Endosteal Biologic Augmentation for Surgical Fixation of Displaced Femoral Neck Fractures

Abstract

Objectives: To report outcomes of a cohort with displaced Femoral Neck Fractures (FNF) 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 twenty-seven 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 two fully threated 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 was evaluated using a specialized sequence of contrast-enhanced MRI obtained at 3 and 12 months postoperatively. Results: This construct resulted in high union rates (89%; 24/27). Two patients suffered early catastrophic failure and one patient developed fracture non-union, all of wish underwent uneventful conversion to total hip arthroplasty. Three (11%) additional patients had removal of symptomatic implants. The clinical and radiographic outcomes were excellent. Twelve months 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 sign of osteonecrosis or segmental collapse. Conclusion: 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 intra-operative 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. 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 sy...

Novel Treatment Options for the Surgical Management of Young Femoral Neck Fractures

“…33,34 More recently, this concept has been introduced to other fractures that are prone to subsidence, loss of reduction, or poor bony fixation including tibial plateau fractures 35,36 and femoral neck fractures. 37–39 One technique using a fibular strut allograft, described by Lorich et al in 2013 was developed with the benefits of fixed-angle, length stable fixation in mind. 40 The technique also seeks to capitalize on the biomechanical benefits (increased stiffness and decreased fracture displacement) of widely spread inverted triangle cannulated screw constructs with a Pauwel screw placed perpendicular to the fracture.…”

“…41 In this described approach, a Watson-Jones approach to the hip is performed to allow direct fracture reduction and implant insertion via the same incision. 37 Alternatively, a Smith-Peterson approach for fracture visualization and reduction and separate laterally based incision can be used for implant insertion. Reduction is performed followed by compression across the tension side of the fracture (inferior in valgus and superior in varus deformities) with 7.3mm partially threaded cannulated screw.…”

“…By virtue of this screw also passing through the fibular graft into the femoral calcar, it also creates a fixed-angle construct between the native femoral neck and the allograft strut. 37 Although no biomechanical studies have been performed comparing this construct to other fixed-angle constructs, the initial published clinical results of patients undergoing this technique have been promising. 37 In this study, 27 physiologically young (18 less than 65 years of age) patients had an overall non-union rate of 4% and 0% AVN rate at mean of 19-month follow-up (range 12–30 months).…”

“…37 Although no biomechanical studies have been performed comparing this construct to other fixed-angle constructs, the initial published clinical results of patients undergoing this technique have been promising. 37 In this study, 27 physiologically young (18 less than 65 years of age) patients had an overall non-union rate of 4% and 0% AVN rate at mean of 19-month follow-up (range 12–30 months). Two (7.4%) catastrophic failures occurred in Garden IV fractures, one in a patient who was non-compliant with weight bearing recommendations and the other in a patient who sustained a post-operative fall.…”

“…Post-operative MRIs performed at 3 months and 12 months revealed at least partial incorporation of the biologic strut into the host bone (57% at 3 months and 86% at 12 months). 37 This spot welding phenomenon enhances the construct stability through the host bone-allograft interfaces over time, which is unique compared to conventional fixation methods that do not use biologic augments. The finding of osseointegration is unlikely to occur in constructs that do not allow stable, anatomic fixation at the fracture site as well as Pauwel screw fixation through the graft.…”