Stress fractures occur from overuse of a specific part of the body, and are often seen in athletes and people with very active lifestyles. Your bone is constantly trying to remodel and repair itself, especially when put under intense pressure. For example, for every mile a runner completes, 110 tonnes of force is absorbed by their legs — an incredible amount of pressure that can lead to a stress fracture requiring treatment.
The most common bones to suffer stress fractures are the femoral neck, proximal tibia, distal fibula, tarsals, and metatarsals — all found in weight-bearing areas such as the legs and feet. Depending on your symptoms, your doctor might refer you for an MRI scan to confirm whether you have a stress fracture and determine the best course of treatment.
An MRI uses radio waves and a strong magnetic field to create detailed images of your bones and their surrounding soft tissues. It is a non-invasive medical procedure that does not use radiation, making it suitable for a greater number of patients without the associated risk factors.
An MRI is considered the best imaging option for diagnosing stress fractures, as it can detect lower-grade stress injuries before any changes appear on an X-ray. MRIs can also help distinguish between stress fractures and soft tissue injuries in most patients.
Not long ago, X-rays were the primary method for diagnosing stress fractures — however, X-rays only have a 15 to 35% chance of detecting stress fractures on initial examination, making them relatively ineffective on their own.
MRI scans have now surpassed X-rays as the preferred imaging tool for stress fractures, offering better sensitivity and higher specificity (around 85%). This provides greater anatomical detail and a better insight into the tissues surrounding the injury. You may be referred directly for an MRI, or taken for an X-ray first and then referred after inconclusive findings.
Before your MRI appointment, you should generally be able to eat, drink, and take your medications as normal. Depending on the location of your stress fracture, you may be asked to withhold food for up to four hours, or to drink plenty of water beforehand. Your health provider will advise you on the specific preparation required.
You may also find it helpful to prepare questions for your doctor ahead of the appointment, such as:
* How long will I have to stop exercising for?
* Do I need to see a specialist?
* What are the likely causes of my symptoms?
As the MRI machine involves a large magnet, all metal items should be left at home or stored in the locker provided. Inform your doctor beforehand of any metallic medical devices such as pacemakers or pins, as these may affect whether you are able to have the scan.
Upon arrival, radiology staff will check you in and verify your appointment. You will be given a gown to change into and a secure space to store your belongings. Ensure everything is left in your locker — including jewellery, keys, and hearing aids — before entering the scan room.
Once ready, the technologist will position you in the scanner. If your symptoms are in your legs or feet, you will most likely lie on the bed and enter the scanner fully. The machine is quite loud, so headphones will be provided to keep you comfortable during the 45 to 60 minute scan. You will need to lie completely still throughout, as movement can reduce image quality. You can speak to your radiologist at any time if you feel uncomfortable.
After the scan, you will be taken back to your belongings and left to change. As long as you are feeling well, you are free to leave and await your results. If a sedative was administered, you may need to wait for it to wear off, or arrange for someone to drive you home. Your doctor should be in contact within a few days to discuss the results.
Greater accuracy than other imaging options
MRI scans can detect stress fractures and surrounding soft tissue issues with a significantly higher success rate than X-rays — around 85% compared to 15 to 35% for X-rays.
Non-invasive
MRIs do not use radiation and can assess the internal structures of your body without any invasive procedures.
Distinguishes between stress fractures and soft tissue damage
Some stress fractures can be mistaken for soft tissue injuries. An MRI can differentiate between the two, ensuring you receive the correct treatment as quickly as possible.
Detailed imaging
MRI scans provide clear, detailed images that give your doctor a thorough understanding of the injury and surrounding tissues.
There are very few risks associated with a Stress Fracture MRI, as it does not use ionising radiation. However, as the MRI machine contains a large magnet, it is essential to disclose any metal medical devices to your doctor before the scan. If you have had previous surgeries involving pins or plates, your doctor will also need to be informed.
There are several symptoms you might experience when dealing with a stress fracture, including: pain that starts or worsens with physical activity; pain that does not improve after stopping activity; pain that is more noticeable at rest; tenderness near or on the affected bone; and swelling and redness.
Most Stress Fracture MRI scans take between 45 and 60 minutes, though this can vary depending on the number of images required. Some scans may take as little as 15 minutes, while others may extend to 90 minutes. If there is significant movement during the scan, additional time may be needed to capture clear enough images for a diagnosis.