[Significance of three-compartment digitalized arthrography in the diagnosis of post-traumatic instability of the radiocarpal complex].

INTRODUCTION

The radiocarpal complex is the structure formed by the distal radioulnar, radiocarpal and midcarpal joints; these joints are compartments, each anatomically separated from the other. An appropriate arthrographic study with three-compartment injection better demonstrates the capsuloligamentous structures than conventional radiography. The diagnosis of any condition in this complex may therefore be easier to make.

MATERIAL AND METHODS

From January 1993 to December 1996, twenty-six patients with mild to moderate wrist and carpal sprain and previously examined with radiography, were submitted to digital three-compartment arthrography at the Imaging Diagnostic Service of the Rizzoli Orthopedic Institute. Of 17 patients with previous radiographic diagnosis of scapholunar diastasis, 1 patient had a negative radiographic picture, 15 had an incomplete tear of the scapholunar ligament and 1 a double injury of the scapholunar and triquetro-lunar ligaments. Of 10 patients with mild to moderate triquetro-lunar diastasis, 8 had and arthrographic picture of pyramido-lunar ligament injury, 1 had a double injury of the triquetro-lunar and scapholunar ligaments and another one of triangular fibrocartilage complex injury.

RESULTS

Three-compartment contrast agent injection permitted the diagnosis of interruptions between the different compartments and more injuries of scapholunar and triquetro-lunar ligaments than single compartment injection. We examined 27 patients with small arch injuries with three-compartment digital arthrography and found scapholunar diastasis in 17 (63%) and triquetro-lunar diastasis in 10 (37%). In the first group of 17 patients, three-compartment arthography demonstrated more scapholunar ligament injuries (13 cases) than single compartment injection; image subtraction, allowed by the digital technique, showed 2 injuries not visible otherwise. Injuries of the scapholunar and triquetro-lunar ligaments were demonstrated with and without digital subtraction. One patient had no ligament injury. In the other group of 10 patients, three-compartment arthrography showed more triquetro-lunar ligament injuries (6 cases) than single compartment injection; image subtraction demonstrated 2 injuries not visible otherwise in this group too. Injuries of the scapholunar and triquetro-lunar ligaments were demonstrated with and without digital subtraction. The injury of triangular fibrocartilage and contrast agent leak into soft tissues were shown in one patient with the injection of the distal radioulnar compartment alone, regardless of image subtraction.

CONCLUSIONS

Arthrography, combined with conventional static and dynamic radiography, increases the detection rate of capsuloligament joint defects in the wrist-carpal complex. The three-compartment digital technique combines the advantages of fluoroscopic monitoring and videorecording and allows real time imaging of the contrast agent flow during injection in different compartments. Moreover, the digital technique permits the complete study of all joints in a single session, while image subtraction reveals even minimal ligament changes. This technique becomes therefore a fundamental tool for surgical planning.