In contrast, increased distance between the sigmoid notch and the distal ulna indicates dorsal ulnar dislocation.
(14) The congruency method is a subjective measurement of the congruency from the distal ulna to the sigmoid notch. (15) The most recent method, described by Lo and colleagues evaluates congruity by the radio-ulnar ratio.
Af Ekenstam (32) reported on the differing radii of curvature of the sigmoid notch and ulnar head.
The sigmoid notch has also been reported as a site of malunion correction.
The reconstruction failed in only two patients: one with incompetent wrist ligaments and one with a sigmoid notch deficiency.
Watson then went on to further refine the procedure into the "matched" hemiresection, which emphasized the congruency of the resected distal ulna to the retained sigmoid notch. (53,54) Watson and Gabuzda reported good to excellent results were noted in 24 of 32 patients and that the outcome was related to the severity of the patient's initial problem.
This implant requires a competent TFCC as well as a congruent sigmoid notch. Complications following implantation of the ulnar head include recurrent instability, which may be multifactorial and attributable to technical errors, such as over-reaming or failure to recognize subchondral defects.
Distal radioulnar joint instability in distal radius fractures: the role of sigmoid notch and triangular fibrocartilage complex revisited.
