A previously unreported type of extra-articular triplane fracture: A revised classification system.

BACKGROUND: Atypical triplane fractures are defined as triplane fractures that are intra-articular but affect the non-weight-bearing area of the tibia plafond or extra-articular triplane fractures where the epiphyseal fracture line exits outside the articulating cortex of the medial malleolus. These fractures are scarcely reported in the literature. Here, we study the fracture pattern, mechanisms, and recommendations for management.

METHODS: This is a retrospective study of all triplane fractures identified from 2012 to 2016 in a tertiary referral center. There were 10 atypical triplane fracture patterns identified in this cohort. All patients were followed up with an average of 19 months. A modified atypical triplane fracture classification was devised and compared with previously reported classification systems. Clinical outcomes measured included treatment complications, ankle range of motion, and time needed to return to sports.

RESULTS: We identified a new extra-articular triplane fracture variant with an anteromedial epiphyseal sleeve fragment (fracture variant). There were no long-term complications from operative closed reduction and percutaneous screw fixation. Operative cases had earlier ankle mobilization and regained full range of motion (12.8 weeks vs 13.3 weeks) earlier. The average time to return to sports was 5.2 months.

CONCLUSIONS: We propose a modified classification for atypical triplane fractures and recommend closed reduction and percutaneous screw fixation for displaced atypical triplane fractures.

LEVEL OF EVIDENCE: IV (Case Series).