Posttraumatic limb-length discrepancies secondary to femoral malunion can be treated with a variety of external or internal lengthening systems. The PRECICE nail is an intramedullary device featuring an external remote control to activate a magnetically driven internal distraction mechanism. While this intramedullary system avoids the soft-tissue complications common to external lengthening, it has unique mechanisms of failure that are difficult to diagnose and that require a systematic approach.