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

2. Outline Pathophysiology Risk Factors Associations Diagnosis
General Treatment
Specific Cases

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

4. 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

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

6. 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

7. 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

8. 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

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

10. 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

11. 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

12. 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)

13. IMAGING X-ray Only ~ 30% positive on initial examination
% never show up on plain films
If a positive x-ray
Localized periosteal reaction
Radiolucent line
Cancellous bone - band-like focal sclerosis

14. Early Metatarsal Stress Fracture

15. One Week Later…..

16. 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

17. 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

18. 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

19. RADIATION COMPARISON Study mSv relative radiation
Plain film foot < < 1.5 days
Plain film CXR days
Plain film pelvis mo
Tech-99 bone scan 3 (150 CXR) yrs
CT L-spine (300 CXR) yrs
CT abd / pelvis (500 CXR) yrs

20. 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)

21. ACTIVITY MODIFICATION
Activity should be pain free
Approximate desired activity
Cycle
Swim
Walk
Elliptical
Deep water running
MUST BE PAIN FREE

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

23. Site of Stress Fractures
Tibia %
Metatarsals %
Fibula %
Navicular - 8.0%
Femur - 6.4%
Pelvis - 1.9%

24. 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

25. 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

26. Dreaded
Black
Line

27. 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

28. 5th metatarsal
stress fracture

29. Types of Proximal 5th MT Fractures

30. Mgmt. of 5th Metatarsal Stress Fx
High risk for delayed union or nonunion
Non-weight-bearing cast for 6 weeks versus IM screw fixation

31. IM Screw Fixation

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

33. Sports Associated with Spondys
Football (offensive lineman)
Gymnastics
Wrestling
Diving
Tennis
Volleyball

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

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

36. SPECT scan showing bilateral pars defects

37. 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.

38. 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

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

40. 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

41. 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

42. Tarsal Navicular Stress Fx
Consider in: Sprinters, Jumpers, Hurdlers, Basketball, Football
Mean interval of months before diagnosis
Vague mid-foot pain
Pain on dorsum of foot
Foot cramping

45. Tarsal Navicular Stress Fx
X-rays usually negative
Bone scan vs. MRI vs. thin cut CT

46. 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

47. 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

48. 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

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

50. 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

51. 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

52. 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

53. 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)

54. QUESTIONS?