Development of a novel anatomical thin titanium mesh plate with reduction guidance and fixation function for Asian zygomatic-orbitomaxillary complex fracture

The Effectiveness of Three-Dimensional Osteosynthesis Plates versus Conventional Plates for the Treatment of Skeletal Fractures: A Systematic Review and Meta-Analysis

PURPOSE

To assess the difference between preformed anatomically shaped osteosynthesis plates and patient-specific implants versus conventional flat plates for the treatment of skeletal fractures in terms of anatomical reduction, operation time, approach, patient outcomes, and complications.

MATERIAL AND METHODS

MEDLINE (1950 to February 2023), EMBASE (1966 to February 2023), and the Cochrane Central Register of Controlled Trials (inception to February 2023) databases were searched. Eligible studies were randomised clinical trials, prospective controlled clinical trials, and prospective and retrospective cohort studies (n ≥ 10). Inclusion criteria were studies reporting the outcomes of preformed anatomically shaped osteosynthesis plates and patient-specific implants versus conventional flat plates after treating skeletal fractures. Outcome measures included anatomical reduction, stability, operation time, hospitalisation days, patients' outcomes, and complications. Two independent reviewers assessed the abstracts and analysed the complete texts and methodologies of the included studies.

RESULTS

In total, 21 out of the 5181 primarily selected articles matched the inclusion criteria. A meta-analysis revealed a significant difference in operation time in favour of the preformed anatomical plates and patient-specific implants versus conventional plates. Significant differences in operation time were found for the orbital (95% CI: -50.70-7.49, p = 0.008), upper limb (95% CI: -17.91-6.13, p < 0.0001), and lower limb extremity groups (95% CI: -20.40-15.11, p < 0.00001). The mean difference in the rate of anatomical reduction in the lower limb extremity group (95% CI: 1.04-7.62, p = 0.04) was also in favour of using preformed anatomical plates and patient-specific implants versus conventional plates.

CONCLUSIONS

This systematic review showed a significant mean difference in surgery time favouring the use of preformed anatomical plates and patient-specific implants for orbital, upper, and lower limb extremity fractures. Additionally, preformed anatomical plates and patient-specific implants in the lower limb group result in a significantly higher rate of anatomical reduction versus conventional flat plates.

Reduction malarplasty using a simulated surgical guide for asymmetric/prominent zygoma

Background

The present study introduces a reduction malarplasty using a three-dimensional (3D)-printed surgical guide and evaluates the guide’s technical applicability.

Methods

Twenty malarplasties were performed for 12 subjects with zygomatic asymmetry/prominency using the current method. 3D reconstruction of the craniomaxillofacial region and fine dental occlusion was made with image data from computed tomograpy and dental scanning. A computer-assisted surgical simulation was performed for reduction malarplasty and a surgical guide was designed for later 3D printing. The manufactured surgical guide was introduced to the operation field to guide the surgery; its surgical accuracy was confirmed by comparing five corresponding points from preoperative simulation and postoperative data.

Results

We successfully performed the reduction malarplasty with the surgical guide. The accuracy level of surgery fell to 0.93 mm of total median difference for the corresponding zygoma points of preoperative simulations and postoperative zygoma. The anterior and upper points showed less error level (0.59 and 0.73 mm difference, respectively) than did other points.

Conclusions

We developed a computer-assisted surgical technique using a surgical guide for asymmetrical/prominent zygoma which proved to be simple, practical, and accurate; it is expected to help surgeons perform reduction malarplasty with ease and accuracy.

Evaluation of the Midface by Statistical Shape Modeling

PURPOSE

The aim of this investigation was to generate a statistical shape model (SSM) of the midface and evaluate symmetry, gender aspects, and bone thickness.

METHODS

About 102 computed tomography scans were analyzed to create the SSM. This included segmentation, landmark attribution, and Procrustes and principal component analysis. Afterward, symmetry and gender differences were visualized by registration and color coding. Bone thickness was calculated by measuring the distance between outer and inner surfaces.

RESULTS

Symmetry was high in all models. The male model showed a more prominent forehead, nasal bones, and larger bizygomatic width. Bone thickness resembled the concept of vertical and horizontal maxillary pillars and buttresses.

CONCLUSIONS

SSM can be used to analyze midface morphology and help in virtual surgery planning. Calculation of bone thickness could also be a useful tool in surgical planning and biomechanics.

Analysis of the accuracy of a novel preformed osteosynthesis plate for the reduction and fixation of zygomaticomaxillary complex fractures

INTRODUCTION

There has been a shift toward surgical treatment of ZMC (zygomaticomaxillary complex) fractures with open reduction and subsequent fixation in the past decades. Anatomically preformed osteosynthesis plates, already used in the field of craniomaxillofacial surgery for the treatment of fractures of the mandible and the orbit, might be a suitable option for ZMC fractures as well.

MATERIAL AND METHODS

A statistical shape model was created from 179 cranial CT scans. Based on this surface model, an anatomically preformed plate for the reduction and fixation of ZMC fractures was developed in 3 sizes (S, M, L). Virtual analysis of the accuracy of the plate was performed on a dataset consisting of 120 CT scans.

RESULTS

Within a determined tolerance range of 0-1.5 mm, analysis revealed a high accuracy of the plate in 70-87 % of the CT scans. The S-sized plate has the highest overall accuracy, whereas the L-sized plate has highest accuracy at the "base" region which is essential for the placement of the plate.

DISCUSSION

The newly developed plate can be placed via an intraoral approach and analysis of the plate has confirmed its accuracy to be sufficient to ensure an adequate fracture reduction and fixation. It thus might allow for a less extensive approach and less approaches/incisions necessary overall to reduce and fixate ZMC fractures.

BIOMECHANICAL ANALYSIS TO VERIFY THE BUTTRESS THEORY WHEN USING THE ANATOMICAL THIN TITANIUM MESH PLATE FOR ZYGOMATICOMAXILLARY COMPLEX BONE FRACTURE

Objective: The aim of this study was to investigate the biomechanics of the facial skeletal for understanding the buttress after fixation with standard and modified anatomical thin titanium mesh (ATTM) plates by finite element (FE) analysis. Methods: Standard ATTM (SATTM) plate designed as the “L”-shape anticipated to be fixed in the ZMC anterior maxilla and lateral buttress to increase the fixation screw anchoring strength and another modified ATTM (MATTM) plate with a protrusion in the medial side and a slot and barb design in the lateral side to enhance the zygomaticomaxillary/nasomaxillary buttresses and provide precise positioning to the ZMC segments were studied by the FE analysis under masticatory forces with 250[Formula: see text]N. Result: The FE simulation results indicated that the total displacement distribution of the maxillary for ZMC fracture fixation with MATTM plate was smaller than that of SATTM plate. Stress concentration was found at the frontal and alveolar processes of the maxillary bone for SATTM plate fixation. Local vector plots of the first principal stress near the frontal process of the maxillary and zygomaticofacial formen of the zygomatic indicated that the stress flow for MATTM plate fixation was relatively close to nasomaxillary buttress, and the zygomaticomaxillary buttress, respectively. Conclusions: This study concluded that “L”-shape ATTM plate designed with a protrusion in the medial side and a slot and barb design in the lateral side can enhance the zygomaticomaxillary/nasomaxillary buttresses under uniform occlusal condition.

Anatomical Thin Titanium Mesh Plate Structural Optimization for Zygomatic-Maxillary Complex Fracture under Fatigue Testing

This study performs a structural optimization of anatomical thin titanium mesh (ATTM) plate and optimal designed ATTM plate fabricated using additive manufacturing (AM) to verify its stabilization under fatigue testing. Finite element (FE) analysis was used to simulate the structural bending resistance of a regular ATTM plate. The Taguchi method was employed to identify the significance of each design factor in controlling the deflection and determine an optimal combination of designed factors. The optimal designed ATTM plate with patient-matched facial contour was fabricated using AM and applied to a ZMC comminuted fracture to evaluate the resting maxillary micromotion/strain under fatigue testing. The Taguchi analysis found that the ATTM plate required a designed internal hole distance to be 0.9 mm, internal hole diameter to be 1 mm, plate thickness to be 0.8 mm, and plate height to be 10 mm. The designed plate thickness factor primarily dominated the bending resistance up to 78% importance. The averaged micromotion (displacement) and strain of the maxillary bone showed that ZMC fracture fixation using the miniplate was significantly higher than those using the AM optimal designed ATTM plate. This study concluded that the optimal designed ATTM plate with enough strength to resist the bending effect can be obtained by combining FE and Taguchi analyses. The optimal designed ATTM plate with patient-matched facial contour fabricated using AM provides superior stabilization for ZMC comminuted fractured bone segments.