• eurico marques

Bone Stress Injuries Part 3 - Classified!

Updated: Mar 31


#Physiotherapy #InjuryPrevention #Stress #Running


As I successfully overcame the momentous challenge of the 2019 Comrades Marathon, I was left in awe at the phenomenal times by both male and female athletes in this years’ up run. The Comrades Marathon is synonymous with South African culture as it transcends all socio-cultural domains to create a harmonious ebb and flow of trampling feet from Durban to Pietermaritzburg. The pure rawness of the event left me emotional on more than one occasion. For other athletes and I, we begin to wind down the training for the remainder of June, but we will continue our journey of uncovering Bone Stress Injuries (BSI). In Part 1 (here) we discussed the clinical diagnosis of BSI and followed that with identifying who is at risk in Part 2 (here). In Part 3 we will look at classifying BSI and the implications for clinical practice.


Classifying injuries is an important aspect of the management process. It gives the clinician and the athlete an indication of the timeframes and interventions, and aids in the management of expectations. In the case of BSI this is no different. The challenge with BSI classification is that there isn’t one universally accepted classification system, however, the framework for the development of the current classification systems is built on three comparable pillars. These pillars include symptoms, location, and appearance on imaging[1].


First and foremost, the presence of pain is important in the diagnosis and classification of a BSI[1]. Imaging studies have identified changes associated with BSI in asymptomatic individuals[1]. Thus, the presence of pain is paramount before the diagnosis of a BSI can be made. Imaging findings in isolation are most likely incidental and offer no prognostic value[1]. Treating the athlete rather than the image is an important aspect of BSI management. When an athlete presents with pain and imaging findings that are consistent with the anatomical location of their symptoms, a BSI may be suspected.


Once a diagnosis has been made, BSIs can be classified into 2 groups: High Risk or Low Risk[1]. One classification system is based on the location of the stress injury. Low risk injuries typically recover with a low incidence of complications and without the need for aggressive interventions[1]. High Risk injuries present with treatment challenges and should be treated with caution as they are susceptible to delayed union and progression to a complete fracture[1].

A second classification system that can be used is based on the imaging findings. Using Magnetic Resonance Imaging (MRI) we can grade BSI as either low risk or high risk. Grade 1 and 2 BSIs can be classified low risk and grade 3 and 4 categorised as high risk.

Although MRIs are useful for identifying the grade of BSI, in clinical practice for majority of clients they are not economically viable. In my experience, the referral for MRI is predominately used in high risk locations (as above) and population groups. High risk groups include adolescents, athletes where Relative Energy Deficiency Syndrome (RED-S) is suspected and professional athletes where resources are not in question. Therefore, for most cases grading the suspected BSI is often based on the degree of pain during activity and palpation, the injury timeline and the objective findings on assessment. The use of the simple Visual Analogue Scale (VAS) is a reliable tool for understanding the severity of the BSI. I would generally create a VAS score for the subjective and objective findings in order to paint a clearer picture.


Once a BSI is suspected and graded an individualised rehabilitation plan is put into place and the client’s response (subjective and objective) is monitored on a regular basis (weekly if possible). As MRI investigations are not routinely utilised in my context, I err on the side of caution during the initial phases and communicate with the client on a regular basis in order to attempt to create further clarity around the grade of the BSI and the likely prognosis. Don’t be afraid to hold back on giving the client a conclusive grading as the picture tends to get clearer as you start to manage their symptoms.


Then, after categorization of the BSI has been established, we are able to estimate a recovery time and manage athlete and coach expectations. Low-grade BSIs generally recover quicker and require less invasive management strategies[1]. Return to Sport (RTS) times can vary from 13 to 23 weeks depending where on the continuum the BSI lies[1]. Further studies have been able to estimate RTS timelines with low grade/low risk demonstrating RTP in around 8 weeks and low risk/high grade and all high risk BSIs demonstrating RTS times around 20 weeks[1].


Using the information discussed in the diagnosis, identification of risk factors and classification we can formulate a management plan that is athlete-centred and multimodal. It must be noted that there remains high variability in the RTS timelines in athletes with BSI due to the multiple factors at play and the range of risk factors that need to be considered. In Part 4 we will discuss the management strategies that could be used by clinicians to successfully manage their athletes. Until then, happy miles!

  1. Management and Prevention of Bone Stress Injuries in Long-Distance Runners. Warden, S.J, Davis, I.S & Fredericson, M. 2014, Journal of Orthopaedic & Sports Physical Therapy, pp. 749-765.

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