Patients will often ask me: “Doc why do I need an X-ray, why don't we just get an MRI?” I have also recently had a patient specifically ask me: “Doc, why do you get X-rays anymore when you can get MRIs?”

There can be a lot of confusion amongst patients (and medical practitioners alike) as to the value of X-rays versus the value of MRI.

To simplify things, an X-ray is an image that is performed by projecting X-rays, which are a form of radiation, through a particular body part. The X-rays will travel through the soft tissues, but they will not travel through the hard tissues such as bones, calcium deposits, teeth, etc. This leaves an image/picture on the X-ray film that gives us valuable information.

Also simplifying things, an MRI is produced by a large magnet that produces a magnetic field. The scanner is then able to pick up the different signals given off by the tissues in our body when exposed to a magnetic field. With the help and enhancement of a computer the MRI scanner is able to generate a very sophisticated image that is especially good for looking at soft tissues. It can also show us many things about bone that we would never see on a plain X-ray.

X-rays themselves are very, useful for orthopedic surgeons because orthopedic surgeons are sometimes referred to as “bone doctors.” Orthopedic surgeons do not only deal with bones, but also deal with joints, muscles, tendons, ligaments, etc.

However, the reality is orthopedic surgeons do spend a lot of time looking at bones on X-rays. X-rays are very good at picking up fractures, the shape of fracture, the type of fracture, as well as other abnormalities in the bones and joints.

Also, X-rays are very good for evaluating arthritis, because on an X-ray we see “joint space narrowing” with arthritis. It is really not necessarily that the joint space is narrowed, it is that the cartilage has worn down on the end of the bone. The cartilage does not normally have calcium in it, so it does not usually show up on an X-ray, whereas bone has calcium in it, so it shows up white on X-ray.

When looking at an X-ray, the “space” between the bones is actually the amount of cartilage that remains. When there is “no space” between the bones on an X-ray that indicates that the cartilage on the end of the bone is worn down which is basically what arthritis is. Therefore X-rays are very important in helping us determine if a patient has arthritis, and if so, how severe it is.

MRIs are outstanding studies for looking at soft tissues such as muscles, tendons, ligaments, cartilage etc. MRI has also allowed physicians to be able to look at bones in a different light. In the past, we never knew that bones could actually get bruised, just like our skin, muscles, etc. We can now see “bone bruises” on MRI. We can also see stress fractures much better on an MRI than on an X-ray. With regards to diagnosing a stress fracture, an MRI is almost like looking at a bone “with a magnifying glass,” where as plain X-ray film is more like looking at it with the “naked eye.”

Both studies show different things that are useful when put together to help complete the “pieces of the puzzle” when orthopedic surgeons try to come up with a diagnosis and treatment plan for a patient. This is rather simplified, but does hopefully allow people to understand why both X-rays and MRIs are very important in their own light and why one cannot substitute for the other in most cases. They are complementary, but they are not mutually exclusive.

Dr. Marc P. Pietropaoli is a board certified/fellowship trained

orthopedic surgeon/sports medicine specialist and is president of

Victory Sports Medicine & Orthopedics in Skaneateles.