Abstract
PURPOSE OF THE STUDY Scapholunate (SL) ligament disruption frequently occurs together with distal radius fractures. If it is not diagnosed and treated, instability develops and will eventually be manifested as arthritic lesions known as scapholunate advanced collapse (SLAC) of the wrist.
The aim of this study was to record the occurrence of SL ligament disruption in the patients treated conservatively for displaced fractures of the distal radius and to find out which fracture types are most often associated with injury to the SL ligament. MATERIAL AND METHODS A total of 75 patients treated conservatively for distal radius fractures in 1997-98 were included in the study.
The group comprised 41 women and 34 men, with fractures of the right upper limb in 44 and fractures of the left upper limb in 31 patients. They all were at active age, i. e., between 18 and 60 years, and came for a check-up 3 years after injury.
They were examined for radiographic findings of SL instability and signs of SLAC development. Radiographs obtained after injury and images taken after reduction and then after bone union were retrospectively evaluated to look for signs of SL instability.
The initial fractures were categorized on the AO classification and, for each fracture type, the percent of patients with co-existent SL instability was assessed. RESULTS In the group of 75 patients examined at 3 years after injury, 16 (27 %) wrists showed radiographic signs of instability with SLAC development in 13 patients and no arthritic lesions in three.
All patients with SL instability reported pain, restricted range of motion in the wrist or reduced grip strength.The distribution of instability in relation to AO fracture type, expressed as percent, was as follows: SL instability associated with type A2 fracture was found in 38 %, with type A3 fracture in 17 %, and with type B in 25 % of the patients. SL instability was associated with type C1, type C2 and type C3 in 21 %, 27 % and 8 % of the patients, respectively.
In radiographs taken after reduction, signs of damage to the SL ligament were apparent in 56 % of these patients. Radiographic findings at 6 weeks after injury showed signs of SL instability in as many as 81 % of the patients.
DISCUSSION Our results show that SL instability is found in association with type A2 and type A3 fractures, in which trauma force is "used" to break the distal radius and subsequently, due to carpal supination, to disrupt the SL ligament. In type B1 fractures, SL disruption results from an avulsion fracture of the radial styloid process due to ulnar deviation of the wrist.
The retrospective evaluation of radiographs revealed that, immediately after reduction, signs of SL instability were obvious in 56 % of the cases. At that stage the condition could have been treated by K-wire transfixation and reattachment of the SL ligament.
At 6 weeks, radiographic evidence of SL ligament disruption was found in 81 % of the patients. Even at that stage repair would have been possible by either reattachment or reconstruction of the ligament.
It is apparent from these results that the evaluation of radiographic findings after reduction and during follow-up should also focus on other changes in the wrist in addition to signs of bone union. CONCLUSIONS Fractures of the distal radius are no longer frequent only in elderly women, as has recently been common, but they are found more and more often in active young persons.
Because their bones are healthier, soft tissues are affected more frequently. Injury to the SL joint results in the development of arthritic lesions which may rapidly progress in active patients.
SLAC development can be prevented by early diagnosis of soft tissue lesions on X-ray images, because these are usually apparent after reduction or at follow-up. If doubts arise, arthroscopy or another examination should be done, even though these may not be sufficiently reliable.