Thumb carpo- metacarpal joint.

A) Anatomy:

-Take care that when you are looking for the coronal MR view of the wrist you are looking at the same time to sagittal view of the thumb while when you are looking for sagittal view of the wrist you are looking also to coronal view of the thumb.

Here is the sagittal view of the wrist where  you are really looking to coronal view of the thumb 

the articular surface of the metacarpal base (blue dotted line) is convex and that of the trapezium (red dotted line) is concave in the radial - ulnar plane. R= radial, U= ulnar. 

Here is the coronal view of the wrist where  you are really looking to sagittal view of the thumb. The articular surface of the metacarpal base is concave (blue dotted line) and that of the trapezium is convex (red dotted line), in the dorsal to volar plane. D = dorsal, V = volar.

At the radial aspect of the thumb trapeziometacarpal joint (A), the dorsoradial ligament (DRL) and overlying abductor pollicis longus (APL) tendon cannot be distinguished from one another adjacent to the radial aspect of the dorsal tubercle of the trapezium.

 In (B), just ulnar to the DRL ligament¬, the dorsal central ligament (DCL) lies directly beneath the extensor pollicis brevis tendon (EPB).

 The next ulnar image in (C), is the junction of the DCL and posterior oblique ligament (POL). At the volar aspect, the anterior oblique ligament (AOL) attaches to the articular margin.

Nearing the ulnar aspect of the joint on the next image slice, the posterior oblique ligament (POL) and anterior oblique ligament (AOL) are both identified.

 On successive coronal STIR images moving from volar to dorsal, the intermetacarpal ligament (IML) extends between the first and second metacarpal bases.

A 44 year-old male with dorsoradial thumb CMC joint dislocation (following reduction) due to fall on the outstretched hand 6 days ago. Sequential coronal STIR images moving from radial (A) to ulnar (D) a reveal a high grade partial tear of the AOL with distal retraction of its attachment to metacarpal base (arrow, A) with periosteal stripping and with small avulsed cortical fragment (arrowheads in A and B). A severe partial tear of the trapezial aspect and attachment of the dorsal ligaments is present (asterisks) - DRL in (A), DRL/DCL in (B), DCL in (C), POL in (D).


Reference