gms | German Medical Science

Objectives: Axial malrotation is a common complication of long-bone intramedullary nailing. Uncorrected malrotation can lead to early joint degeneration and arthrosis. Rates of malrotation in the femur have been commonly reported to range between 20-35% of cases. Intraoperative rotation control is hard to achieve and many methods have been proposed, including the cortical step sign and the diameter difference sign. While malrotation of the tibia has not received as much attention in the literature, but recent reports using mnewer imaging techniques have reported a tibial malrotation incidence of 23-36%. In the current study, we aimed to quantify radiographic parameters of tibial malrotation and to develop new intraoperative techniques for detecting malrotation using radiographic imaging.

Methods: 19 human tibia specimens were harvested and used in this study. An intramedullary rod was applied to each specimen for stability and transverse fractures of the proximal, middle and distal thirds of the tibia were simulated through osteotomy. At each segment, 5-degree stepwise increases in internal and external malrotation were performed from 0 to 30 degrees. At each step, AP and lateral fluoroscopic images were obtained, as well as a 3D scan using a C-arm with 3D capability. The differences in cortical thickness and tibial diameter between the proximal and distal segments at each osteotomy location were measured at each 5-degree step. In addition, the 3D images were analyzed to find correlations between several anatomic parameters and clinically relevant malrotation.

Results and conclusion: We were able to successfully simulate transverse fractures of the proximal, middle and distal thirds in all tibial specimens. The differences in cortical thickness and tibial diameter may be helpful clues in identifying clinically relevant malrotation intraoperatively. We are currently analyzing the three-dimensional image scans to develop a comprehensive method for accurate detection of intraoperative malrotation. The final results of this research are ongoing and will be available in short fashion. This research has the potential to impact routine orthopaedic trauma practice by improving the detection of intraoperative tibial malrotation and reducing the need for revision surgery.