Ulnomeniscal homologue

The ulnomeniscal homologue (UMH) is an obliquely oriented, fibrocartilaginous structure, that forms part of the ulnar collateral ligament complex (ULC).

The UMH is located between the ulnar styloid process and the triquetrum. It adheres to the ulnar joint capsule and merges with the ulnar carpal collateral ligament, and the sheath of the extensor carpi ulnaris (ECU) tendon. These structures normally cannot be differentiated by imaging. Dorsally, the UMH inserts into the radial notch together with the dorsal radio-ulnar ligament 1.

From proximal to distal, the UMH can be divided into four components: 

  • styloid
  • radioulnar
  • collateral
  • distal insertion

The styloid component is the principal part, it has a triangular shape on coronal sections. The other parts serve as a suspension system, that attaches to the styloid process proximally, and the triquetrum and hamatum distally.

The UMH is separated from the TFC by the prestyloid recess of the wrist joint.

There are three variants of this recess 2:

  • wide opening
  • narrow opening
  • absent
MRI

MRI is the method of choice for depicting the ULC. As with fibrocartilage in other parts of the body, it normally appears hypo-intense on T1- and T2-weighted images. As in the TFCC, there is a more signal intense, central ulnar portion due to fibro-vascular connective tissue. Assessment of the UMH and the prestyloid recess is only possible in the presence of effusion or intra-articular contrast (MR-arthrography). The appearance of this recess is highly dependent on the wrist position at imaging: if present, it collapses on ulnar abduction.

An ulnar detachment injury of the UMH has been described at arthroscopy 3. However, this has never been documented with MRI or MR arthrography.

Upper limb anatomy
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Article information

rID: 16393
Section: Anatomy
Synonyms or Alternate Spellings:
  • Ulnomeniscal homologue (UMH)

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    T2*
    Case 1
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