Adding a protective screw improves hinge's axial and torsional stability in High Tibial Osteotomy

Abstract

Backgrounds: Despite the use of a locking plate a 30% incidence of lateral hinge fracture after Open-Wedge High Tibial Ostetomy was described in the literature.A finite element model was used to analyze if the presence of a hinge-securing screw in the osteotomy area, using Patient Specific Cutting Guides with a locking plate, decreases the stresses within the lateral hinge during compression and torsion. Methods: A 3D model of a tibial sawbone was used to simulate an opening wedge of 10°. To apply loads on the tibial plateau, two supports were modelled on each tibial plateau to simulate the femoral condyles forces. A two second model with a hinge-stabilizing was defined with two different screws (diameter 2 mm and 4 mm). Two cases of static charges were considered 1) compression test (2500 N) 2) Torsion test (along the tibial mechanical axis). Findings: During compression simulation, 17% of the total surface of lateral hinge was stressed between 41-50Mpa without hinge-securing screw while the amount of surface under stress between 41 and 50 MPa dropped significantly under screw stabilization (1% for the 2 mm and 3% for the 4 mm).During torsion stress simulation a decrease of the value of the maximal stress in the lateral hinge was also observed with the addition of a hinge-securing screw (37 MPa without screw, 27Mpa with a 2 mm screw and 25 Mpa with a 4 mm screw). Interpretation: Positioning a screw intersecting the cutting plane at the theoretical lateral hinge location associated with a locking plate reduces lateral hinge stress in both compression and torsion. Those findings need to be confirmed by further specimens' mechanical testing.

Incidence and Factors Affecting the Occurrence of Lateral Hinge Fracture After Medial Opening-Wedge High Tibial Osteotomy

“…14 Previous studies have reported that protective wire or screw insertions may reduce the occurrence of hinge fractures and further displacement. 2,5,10 Based on these results, we suppose that a protective K-wire fixation may help prevent the LHF when a large correction (>11 mm of gap width) is planned.…”

Influence of the Screw Positioning on the Stability of Locking Plate for Proximal Tibial Fractures: A Numerical Approach

“…Accordingly, it can be deduced that the configuration (Figure 9) with a higher value of the reaction force (F) is more stable, and the one with a lower pressure (pmax) ensures reduced damage of the bone and, consequently, a higher stability of the implant. To obtain highly reliable numerical models, we set up the FEM models following a largely validated protocol [19,37,39]. Table 3 summarizes the main results obtained for each configuration analysed.…”

“…To obtain highly reliable numerical models, we set up the FEM models following a largely validated protocol [19,37,39]. Table 3 summarizes the main results obtained for each configuration analysed.…”

“…In recent years, many studies have examined the finite element method (FEM) analysis of locking plates in order to better understand which parameters can affect the performance of this type of fixation system. They typically investigate how number, length, type, or shape of the screws and the shape of the plates affect the implant stability [4,8,[17][18][19][20][21]. Some authors [22] have demonstrated the influence of the screw configuration on the stability of tibial tubercle osteotomy (without plates), but as far as we know, the influence of the screw configuration on the stability of tibial locking plates has not yet been adequately analysed.…”

Biomechanical Analysis of Two Types of Osseointegrated Transfemoral Prosthesis

“…In particular, a FEM-based approach has been used and virtual simulations [24,46] have been performed using the commercial software Ansys Workbench (Ansys Inc., Canonsburg, PA, USA). To obtain highly reliable numerical models, the FEM models have been set up following a largely validated protocol [30,47,48]. Ten-node tetrahedral elements (SOLID187) were used to mesh the femur and the implant, and eight-node surface-to-surface (CONTA174 and TARGE170) contact elements [30] were used to mesh the bone/prosthesis interfaces (Figure 7).…”