Abstract
Introduction
Diaphyseal tibial fractures account for approximately 1.9% of adult fractures. Studies have demonstrated a high proportion have ipsilateral occult posterior malleolus fractures. We hypothesize that this rotational element will be highlighted using the Mason & Molloy Classification.
Materials and Methods
A retrospective review of a prospectively collected database was performed at Liverpool University Hospitals NHS Foundation Trust between 1/1/2013 and 9/11/2020. The inclusion criteria were patients over 16, with a diaphyseal tibial fracture, who underwent a CT. The Mason and Molloy posterior malleolus fracture classification system was used.
Results
764 diaphyseal tibial fractures were analysed, 300 had a CT. 127 were intra-articular fractures. 83 (27.7%) were classifiable using Mason and Molloy classification. There were 8 type 1 (9.6%), 43 type 2 (51.8%), 5 type 2B (6.0%) and 27 type 3 (32.5%). 90.4% (n=75) of the posterior malleolar fractures, were undisplaced. The majority of PM fractures occurred in type 42A1 (65 of 142 tibia fractures) and 42B1 (11 of 16).
Conclusions
Most PM fractures occurred after a rotational mechanism. Unlike, the PM fractures of the ankle, the majority of PM fractures associated with tibia fractures are undisplaced. We theorise that unlike the force transmission in ankle fractures where the rotational force is in the axial plane in a distal-proximal direction, in the PM fractures related to fractures of the tibia, the rotational force in the axial plane progresses from proximal-distal. Therefore, the force transmission which exits posteriorly, finally dissipates the force and thus unlikely to displace.
