# Can Anatomical Differences Contribute to the Etiology of Danis-Weber Type B Lateral Malleolus Fractures?

## TL;DR

This study finds that certain ankle anatomy differences increase the risk of lateral malleolus fractures, suggesting that anatomical factors play a role in their occurrence.

## Contribution

The study identifies specific anatomical parameters associated with increased susceptibility to Danis-Weber Type B lateral malleolus fractures.

## Key findings

- Individuals with a longer medial malleolus and valgus-oriented ankle are at higher risk for lateral malleolus fractures.
- Reduced tibial anterior inclination and anteriorly positioned fibula also correlate with increased fracture risk.
- DTAS angle and TCA showed the largest effect sizes in differentiating fracture and control groups.

## Abstract

Introduction

Lateral malleolus fractures are among the most common ankle fractures, but the anatomical factors that may predispose individuals to this specific type of fracture are not fully understood. This study aims to explore whether distinct anatomical characteristics of the ankle joint contribute to an increased susceptibility to lateral malleolar fractures.

Methods

A retrospective analysis was conducted on 73 patients diagnosed with isolated lateral malleolar fractures between 2020 and 2023. An array of radiologic parameters, including distal tibial articular surface (DTAS) angle, bimalleolar tilt (BMT), medial malleolar length (MML), lateral malleolar length (LML), medial malleolar relative length (MMRL), lateral malleolar relative length (LMRL), medial malleolar slip angle (MMSA), talocrural angle (TCA), anterior inclination of the tibia (AI), and fibular position (FP), were meticulously measured on anteroposterior and lateral ankle radiographs for each study participant. We also measured the same parameters in 126 individuals who had not experienced an ankle fracture for comparison.

Results

Statistically significant differences were observed between the fracture group and the control group for DTAS angle, BMT, MML, MMRL, LMRL, TCA, AI, and FP (p<.05). Conversely, LML and MMSA displayed no significant variations between the two groups (p=0.745 and p=0.623). Effect sizes were notably large for DTAS and TCA, medium for MMRL, BMT, and AI, and small for LMRL, MML, and FP.

Conclusion

Our findings indicate an increased risk of lateral malleolus fractures in individuals with a relatively longer medial malleolus, a valgus-oriented ankle, reduced anterior inclination of the tibia, and an anteriorly positioned fibula. Taking protective measures during risky activities in individuals with these differences may help to prevent fractures.