It’s becoming more and more routine to obtain an MRI scan if a thrower has a suspected injury to their UCL. But what does the MRI really tell us?
The UCL tears in variety of ways, and we characterize the tear based on the location, the degree of tearing, and if chronic features exist. An MRI will not show a small slight stretch to the ligament to be a tear. It will however show swelling around the ligament. A partial tear will show some fibers are disrupted and some are still intact. Whereas, a full tear, just as implied, has no intact fibers.
It’s also important where the tear is located, as it can be either on the top end, the middle, or the bottom portion of the ligament. Lastly, some tears happen with chronic changes to the ligament. In this instance, chronic refers to a process where the ligament has had prior small injuries that were able to heal, but the ligament is changed from its normal state. For example, the ligament may become thickened or even have calcium deposits.
Why is this important? The tear’s characterstics can help determine the capacity of the ligament to heal with out surgery. For example, partial tears at the top of the ligament heal much better without surgery compared to partial tears at the bottom of the ligament. While full tears at the bottom of the ligament have even less of a chance of healing.
Figure 1. Shows partial ligament tear at the bottom insertion site onto the ulna bone.
Figure 2. Shows a full tear in the midsubstance of the ligament.
Figure 3. Shows a full tear at the top insertion site onto the humerus bone.
With the technology and technique available today, it’s truly amazing to think back to 1974, a time when Tommy John was diagnosed with a UCL tear by Dr. Frank Jobe before MRI was available.