Morphological Observations of Torsional Fractures of the Adult Tibial Shaft

Abstract

The present study is an analysis of the radiographic morphology of 250 consecutive clinical torsional fractures of the adult tibial shaft. The site, extent, degree of comminution and orientation of the principal fracture plane were determined, with special attention paid to the initial lateral displacement as an estimate of injury to the interosseous membrane.

The predilection site of the torsional fractures was at the junction of the middle and distal thirds of the tibia. An additional moment of axial compression in the causative violence seemed to result in a more distal fracture. The orientation of the principal fracture plane did not occur at random. The centre of the actual spiral component of the fracture line was located in the anterolateral and the vertical element of the fracture in the posteromedial quadrant of the tibial circumference in 78 per cent of cases. A latero-medial orientation of the fracture, approaching the sagittal plane and perpendicular to the interosseous membrane, showed increased frequency of severe initial lateral displacement as compared with postero-anterior fractures, lying in the coronal plane (P < 0.01). Tibial fractures with intact fibulae were seen only in the young, with a mean age of 25 years for these patients, but no other age-associated fracture characteristics were found.

Key words:

• biomechanics
• computerised tomography diaphyseal bone
• stress
• mechanical