Temporary Cast Application in Dislocated Ankle Fractures Leads to High Rates of Secondary Loss of Reduction: Does the Lauge-Hansen Injury Type Matter?

BACKGROUND: For the temporary treatment of ankle fracture dislocations (AFDs), previous studies indicate higher rates of secondary loss of reduction (LOR) with splint immobilization, prompting consideration for expanding indications for external fixation (ExFix). However, these studies did not investigate the influence of fracture morphology to further improve patient selection. The aim of this study was to investigate the influence of Lauge-Hansen injury type on the LOR rate in bimalleolar or trimalleolar AFDs for temporary cast vs ExFix immobilization.

METHODS: In this retrospective cohort study, patients with isolated AFD cases treated at our institution from 2011 to 2020 were reviewed. Inclusion criteria required radiographs depicting initial dislocation and appropriate reduction after Cast or ExFix immobilization. Exclusion criteria encompassed concomitant injuries, open fractures, conservative management as well as surgery performed within 48 hours or at a different facility. Patients were grouped by temporary treatment (Cast or ExFix). The primary endpoint was LOR prior to definitive surgery across various Lauge-Hansen types.

RESULTS: The LOR rate was significantly higher in the cast group (40/152, 26.3%) compared to the ExFix group (5/191, 2.6%; P  < .0001). In the cast group, LOR was associated with an increase in time to definitive surgery by a mean of 3 days ( P  < .002). During cast treatment, LOR was significantly more likely for pronation abduction ( P  = .001) and supination external rotation injuries ( P  < .0001), whereas no significant differences were observed for pronation external rotation ( P  = .006), supination adduction ( P  > .99), and fractures not classifiable ( P  > .99).

CONCLUSION: In cases of AFDs resulting from supination external rotation or pronation abduction trauma according to the Lauge-Hansen classification, especially in the setting of an additional posterior malleolar fracture, primary application of external fixation should be considered to reduce the risk for secondary loss of reduction.

LEVEL OF EVIDENCE: Level III, retrospective cohort study.