping,
hopping
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Good ROM,
strength. No
ecchymosed, or
swelling
“N spot” tender 81%
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Plain radiographs: 33%
sensitive
Even then require 10d to 3w to
show up
Triple phase bone scan: 100%
sensitive
Remains positive for 2 years
However, positive bone scans
must always be followed up
with CT or MRI due to lack of
resolution
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Non-weight bearing cast for >=6 weeks: 86%
Limitation of activity >=6 weeks: 26%
Nothin’: 20%
Operation: failure of above, if non-union or
in young if need for quick healing (3.8 mo
vs. 5.6 mo)
Always check for tenderness over the “N
spot;” any tenderness requires 2 more weeks
of non-weight bearing.
Scintigraphy is highly sensitive but not specific
 MRI detects the full range of stress injury
 Most common MRI findings:
1.Bone marrow edema(97.2%)…first evidence of
stress injuries to bone
2.Periosteal edema(88.9%)…with or after
periosteal edema on MRI, cortical rxn seen on
conventional radiograph
3. Actual fracture line(38.9%)…also strongly
suggested by endosteal edema
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Cost is a major drawback to MRI
Standard Xrays miss 30% to 50% of stress
fractures even when repeated
Bone Scans and CT are also very expensive
CT radiation exposure is a major risk
Radio-isotope issues are affecting scanning
MSK US may gain an increasing role
although radiology in USA will be very
reluctant to endorse this