Biomechanical analysis of titanium alloy porous spacer-enhanced high tibial osteotomy versus conventional T-shaped plate and bone grafting

Abstract

BACKGROUND: High tibial osteotomy is an effective treatment for certain patients with knee osteoarthritis; however, traditional T-shaped plates have multiple limitations. OBJECTIVE: To compare the biomechanical performance of titanium alloy porous blocks with that of conventional T-shaped plates and bone grafting schemes in high tibial osteotomy using finite element analysis. METHODS: A computer simulation experiment was conducted, performing three-dimensional finite element analysis on a 55-year-old male patient who underwent high tibial osteotomy. Three different implant geometries were constructed: a conventional T-shaped plate high tibial osteotomy model (Model A), a bone graft–augmented high tibial osteotomy model (Model B), and a titanium alloy porous block–augmented high tibial osteotomy model (Model C). These models were used to evaluate the effects of each implant on total displacement and stress distribution under two loading conditions: standing and initial rising from a seated position. RESULTS AND CONCLUSION: (1) Validation results confirmed that the finite element models were effective. (2) In terms of stability, Model C (titanium alloy porous block–augmented high tibial osteotomy) demonstrated the best reduction in total displacement, with maximum displacements under both standing and rising conditions significantly lower than those of the other two models. (3) Stress analysis revealed that Model C had the lowest T-shaped plate stress levels, (40.9±36.5) MPa (standing) and (66.1±44.7) MPa (rising), reduced by 91.2% and 92.9% compared to Model A; additionally, the average stress at the lateral hinge site was significantly lower than Models A and B, indicating an advantage in reducing lateral hinge fracture risk. Stress distribution at the proximal osteotomy contact surface and hinge site showed that Model C had better stress stimulation effects, promoting bone healing while reducing hinge fracture risk. (4) These findings suggest that the titanium alloy porous block not only enhances initial stability of the surgical area but also optimizes stress transmission pathways and provides a favorable biocompatible environment, offering a new approach to address the limitations of existing plates in mechanical stability and biological fusion, with potential clinical application value.

1. Introduction

High tibial osteotomy (HTO) is a surgical procedure that corrects lower limb alignment and reduces medial compartment pressure, making it an important treatment option for patients under 65 years with medial compartment knee osteoarthritis [1-5]. However, current HTO techniques are associated with various postoperative complications, such as patella baja, gait changes, hinge fractures, tibial tubercle fractures, vascular injuries, and delayed union, which fail to meet the growing clinical demands. Although some T-shaped internal fixation systems can partially address these issues, they still have five major drawbacks: (1) poor plate-to-tibia fit, increasing the risk of lateral hinge fractures [6]; (2) limited placement options, leading to stress concentration and plate breakage [7]; (3) suboptimal screw direction, posing a risk to the popliteal vessels [8]; (4) lack of posterior medial support, resulting in increased posterior tibial slope [9]; and (5) mismatch between the support and the osteotomy line, affecting stability in large-angle corrections [6]. Therefore, there is an urgent need to develop systematic, precise, and personalized fixation strategies that integrate anatomical and mechanical characteristics, achieving synergistic innovation between surgical techniques and fixation systems to meet the increasing clinical demands in an aging population.

Although locking plate systems such as TomoFix have met the biomechanical strength requirements for postoperative weight-bearing, clinical practice still observes complications such as plate stress concentration, lateral hinge fractures, and nonunion. This indicates that relying solely on plate strength cannot fully address all biomechanical challenges of HTO. The authors' research group encountered a typical case of HTO failure: a patient still had nonunion at the osteotomy site two years postoperatively, with imaging showing obvious bone defects (Figure 1). This case highlights the limitations of existing internal fixation systems in promoting bone healing. Although HTO generally has relatively fast healing due to the cancellous bone at the osteotomy site and does not routinely require bone grafting, for patients with large-angle corrections, osteoporosis, or other risk factors for impaired bone healing, nonunion or loss of correction may still occur [10]. This study, based on a typical clinical failure case, explores the potential of a titanium alloy porous spacer to enhance HTO biomechanics.