SUMMARY
Background: Closed surgical treatment of long bone fractures by minimally invasive percutaneous plate osteosynthesis (MIPO) is prone to malrotation. In this study we aimed to determine the transverse plane torsional axis differences of medial surface of distal tibia and tibial diaphysis, involved in anatomical plate minimal invasive percutaneous osteosynthesis.Materials and method: The computerized tomography (CT) images from PACS archive of computerized tomography unit of the institution were reviewed retrospectively. Tibia scans of forty male cases meeting inclusion and exclusion criteria were evaluated. The inclination of the plane of the surface of the tibia was measured. Plane of the surface is defined as axis of the surface of tibia involved in distal medial plating. Sections were measured starting from one centimeter proximal to the tip of medial malleolus and continued proximally in one centimeter intervals for next twenty-five sections. Results were analyzed after grouping the cases according to average stature (as below average and above average). Results: At the level of 5th cm. proximal to medial malleolus, approximately 13º of external rotation of medial surface of tibia was noted. After 11-12th cm level, external rotation exceeds 20º. At 16-19th cm, amount of rotation reaches 30º. Change in the axis occurs more proximally in cases above average stature. More proximally amount of external rotation decreases gradually. At 26th cm level, a mean of 23.21º of external rotation was measured. Amount of rotation did not differ according to stature. Conclusion: Up to 30º of external rotational plane difference was observed notably after 17-20th cm from the tip of the medial malleolus. Inadvertent leaning of proximal extension of a straight/ untwisted anatomical distal tibial plate may result with significant external rotational malalignment, especially in comminuted fractures where fixation was extended towards tibial diaphysis.