Stress fractures can be ongoing healing processes

The healthcare system has often assessed chronic leg pain in elite and hobby athletes as caused by breaks in bone structure. Research at Linköping University, however, demonstrates that the features seen in radiography are an ongoing healing process, requiring rest. 

Photo montage, athletic runner and the scientist Jörg Schilcher Attending Physician and scientist Jörg Schilcher.

Both elite and hobby athletes often experience stress fractures. There are many causes of this type of injury: commonly a relatively sudden increase in exercise volume or a change in the type of exercise. These may lead to overload of the skeleton, with subsequent microdamage.
Stress fracture on X-ray.Stress fracture on radiography.The researchers at LiU have studied this type of damage and the way it heals. When the body attempts to repair the damage, the bone is temporarily weakened. If load is maintained during this sensitive period, cracks may form – sometimes as small as a few tenths of a millimetre. Such cracks often self-heal if the training volume is reduced or training is suspended completely.

Long time to heal

“It is, however, well-known that stress fractures take a long time to heal. During this period, the patient is often troubled by pain not only when the bone is under load, but also after training and at night. Fractures can sometimes take several months to heal, or even more than a year”, says Jörg Schilcher, consultant and orthopaedics specialist in Region Östergötland and docent at Linköping University, Division of Experimental Orthopaedics, Department of Clinical and Experimental Medicine.
Photo of a figure to illustrate leg pain.Some stress fractures can cause the bone to break completely.
Photo: Pixabay.
So why does the microdamage heal so slowly? Strangely enough, the fact that the crack is so small is probably one important reason.
“Bone is flexible: it bends slightly when put under load. The small changes in the shape of the crack are then relatively large, compared to its size. The cells that are trying to heal the crack cannot withstand the load and this means that they can’t heal it – somewhat similar to when one has cracked skin.” 

Some stress fractures can cause the bone to break completely, and in some cases orthopaedic specialists recommend surgery to stabilise the bone, to prevent the injury becoming more serious. The current standard treatment for difficult-to-treat stress fractures is extensive surgery, applying screws and plates or pins to fix the crack. This treatment involves risk and usually several surgical procedures. Another approach is to remove the damaged region by drilling, and in this way make space for the cells to grow into the crack and heal it. 
While studying this method, the LiU researchers discovered the ongoing healing process. 
Portrait photo Jörg Schilcher, scientist and physician.Jörg Schilcher, scientist and attending physician.“We initially thought that we had drilled in the wrong place, until we realised that the ‘crack’ in the radiography images was an ongoing healing process, and not a fault in the bone structure”, says Jörg Schilcher. 

A tried and tested method

The results of the study have led the researchers to recommend a tried and tested method for overload injuries, namely rest.
“It’s important to rest and give the healing processes time to fix the microdamage. This doesn’t mean sitting still, but avoiding types of loading that cause discomfort. But this is difficult for elite athletes, who must always perform at the top of their game. We’ve seen many examples of this”, says Jörg Schilcher.
The results have been published in the Scandinavian Journal of Medicine and Science in Sports.
“This is the result of ten years of research. It’s particularly satisfying that the article has been selected as ‘Editors choice’ in this issue of the journal, with our micrograph on the cover. Persistence pays off”, says Jörg Schilcher.
(Translated by George Farrants)

The article: “Chronic anterior tibial stress fractures in athletes: No crack but intense remodeling”, Jörg Schilcher, Magnus Bernhardsson, Per Aspenberg, (2019), (Scandinavian Journal of Medicine and Science in Sports), published online 12 September 2019, doi: 10.1111/sms.13466 
 

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