Wednesday, January 9, 2008

Evaluation of Thumb UCL Tears

The ulnar collateral ligament of the first MCP joint can be evaluated by MRI, but like most things in life, some do it better than others. A high-field scanner (at least 1.0 Tesla) with strong gradients is critical. With good hardware and proper protocols, one can get excellent images.

The critical question in the setting of a tear of the UCL is whether there is a Stener lesion. This occurs when the torn UCL retracts and becomes superficial to the aponeurosis of the adductor pollicis. The ligament can no longer heal, and chronic instability results. A Stener lesion can be repaired surgically.

Example of a torn UCL, without a Stener lesion:

(click on image to enlarge)

Red arrows = torn UCL
White arrows = intact RCL (for comparison)
Yellow arrows = aponeurosis transverse head adductor pollicis
Pink arrows = aponeurosis oblique head adductor pollicis
Green arrow = intact accessory collateral ligament

Thus, in this case, the torn UCL is beneath the adductor aponeurosis, and there is clearly no Stener lesion.

MRI sometimes gets a bad rap for the evaluation of Stener lesions, because the test is often done poorly, and interpreted incorrectly. In the hands of a good MSK radiologist, however, it an excellent test.


Anonymous said...

Hi Vic!

Thank you for interesting pictures on the UCL oft the thumb. As you write, this can be hard to diagnose. What would you recommend as parameters and sequences for imaging of the thumb and the collateral ligaments?

Regards Roar Pedersen, Norway

Vic David MD said...

It's hard to get good images of the thumb UCL at less than 1.5 Tesla. Images start looking good with 8 channel coils and strong gradients e.g slew rate> 120 T/m/s and gradient strength >35 mT/m.

Best sequence is intermediate and intermediate fatsat. Sample parameters with an 8 ch knee coil, GE system: FOV 12 cm, ETL 6-8, matrix 384x224, slice thickness 2.6/0.1, BW 25, 3 NEX. Use oblique coronal, set up from an axial of first metacarpal head.

Works for me, your mileage may vary depending on your hardware and software...