Stress Fractures of the Calcaneus (Heel Bone)
Stress fractures are cracks in bones that occur from chronic repetitve trauma. It is relatively easy to understand how bones are broken in trauma such as falls or collsions with objects as there is a readily identifiable event as the culprit.
Consider a paperclip that, after being bent several times, will break in two. If it takes 4 bends to break a paperclip then a paperclip that has been bent three times, that appear to be in one piece is not a normal paperclip since one more bend will break it.
Human bones, when loaded or bent repeatedly beyond their capacity may form small cracks which can eventually break. The small cracks are generally not visible on x-ray. The difference between bone and the metal of a paperclip is that bone is continually healing or building up on the area of stress. If the building up or repair process exceeds the damage caused by repetitive stress, then there is not an issue.
The human heel strikes the ground at each step with about 1.5 times body weight during normal walking. Running can increase the force to 2 to 3 times body weight. Shoes with poor heel protection, poor running form, shoes with lack of shanks, or faulty foot mechanics can significantly increase stress and strain on the heel bone.
Pain from calcaneal or heel bone stress fractures may cause pain througout the day unlike plantar fasciitis which is more noticeable after arising in the morning or after rest. Swelling or bruising may be present. One simple test is known as the “squeeze test” in which one can squeeze the bottom portion of the heel bone which, if painful, may be a sign of a calcaneal stress fracture.
Stress fractures of the heel bone, like other stress fractures, are often diagnosed clinically as imaging may not readily reveal the fracture. Radiographs are often negative when stress fractures occur so early immobilization via CAM walkers (cast boots) or casts may be considered while awaiting more definitive imaging with MRI or CT scans.
The good news is that the heel bone tends to heal well once immobilization has been provided. It is important to recognize the underlying causes of the stress fracture and take measures to prevent recurrence.
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