An uncapped nail fills with bone. Over the months after implantation, the open lumen of the nail invites ingrowth that locks the implant to the canal from the inside — invisible on imaging, decisive at removal. The end cap exists to close that door, and in revision and removal cases it is the difference between a routine extraction and a fight.
Extended cap versions answer a second, quieter problem: when the nail sits a few millimetres deeper than planned, an extended cap restores the intended relationship between nail top and entry portal without exchanging the implant. Caps are matched to their nail family — the cephalomedullary and antegrade systems take different threads — and selection follows the operative record kept by the surgeon.
