Reinforcement strategy for medial open-wedge high tibial osteotomy: a finite element evaluation of the additional opposite screw technique and bone grafts

Preliminary exploration of finite element biomechanical preoperative planning for complex tibial plateau fractures

The aim of this study was to compare the clinical outcomes, biomechanical performance, and cost-effectiveness of finite element planning (FEP) with those of traditional (Trad) methods in the treatment of complex tibial plateau fractures in middle-aged and elderly patients to ultimately optimize treatment protocols, improve surgical efficiency, and reduce the economic burden on patients. Sixteen patients with complex tibial plateau fractures were randomly divided into FEP and Trad groups, with eight patients in each group. The FEP group underwent preoperative finite element analysis for personalized surgical planning and dual-plate fixation; the Trad group participated in traditional preoperative discussions and underwent a multi-plate fixation. Perioperative and postoperative indicators were collected from both groups, and the stress distribution and displacement under different internal fixation modes were evaluated using finite element analysis. Additionally, a cost-effectiveness analysis was conducted to compare the total costs of internal fixation and hospitalization. The surgical times were significantly shorter in the FEP group than in the Trad group (170.00 ± 59.52 vs. 240.00 ± 59.04 min, p = 0.033), and patients in the Trad group had shorter times to ambulation (12.88 ± 0.99 vs. 14.25 ± 1.49 days, p = 0.047). There were no significant differences between the groups in terms of postoperative orthopaedic scores, mobility indices, fracture healing times, or radiological indicators. Biomechanical analysis revealed that the multiplate fixation mode provided a more uniform stress distribution, but this difference was not statistically significant. In the FEP group, the total costs of internal fixation (4772.25 ± 217.31 vs. 8991.88 ± 2811.25 yuan, p = 0.004) and hospitalization (34796.75 ± 9749.19 vs. 65405.14 ± 28684.80 yuan, p = 0.013) were significantly lower. While ensuring clinical effectiveness, FEP demonstrated greater cost-effectiveness by shortening the surgery time and reducing internal fixation costs. Although the multiplate fixation mode was biomechanically superior to the dual-plate mode, it did not result in significant clinical advantages and was more costly. FEP improves the economic efficiency of treatment for complex tibial plateau fractures in middle-aged and elderly patients and is recommended. This study has certain limitations, such as a small sample size and a short follow-up period. Thus, larger-scale studies with longer-term follow-up data are needed to further validate these findings and explore whether all patient populations can benefit from these practices or if the benefits are limited to specific groups, such as elderly patients or those with certain types of fractures.

Editorial Commentary: Biomechanical Studies Show Lateral Hinge Screws May Increase Load to Failure After Medial Opening-Wedge High Tibial Osteotomy

Lateral hinge fracture is a common complication after medial opening-wedge high tibial osteotomy, occurring in up to 32% to 50% of cases. This can lead to delayed union, nonunion, and loss of correction. A larger medial opening gap width is the most consistently identified risk factor, although lateral hinge width, osteotomy level, and uniplanar versus biplanar technique have also been implicated. To mitigate the risk of postoperative lateral hinge fracture, lateral hinge screws, inserted after osteotomy fixation, have been proposed. Biomechanical studies suggest these improve the ultimate strength of the osteotomy construct, with load to failure increasing 30% in response to varus loading and 2- to 3-fold in response to compressive stress. Despite these biomechanical findings, clinical translation remains a critical next step.

A Single Lateral Hinge Screw Increased Resistance to Varus Stress After Medial Opening-Wedge High Tibial Osteotomy in a Synthetic Bone Model: A Biomechanical Analysis

PURPOSE

To determine whether use of a tibial screw placed across the lateral tibial hinge results in significantly greater failure load compared with no lateral screw after medial opening wedge high tibial osteotomy (MOWHTO).

METHODS

Twelve Sawbone tibias were used for the study. A MOWHTO was performed in each specimen using a computed tomography-based patient specific correction guide, and 6 specimens received a lateral hinge screw. Cantilever varus bending load was applied to failure, and failure load, displacement at failure, and stiffness of the osteotomy before hinge failure were recorded.

RESULTS

Failure load was statistically higher in the hinge screw group compared to the control group, 437.0 ± 82.0 N vs 336.0 ± 55.9 N, P = .046 (mean ± standard deviation). This load to failure was 30% greater in MOWHTO using a hinge screw versus the control.

CONCLUSIONS

Using a Sawbone model, the current data showed that placement of a lateral hinge screw significantly increased resistance to varus stress following MOWHTO compared with a construct having no tibial screw. Additionally, no significant difference in displacement or stiffness was observed between the hinge screw and the control groups.

CLINICAL RELEVANCE

The current biomechanical findings suggest that the use of a laterally based proximal tibial screw can potentially reduce the risk of lateral hinge fracture and its associated morbidity after MOWHTO.

Evaluating the Effectiveness of a Structural Allograft in Medial Open Wedge High Tibial Osteotomy in Patients With and Without a Lateral Hinge Fracture

BACKGROUND

A lateral hinge fracture is a common complication in medial open wedge high tibial osteotomy (MOWHTO) and is associated with delayed union or nonunion. A comparison of outcomes between patients with or without a lateral hinge fracture after MOWHTO with a structural allograft has not been investigated.

PURPOSE

To validate the outcomes of MOWHTO with a structural allograft, especially in the presence of a lateral hinge fracture.

STUDY DESIGN

Case series; Level of evidence, 4.

METHODS

We conducted a single-surgeon cohort study at a tertiary referral hospital between April 2017 and August 2022 and included patients who had undergone MOWHTO with a structural allograft for isolated medial compartment osteoarthritis with genu varum. We compared the incidence of delayed union or nonunion events and functional scores between patients with a lateral hinge fracture and those without using the Fisher exact test and independent t test.

RESULTS

A total of 88 MOWHTO procedures (77 patients) were analyzed. The overall incidence of lateral hinge fractures was 29.5% (n = 26), including type I (n = 20 [22.7%]) and type II (n = 6 [6.8%]). Notably, 42.3% (n = 11) of these fractures had not been detected intraoperatively but during the follow-up visits. The overall Knee Society Score (KSS), Knee Society Score-Function (KSS-F), and Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores were 90.0 ± 10.0, 93.4 ± 10.8, and 93.8 ± 7.1 points, respectively. None of the patients had delayed union or nonunion, and none underwent a reoperation because of bony union problems. The functional scores (KSS, KSS-F, and WOMAC) were not different between patients who had a lateral hinge fracture and those who did not (P > .05).

CONCLUSION

The routine use of a structural allograft was associated with satisfactory outcomes after MOWHTO, regardless of whether there was a lateral hinge fracture.

Importance of the Posterior Plate in Three-Column Tibial Plateau Fractures: A Finite Element Analysis and Clinical Validation

OBJECTIVE

Dual-plate fixation was thought to be the gold standard for treating complicated bicondylar tibial plateau fractures, yet it was found to be hard to accommodate the posterior column in three-column fractures. Currently, column-specific fixation is becoming more and more recognized, but no comprehensive investigation has been performed to back it up. Therefore, the objective of this study was to validate the importance of posterior column fixation in the three-column tibial fractures by a finite element (FE) analysis and clinical study.

METHODS

In FE analysis, three models were developed: the longitudinal triple-plate group (LTPG), the oblique triple-plate group (OTPG), and the dual-plate group (DPG). Three loading scenarios were simulated. The distribution of the displacement and the equivalent von Mises stress (VMS) in each structure was calculated. The comparative measurements including the maximum posterior column collapse (MPCC), the maximum total displacement of the model (MTD), the maximum VMS of cortical posterior column (MPC-VMS), and the maximum VMS located on each group of plates and screws (MPS-VMS). The clinical study evaluated the indicators between the groups with or without the posterior plate, including operation time, blood loss volume, full-weight bearing period, Hospital for Special Surgery Knee Scoring system (HSS), Rasmussen score, and common postoperative complications.

RESULTS

In the FE analysis, the MPCC, the MPC-VMS, and the MTD were detected in much lower amounts in LTPG and OTPG than in DPG. In comparison with DPG, the LTPG and OTPG had larger MPS-VMS. In the clinical study, 35 cases were included. In the triple-plate (14) and dual-plate (21) groups, the operation took 115.6 min and 100.5 min (p < 0.05), respectively. Blood loss in both groups was 287.0 mL and 206.6 mL (p < 0.05), and the full-weight bearing period was 14.5 weeks and 16.2 weeks (p < 0.05). At the final follow-up, the HSS score was 85.0 in the triple-plate group and 77.5 in the dual-plate (p < 0.05), the Rasmussen score was 24.1 and 21.6 (p < 0.05), there were two cases with reduction loss (9.5%) in the dual-plate group and one case of superficial incision infection found in the triple-plate group.

CONCLUSION

The posterior implant was beneficial in optimizing the biomechanical stability and functional outcomes in the three-column tibial plateau fractures.

Model Properties and Clinical Application in the Finite Element Analysis of Knee Joint: A Review

The knee is the most complex joint in the human body, including bony structures like the femur, tibia, fibula, and patella, and soft tissues like menisci, ligaments, muscles, and tendons. Complex anatomical structures of the knee joint make it difficult to conduct precise biomechanical research and explore the mechanism of movement and injury. The finite element model (FEM), as an important engineering analysis technique, has been widely used in many fields of bioengineering research. The FEM has advantages in the biomechanical analysis of objects with complex structures. Researchers can use this technology to construct a human knee joint model and perform biomechanical analysis on it. At the same time, finite element analysis can effectively evaluate variables such as stress, strain, displacement, and rotation, helping to predict injury mechanisms and optimize surgical techniques, which make up for the shortcomings of traditional biomechanics experimental research. However, few papers introduce what material properties should be selected for each anatomic structure of knee FEM to meet different research purposes. Based on previous finite element studies of the knee joint, this paper summarizes various modeling strategies and applications, serving as a reference for constructing knee joint models and research design.

The best position of bone grafts in the medial open-wedge high tibial osteotomy: A finite element analysis

BACKGROUND AND OBJECTIVE

The application of wedge-shaped bone grafts can increase the biomechanical stability of knee during the medial open-wedge high tibial osteotomy (MOWHTO) by reducing the von Mises stress of the medial plate and lateral cortical hinge area. However, the optimal position of bone grafts it remains unclear, so we aimed to determine search for the optimal position of the bone grafts in MOWHTO by using finite element analysis.

METHODS

In the finite element analysis, MOWHTO models were established with three different osteotomy distraction heights and assembled into four groups according to different conditions, including the no bone grafts (NBG) group, the anterior bone grafts (ABG) group, the middle bone grafts (MBG) group, and the posterior bone grafts (PBG) group. Based on previous studies, 600 N and 1800 N loads were applied to the knee joint to simulate the static forces during a double and single leg stance to measure the von Mises stress of the medial implant area and lateral hinge area, the maximum displacement of different models, the relative displacement of the osteotomy area and the stress distribution in the bone grafts.

RESULTS

Compared to the NBG and ABG groups, the stress of the lateral cortical hinge area and the medial implate area was significantly lower in the PBG group. For example, under the 600N force load, when the height of the osteotomy area was 10 mm, 15 mm, and 20 mm, the maximum von Mises stress of the medial implate area and lateral cortical hinge area in the NBG group were 140, 141, 172, and 53, 57, 60 MPa, respectively. Compared with the NBG group, the maximum von Mises stress of the medial implate area and lateral cortical hinge area in the PBG group were reduced by 45%, 56%, 63% and 14%, 39%, 68% at distraction height of 10 mm, 15 mm, and 20 mm, respectively. The bone grafts in the posterior parts provide the best stability,with the stress of the middle and posterior bone grafts are mainly concentrated in the edge.

CONCLUSIONS

The posterior part of the osteotomy area is the best position for bone graft placement since it provides optimal stability and reduces von Mises stress in the medial plate and lateral cortex hinge area, with the stress of the posterior bone grafts mainly concentrated in the edge. These findings guide bone graft placement sites in clinical surgery and are a basis for future research on bone graft materials and structures in MOWHTO.