Placing distal locking screws into an intramedullary nail (IMN) can be a difficult step for the young surgeon to master. Crucial preparation for successful placement often includes the use of the image intensifier and the gaining of “perfect circles.”1 Once these “perfect circles” have been achieved a drill is passed through near side cortical bone, near screw hole, far screw hole and then far side cortical bone. Small misdirection in the drill trajectory, will lead either malplacement of the screw, or damage to the nail from the drill, which can potentially weaken the nail. We propose a step-by-step approach to drilling the distal locking screw holes.
Place the drill in the appropriate “center center” position within the “perfect circle” (Fig. 1). Drill the near cortex. Release the drill bit from the power drill and by hand and gentle taps of the mallet, guide the drill bit through the near and far screw holes of the nail (Video 1, Supplemental Digital Content 1, http://links.lww.com/TIO/A26). Drill the far cortex, measure and place the screw (Fig. 2). To avoid inadvertent fracture, be sure to drill and not to tap the drill bit across the far cortex.
The placement of screws into an IMN can be challenging to perform and teach. Indirect visualization with the aid of an image intensifier adds to the difficulty. Once a false screw hole has been placed, drilling eccentrically through the nail can cause significant damage, potentially weakening the nail and causing implant failure. Also salvage maneuvres to redirect both the drill and subsequent screw will be required. While the experienced trauma surgeon will often pass the drill in a single motion, training surgeons may lack the tactile feedback and spatial awareness (that comes with experience) to successfully and consistently perform this passage.
Trauma surgeons at the major adult trauma center in Bristol perform over 200 IMNs per year with the majority being performed by training surgeons under consultant supervision. The described technique has been used by the trauma team with a significant improvement in successful first time screw placements. By drilling the near cortex first, uncoupling the drill bit and guiding this through the nail and then drilling through the far cortex, successful passage can be competently and expeditiously achieved by junior surgeons or those who infrequently perform IMN procedures.
1. Middleton PR, Ng L, Humphrey A. A technique
to aid the insertion of distal locking screws. Ann R Coll Surg Engl. 2012;94:364–365.