Clinical and radiographic factors associated with distal radioulnar joint instability in distal radius fractures

Abstract

Background: Distal radioulnar joint (DRUJ) instability is an important cause of ulnar-sided wrist pain in distal radius fractures. However, instability is frequently undiagnosed and the clinical and radiographic factors associated with instability are not well understood.

Questions/purposes: We therefore identified clinical and radiographic factors associated with DRUJ instability in distal radius fractures.

Patients and methods: We retrospectively reviewed all 221 patients who underwent surgical treatment for unstable distal radius fractures from 2007 to 2010. Ten patients (five men and five women) had DRUJ instability by intraoperative manual testing (Group I); these patients had a median age of 52 years. The other 211 patients (81 men and 130 women) (Group II) had a median age of 55 years. Clinical and radiographic data were compared between the groups.

Results: The incidence of open wounds at the wrist and the relative ulnar length measured on the prereduction radiograph were greater in Group I. An open wound at the wrist and positive ulnar variance of 6 mm or greater on the prereduction radiograph increased the risk of DRUJ instability (relative risks = 45 and 17, respectively) in distal radius fractures.

Conclusions: An open wound at the wrist or positive ulnar variance of 6 mm or greater observed on the prereduction radiograph in patients with distal radius fractures should alert the physician to the possibility of DRUJ instability.

Level of evidence: Level II, prognostic study. See the Guidelines for Authors for a complete description of levels of evidence.

Fig. 1

A flow chart shows the study cohort.

Fig. 2A–D

A 47-year-old woman sustained a distal radius fracture while mountain climbing. (A) She had an abrasion wound on the radial side and a pinpoint-sized open wound on the ulnar side of the injured wrist. On the prereduction (B) PA and (C) lateral radiographs, ulnar variance was greater than 20 mm. After stable fixation of the fracture, the DRUJ was unstable. (D) During surgical exploration, the triangular fibrocartilage complex was completely avulsed from the fovea of the ulnar head. Arrow = remaining stump of the avulsed triangular fibrocartilage complex at the fovea of the ulnar head, arrowhead = tip of the avulsed triangular fibrocartilage complex, asterisk = ulnar head.

Fig. 3A–E

A 52-year-old man sustained an open fracture of the distal radius. (A) The open wound was present at the volar ulnar side of the wrist. The ulnar variance was greater than 1 mm, and bony fragments (arrow) were observed in front of the volar margin of the sigmoid notch on the (B) PA and (C) semisupinated views of the wrist radiographs and on (D) the CT scan. (E) These fragments were attached to the avulsed deep part of triangular fibrocartilage complex, ie, the volar distal radioulnar ligament. A forcep is holding one of the fragments (arrowhead).

Fig. 4A–D

One of two reference points, the volar (*) or dorsal (▲) margin of the sigmoid notch, may be used for measurement, as shown in these (A) PA and (B) lateral radiographs. In a dorsally displaced fracture of the distal radius, the dorsal margin of the sigmoid notch is used for measuring ulnar variance, radial inclination, and radial length, and in a volarly displaced fracture, the volar margin of the sigmoid notch is used for these measurements, as shown on these (C) PA and (D) lateral radiographs. RL = radial length, RI = radial inclination, UV = ulnar variance, DT = dorsal tilt.