STRESS FRACTURESSTRESS FRACTURES

DAVE HAIGHT, MD

Sports Medicine Fellow

April 2009

OutlineOutline

• Pathophysiology• Risk Factors• Associations• Diagnosis• General Treatment• Specific Cases

CAUSECAUSE

• Change in load

• Small number of repetitions with large load

• Large number of reps, usual load

• Intermediate combination of increased load and repetition

PATHOPHYSIOLOGYPATHOPHYSIOLOGY

• 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)

• Stress fracture: imbalance between bone resorption and formation

• Microfracture -> continued load -> stress fracture

EPIDEMIOLOGYEPIDEMIOLOGY

• 1% of general population

• 1-8% of collegiate team sports

• Up to 31% of military recruits

• 13-52% of runners

RISK FACTORSRISK FACTORS

• History of prior stress fracture• Low level of physical fitness, non-athlete• Increasing volume and intensity• Female Gender• Menstrual irregularity• Diet poor in calcium• Poor bone health• Poor biomechanics

RISK FACTORS contRISK 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• >1cm decrease in calf girth• Less lean mass in LE• Less than 7 months prior strength training

INTRINSIC FACTORSINTRINSIC FACTORS

• Extreme arch morphologies:• Pes cavus• Pes planus

• Biomechanical factors:• Shorter duration of foot pronation• Sub-talar joint control• Tibial striking torque• Early hindfoot eversion

EXTRINSIC FACTORSEXTRINSIC FACTORS

• Activity type and intensity

• Footwear• Older shoes

• Shock absorbing cushioned inserts

• Running Surface• Treadmill

• Track

ASSOCIATIONSASSOCIATIONS

• Ballet:• Runners:• Sprinters: • Long dist runner:• Baseball, tennis: • Gymnasts: • Rowers, golfers:• Hurdlers:• Rowers, Aerobics:• Bowling, running:

Lumbar, femur, metatarsalTibia, metatarsalNavicular Femoral neck, pelvisHumerusSpine, foot, pelvisRibsPatellaSacrumPelvis

Classic Clinical HistoryClassic Clinical History

• Change in training or equipment

• Gradual onset over 2 to 4 weeks

• Initially pain only with activity

• Progresses to pain after activity

• Eventually constant pain with ADLs

DIAGNOSISHistory

DIAGNOSISHistory

• Sports participation • Significant change in training

• Hills, surface, intensity

• Dietary History: adequacy, Vit D, Calcium• Menstrual History• General Health• Occupation• Past medical history• Medications• Family history (osteoporosis)

IMAGINGX-ray

IMAGINGX-ray

• Only ~ 30% positive on initial examination

• 10 - 20% never show up on plain films

• If a positive x-ray

• Localized periosteal reaction

• Radiolucent line

• Cancellous bone - band-like focal sclerosis

Early Metatarsal Stress Fracture

Early Metatarsal Stress Fracture

One Week Later…..One Week Later…..

Bone ScanBone Scan

• 95% show up after 1 day

• Extremely sensitive but not as specific with up to 24% false-positive results (stress reaction)

• Differentiate between acute and old lesions

• Acute stress fracture: three phase positive

• Shin splint: delayed phase only

MRI vs. bone scan, CJSM 2002

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

How I Decide Between an MRI and Bone Scan

How I Decide Between an MRI and Bone Scan

• MRI• Usually can be done more quickly (1 vs. 4

hours) and scheduled for a sooner date• No radiation• Better soft tissue detail

• Bone Scan• Covers a wider area of the body (if bilateral or

diffuse symptoms)• Sometimes easier to interpret• Cheaper

RADIATION COMPARISONRADIATION COMPARISON

Study mSv relative radiation

Plain film foot <0.01 < 1.5 daysPlain 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 yrsCT abd / pelvis 10 (500 CXR) 4.5 yrs

GENERAL TREATMENTGENERAL TREATMENT

• PROTECTION• Reduce pain• Promote healing• Prevent further bone damage• ADLs are permitted

• Stretching and flexibility exercises

• Cross-training (non-weight-bearing exercise)

• Modified rest for six to eight weeks (or until pain-free for two to three weeks)

ACTIVITY MODIFICATIONACTIVITY MODIFICATION

• Activity should be pain free• Approximate desired activity

• Cycle• Swim• Walk• Elliptical• Deep water running• MUST BE PAIN FREE

REHAB EXERCISEREHAB EXERCISE

• Address biomechanical issues: • Muscle inflexibility• Limb Length Discrepancy • Excessive pronation, pes cavus, pes

planus• Replace running shoes• Strength training

Site of Stress FracturesSite of Stress Fractures

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

HIGH RISKHIGH RISK

• High Risk• Talus• Tarsal navicular• Proximal fifth

metatarsal

• Great toe sesamoid

• Base of second metatarsal

• Medial malleolus

• High Risk• Pars interarticularis• Femoral head• Femoral neck

(tension side)• Patella• Anterior cortex of tibia

(tension side)

High-Risk Tibial Stress FxHigh-Risk Tibial Stress Fx

• Anterior, middle-third stress fractures are very concerning

• Tension side of bone

• May present like shin splints

• Seen more commonly in jumpers and leapers

• See “dreaded black line” on x-ray

• Heal very poorly

Dreaded Black Line

Management of High-Risk Tibial Stress Fx

Management of High-Risk Tibial Stress Fx

• Immobilization

• 4-6 months of rest

• Pulsed low-intensity U/S or electrical stimulation may decrease symptoms and speed return to activity, 30 minutes/day x 3-9 mos.

• IM rod for failed conservative or patient preference

5th metatarsal stress fracture

Types of Proximal 5th MT Fractures

Types of Proximal 5th MT Fractures

Mgmt. of 5th Metatarsal Stress Fx

Mgmt. of 5th Metatarsal Stress Fx

• High risk for delayed union or nonunion

• Non-weight-bearing cast for 6 weeks versus IM screw fixation

IM Screw FixationIM Screw Fixation

Femoral Stress FxFemoral Stress Fx

• Primary presenting symptom is groin pain; possibly thigh or knee pain

• Hip motion may be painful

• Hop test

• Fulcrum test for shaft fx

Femoral Neck Stress FxFemoral Neck Stress Fx

• Early diagnosis critical

• If x-rays negative, bone scan/MRI

• MRI diagnostic imaging of choice for femoral neck stress fractures

Femoral Neck Stress FxFemoral Neck Stress Fx

• Compression side.• Inferior part of femoral neck

• Younger patients

• Less likely to become displaced

• Complications possible

• Treatment-non-weight bearing, followed by touch-down WB, then partial WB over a total of 8-12 weeks

Femoral Neck Stress FxFemoral Neck Stress Fx

• Distraction side

• Superior cortex or tension side of neck

• High propensity to become displaced

• Frequent complications

• Treated acutely with internal fixation

Tarsal Navicular Stress FxTarsal Navicular Stress Fx

• Consider in: Sprinters, Jumpers, Hurdlers, Basketball, Football

• Mean interval of 7 -12 months before diagnosis

• Vague mid-foot pain• Pain on dorsum of foot• Foot cramping

Tarsal Navicular Stress FxTarsal Navicular Stress Fx

• X-rays usually negative• Bone scan vs. MRI vs. thin cut CT

Mgmt. of Navicular Stress Fx

Mgmt. of Navicular Stress Fx

• Most studies suggest that allowance of weight-bearing immediately after diagnosis increases the non-union rate

• General/simple rules:• (+) bone scan/MRI/CT and/or incomplete fx-

NWB cast x 6-8 weeks, and then gradual rehab

• Complete fx and/or bony sclerosis- ORIF with compression screw +/- bone graft

Orthopedic ConsultationOrthopedic Consultation

• High Risk Fracture sites• Femoral Neck - tension side• Navicular • 5th Metatarsal• Anterior tibial shaft

• High Level Athlete/Laborer

• Failed conservative therapy

PREVENTIONPREVENTION

• Small incremental increases in training FITT• Shock absorbing shoe/boot inserts• Calcium 200mg, Vit D 800IU (27% decr.)• OCPs: sig increase in bone mineral density,

no impact on stress fracture rate• Modification of female recruit training:

• Lower march speed• Softer surface• Individual step length/speed• Interval training instead of longer runs

Take Home PointsTake Home Points

• Avoid a delay in diagnosis, image early

• REST is a 4-letter word to athletes; thus advise relative rest, allowing for cross-training or unaffected body-training during the healing period

Take Home PointsTake Home Points

• Correct underlying nutritional, hormonal or biomechanical abnormalities to promote healing and prevent recurrence

• Despite our best efforts, some athletes will never return to their pre-injury level of competition due to some specific stress fractures (navicular, femoral neck, anterior tibia)

QUESTIONS?QUESTIONS?