12 May Bone stress injuries
Did you know bone stress stress injuries (BSI) accounts for 10% of all sports-related injuries? And it is not just sports people that suffer with these injuries.
What are bone stress injuries?
Bone stress injuries (BSI) are an overuse injury to the bone. It occurs when bones suffer repeated over-loading and not enough rest periods. This causes bone fatigue resulting in loss of structural integrity and function of the bone, which means it can longer withstand the repetitive loading. Often then localized pain will be felt in the bone with repetitive loads and it may be painful on touch.
When a normal bone is loaded a micocrack is formed, which activates cells called osteoblasts and osteoclasts. Osteoclasts “clean up” the microdamage and osteoblasts deposits new bone. The new bone becomes mineralised over time into healthy new bone. This process occurs over time so that bones are able to tolerate more load.
Stress injuries occur when the microcracks are occurring at a greater rate than the body can keep up with. For example high intensity training without adequate resting time for the bone repair and remodelling phase means that the micro-damage will never fully recover and will accumulate over time.
BSI differ in severity, from periosteal edema and marrow edema up to more severe injuries such as stress fractures and bone fractures. The progressive stages of a BSI include:
- Bone strain or bone stress response. In this stage, symptoms (pain) is not yet felt, but imaging (eg. MRI, bone scan) would show signs of stress.
- Bone stress reaction. Pain would now be felt and especially during loaded and repetitive activities. Also the bone will be tender on touch.
- Bone stress fracture. Fractures or breaks in the bone have developed and often this is now seen on imaging. Often significant pain is felt, which is localised to the bone and now can be aggravated by simple weight-bearing or loading.
Why does a bone stress injury occur?
Stress injury occurs due to a range of contributing factors, which we can break up into two categories: biomechanical factors and biological factors.
Biomechanic factors
These are all things that can affect or modify the actual loads that goes through a bone. Some of the contributing factors for BSI include:
- Increased training load (increased training frequency, intensity or volume, and/or reduction in rest periods);
- Changes in training surface (particularly a harder or more rigid surface);
- Changes in footwear (wearing the wrong shoes, using older ‘worn-out’ shoes);
- Poor muscle strength;
- Poor technique or control with activity.
Biological factors
These are factors which affect how our bones react to loads. Some of the contributing factors include:
- Poor bone health and bone density;
- Genetics (family history of BSI, osteopororis/osteopaenia);
- Insufficient Calcium and/or Vitamin D;
- Poor diet and nutrition;
- Previous history of BSI;
- Relative energy deficiency syndrome (RED-S)
- A syndrome caused by a deficit in energy intake
Do only sports people get bone stress injuries?
Although BSI do make up a high percentage of sports-related injuries (especially amongst running athletes), these injuries can occur in everyone. Often it is seen in anyone who has started or undergone an increase in intense physical activity.
Jessica Bank
Physiotherapist
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References
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Warden SJ, Davis IS, Fredericson M. Management and prevention of bone stress injuries in long-distance runners. J Orthop Sports Phys Ther. 2014 Oct;44(10):749-65. doi: 10.2519/jospt.2014.5334. Epub 2014 Aug 7. PMID: 25103133.
Fuchs, R. K., Thompson, W. R., & Warden, S. J. (2019). Bone biology. In Bone Repair Biomaterials (pp. 15-52). Woodhead Publishing.
Warden, S. J., & Fuchs, R. K. (2018). Physical Activity to Promote Bone Health in Adolescents. In A Practical Approach to Adolescent Bone Health (pp. 53-76). Springer, Cham.
Hoenig T, Eissele J, Strahl A, et al
Return to sport following low-risk and high-risk bone stress injuries: a systematic review and meta-analysis
British Journal of Sports Medicine Published Online First: 31 January 2023. doi: 10.1136/bjsports-2022-106328