SACRAL BONE STRESS INJURIES
Sacral bone stress injuries in runners are often misdiagnosed as a problem with the SI joint. They’re considered an uncommon cause of low back pain but they likely occur much more often than we think due to both a lack of awareness and the nonspecific nature of symptoms.
Distance runners are the most common type of athlete to experience sacral BSI and they occur more frequently in females than males.
So when should you suspect sacral BSI in runners?
Anytime a runner presents with unilateral low back pain, you should have sacral BSI on your radar. Subjective reports are often more important in diagnosing or suspecting BSI than objective findings, so if an athlete reports any of the following, BSI should be even higher on your list:
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Since the sacrum is made up of primarily trabecular bone and these typically have longer healing timelines than cortical BSIs, sacral BSIs are classified as moderate-risk, meaning it’s possible but not highly likely for them to progress to nonunion or require surgical intervention.
Once diagnosed on MRI, athletes with a sacral BSI are encouraged to be non-weight bearing until they can walk without pain. This usually takes 1-2 weeks. During this time, non-weight bearing and pain-free strength training should be initiated or continued to maintain as much bone density & muscular strength as possible. Non-impact training like stationary biking, aquajogging and/or swimming can also be started during this time as long as it is pain-free.
Bone responds & remodels in response to muscular contraction forces at specific sites - so for a sacral bone stress injury, we want to prescribe exercise targeting muscles that attach to the sacrum. Initially, these exercises should be performed bilaterally and in a non-weight bearing position to reduce the total strain on the site of injury. They’ll gradually progress to double leg weight-bearing and then to single leg exercises to progressively overload the bone enough to stimulate bone remodeling without inducing pathological damage. Sacral BSI rehab will look different for each individual athlete, but could look something like the example here:
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Typically, athletes with a sacral BSI will be cleared for returning to running between 8-12 weeks post-diagnosis. Returning to your typical training levels typically takes between 3-6 months. This timeline may vary depending on the athlete’s initial grade of injury (e.g. stress reaction versus stress fracture), individual symptoms, and current bone health and nutritional status.
Questions about stress fracture rehab? Get in touch below!
References
Tenforde, A. S., & Fredericson, M. (Eds.). (2021). Bone Stress Injuries: Diagnosis, Treatment, and Prevention. Springer Publishing Company.
Mantyh, P. W. (2014). The neurobiology of skeletal pain. European journal of Neuroscience, 39(3), 508-519.
Fredericson, M., Salamancha, L., & Beaulieu, C. (2003). Sacral stress fractures: tracking down nonspecific pain in distance runners. The Physician and sportsmedicine, 31(2), 31-42.
​​Alsobrook, J., & Simons, S. M. (2007). Sacral stress fracture in a marathon runner. Current Sports Medicine Reports, 6(1), 39-42.