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Dr. Darrell Menard: What is a stress fracture?

What is a stress fracture?

Dr. Darrell-Menard

Q:   To celebrate Canada 150 I decided to do the Nijmegen March.  After a relatively inactive winter I tried to make up for lost time by training harder.  I quickly increased the length of my rucksack marches and after 4 weeks was comfortably marching eighty kilometers/week.  Seven weeks into my training, my left foot suddenly became sore and eventually I was unable to walk around the block.  Despite having normal x-rays, I was diagnosed with a stress fracture and told to stop all impact activities for at least 8 weeks.  What exactly is a stress fracture and how did this happen to me?  Discouraged

A: Dear Discouraged: Your history is classic for a stress fracture.  Stress fractures are often referred to a hair line or march fractures and they are basically overuse injuries of bones.

Bones are dynamic living tissues that constantly repair and remodel themselves in response to the stresses they experience.  They do this using two unique cells – osteoclasts (bone digesters) and osteoblasts (bone builders) that work hard to remove damaged bone and replace it with new bone. When bones are subjected to more repetitive stress than they are used to, osteoclasts are stimulated to clean up the damage faster than the osteoblasts can repair it.  The net result is that microtrauma accumulates and the architecture of the bone is weakened. If the stress continues, the bone can be weakened to the point it fails and you develop a stress fracture.

Stress fracture symptoms include pain especially with weight bearing activity.  The more active you are, the more pain you will have.  There may be swelling and tenderness to touch over the fracture site.  Stress fractures are usually too small to be seen with x-rays.  To confirm the diagnosis you often need an MRI or bone scan.   The best strategy to prevent stress fractures is to avoid sudden large increases in your training workload and this can be done by limiting the increases in your training volume to 5-10%/week.  When stress fractures occur, the best treatment is to avoiding all high impact activity for a minimum of 4-8 weeks.

The bottom line:  Stress fractures almost always result from failing to allow bones adequate time to repair and remodel after they have been stressed and this is exactly how you sustained your injury.  The good news is that once you are completely healed you can begin slowly building up for next year’s Nijmegen March.   Exercise is medicine!

Dr. Darrell Menard OMM, CD, MD (former Physical Education Officer at RMC) now a Sport Medicine Physician