MRI versus the Stress Test: Which one do you need?Foot and Ankle
Mark Yakavonis, MD, MMS, is an orthopedic surgeon who specializes in foot and ankle surgery. Dr. Yakavonis has expertise in treating a variety of foot pain and deformity related conditions including Achilles tendonitis, ankle instability, cartilage injuries, bunions and hammer toes and keeps up to date with the latest breakthroughs in the field. Most recently, the unnecessary reliance on the MRI compared to conducting a simple stress test has caught his attention. The following is what he wants you to know:
Nowadays, orthopedic surgeons will frequently order Magnetic Resonance Imaging (MRI) studies for patients suffering from acute or chronic musculoskeletal injuries. Radiographs, also known as plain films, show a two dimensional projection or shadow of bone. It is useful for diagnosing obvious displaced fractures, but subtle findings are often missed.
The MRI is advanced technology that provides information in three dimensions about bone, tendon, muscle, ligament, fat, swelling, fluid, etc., but are unlike plain films, which just show bone. Basically, it shows us just about everything we need to know short of nerves and other subtle dynamic findings. It uses no radiation and is incredibly safe.
But in the setting of an ankle fracture – where either the fibula or tibia is broken near the ankle and our job as surgeons is to determine which ankles will be fine with a cast and which need a surgical correction – AN MRI IS OF NO ADDED BENEFIT. What I want to determine in this setting is whether the fracture is “stable.”
An unstable fracture will shift with time, even with a good cast, and certainly once a patient begins walking. Shifting is a very bad thing, especially in the ankle. It leads to abnormal pressures on the joint, cartilage wearing, degenerative changes, and stiffness, also known as post traumatic arthritis. In an active and healthy patient, that is unacceptable. A significantly better outcome is achieved with a one hour surgery to fix the fracture and restore anatomic alignment and stability.
The main problem with an MRI is that it is a static test. The images are taken with the patient lying flat on a table. There is no weight or force across the ankle joint. While an MRI can image the ligaments in the setting of an ankle fracture, these ligaments are always injured, but whether they are injured to the point of instability is indeterminable.
A simple test that costs very little and takes about 5 minutes is a stress radiograph. Using either gravity or the hands of a surgeon, a mild stress is placed across the ankle joint. If the joint widens or shifts I know that it will do the same in the future. The most up to date orthopedic literature supports stress x-rays are the best way to decide between surgical and non-surgical treatment, not MRIs.
The other problem with an MRI is cost and time. It is a 30-45 minute test and carries with it a significant cost. The burden of the cost is shared by the patient, the insurance company, and society as a whole. With the skyrocketing costs of healthcare in our country we should reject the notion of ordering tests when they should have no effect on our decision.
A 2014 article supports this from the Journal of Bone and Joint Surgery, the official scientific journal of the American Academy of Orthopaedic Surgeons.