The nail-insertion point in unreamed tibial nailing and its influence on the axial malalignment in proximal tibial fractures.

The consequence of choosing a point of insertion for the nail (i.e. medial or lateral of the lig. patellae) in unreamed tibial nailing (AO unreamed tibial nail, UTN) was studied in 22 formaldhyde-fixed tibiae. A lateral osteotomy at the transition from the first to the second fifth of the tibia was used as a model for the fracture. A nail insertion point medial of the lig. patellae caused a valgus deformity, combined with a shift of the distal fragment to the medial side. A lateral point of entry resulted in a varus deformity, together with a lateral shift of the distal fragment. Our results show that the insertion point of the nail is important for the alignment of the axis. Choosing a different point for the insertion of the nail can be useful in operative correction of malalignment of the tibia.