Distal Radius Fractures and Concomitant Injuries: Experimental Studies Concerning Pathomechanisms

Abstract

Since Colles’ description of the distal radius fracture (1814) and the publication by Dupuytren (1834), the frequency of this fracture, and the problems associated with it, have been increasingly recognized. Not only the treatment but also the mechanism of injury of the different types of fracture have been analysed repeatedly. The various theories concerning the pathomechanism have led to names such as “sprain fracture”, “bent fracture”, “thrust fracture”, “compression fracture”, “snap fracture” and others.

In our experimental studies, we attempted to simulate the pathomechanics of distal radius fractures, and to represent it illustratively. With the aid of a materials testing machine, 63 prepared cadaver parts were hyperextended at the wrist joint until distal radial fracture occurred. Accompanying injuries were identified radiologically and by dissection. Furthermore, the cadaver parts were deep-frozen and examined by means of computer tomography and cryo-section, using Kathrein’s method.

Through experimental hyperextension, it was possible to generate dorsal, central and palmar types of fracture. We produced 42 dorsal, 14 central and seven palmar fractures. The extent to which the carpal bones of the proximal row were pressed against the dorsal or palmar edge; or the centre of the distal radial articular surface, was fundamental. Subsequent dissection showed multiple concomitant injuries in 40 cases (63%), and none in 23 cases (37%). One reason for the occurrence of such concomitant injuries may be the relative strengths of the bone and ligaments. Most frequently (27 cases, or 43%), we found a destabilization of the triangular fibrocartilage, with or without a bony avulsion fragment (fracture of the ulnar styloid process), followed by ruptures of the interosseous ligaments between the scaphoid and the lunate (20 cases, or 32%) and between the lunate and triquetrum (11 cases, or 18%).

The application of knowledge gained from experimental studies carried out on fixed cadaver parts to clinical cases is problematic. This holds true for both concomitant injuries and fracture types.

The lack of physiological defence reflexes as well as the deliberately slowed experimental procedure must be taken into account. On the other hand, in this series of experiments it was possible to generate experimentally many of the radius fractures found in clinical practice, together with their concomitant injuries.