A quantitative biomechanical study of positive buttress techniques for femoral neck fractures

Abstract

Background:Refractory femoral neck fractures cannot be anatomically reduced by closed traction reduction which may affect fracture healing. We evaluated the biomechanical effects of positive, negative, and anatomic reduction of various degrees of displacement in Pauwels I femoral neck fractures by a finite element analysis.Methods:Five reduction models of Pauwels type I femoral neck fracture were established using the Mimics 17.0 (Materialize, Leuven, Belgia) and Hypermesh 12.0 (Altair Engineering, Troy, MI, USA). According to the degree of fracture displacement, there were three models of positive support, an anatomic reduction model, and a negative 2 mm reduction model. Finite element analysis was conducted using the ABAQUS 6.9 software (Simulia, Suresnes, France). The von Mises stress distribution and the stress peak of internal fixation in different models, the displacement between fracture blocks, and the principal strain of the femoral neck cancellous bone model were recorded under the axial stress of 2100 N.Results:The peak von Mises stress on screw of each model was located at the thread of the screw tip. The peak von Mises stress was the lowest at the tip of the anatomic reduction model screw (261.2 MPa). In the positive 4 mm model, the von Mises stress peak was the highest (916.1 MPa). The anatomic reduction model showed the minimum displacement (0.388 mm) between fracture blocks. The maximum displacement was noted in the positive 4 mm model (0.838 mm). The displacement in the positive 3 mm model (0.721 mm) was smaller than that in the negative 2 mm model (0.786 mm). Among the five models, the strain area of the femoral neck cancellous bone was mainly concentrated around the screw hole, and the area around the screw hole could be easily cut.Conclusions:Compared with negative buttress for femoral neck fracture, positive buttress can provide better biomechanical stability. In Pauwel type I fracture of femoral neck, the range of positive buttress should be controlled below 3 mm as far as possible.

Nonanatomical Reduction of Femoral Neck Fractures in Young Patients (≤65 Years Old) with Internal Fixation Using Three Parallel Cannulated Screws

“…Recently, there have also been studies verifying the effectiveness of positive buttress position reduction through biomechanics and animal experiments [ 27 , 28 ]. In 2019, Wang et al [ 28 ] investigated that better biomechanical stability was shown in the positive buttress position reduction group compared to that in the negative buttress position reduction group in a finite element analysis. It was worth mentioning that they further quantified the range of positive buttress and concluded that the range of positive buttress should be controlled within 3 mm as much as possible.…”

Clinical Outcome and Biomechanical Analysis of Dynamic Hip Screw Combined with Derotation Screw in Treating Displaced Femoral Neck Fractures Based on Different Reduction Qualities in Young Patients (≤65 Years of Age)

“…Multiple attempts of closed reduction or open reduction with the aim of anatomical reduction can damage the blood supply of the femoral head and increase the incidence of fracture nonunion or necrosis of the femoral head [ 12 ]. Recently, nonanatomical reductions of FNF, which include positive buttress reduction and negative buttress reduction, have attracted wide attention [ 13 – 15 ]. The definition of the former is that the distal fracture segments is positioned medially to the lower-medial edge of the proximal segment, while the latter is that the proximal fracture segment is positioned medially to the upper medial edge of the distal segment [ 16 ].…”

“…The definition of the former is that the distal fracture segments is positioned medially to the lower-medial edge of the proximal segment, while the latter is that the proximal fracture segment is positioned medially to the upper medial edge of the distal segment [ 16 ]. Since Gotfried et al first proposed the concept of nonanatomical reduction in 2013, numerous studies have compared the effect of nonanatomical reduction and anatomical reduction in FNF [ 10 , 13 – 15 ]. However, all of these studies focused on internal fixation with CCS.…”

Effect of a Traction Exercise Neck Brace on Cervical Spondylopathy Radiculopathy: A Clinical Study and Finite Element Analysis

“…To study the impact of traction on the cervical vertebra, therefore, a finite element (FE) analysis model of spinal segments is appropriate in which the cervical dysfunctions in the pathologic degenerative condition can be simulated. This computational method provides insight into the detailed biomechanics of the human neck both with and without traction, revealing the impact of tractor on the inner workings of cervical spine [ 16 , 17 ]. Therefore, in this study, the present work investigated the effects of TENB on CSR in the volunteers enrolled as compared with conventional therapy of JOBT.…”