[Comparison of Plaster Fixation and Kirschner Wire Transfixation as Temporary Fixation of Displaced Ankle Fractures - Randomised Prospective Study].

: PURPOSE OF THE STUDY The purpose of the study was to assess two therapeutic procedures of temporary fixation of displaced ankle fractures, namely the plaster fixation or Kirschner wire (KW) transfixation via the sole of the foot. MATERIAL AND METHODS Group of patients The randomised prospective study conducted in the period 02/2016-02/2017 compared two methods of temporary fixation of displaced ankle fractures. In total, 38 patients were included in the study (18 patients treated with plaster fixation, 20 patients treated with KW). Methods During the randomisation (by envelopes, drawing of lots by the patient), in one group of patients, temporary stabilisation by plaster fixation was performed, whereas the other group was treated by percutaneously inserted KWs. The attention was focused on the quality of achieved reduction, its retention until the final treatment, and soft tissue status. After one year, the final examination was performed, in which we focused on the assessment of the clinical condition of the ankle joint with the use of the Olerud-Molander Ankle Score (OMAS), the AOFAS (American Orthopedic Foot and Ankle Society) score, and the Visual Analogue Scale (VAS) measuring the overall satisfaction. Moreover, in both the methods potential incidence of arthritic changes was monitored on radiographs. RESULTS Both the methods achieved 100% successful reduction rate. The group with plaster fixation reported a loss of reduction in six patients (33.3%) as against the KW group where no loss of reduction occurred. This difference was significant (p = 0.007). In plaster fixation method, after its removal local complications occurred on skin in 56%, of which skin necrosis in 16.7%, and it always occurred in association with the loss of reduction, which was statistically significant (p = 0.245). In KW method, local complications on skin were present in 25% only. In the group of patients with KW, there was not a single case of surface or deep infection reported. No KW migration was observed. DISCUSSION Potential complications of conservative treatment of displaced fractures with plaster fixation include the migration of fragments and widening of the ankle fork during the further course which may threaten the vitality of soft tissues. A total of six patients (33.3%) treated with plaster fixation showed a failure of reduction, which is by approximately 10% more than described in literature. In seven cases after the plaster fixation removal bullae were observed (38.9%) and in three cases skin necrosis was present (16.7%), which occurred in re-displaced fractures only. The bullae were present whether the reduction was successfully maintained or not. In literature, local complications after plaster fixation removal are reported in roughly 14%. Temporary percutaneous ankle KW transfixation is applied to maintain the reduced fracture in a favourable position and to facilitate monitoring and treating the soft tissues. Prior to the final surgical solution, bullae were observedin four cases (20%), of which skin necrosis in one case (5%). Bullae formation and necrosis are most likely related to the initial damage to soft tissues due to the injury and were not caused by the KW insertion. The literature describes local complications in 7% with respect to the KW technique, however, the type of complications is not specified. In our group, at a one-year follow-up arthritic changes grade I and II according to Kellgren and Lawrence scale were reported in 70% of cases with KW technique. Whether the osteoarthritis was caused by fixation or the fracture itself and what would be the percentage of individual types of osteoarthritis after several years of follow-up is a question. CONCLUSIONS Plaster fixation or Kirschner wires for temporal fixation of displaced ankle fractures shall be applied on a case by case basis. Based on our findings, the application of plaster fixation to displaced ankle fractures does not provide adequate stability of the reduced fracture and in case of re-displacement the status of soft tissues deteriorates. The impossibility to control the status of soft tissues in plaster fixation and the lower complication rate in fixation with K wires constitute additional reasons why this fixation technique via the sole of the foot appears to reap more benefits. Key words:displaced ankle fractures, temporal fixation, plaster fixation, Kirschner wire transfixation, complications.