Anna Hirschmann MD, Presenter: Nothing to Disclose

Reto Sutter MD, Abstract Co-Author: Nothing to Disclose

Andreas Schweizer MD, Abstract Co-Author: Nothing to Disclose

Christian W. A. Pfirrmann MD, MBA, Abstract Co-Author: Nothing to Disclose

To characterize the MR appearance of the trapeziometacarpal (TM) ligaments and quantify joint alignment in asymptomatic volunteers.

This prospective study was approved by the institutional review board. Informed consent was obtained. 34 asymptomatic volunteers underwent MR of the thumb (17 women, 17 men; mean age 34 years, SD 9 years) on a dedicated 1.5T extremity MR scanner. Two musculoskeletal radiologists quantified visibility and signal intensity (SI) characteristics on a 4-point scale (hypointense, intermediate, striated, not visible) and thickness for the anterior oblique/beak (AOL), the posterior oblique (POL), the intermetacarpal (IML) and the dorsoradial ligament (DRL) of the TM joint. The alignment of the metacarpal base with the trapezium was quantified in two planes. Data were analyzed with a Mann-Whitney U test.

The POL and IML were visible in all 34 (100%) volunteers, the AOL and DRL in 33 (97%). On intermediate weighted fat-saturated images the POL (65%) and DRL (56%) were commonly of intermediate SI, while the IML had a striated appearance in 91% of subjects. The AOL showed a variable SI distribution (35% low, 26% intermediate, 35% striated). Mean thickness was 1.4mm for the AOL (SD 0.6mm), 2.3mm for the POL (SD 0.6mm), 2.9mm for the IML (SD 1.0mm), and 1.2mm for the DRL (SD 0.5mm). The AOL was significantly thicker in men (2.1mm) than in women (1.3mm; p=0.023). There was a mean dorsal subluxation of 1.8mm (SD 1.0mm) and radial subluxation of 2.8mm (SD 1.5mm) of the metacarpal base. Radial shift was significantly larger in men (2.1mm) than in women (1.4mm; p=0.02). No shift in palmar or ulnar direction was seen.

The signal intensity of TM joint ligaments is variable. The IML is typically striated and thicker compared to the other ligaments. Radial and dorsal subluxation of the TM joint is normal in standard MR imaging.

Reference values for ligaments and incongruity of the TM joint are presented, which may be useful for MR evaluation of trapeziometacarpal disease.

Hirschmann, A, Sutter, R, Schweizer, A, Pfirrmann, C, MR Imaging and Anatomical Variants of the Trapeziometacarpal Joint.  Radiological Society of North America 2012 Scientific Assembly and Annual Meeting, November 25 - November 30, 2012 ,Chicago IL. http://archive.rsna.org/2012/12033531.html