With the warmer months approaching, running training often ramps up for a lot of athletes. Bone Stress Injury (BSI) can be a dreaded injury for any runner due the potential for lengthy recovery times, sometimes well over 6 months.
BSI’s represent the inability of bone to withstand repetitive loading, resulting in structural fatigue and localised bone pain and tenderness.
These injuries sit on a continuum whereby they begin with a stress reaction (often described as a ‘hot spot) which can progress towards a stress fracture and ultimately, towards a complete bone fracture. Essentially, the further the BSI progresses along the continuum, the longer the recovery time. Therefore, an understanding and early recognition of these injuries is critical to any athlete and their running goals.
Cause of Bone Stress Injuries
Bone is Mechanosensitive, meaning skeletal bone responds to mechanical loading (such as running) stimulating bone to adapt and become stronger. This is a key factor in osteoporosis, a disease affecting bone mass and strength. That is, exercise and strengthening are essential elements to promote bone remodelling and thereby optimise skeletal strength. However, in the active athlete, a BSI develops when the load being applied to an adapting bone, exceeds the threshold for what that bone can tolerate (i.e. it is being overloaded). Hence, the bone becomes ‘stressed’ and if left un-noticed, can progress down the nasty continuum towards a stress fracture.
Whilst BSI’s are strongly determined by an athletes training loads, there can be numerous individual contributing factors that may predispose to injury.
These can include:
- Biomechanics – for eg. Running technique
- Training errors: for eg. Large increases in training loads (not allowing the bone sufficient time to ‘adapt’)
- Muscle strength and endurance
- Previous history of injury, especially a previous BSI
- Diet and Nutrition
- General Health
- Training surfaces & footwear
Diagnosis of Bone Stress
BSI’s are an overuse injury that is typified by a gradual onset of pain with activity. A thorough review of the athletes training history is essential, looking for a spike, or rapid change in training load. In the early stages of the continuum, pain may be a mild diffuse ache during running that eases upon rest. As the stress reaction progresses, pain can be significant during loading and in the late stages, pain may be present even at rest or with low load tasks such as walking or at night. Pain is often localised and will be tender to palpate. Often, imaging such as an X-ray or MRI is required to confirm diagnosis.
Common Locations of Bone Stress
BSIs are often categorised into low-risk BSIs or high-risk BSIs. Those regarded as low risk are those that generally recover with minimal complications or prolonged modified weight bearing. Examples of low-risk BSIs include, the fibula (small bone of the leg), calcaneus (heel bone) or the metatarsal shafts (bones of the foot).
High Risk BSIs are those that can present treatment challenges owing to much longer recovery times, and sometimes a failure to heal at all. These often develop into complete fractures and may require surgery. Examples of high-risk BSIs include, the neck of the femur, anterior aspect of the tibia or the navicular in the midfoot. The navicular can be particularly nasty and has prematurely ended or restricted many elite AFL athletes playing careers in the past.
If you have any concerns with running related pain, ensure BSIs are considered and reviewed by an experienced Sports Physiotherapist or Sports Doctor. Early and optimal management is crucial for a successful recovery and ability to perform.