This blog will be discussing what a Bone Stress Injury is and how these injuries can develop. The running and triathlon season is in full swing with recent the Sydney running festival, Melbourne marathon and several ultra marathon events. As the weather starts to improve we also notice more and more runners in the street over the summer period. Running related injuries can be extremely frustrating for those involved, especially when training for an event. Depending on the tissue that is involved, injury rehabilitation time frames can vary significantly. Therefore, following a structured training program and understanding modifiable and non-modifiable risk factors is essential.
Bone stress injuries are common amongst runners. 0.7-20% of all sports medicine injuries that present to clinicians are bone stress injuries (Bennell et al 1999). Tenforde et al (2015) reported an annual incidence amongst collegiate track and field and cross country runners to be 20% for both male and female athletes.
Unfortunately Bone stress injuries are common in middle to long distance runners, particularly with increasing in training blocks, and even more unfortunately these injuries are often ignored, misunderstood or simply missed until it is too late.
Bone stress injury represents the inability of bone to withstand repetitive loading, which results in structural fatigue and localized bone pain and tenderness. Bone Stress Injury occurs along a pathology continuum that begins with a stress reaction, which can progress to a stress fracture and, ultimately, a complete bone fracture.
The mechanism of the development of bone stress injuries is the response of imbalance between load-induced microdamage formation and its removal.
In normal healthy bone new activities or prolonged levels of loading stimulate a turn-over of bone cells, this is known as targeted remodeling. First, the body breaks down selected portions of the bone (areas of micro-damage), temporarily weakening it. Then within 1-2 weeks new bone tissue is laid down. Once established, the new bone is stronger, denser, and better accustomed to the new activity or increased load. However, if we continue high loading or impact activities during this turn-over period and don’t give our bones adequate time to recover, over time, the overloaded bone will accumulate micro-fractures and eventually break down, developing into what we call a bone stress injury. (1)
Targeted remodeling maintains homeostasis between microdamage formation and its removal
● Preserves skeletal mechanical integrity
● Reduces tissue age
● Enables bone to adapt over time to meet changing demands
Read here for more blogs on Bone Stress Injuries and risk factors in developing stress fractures.
Reference:
1. Warden SJ, Burr DB. Bone Stress Injuries. Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism. 2018 Sep 25:450.
