STRESS FRACTURES

1
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

• Wolffs 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 -gt continued load -gt 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
• gt1cm decrease in calf girth
• Less lean mass in LE
• Less than 7 months prior strength training

8
INTRINSIC 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

9
EXTRINSIC FACTORS

• Activity type and intensity
• Footwear
• 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
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)

13
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

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

• 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

19
RADIATION COMPARISON

• Study mSv relative radiation
• Plain film foot lt0.01 lt 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

20
GENERAL 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)

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

24
HIGH 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)

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)

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 7 -12 months before diagnosis
• Vague mid-foot pain
• Pain on dorsum of foot
• Foot cramping

43
(No Transcript)
44
(No Transcript)
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.2008. 40(11S)S623?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?