Morphologic Characteristics of the Medial Malleolar Fragment based on CT Scan in Ankle Fractures

CATEGORY: Ankle; Trauma INTRODUCTION/PURPOSE: The aim of this study was to describe and evaluate the morphologic characteristics of the medial malleolar fragment in ankle fractures and suggest the guideline for proper fixation of the fragment METHODS: From August 2011 to June 2018, 172 cases were enrolled. There were performed the operation in ankle fractures with a medial malleolar fragment. All cases were divided into three types, based on the transverse fracture line of the medial malleolar by the CT (computed tomography) scan; type 1 was involved in the anterior colliculus, type 2 was the intercollicular groove and type 3 was the posterior colliculus. All cases were classified by Lauge-Hansen classification and compared with the groups statistically. The fixation methods by the groups were reviewed and compared. All cases were analyzed by SPSS 19.0, the p-value was less than 0.05. RESULTS: According to the CT scan, type 1 was 14 cases (8.1%), type 2 was 48 cases (27.9%) and type 3 was 110 cases (63.9%). Based on the Lauge-Hansen classification, SER (supination-external rotation) type was 136 cases(76.4%), PER (pronation-external rotation) was 30 cases(17.4%) and PA(pronation abduction) was 8 cases(4.7%).In SER type, type 1 was 6 cases(4.4%), 2 was 42 cases(30.9%) and 3 was 86 cases(63.2%). In PER type, 1 was 6 cases (20%), 2 was 4 cases (13.3%) and 3 was 20 cases (18.9%). In PA type, 1 was 2 cases (25%), 2 was2 cases (25%) and 3 was 4 cases (50%). The fixation methods were various, such as a tension band wiring, 4.0 cannulated screw, hook plate. CONCLUSION: The morphology of a medial malleolar fragment based on CT scan in ankle fractures were 3 types. There was common a morphology involved the posterior colliculus, Type 3. We suggest that the operators should choose the proper fixation method by the morphology of the fragment and should be careful to avoid the injury of the posterior tibialis tendon.