Stress Fractures - PowerPoint PPT Presentation

Stress Fractures

Kevin deWeber, MD, FAAFP, FACSM

Director, Military Sports Medicine Fellowship

USUHS/Ft. Belvoir

2011

(many slides courtesy Dave Haight, MD

• Pathophysiology
• Risk Factors
• Associations
• Diagnosis
• General Treatment
• Treatment of High-Risk Cases

• 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.

• 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, osteogenesisimperfecta, etc.) or in a bony region (eg, demineralization in a limb due to disuse).

• 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.

• 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

• Tibia - 39.5%
• Metatarsals - 21.6%
• Fibula - 12.2%
• Navicular - 8.0%
• Femur - 6.4%
• Pelvis - 1.9%
• OTHER – 10.4%

Weight-

bearing

• 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

• 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

• Intrinsic:
• Gender, genetics
• Anatomical malalignment/ biomechanical
• Dietary
• Muscle weakness/imbalance
• Extrinsic
• Training errors
• Equipment mismatch
• Technique errors
• Environmental
• Sports-imposed deficiencies

• 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

• 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

• 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

• BIOMECHANICAL FACTORS
• Shorter duration of foot pronation
• Sub-talar joint control
• Tibial striking torque
• Early hindfooteversion
• Pescavus (unproven)
• Pesplanus (unproven)

Tibial

stress

Fractures

(retrospective)

• Increasing volume and intensity
• Footwear
• Older shoes
• Absence of shock absorbing inserts
• Running Surface?: mixed results
• Treadmill vs Track
• Activity type

• 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

• 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.

• 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)

“High-Speed

Digital Imaging”

• Localized tenderness to palpation in a location known to commonly sustain 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

• 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, genuvarus or valgus)
• Foot type (eg, pescavus or planus)
• Gait analysis in shoes worn during physical activity
• Core muscle strength (eg, abdominal, back, and hip musculature)

• Poor sensitivity
• ~ 30% positive on initial examination
• 4 Possible findings
• Localized periostealelevation
• Cortical thickening
• Focal sclerosis
• Radiolucent line
• 10 - 20% never show up on plain films

• 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

• Excellent fracture line detail
• More specific than bone scan
• Useful for fracture age/non-union
• Pars interarticularis, sesamoids, etc.
• DOWNSIDE: high radiation dose

• 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

• 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 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

Study mSvrelative radiation

Plain film foot <0.01 < 1.5 days

Plain film CXR 0.02 2.4 days

Plain film pelvis 0.7 3.2 mo

Tech-99 bone scan 3 (150 CXR)1.2 yrs

CT L-spine 6 (300 CXR) 2.3 yrs

CT abd / pelvis 10 (500 CXR) 4.5 yrs

• Muscle strains
• Tendinopathy
• Nerve entrapment
• Medial tibial stress syndrome
• Neoplasm
• Infection

• Talus
• Tarsal navicular
• Proximal fifth metatarsal
• Great toe sesamoid
• Base of second metatarsal
• Medial malleolus

• Pars interarticularis
• Femoral head
• Femoral neck

(tension side)

• Patella
• Anterior cortex of tibia

(tension side)

• 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

• 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 should be pain free
• Approximate desired activity
• Cycle
• Swim
• Walk
• Elliptical
• Deep water running

• Muscle flexibility
• Strength training
• Excessive pronation, pescavus, pesplanus
• Limb Length Discrepancy
• Replace running shoes every…

<300 miles

• 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 for

delayed union , nonunion,

refracture

• Talus
• Tarsal navicular
• Proximal fifth metatarsal
• Great toe sesamoid
• Base of second metatarsal
• Medial malleolus

• Pars interarticularis
• Femoral head
• Femoral neck

(tension side)

• Patella
• Anterior cortex of tibia

(tension side)

• 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

• 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

• 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!

• Stress fracture of the pars interarticularis
• Caused by repetitive hyper-extension
• Often develops in the teenage or pre-teen years
• May be bilateral

• Football (offensive lineman)
• Gymnastics
• Wrestling
• Diving
• Tennis
• Volleyball

• Tenderness to palpation over spines > paraspinal muscles
• Extension exacerbates pain

“Stork test”—not very sensitive

• Tight hamstrings- cause or effect?

• 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

• 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

• 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

Iliopsoas bursa

• 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

• Tension side: HIGH-RISK
• Superior cortex or

tension side of neck

• High propensity to become displaced
• Frequent complications
• Treated acutely with internal fixation

• Consider in: Sprinters, Jumpers, Hurdlers, Basketball, Football
• Mean interval of 7 -12 months before diagnosis
• “DON’T BE THAT GUY” WHO MISSES IT
• Vague mid-foot medial arch pain
• Foot cramping

• X-rays usually negative
• MRI or thin-cut CT better than bone scan

• 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

• 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

• Risk: Sudden start-stop sports
• Repetitive forced dorsiflexion

• Tx: NWB x 6 weeks with cast to tip of great toe to prevent DF
• Failure: Surgery (excision or grafting)

• 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

• 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

• Tx: NWB
• Ortho referral; high rate of arthroplasty

• 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

• High Risk Fracture sites
• High Level Athlete/Laborer
• Failed conservative therapy

• 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