Subcutaneous internal anterior fixation of pelvis fractures-which configuration of the InFix is clinically optimal?-a retrospective study

Introduction Subcutaneous internal fixation (InFix) has become a valid alternative for anterior fixation of pelvic ring injuries. Complications associated with this technique are lateral femoral cutaneous nerve (LFCN) irritation and anterior thigh pain due to prominent implants. The aim of this study was to identify a configuration of the InFix that causes the least adverse side effects. Methods Nineteen patients (6 females, mean age 61 years) with 38 hemipelves were included. Rod-to-bone distance and symphysis-rod distance were measured on AP- and outlet- radiographs. These distances were analyzed in relation to the primary outcomes: early removal of the InFix, post-operative complications and damage of the LFCN. Results Regarding rod-to-bone distance, a distance of 20 to 25 mm causes less complications, LFCN damage and no early removals of the InFix. Symphysis-to-rod distance analysis showed the best results regarding LFCN damage and other complications when the rod had a distance of less than 40 mm to the symphysis. A distance more than 40 mm was associated with fewer early removal of the InFix. Conclusions Planned optimized configuration of the InFix with a rod-to-bone distance between 20 and 25 mm may reduce postoperative complications. Regarding LFCN damage, the rod-to-symphysis distance should not be more than 40 mm.