Do X-rays show stress reactions/fractures

A bone scan could reveal a fracture when an X-ray didn't.

Plain x-rays generally do not show stress fractures. Several weeks after the injury an x-ray might show some evidence of healing without actually showing the fracture, but not always. And they do not show stress reactions.

The MRI has become the test of choice for this type of injury. Very very sensitive, and will also show surrounding structures (muscles, tendons, joint cartilage, etc). And no exposure to radiation.

Studies vary, but IIRC x-rays have about 30% sensitivity and ~90% specificity. This means that only 3/10 real stress fractures will show up on an x-ray (i.e. true positives correctly identified), but 9/10 non-stress fractures will be correctly ruled out. An x-ray is a good starting point only because it is cheap and easy to do. An MRI is necessary to rule out a stress fracture. Bone scans are also nearly as accurate. Personally I think the MRI is superior given that you can grade the severity of a stress fracture, giving an estimate of how long you'll have to take off.

So anyways, yes get an MRI asap.

Agree with poster above. MRI in conjunction with scan is best.

My daughter had ongoing shin pain for months that was getting worse. Had an Xray taken that showed nothing. Had an MRI, shin was lit up like a Christmas tree showing a stress reaction. Go with the MRI.

I've had two stress fractures in my left femur. Both times the x-ray did not indicate the fracture, but the MRIs did.

The way you make it sound, I would go back to the doctor and see if you can get an MRI.

MRIs are great for detecting stress fracture and a combination of STIR and FSE sequences are basically 100% sensitive for stress fracture. The correct evaluation is first a plain X-ray, and if that is negative and further imaging is needed then usually MRI is the test of choice. There are circumstances where a nuclear scintigraphic bone scan is preferred but for young runners MR is the go to.

That all being said, MR is very expensive and usually has high copays for orthopedic indications, and very rarely changes the treatment plan. My general recommendation is to avoid it except for 1) unusual locations 2) usual locations where there is a reasonable differential diagnosis including soft tissue pathology e.g. navicular 3) symptoms extremely resistant to conservative treatment (>8-12 strict weeks)

MRI is definitely not 100% sensitive for picking up a stress fracture but it is a good choice as it also visualizes the soft tissue and can pick up a "stress reaction" or pre stress fracture. Nothing is 100% accurate.

Bone scan is very sensitive but not as specific.

CT scan is another alternative - it is excellent for visualizing cortical bone.

If there is more pain as the run progresses that is one sign for a stress fracture.

A negative x-ray means nothing.

I recently had a serious runner with knee pain. X-rays were negative as was the MRI ordered by another physician (it was read negative, I did not see the actual scan, just the report)

As is the case with most runners, she is very knowledgeable about injuries. With a negative MRI and negative X-ray but still unable to run I decided to order an bone scan and it detected a Tibial stress fracture not seen on the other imaging modalities.

Stay away from CT scans. Too much radiation for a running injury.

Frankly, by the time you get in to have an MRI or bone scan, get the results read and get back to the Dr., you will have probably waited three to four weeks and burned through your $1,500 deductible. Why not just take 3-4 weeks off and go get an x-ray to see whether you can see the bone callous starting to form over the stress fracture (usually takes that long for it to show up)? X-rays should cost you $100-200.