Fact-sheet: Ulno carpal abutment syndrome
Updated on 09/12/2019 at 11:26 AM
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Definition
Degenerative condition caused by excessive loading on the ulnar compartment of the wrist.
An anatomical predisposition is often found: long ulna (positive ulnar variance >1 mm), congenital or acquired (fracture...).
It is a classic complication of a poorly reduced Colles' fracture.
This impaction leads to thinning and then perforation of the triangular fibrocartilage complex and chondropathy of the superomedial aspect of the lunate.
TFCC lesions are type II according to the Palmer classification, unlike traumatic lesions (type I).
It progresses to ulnocarpal osteoarthritis, often with a luno triquetral ligament tear.
Clinical features
Chronic or subacute pain on the dorsal aspect of the wrist, worsened by extreme rotational movements and ulnar deviation
Radiography
A long ulna is often found: positive ulnar variance >1mm.
MRI
Subchondral edema of the ulnar aspect of the lunate
Chondropathy of the superomedial aspect of the lunate
Positive ulnar variance (inconstant)
Palmer type II tear of the triangular fibrocartilage complex
Management
Treatment depends on the Palmer stage of the TFCC lesion as well as the ulnar variance, and may consist of partial or complete resection of the ulnar head
Classification
Ulnocarpal impaction corresponds to class II degenerative lesions of the triangular fibrocartilage complex (TFC), and are subdivided into:
- type IIa = TFC degeneration
- type IIb = TFC degeneration + lunate, triquetrum lesion +/- ulnar chondromalacia
- type IIc = TFC perforation + lunate, triquetrum lesion +/- ulnar chondromalacia
- type IId = TFC perforation + lunate, triquetrum lesion + ulnar chondromalacia + luno triquetral ligament perforation
- type IIe = Same as above + ulnocarpal osteoarthritis
Differential diagnosis
The other etiologies responsible for ulnar-sided wrist pain are numerous:
- Traumatic tear of the TFCC or of the luno triquetral ligament (Palmer I)
- Sprain of the dorsal band of the extrinsic carpal ligaments
- Sprain of the medial collateral ligament of the wrist
- Extensor carpi ulnaris tendinopathy
- Kienböck disease (lunate osteonecrosis)
- Hydroxyapatite deposition disease of the flexor carpi ulnaris