Endosteal Biologic Augmentation for Surgical Fixation of Displaced Femoral Neck Fractures.

Objectives:To report outcomes of a cohort with displaced femoral neck fractures (FNFs) treated with a length/angle-stable construct augmented with an endosteal fibular allograft serving as a biologic dowel.Design:Prospective.Setting:Level I Trauma Center.Patients:The study group consists of 27 patients with isolated FNF surgically treated by a single surgeon.Intervention:Open reduction of the femoral neck, fixed with a length- and angle-stable construct of 2 fully threaded cannulated screws augmented with an endosteal fibular allograft serving as a biologic dowel.Main Outcome Measurements:Clinical and radiographic outcomes of the fixation construct and the viability of both the femoral head and the fibular allograft, host response to the allograft and osseous union were evaluated using a specialized sequence of contrast-enhanced magnetic resonance imaging (MRI) obtained at 3 and 12 months postoperatively.Results:This construct resulted in high union rates (89%; 24 of 27). Two patients suffered early catastrophic failure and 1 patient developed fracture nonunion, all of wish underwent uneventful conversion to total hip arthroplasty. Three additional patients (11%) had removal of symptomatic implants. The clinical and radiographic outcomes were excellent. Twelve-month MRIs revealed either partial or complete osseous incorporation of 86% the fibular allografts without signs of adverse reaction of the host to the allograft. Femoral head osteonecrosis segments were noted in 76% of patients on MRI; however, radiographically, there were no signs of osteonecrosis or segmental collapse.Conclusions:The fibular allograft reconstructs the comminuted femoral neck, and the osteointegration overtime increases the strength of the host bone-graft interface. This added strength seems to provide the stability needed to better preserve the intraoperative reduction, obtain good outcomes, and reduce the complications associated with FNF.Level of Evidence:Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.