Stress fracture

Tumor biology and incidence

Also known as fatigue fracture
Results from overuse
Typically associated with muscle fatigue leading to decreased support of bony architecture
Patient's with osteogenesis imperfecta, Paget's disease, osteoporosis, osteomalacia, fibrous dysplasia, and osteoperosis at risk for stress fractures (insufficiency fractures)
Estimated incidence in athletes and military recruits is 5-30%

Age

All ages

Gender

More likely to occur in females than in males, especially among females with the female athlete triad of amenorrhea, disordered eating, and osteoporosis

Presentation

Pain that increases with activity, decreases with rest
- May also occur at an earlier point in each subsequent workout
Night pain common
Typically one specific spot that feels more tender than other areas if same bone

Physical findings

Localized swelling and pain on palpation of affected area
Pain may be reproduced by having patient load affected bone

Plain films

No significant findings on X-ray early stress fracture development
Periosteal reaction may be seen after several weeks
Area of cortical lucency may be seen further along in disease process, suggesting a nonhealing stress fracture

Site

More than half occur in lower extremities
Common sites: metatarsal fractures ("march" or "soldiers" fracture), tarsal navicular, tibia and fibula (long distance running and jumping), obturator ring (repeated stooping), rib (repeated coughing)

Size

Variable; depends on length of disease process and affected bone

Tumor effect on bone

Incomplete separation within the cortex; typically occurs in only one cortex

Bone response to tumor

Periosteal reaction and thickening of cortex while remodeling occurs

Cortex

Typically thickened compared with cortex at distant site in same bone

Soft tissue mass

Not present

Bone scan

Considered to be positive if focal isotope uptake occurs in area of clinical interest on third phase of the scan
- If no uptake, stress fracture unlikely
Isotope uptake may occur prior to clinical symptoms and may persist after symptoms resolve

CT scan

Facilitates visualization of bony architecture and extent of stress fracture

MRI

Shows bone marrow edema and periosteal reaction associated with pathologic process of stress fracture, as well as subclinical extent of disease

Differential diagnosis

Fracture
Osteomyelitis
Bone metastases
Osteoid osteoma
Exertion-related compartment syndrome
Bone contusion
Shin splints (medial tibial stress syndrome, tibial traction periostitis)

Diagnosis and treatment

Primary treatment is rest, cessation of activity causing pain for 4-12 weeks; patient may resume activities following rest period
NSAIDs and other analgesics may be used to limit pain
Maintain healthy diet that includes calcium and vitamin D
Bisphosphonates may be prescribed if lack of healing noted after 2-3 months of rest

Complications

Avascular necrosis
Nonunion
Malunion
Post-traumatic arthrosis
Continuous pain