Spatial Bridge Locking Fixator versus Traditional Locking Plates in Treating AO/OTA 32‐A3.2 Fracture: Finite Element Analysis and Biomechanical Evaluation

Abstract

Objective To compare the biomechanical behaviors of the spatial bridge locking fixator (SBLF), single locking plate (SP), and double locking plate (DP) for AO/OTA 32‐A3.2 fractures using finite element analysis and biomechanical tests. Methods Axial loading of 700 N was conducted on the AO/OTA 32‐A3.2 model via finite element analysis. The von Mises stress and the interfragmentary movement (IFM) were comparatively analyzed in the three configurations above. On the mechanical tester, axial and torsional loading of 30 synthetic femurs (five specimens of each configuration for each test at random) was performed, and the interfragmentary movement, torsion angle, stiffness, and ultimate load were recorded and analyzed. Results The finite element analysis (FEA) results showed that the von Mises stress of the spatial bridge locking fixator (SBLF) was lower than that of the single locking plate (SP) and higher than that of the double locking plate (DP). At 700 N, the axial IFMs were 0.15–0.38 mm (SBLF), 0.03–0.84 mm (SP), and 0.02–0.07 mm (DP). The biomechanical experiment indicated that the axial interfragmentary movements (IFMs) were 0.44 ± 0.23 mm (SBLF), 1.02 ± 0.40 mm (SP), and 0.07 ± 0.07 mm (DP) ( p < 0.001). The axial IFM of the SBLF group had the highest probability (79.26%) of falling within the ideal range (0.2–0.8 mm), and the SP and DP groups had probabilities of 27.10% and 3.14%, respectively. The axial stiffness in the SBLF group (1586 ± 130 N/mm) was significantly lower than that in the DP group (10,264 ± 2671 N/mm) ( p < 0.001) but greater than that in the SP group (725 ± 178 N/mm) ( p = 0.396). The range of axial loads to ultimate failure was 3385–4527 N (SBLF), 3377–4664 N (SP), and 3780–4804 N (DP). The shear motion of the fracture end was 0.35 ± 0.14 mm (SBLF), 0.16 ± 0.10 mm (SP), and 0.08 ± 0.04 mm (DP) ( p < 0.001). The torsional stiffness was 1.68 ± 0.14 Nm/degree (SBLF), 2.32 ± 0.29 Nm/degree (SP) (SBLF&SP, p < 0.001), and 3.53 ± 0.73 Nm/degree (DP) (SBLF&DP, p < 0.001). Conclusions The SBLF structure may exhibit a better biomechanical performance compared with the SP and DP in providing the best quantity and more symmetrical interfragmentary movement for AO/OTA 32‐A3.2 fractures.

Effect of Plate Configuration in the Primary Stability of Osteotomies and Biological Reconstructions of Femoral Defects: Finite-Element Study

“…Nevertheless, considerable controversy has arisen regarding the appropriate number of osteosynthesis plates required to ensure stability and avoid implant fracture [22]. Hence, the primary aim of this study was to investigate the biomechanical behavior differences produced using two osteosynthesis plates instead of only one for treating femoral shaft osteotomies [24]. Previous studies [22,25,26] have shown that double orthogonal locked plate constructions present higher stiffness than any other configuration.…”

In vitro analysis and in vivo assessment of fracture complications associated with use of locking plate constructs for stabilization of caprine tibial segmental defects

“…The locking plate and locking compression plate combine mechanical stability of a type‐1 external fixator with the benefits of internal fixation such as lower infection risk and lack of external interference [30]. Mechanical testing of LCP stabilized gap defects in vitro have documented superior strength against bending and compressive forces in vitro when compared to conventional dynamic compression plates, but questions have been raised regarding the fixation’s torsional strength [1–3, 14, 15, 21]. In a biomechanical study of tibiofemoral contact forces in sheep, Taylor et al documented significant axial force conveyed to the tibia from the tibiofemoral joint, but unlike humans, sheep experience a greater magnitude of craniocaudal and mediolateral sheer force originating at the stifle [31].…”

“…Avoidance of early loading and carefully monitored rehabilitation following plate fixation are common practices in human orthopedics to maximize fixation stability and reduce the risk of early fatigue, and immediate postoperative weightbearing in preclinical animal models poses a significant challenge to fixation longevity. Bridge plating osteosynthesis relies on a small degree of interfragmentary motion to stimulate callus formation, thus discouraging excessively stiff fixation [ 14 , 34 ]. Conventional dynamic compression plating requires adequate plate to bone contact during screw tightening to achieve desired stability between the plate and bone surface, and potential complications such as periosteal vascular compromise, stress risers, and loss of compression in compromised bone may lead to fracture complications [ 8 , 22 , 35 ].…”

The Impact of Coronal Configuration of the Proximal Femur on its Mechanical Properties and the Validation of a New Theoretical Model: Finite Element Analysis and Biomechanical Examination

“…Fifteen fourth-generation osteoporosic composite artificial left femurs (#3503; Pacific Research Laboratories, Vashon, DC, USA) were purchased in advance. 21 Referring to the coronal plane angles for embedment selected in the FEA, these artificial femurs were assigned into five groups randomly with three in each group. To ensure the consistency of the osteotomy distance and the embedding angle within each group, the purchased digital model of the fourth-generation osteoporotic composite artificial femur (#3503; Pacific Research Laboratory; Vashon, DC, USA) was conducted into Unigraphics NX (Siemens, Plano, TX, USA) to design the tooling for osteotomy and embedding.…”