Bone Stress Injury- causes and treatment

What is a bone stress injury?

In simple terms, a bone stress injury is when the bone and often the surrounding tissues become painful. There is an inflammatory reaction in the bone, and this can then lead to bone oedema, a build-up of fluid in the bone (like swelling).  

If the injury is not managed, a bone stress injury can progress to a stress fracture (a break in the bone). 

Why do we develop bone stress injuries?

As with other atraumatic running injuries, bone stress injuries occur when the demand placed on the bone exceeds that of the bone's capacity to withstand the load. There are known risk factors that might reduce bone health and therefore reduce the capacity of the bone to meet the demands of the sport/activity. If this is then combined with an increase in the amount of training or a lack of recovery between training sessions, the bone is left vulnerable. There are a few intrinsic factors that make someone more vulnerable to develop a bone stress injury and these should raise a clinician's suspicion of this diagnosis.

Risk Factors

  • The biggest predictor of a bone stress injury/stress fracture is having a prior bone injury or stress fracture.   
  • Females have a higher risk of stress fracture than males.  
  • Menstrual cycle changes - hormonal imbalances associated with having a longer menstrual cycle or a loss of periods can influence bone health.  
  • Menopause - post menopausal hormonal changes can affect bone density.   
  • Known low bone density - osteoporosis and osteopenia. 
  • Low BMI- being underweight can have consequences. to our bone density.
  • A history of an eating disorder- this can lower bone density.  
  • Diet and nutrition - particularly those with low vitamin D and calcium intake. We need to take on enough calories to meet the demands of daily life and our sport. 
  • History of taking oral steroids or anticonvulsant medication. 
  • Lack of sleep. 
  • High stress levels. 

Symptoms

  • Periosteal inflammation (First stage) - People often describe a diffuse ache along surface of bone when there is impact on the limb, this then settles with rest. This pain then often builds up if running is continued. This is different to tendon pain which often has a warm up effect and can ease with running.   
  • Bone oedema (Second stage) – The ache often worsens and may include pain at rest. There may be swelling visible.  
  • Stress fracture (some bone injuries progress to a stress fractures)– Pain becomes more localised and might be present in light weight-bearing activities. Some will have night pain. Often there is pain at rest and swelling. Some stress fractures, such as the femoral neck (top of the thigh) can give rise to diffuse pain. An anterior superficial tibial fracture is often more localised. Type of pain can vary depending on the area of the fracture.  
  • It is important to note that not everyone will follow these symptoms. For example, bone oedema can be found on MRI on those with no symptoms. 

Treatment

  • Rest - Unlike soft tissue injuries, bone stress injuries and certainly stress fractures, require a period of rest from sport. Stress fractures require a period of non weight-bearing. With bone stress injuries, the appropriate level of weight-bearing should be established, if minimal weight-bearing is painful then complete rest should be advised.  
  • During the rest stage, non-impact cross training can be commenced, for example, cycling and swimming. Non weight-bearing strengthening can also be implemented.  
  • Strength and conditioning- Strength training for the whole limb should be started. Progressive resistance training is thought to improve bone density. Having stronger muscles is thought to reduce the impact on the bones during running.  
  • Gait re-education - Looking at running and walking patterns can sometimes play a role in the rehab of these injuries and prevention of future bone stress injuries.  
  • Bone loading programme- Bones adapt, become stronger and more resilient through weight-bearing exercises, but this must be gradual to avoid set backs. Short bursts of weight-bearing exercise is optimal for bone strength, for example jogging on the spot for 1-2 minutes. Weight-bearing exercise should be pain-free. These exercises should be progressed for speed and intensity and multidirectional exercises should also be used to help bone strength. This should be guided by a physiotherapist to ensure a safe return to running.  
  • Gradual return to running/sport- To return to running/sport, the activity must be pain-free and ideally strength needs to be restored so that the right side equals the left side. A run/walk programme is ideal at first with a gradual reduction of the walking element. There needs to be careful monitoring of the symptoms. Gradually over time, full running should be restored.