DAVE HAIGHT, MD Sports Medicine Fellow April 2009 STRESS FRACTURES DAVE HAIGHT, MD Sports Medicine Fellow April 2009

Outline Pathophysiology Risk Factors Associations Diagnosis General Treatment Specific Cases

CAUSE Change in load Small number of repetitions with large load Large number of reps, usual load Intermediate combination of increased load and repetition

PATHOPHYSIOLOGY 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

EPIDEMIOLOGY 1% of general population 1-8% of collegiate team sports Up to 31% of military recruits 13-52% of runners

RISK 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 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 FACTORS Extreme arch morphologies: Biomechanical factors: Pes cavus Pes planus Biomechanical factors: Shorter duration of foot pronation Sub-talar joint control Tibial striking torque Early hindfoot eversion

EXTRINSIC FACTORS Activity type and intensity Footwear Running Surface Older shoes Shock absorbing cushioned inserts Running Surface Treadmill Track

ASSOCIATIONS Ballet: Runners: Sprinters: Long dist runner: Baseball, tennis: Gymnasts: Rowers, golfers: Hurdlers: Rowers, Aerobics: Bowling, running: Lumbar, femur, metatarsal Tibia, metatarsal Navicular Femoral neck, pelvis Humerus Spine, foot, pelvis Ribs Patella Sacrum Pelvis

Classic 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

DIAGNOSIS History 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)

IMAGING X-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

One Week Later…..

Bone 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 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 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 COMPARISON Study mSv relative 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

GENERAL TREATMENT PROTECTION Stretching and flexibility exercises 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 MODIFICATION Activity should be pain free Approximate desired activity Cycle Swim Walk Elliptical Deep water running MUST BE PAIN FREE

REHAB EXERCISE Address biomechanical issues: Muscle inflexibility Limb Length Discrepancy Excessive pronation, pes cavus, pes planus Replace running shoes Strength training

Site of Stress Fractures Tibia - 39.5% Metatarsals - 21.6% Fibula - 12.2% Navicular - 8.0% Femur - 6.4% Pelvis - 1.9%

HIGH RISK High Risk High Risk Great toe sesamoid 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

High-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 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

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 Fixation

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 Spondys Football (offensive lineman) Gymnastics Wrestling Diving Tennis Volleyball

Physical Exam- Spondy Tenderness to palpation over paraspinous muscles Positive one-legged hyperextension test “Stork test” Tight hamstrings- cause or effect?

Radiographs- Spondy ? Need to get oblique images Look for “Scotty Dog” sign SPECT scan MRI not reliable in diagnosing

SPECT scan showing bilateral pars defects

Treatment- Spondy Relative rest (avoid lunges, cleans, squats, other extension maneuvers, etc.) Williams flexion exercises: Pelvic tilt, Single Knee to chest, Double knee to chest, Partial sit-up, Hamstring stretch, Hip Flexor stretch, Squat (no weight) Anti-lordotic bracing Return to activity in brace when pain-free Brace 6 weeks - 6 months (controversial) Pelvic tilt. 2. Single Knee to chest. 3. Double knee to chest. 4. Partial sit-up. 5. Hamstring stretch. 6. Hip Flexor stretch. 7. Squat.

Femoral 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 Fx Early diagnosis critical If x-rays negative, bone scan/MRI MRI diagnostic imaging of choice for femoral neck stress fractures

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

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

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 Fx Risk: Sudden start-stop sports Repetitive forced dorsiflexion Conservative tx rarely effective Tx: Non-weight bearing x 6 weeks, 2-4 weeks protected weight bearing Sick sesamoid syndrome: failure to respond -Surgery indicated

Orthopedic Consultation High Risk Fracture sites Femoral Neck - tension side Navicular 5th Metatarsal Anterior tibial shaft High Level Athlete/Laborer Failed conservative therapy

PREVENTION 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

Israeli Army Prevention Study Shoe modifications, orthoses, and pharmacological treatment with risedronate not effective in lowering the incidence of stress fractures in Israeli army recruits Greater than 60% decrease in stress fractures was achieved by enforcing a minimum sleep regimen and lowering the cumulative marching during infantry training. FINESTONE, A., and C. MILGROM. How Stress Fracture Incidence WasLowered in the Israeli Army: A 25-yr Struggle. Med. Sci. Sports Exerc.2008. 40(11S):S623ﾐS629

Take 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 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?