Identifying the optimal inlet for antegrade tibial intramedullary nailing via magnetic resonance imaging

Tibial shaft fractures treated with antegrade rigid tibial intramedullary nailing has been supported worldwide. However, the optimal inlet for nailing is still controversial. Practically, varied inlets may significantly affect the tibial alignment. This retrospective study intended to utilize magnetic resonance imaging (MRI) to investigate the optimal inlet for antegrade tibial nailing.

MRIs of 100 consecutive adult patients (50 men and 50 women, average 27 years) were used in this study. All patients had MRIs for meniscus or knee ligament injuries. There were no fractures or prior bony anomalies. The center of the tibial width (TW) at the level of the tibial tubercle (TT) was considered the optimal inlet and was positioned on the axial view of the MRIs. Various related anatomic landmarks were investigated concomitantly. All parameters were compared statistically.

The medial edge of the patellar tendon (PT) was 55% from the lateral end of the TW. The apex of the TT was 38% from the lateral end of the TW. The lateral edge of the PT was 19% from the lateral end of the TW. The TT was 2.5 cm distal to the tibial articular surface. The PT width was 2.3 cm. Except for the TW, the distance from the TT to the articular surface, and PT width between genders (p < 0.001), all other parameters showed no statistical significance (p >  0.05).

The optimal inlet for antegrade rigid tibial intramedullary nailing may be at a site 3 mm laterally to the medial edge of the PT. There are normally no differences for the nail inlet between men and women. The PT splitting approach for nail insertion may require modification.