Stress fractures
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Transcript Stress fractures
Kevin deWeber, MD, FAAFP, FACSM
Director, Military Sports Medicine Fellowship
USUHS/Ft. Belvoir
2011
(many slides courtesy Dave Haight, MD
Outline
Pathophysiology
Risk Factors
Associations
Diagnosis
General Treatment
Treatment of High-Risk Cases
Stress fracture
[stress frack-chur]
Break in a normal bone after it is
subjected to repeated tensile or
compressive stresses, none of which
would be large enough individually to
cause the bone to fail, in a person who
is not known to have an underlying
disease that would be expected to cause
abnormal bone fragility.
Insufficiency Fracture
[in-suh-fish-n-see frack-chur]
Fracture due to repeated compressive or
tensile stresses in a bone whose mechanical
strength is reduced due to a condition that is
present either throughout the skeleton
(osteoporosis, osteomalacia, osteogenesis
imperfecta, etc.) or in a bony region (eg,
demineralization in a limb due to disuse).
Pathologic fracture
[path-o-lah-jick frack-chur]
Fracture due to a localized loss of strength
in a bone from a disease process
immediately underlying the bone, eg, bone
tumors , bone cysts, and infections.
PREVALENCE
1% of general population get ‘em
1-8% of collegiate team athletes get ‘em
Up to 31% of military recruits get ‘em
13-52% of runners get ‘em
Most Common Sites of Stress
Fractures
Tibia - 39.5%
Metatarsals - 21.6%
Fibula - 12.2%
Navicular - 8.0%
Femur - 6.4%
Pelvis - 1.9%
OTHER – 10.4%
CAUSE
Change in load (force on the bone)
Small number of repetitions with
large load
Large number of reps, usual load
Intermediate combination of increased load and
repetition
PATHOPHYSIOLOGY
Stress fracture: imbalance between bone resorption and
formation
Wolff’s Law: change in external stress leads to change in
shape and strength of bone
bone re-models in response to stress
ABRUPT increase in duration, intensity, frequency without
adequate rest (re-modeling)
Microfracture -> continued load -> stress fracture
Review of Risk Factor Types
Intrinsic:
Gender, genetics
Anatomical malalignment/ biomechanical
Dietary
Muscle weakness/imbalance
Extrinsic
Training errors
Equipment mismatch
Technique errors
Environmental
Sports-imposed deficiencies
INTRINSIC RISK FACTORS
for Stress Fractures
History of prior stress fracture
Low level of physical fitness
Female Gender
Menstrual irregularity
Diet poor in calcium and dairy
Poor bone health
Poor biomechanics
INTRINSIC RISK FACTORS cont
Prior stress fracture:
6 x risk in distance runner and military recruits
60% of track athletes have hx of prior stress fracture
One year recurrence: 13%
Poor Physical Fitness – [muscles absorb impact]
>1 cm decrease in calf girth
Less lean mass in LE
< 7 months prior strength tng
INTRINSIC RISK FACTORS cont
Why female gender? [1.2-10x]
Higher rates of other risk factors
Poorer bone health, Menstrual irregularity, disordered
eating
Poor bone health:
Supplementing female military recruits with Ca and
Vit D reduced stress fracture incidence
Lappe J, Cullen D, Haynatzki G, et al.. J Bone Miner Res 2008
FamHx osteoporosis: 3x risk
INTRINSIC RISK FACTORS cont
BIOMECHANICAL FACTORS
Shorter duration of foot pronation
Sub-talar joint control
Tibial striking torque
Early hindfoot eversion
Pes cavus (unproven)
Pes planus (unproven)
EXTRINSIC FACTORS
Increasing volume and intensity
Footwear
Older shoes
Absence of shock absorbing inserts
Running Surface?: mixed results
Treadmill vs Track
Activity type
ACTIVITY TYPE ASSOCIATIONS
Ballet: spine, femur, metatarsal
Runners: tibia, MT
Sprinters: navicular
Long dist runner: femoral neck, pelvis
Baseball, tennis: humerus
Gymnasts: spine, foot, pelvis
Rowers, golfers: ribs
Hurdlers: patella
Rowers, Aerobics: sacrum
Bowling: pelvis
Classic Clinical History
Gradual onset of pain over weeks to months
Initially pain only with activity
“can’t run through it”
Progresses to pain after activity
Eventually constant pain with ADLs
Change in training regimen
“too much too soon”
Change in equipment
Shoes, etc.
DIAGNOSIS: take a good History
Sports participation
Occupation
Significant change in training
Hills, surface, intensity
Dietary History: adequacy, Vit D, Calcium
Menstrual History
General Health
Past medical history
Medications
Family history (osteoporosis)
DIAGNOSIS: Examination
Localized tenderness to palpation in a “High-Speed
location known to commonly sustain
Digital Imaging”
stress fractures
Fulcrum test?
Neither sensitive nor specific
Hop test?
Neither sensitive nor specific
Risky in high risk fractures
Tuning fork?
43% sensitive, 49% specific
DIAGNOSIS: Biomechanical
Evaluation
Leg length discrepancy
70% incidence in patients w/ LE stress fractures
Joint range of motion and ligamentous stability
Muscle strength and flexibility
Limb alignment (eg, genu varus or valgus)
Foot type (eg, pes cavus or planus)
Gait analysis in shoes worn during physical activity
Core muscle strength (eg, abdominal, back, and hip
musculature)
IMAGING: X-ray
Poor sensitivity
~ 30% positive on initial examination
4 Possible findings
Localized periosteal elevation
Cortical thickening
Focal sclerosis
Radiolucent line
10 - 20% never show up on plain films
Early Metatarsal Stress Fracture
One Week Later…..
Imaging: Bone Scan
Extremely sensitive
95% show up after 1 day
Not very specific
up to 24% false-positive results (stress reaction)
Differentiate between acute and old lesions
Acute stress fracture: all three phases positive
Shin splint: delayed phase only
Imaging: CT scan
Excellent fracture line detail
More specific than bone scan
Useful for fracture age/non-union
Pars interarticularis, sesamoids, etc.
DOWNSIDE: high radiation dose
Imaging: MRI
Highly sensitive (= bone scan)
More specific than bone scan
still not perfect
Cost may be lower than bone scan some places
Non-invasive, no radiation
Sensitive for soft tissue injury
DOWN: less cortical bony detail than CT
Imaging: Ultrasound
Useful if fracture superficial
Shows hematoma, hypervascularity, periosteal
elevation, cortical defect
Metatarsal fractures: sensitivity 83%, specificity 76%
Balal F, Gandjbakhch F, Foltz V et al. J Rheumatol 2009
MRI vs. bone scan, CJSM 2002
MRI less invasive, provided more information than
bone scan and recommended for initial diagnosis
and staging of stress injuries
“Limited” MRI may be cheaper than bone scan at
some institutions
RADIATION COMPARISON
Study
mSv
relative radiation
Plain film foot
Plain film CXR
<0.01
0.02
< 1.5 days
2.4 days
Plain film pelvis
0.7
3.2 mo
Tech-99 bone scan
3 (150 CXR)
1.2 yrs
CT L-spine
CT abd / pelvis
6 (300 CXR)
10 (500 CXR)
2.3 yrs
4.5 yrs
Differential Diagnosis
Muscle strains
Tendinopathy
Nerve entrapment
Medial tibial stress syndrome
Neoplasm
Infection
HIGH RISK STRESS FRACTURES
Pars interarticularis
Femoral head
Femoral neck
(tension side)
Patella
Talus
Tarsal navicular
Proximal fifth
metatarsal
Great toe sesamoid
Base of second
Anterior cortex of tibia
metatarsal
(tension side)
Medial malleolus
GENERAL TREATMENT for
LOW-RISK STRESS FRACTURES
PROTECTION
Reduce pain
Promote healing
Prevent further bone damage
ACTIVITY MODIFICATION
Rest from painful activities 6-8 weeks (or until pain-free for
two to three weeks)
Cross-training (non-painful exercise)
REHABILITATIVE EXERCISE
Flexibility, strength balance
BIOMECHANICAL CORRECTIONS
Early Treatment Speeds Recovery!
Evaluation < 3 weeks of sx onset:
10.4 weeks to RTP
Evaluation > 3 weeks
18.4 weeks to RPT
Ohta-Fukushima M, Mutoh Y, Takasugi S, et al. J Sports
Med Phys Fitness 2002
ACTIVITY MODIFICATION
Activity should be pain free
Approximate desired activity
Cycle
Swim
Walk
Elliptical
Deep water running
REHAB EXERCISE and
BIOMECHANICAL CORRECTIONS
Muscle flexibility
Strength training
Excessive pronation, pes cavus, pes planus
Limb Length Discrepancy
Replace running shoes every…
Other Treatment Modalities
Ultrasound: unsure
1 study no benefit, 2 studies + benefit
ECSWT: maybe—consider in high-risk sites
Worked in 1 small retrospective study
Medications:
Iloprost: 1 small retrospective study in subchondral
stress fractures of knee
Capicitatively Coupled Electric Fields:
No benefit in recent RCT
HIGH RISK STRESS FRACTURES
High risk for
delayed union ,
nonunion,
refracture
Pars interarticularis
Femoral head
Femoral neck
(tension side)
Patella
Talus
Tarsal navicular
Proximal fifth
metatarsal
Great toe sesamoid
Base of second
Anterior cortex of tibia
metatarsal
(tension side)
Medial malleolus
High-Risk Tibial Stress Fracture
Anterior, middle-third stress fractures are
very concerning
Tension side of bone
May present like shin splints
Seen more commonly in jumpers and leapers
If you see “dreaded black line” on x-ray, poor
prognosis
Management of High-Risk Tibial Stress Fx
4-6 months of rest +/immobilization
? Therapeutic US or SWT
Surgery if not healing in 4-6 months
Intramedullary rod
Proximal 5th
metatarsal
stress fracture
Mgmt. of 5th Metatarsal Stress Fracture
Sxs <3 wks, neg x-rays:
Avoid WB activity; 5th MT unloader orthotic
Sxs > 3 wks or + x-rays
Cast, NWB x 6 wks OR
Screw fixation (faster RTP)
Non-union: Screw-it!
Lumbar Spondylolysis
Stress fracture of the pars interarticularis
Caused by repetitive hyper-extension
Often develops in the teenage or pre-teen years
May be bilateral
Sports Associated with Spondy
Football (offensive lineman)
Gymnastics
Wrestling
Diving
Tennis
Volleyball
Physical Exam- Spondy
Tenderness to palpation over spines > paraspinal
muscles
Extension exacerbates pain
“Stork test”—not very sensitive
Tight hamstrings- cause or effect?
Imaging Suspected Spondy
AP & lateral x-rays
r/o other bony causes
Obliques don’t change management
Also order SPECT bone scan
MRI not as sensitive
CT with fine cuts: prognostic
Acute vs sclerotic
Treatment- Spondy
Relative rest from painful activity
Physical Therapy referral
Williams flexion-based exercises:
Spine Surgeon referral
Anti-lordotic bracing
Brace 6 weeks - 6 months (controversial)
Return to activity in brace when pain-free
Surgery if fail treatment
Femoral Neck Stress Fracture
Vague anterior or medial groin/hip pain
Early diagnosis critical
Anterior hip tenderness
Log-roll pain
Pain with straight-leg-raise
If x-rays negative, order MRI
Crutches/NWB until ruled out!
MRI diagnostic imaging of choice for femoral neck
stress fractures
Femoral Neck Palpation
Iliopsoas bursa
Femoral Neck
Stress Fractures
Compression side.
Inferior part of femoral neck
Less likely to become displaced
Complications possible
Treatment:
Fatigue line <50% neck width:
Crutches/NWB until asymptomatic,
then relative rest 4-6 wks
Fatigue line >50% neck width:
surgical fixation
Femoral Neck Stress Fx
Tension side: HIGH-RISK
Superior cortex or
tension side of neck
High propensity to become displaced
Frequent complications
Treated acutely with internal fixation
Tarsal Navicular Stress Fx:
HIGH-RISK
Consider in: Sprinters, Jumpers, Hurdlers,
Basketball, Football
Mean interval of 7 -12 months before diagnosis
“DON’T BE THAT GUY” WHO MISSES
Vague mid-foot medial arch pain
Foot cramping
IT
Tarsal Navicular Stress Fx
X-rays usually negative
MRI or thin-cut CT better than bone scan
Tarsal Navicular Stress Fracture
Meta-analysis 2010:
NWB cast better than WB
6-8 weeks
Semirigid orthotic during subsequent ambulation
NWB trend better than surgery
Torg JS, Moyer J, Gaughan JP, Boden BP. Am J Sports Med
2010.
Nonunion/displacement: surgery
Navicular Stress Fx Return to Play
After casting, if no tenderness at the “N” spot, then can
gradually return
Reassess every 1-2 weeks, gradual return at 6 weeks if no
symptoms
AFTER 6 weeks of protection, 6 weeks of PT for strength
and flexibility prior to return to run!
Average return to play is 4-6 months
Follow up radiography not helpful for return to activity
Sesamoid Stress Fracture
Risk: Sudden start-stop sports
Repetitive forced dorsiflexion
Sesamoid Stress Fracture
Tx: NWB x 6 weeks with cast to tip of great toe to
prevent DF
Failure: Surgery (excision or grafting)
Talus Stress Fracture
Chronic pain after ankle sprain
Location of fx: body near lateral process
MRI or CT for best imaging
Tx: 6-8 wks NWB in cast
Failure to heal: Excision of lateral
process
Patella Stress Fracture
Risk factors:
cerebral palsy, hurdlers
ACL reconstruction w/ BTB
Tx if x-rays neg:
Non-painful activity
Tx if x-rays + or high-demand athlete
K-wire fixation
Femoral Head Stress Fracture
Tx: NWB
Ortho referral; high rate of arthroplasty
Medial Malleolus Stress Fracture
Seen in runners and jumpers
Risk of non-union
Tx if x-rays neg and MRI w/o fx line:
SLWC or ankle brace; takes 4-5 MONTHS
High-level athlete: surgery (FASTER RTP)
Tx if x-rays + or non-union:
Surgery
Orthopedic Consultation
High Risk Fracture sites
High Level Athlete/Laborer
Failed conservative therapy
PREVENTION of STRESS FRACTURES
Small incremental increases in training FITT
Shock absorbing shoe/boot inserts
Calcium 2000mg, Vit D 800 IU (27% decr.)
Increased dairy products
62% decreased risk SF for each cup of skim milk
Modification of female recruit training:
Lower march speed
Softer surface
Individual step length/speed
Interval training instead of longer runs
??: OCPs (sig increase in bone mineral density, no
impact on stress fracture rate)
NO: HCP selection of military recruits’ running shoes
based on foot morphology
3 prospective studies by Knapik et al
QUESTIONS?