IADMS New York 2002   [back to the Category]

Anterior Tibial Stress Fractures   [read the french version]

Author :   David S. Weiss, MD

Anterior Tibial Stress Fractures


David S. Weiss, MD
NYU Medical Center, NYU-HJD Department of Orthopaedic Surgery,
Harkness Center for Dance Injuries
New York, New York, USA

Purpose: This presentation is intended to provide a review of the physiology, biomechanics, diagnosis (history, physical examination, diagnostic testing), treatment, and rehabilitation for stress fractures of the anterior tibia in dancers.

Anterior stress fractures are common in dancers and also occur in jumping athletes. These fractures can be slow to heal and thus frustrating for the dancer, teacher, and clinician. Diagnosis depends on obtaining a comprehensive history and performing a careful physical examination. The proper use of diagnostic tests will be reviewed. Successful treatment depends on early identification (based on proper differential diagnosis), determination as to whether the fracture is acute or chronic, ensuring sufficient rest, and implementing proper rehabilitation. Rehabilitation entails a graduated exercise program aimed at increasing strength and proprioceptive ability while also slowly increasing stress on the leg. Return to full dance activities may take as long as 6 to 8 months. Due to the slow nature of healing of these fractures, progression of an anterior tibial stress fracture to a chronic stress fracture (also termed a “mal-union” or “dreaded black line”) can occur during treatment. At times a chronic stress fracture may appear as the first presentation of the injury. The evaluation methods and treatment options for a chronic stress fracture of the anterior tibia will also be discussed.

Lecture Outline:
1. Stress Fracture: Definition: An overuse of bone (by bending) such that the bone weakens in one particular area
2. Composition of bone:
Organic 30 % Matrix (collagen, other proteins)
Cells (osteoblasts, osteoclasts, osteocytes)
Mineral 70 % Hydroxyapatite [calcium, phosphate: Ca10(PO4)6(OH)2]
Magnesium, sodium, potassium, fluoride, chloride
3. Bone: A calcium “bank”
You can only make “deposits” until age 25
After age 25: proper daily intake prevents unnecessary “withdrawals”
4. Nutrition: Daily Requirements Calcium* (milligrams elemental calcium)
Children (4 – 8 years) 800
Children / adolescents (9 – 18 years) 1300
Adults (19 – 50 years) 1300
Adults (> 50 years) 1000
*Institute of Medicine of National Academy of Sciences


5. Structure of bone: Cortical (compact) vs. Trabecular (cancellous)
6. Bone is alive ! Bone constantly remodels:
Existing bone removed (by osteoclasts)
New bone produced (by osteoblasts)
Balance: bone can make itself stronger or weaker
7. Stress fractures: Risk factors (physiologic)
Increased risk with:
Chronic amenorrhea
Eating disorders
Restrictive diet
Muscular weakness
8. Stress fractures: Risk factors (environmental)
Increased risk with:
Student or apprentice
New company member
Repetitive rehearsals
Worn pointe shoes
Stiff, non-resilient floor
9. History:
Stress fractures occur with:
Steadily & progressively heavy work-load
Very rapidly increasing work-load
10. Anterior tibial stress fracture
History: pain in middle third of anterior tibia, especially with jumping
Differential diagnosis:
Medial tibial syndrome
(“shin splints”)
Compartment syndrome
Fibular syndrome
11. Medial tibial stress syndrome
History: Onset with recent increase in activity (e.g., after a lay-off)
may become chronic
Signs: Diffuse tenderness along postero–medial border of tibia
(middle and/or distal tibia)
Diagnosis:
No bone scan needed (would show diffuse uptake on delayed images)
Treatment:
Reduce activities
Correct alignment (pronation)
Stretch soleus
Strengthen

12. Anterior tibial stress fracture
Physical examination:
Anterior tibia: Bony excrescence (bump) middle third, anterior edge
Point tenderness at site of excrescence (bump)
Warmth (usually)
Redness (occasionally)
13. Plain radiograph (x-ray)
Inexpensive
Not sensitive for acute stress fractures
But… mandatory to evaluate for possible chronic stress fracture
Lateral view
Shows chronic stress fracture (non-union)
Radiolucent line
(“dreaded black line”)
Assess healing of non-union
14. Bone scan (scintigram)
More expensive
Sensitive, but not specific: some false negatives, many false positives
Positive at 2 – 3 weeks after onset of symptoms
Stays positive for 3 – 10 months
15. False negative bone scans
No bone formation in early stages of stress fracture
Chronic stress fracture
16. Chronic anterior tibial stress fracture
No bone formation
Represents a “non-union” (a failure to unite or heal)
Histopathology: atrophic pseudoarthrosis
17. Anterior tibial stress fractures
Why are they different?
Mechanics: Anterior tibia is under tension (distraction)
Bone healing is stimulated by compression
Increased tension force with: jumping and calf contraction
18. Chronic anterior tibial stress fracture
Cause: Cycling of stress (stress–rest–stress–rest, etc.)
Insufficient rest to allow complete healing
19. Chronic anterior tibial stress fracture: Diagnostic imaging
X-ray: lateral view
Radiolucent line in cortex (“dreaded black line”)
More severe: well-defined (sclerotic edges), wider, longer
Bone scan
Usually not performed; Negative (“cold”)

20. Acute stress fractures: Treatment principles
Rest from dancing until fracture heals (reference normal bone healing)
Limit weight-bearing: For specific fracture type, or as required for pain
Evaluate for risk factors
Restore muscular strength and endurance
Slow, gradual introduction of “stressful” activities:
Allow bone to strengthen (Wolff’s law)
21. Treatment: Acute anterior tibial stress fracture
Rest from dancing: 8 – 12 weeks
Reduce forces (stress) on anterior tibia:
Short leg walking brace (6 weeks)
Crutches (2 weeks or if pain walking)
Physical therapy:
Strengthening (including anterior tibial muscles)
Alignment
Proprioceptive retraining
Jump retraining: Trampoline, pilates, physioball
Dance retraining class
Don’t expect return to full dancing until 4 – 6 months !
(else risk recurrence or non-union)
22. Treatment: Chronic anterior tibial stress fracture
Complete rest from dancing
Stimulate bone healing
Ultrasonic bone stimulation (Exogen)
Electromagnetic bone stimulation (EBI)
Physical therapy
Strengthening (including anterior tibial muscles)
Alignment
Proprioceptive retraining
Expect return to full dancing after 9 - 12 months
Check healing on lateral x-ray: if no progress after 6 months, consider surgery
Surgery
Excise fissure, drill site, place bone graft
If that fails, consider intramedullary nail
23. Stress fracture healing
Athletes (Orava & Hulkko, Finland; Am J Sports Med, 16: 378-382,1988)
369 stress fractures; 37 delayed union or non-union (10%)
27 mid-tibial stress fractures; 6 delayed union or non-union (22%)
24. Stress fracture healing
(Kadel, Teitz, Kronmal, Seattle; Am J Sports Med, 20: 445-449, 1992)
Survey of 54 female ballet dancers
Treatment not studied
27 stress fractures; 6 mid-tibia