Entrapment of the tibialis anterior tendon as a cause of nonunion in fractures of the distal tibia.

Three cases of nonunion of a fracture of the distal third of the tibia are reported. The cause of the nonunion in all three cases was the entrapment of the tibialis anterior tendon between the bone ends. This has not been previously reported as a specific cause of nonunion of the distal shaft of the tibia. This paper draws attention to this occurrence as a possible cause of nonunion in this area especially if the fracture is of the oblique type with an anterior spike at the distal end of the proximal fracture, with the line of fracture running parallel to the line of the tendon of the tibialis anterior. We suggest that fractures of this type should be treated early by internal fixation in view of the complications that can occur, such as nonunion, atrophy, or even complete rupture of the tendon of tibialis anterior, leading to a residual equinus deformity.