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Bone Stress Injuries

Stress reactions and stress fractures are one of those heart sink injuries for all athletes.

These injuries commonly present with localised pain and tenderness over the fracture site.  This presentation will often coincide with a recent change in training such as an increase in intensity and load.  Stress fractures can theoretically occur in any bone. The majority of these injuries are uncomplicated and heal predictably with a period of rest. Good examples of these injuries include most metatarsal shaft fractures, postero-medial tibial stress fractures and injuries involving the fibula, so really all the weightbearing bones in the lower limbs but also the pelvis.  Some of these injuries, such as those involving the femoral neck (hip) or navicular (foot), carry a higher risk of non-union or complete fracture. The management of high-risk fractures requires the clinician to be more aggressive. These injuries require further investigation and often more specialised treatment. 

Investigations

The primary investigations used for the diagnosis (and the subsequent management) of stress fractures are radiological. There are a variety of options available to image this type of injury. It is worth noting that certain bones and situations may require a specific form of investigation, talk to your doctor about appropriate investigations.

X-ray

The X-ray changes of a stress fracture usually occur late in the presentation, if at all. In many cases, stress fractures are never demonstrated on X-ray images.  Whilst worth doing as a first step to assess the presence of a complete fracture, an x-ray should not be used to rule out a bone stress injury. 

CT

This modality may be required to visualise cortical fractures in bones that are not easily visualised with plain two-dimensional X-rays. These bones include the navicular (foot) and the pars interarticularis part of the vertebrae in the back). CT should be used cautiously, particularly in children, due to the increased risk from the radiation dose. 

Bone scan

Nuclear medicine bone scan or scintigraphy uses the injection of a radio-labelled isotope. This technique is very sensitive for detecting increased bony remodelling. The radioisotope uptake remains for a period of time beyond clinical recovery of stress fractures and so bone scan may be less useful in ongoing monitoring of recovery. Also, increased isotope uptake is not specific for a stress fracture as there may be other causes (including infection or tumour).

MRI

MRI provides the benefit of multiplanar imaging of the CT scan with the detection of bony pathophysiology of the bone scan but without the radiation. A stress fracture may be identified as periosteal or bone marrow oedema (swelling) on MRI as well as visualisation of a fracture line in certain sequences. Similarly, to bone scan, bone marrow oedema is not specific for stress fracture on MRI, and the oedema may remain for some time after resolution of the stress fracture.

DEXA scan

Female athletes who have a stress fracture, should consider having a DEXA (dual energy X-ray absorptiometry) scan to assess their bone mineral density. This can have an important impact on their longer-term treatment. These should not routinely be repeated more than once every two years. Any changes that might occur happen slowly.

Case Study

One of Cairns’ elite youth long distance runners Kaiyan Blue (14 years old) who sustained a navicular bone stress injury in February 2021.  In a classical history, this young athlete had returned to training and increased his load significantly.  He reported a pain in his foot following a cross country run at school and couldn’t complete his training sessions that week due to ongoing discomfort.  He was examined and imaged early due to the high suspicion and history.    Kaiyan was lucky that his family were quick to ask for help and investigate his pain appropriately.  He is likely to have avoided a stress fracture through the quick access to a consultant opinion and specialist investigations.  The navicular is of course a high-risk area for stress fractures.

To appreciate the level that this young athlete is at here is a snippet of his CV:

2020 North Queensland Champion 1500m

2020 North Queensland Champion 3000m

2020 Cross Country Queensland State Silver medal winner

2019 Athletics North Queensland Champion 3000m (Setting a record of 9:56)

And for the weekend warriors…his Park Run PB is 17:15! 

Kaiyan would normally comfortably run 5-6 times per week, clocking distances of 5-12k during training.  His injury was identified early, and activity modification was implemented quickly. This involved an initial period of rest and the wearing of a protective boot.  Maintenance of physical conditioning was achieved through deep water running, cycling, swimming and anti-gravity treadmill work.  Kaiyan is maintaining his fitness with a range of non-weightbearing exercises before commencing a graduated return to running programme.  We wish him a speedy recovery and best of luck for the 2021 running season!

Image 1 : Navicular Bone Stress Reaction

Image 2 Deep Water Running

Image 3 Anti-gravity Treadmill