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Stress Fractures Kevin deWeber, MD, FAAFP, FACSM

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1 Stress Fractures Kevin deWeber, MD, FAAFP, FACSM
Director, Military Sports Medicine Fellowship USUHS/Ft. Belvoir 2011 (many slides courtesy Dave Haight, MD

2 Outline Pathophysiology Risk Factors Associations Diagnosis
General Treatment Treatment of High-Risk Cases

3 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.

4 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).

5 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.

6 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

7 Most Common Sites of Stress Fractures
Tibia % Metatarsals % Fibula % Navicular - 8.0% Femur - 6.4% Pelvis - 1.9% OTHER – 10.4% Weight- bearing

8 CAUSE Large number of reps, usual load
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

9 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

10 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

11 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

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 hindfoot eversion Pes cavus (unproven) Pes planus (unproven) Tibial stress Fractures (retrospective)

15 EXTRINSIC FACTORS 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


18 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.

19 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)

20 DIAGNOSIS: Examination
“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? Risky in high risk fractures Tuning fork? 43% sensitive, 49% specific

21 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)

22 IMAGING: X-ray Poor sensitivity 10 - 20% never show up on plain films
~ 30% positive on initial examination 4 Possible findings Localized periosteal elevation Cortical thickening Focal sclerosis Radiolucent line % never show up on plain films

23 Early Metatarsal Stress Fracture

24 One Week Later…..

25 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

26 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

27 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

28 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

29 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

30 RADIATION COMPARISON Study mSv relative radiation Plain film foot <0.01 < 1.5 days Plain film CXR days Plain film pelvis 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

31 Differential Diagnosis
Muscle strains Tendinopathy Nerve entrapment Medial tibial stress syndrome Neoplasm Infection

Pars interarticularis Femoral head Femoral neck (tension side) Patella Anterior cortex of tibia Talus Tarsal navicular Proximal fifth metatarsal Great toe sesamoid Base of second metatarsal Medial malleolus

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

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

Muscle flexibility Strength training Excessive pronation, pes cavus, pes planus Limb Length Discrepancy Replace running shoes every… <300 miles

37 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 for delayed union , nonunion, refracture Pars interarticularis Femoral head Femoral neck (tension side) Patella Anterior cortex of tibia Talus Tarsal navicular Proximal fifth metatarsal Great toe sesamoid Base of second metatarsal Medial malleolus

39 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

40 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

41 Proximal 5th metatarsal
stress fracture

42 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!

43 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

44 Sports Associated with Spondy
Football (offensive lineman) Gymnastics Wrestling Diving Tennis Volleyball

45 Physical Exam- Spondy Tenderness to palpation over spines > paraspinal muscles Extension exacerbates pain “Stork test”—not very sensitive Tight hamstrings- cause or effect?

46 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

47 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 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.

48 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

49 Femoral Neck Palpation
Iliopsoas bursa Illiofemoral ligament - Y ligament of Bigelow, strongest in body - Extends from the base of the AIIS to the intertrochanteric line - Prevents hyperextension, abduction, lateral rotation Pubicfemoral ligament -Extends from superior pubis ramus to the anterior surface of the intertrochantic fossa, and joins iliofemoral ligament -Reinforces the fibrous capsule inferiorly and anteriorly -Tighten during abduction and extension -Prevents overabduction Ischiofemoral ligament -Extends from ischial portion of the acetabulum to the neck of the femur and base of the greater trochanter -Prevents hyperextension of the hip -Fibers relaxed during flexion 49

50 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

51 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

52 Tarsal Navicular Stress Fx: HIGH-RISK
Consider in: Sprinters, Jumpers, Hurdlers, Basketball, Football Mean interval of months before diagnosis “DON’T BE THAT GUY” WHO MISSES IT Vague mid-foot medial arch pain Foot cramping


54 Tarsal Navicular Stress Fx
X-rays usually negative MRI or thin-cut CT better than bone scan

55 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

56 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

57 Sesamoid Stress Fracture
Risk: Sudden start-stop sports Repetitive forced dorsiflexion

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

59 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

60 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

61 Femoral Head Stress Fracture
Tx: NWB Ortho referral; high rate of arthroplasty

62 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

63 Orthopedic Consultation
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

65 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 (11S):S623ミS629


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