A Method of Accurate Bone Tunnel Placement for Anterior Cruciate Ligament Reconstruction Based on 3-Dimensional Printing Technology: A Cadaveric Study

Tunnel Management in Revision Anterior Cruciate Ligament Reconstruction: Current Concepts

Bone tunnel-related complications are frequently encountered during revision anterior cruciate ligament reconstruction (ACLR). Issues with tunnel positioning, enlargement, containment, and hardware interference may complicate surgery and compromise outcomes. As a result, several strategies have emerged to address these issues and optimize results. However, a systematic, unified approach to tunnel pathology in revision ACLR is lacking. The purpose of this review is to highlight the current state of the literature on bone tunnel complications and, although extensive literature on the subject is lacking, present an updated approach to the evaluation and management of tunnel-related issues in revision ACLR.

Design and Mechanical Characterization Using Digital Image Correlation of Soft Tissue-Mimicking Polymers

Present and future anatomical models for biomedical applications will need bio-mimicking three-dimensional (3D)-printed tissues. These would enable, for example, the evaluation of the quality-performance of novel devices at an intermediate step between ex-vivo and in-vivo trials. Nowadays, PolyJet technology produces anatomical models with varying levels of realism and fidelity to replicate organic tissues. These include anatomical presets set with combinations of multiple materials, transitions, and colors that vary in hardness, flexibility, and density. This study aims to mechanically characterize multi-material specimens designed and fabricated to mimic various bio-inspired hierarchical structures targeted to mimic tendons and ligaments. A Stratasys^® J750™ 3D Printer was used, combining the Agilus30™ material at different hardness levels in the bio-mimicking configurations. Then, the mechanical properties of these different options were tested to evaluate their behavior under uni-axial tensile tests. Digital Image Correlation (DIC) was used to accurately quantify the specimens’ large strains in a non-contact fashion. A difference in the mechanical properties according to pattern type, proposed hardness combinations, and matrix-to-fiber ratio were evidenced. The specimens V, J1, A1, and C were selected as the best for every type of pattern. Specimens V were chosen as the leading combination since they exhibited the best balance of mechanical properties with the higher values of Modulus of elasticity (2.21 ± 0.17 MPa), maximum strain (1.86 ± 0.05 mm/mm), and tensile strength at break (2.11 ± 0.13 MPa). The approach demonstrates the versatility of PolyJet technology that enables core materials to be tailored based on specific needs. These findings will allow the development of more accurate and realistic computational and 3D printed soft tissue anatomical solutions mimicking something much closer to real tissues.

Application of three-dimensional printed navigation templates to correct lower limb deformities in children by the guided growth technique

Objective

Currently, individualized navigation templates are rarely applied in pediatric orthopedic surgery. This study aimed to explore the potential of navigation templates obtained using computer-aided design and three-dimensional (3D) printing to correct lower limb deformities in children by the guided growth technique.

Methods

We prospectively studied 45 children with leg length discrepancy (LLD) or lower limb angular deformities, who underwent guided growth surgery involving 8-plate. In total, 21 and 24 children were included in the navigation template (group A) group and in the traditional surgery (group B) group, respectively. Mimics software was used for designing and printing navigation templates. The operation time, X-ray radiation exposure, damage to cartilage, and postoperative complications were recorded.

Results

The mean operation time in groups A and B were 20.78 and 28.39 min, respectively, and the difference was statistically significant. Compared with group B, the intraoperative exposure of X-rays in group A was reduced by 25% on average. After 9–24 months of follow-up, the deformities were corrected in both groups. No significant differences in the treatment effect were noted between the groups, and no complications occurred.

Conclusions

Using the individualized navigation template in the guided growth technique made the surgical procedure convenient and simple to perform. In addition, the operation time and intraoperative exposure to X-rays were reduced. We consider that 3D printed navigation templates can facilitate the accurate completion of corrective surgeries for lower limb deformities in children, which is worthy of promotion and application.

Preoperative Planning Using 3D Printing Technology in Orthopedic Surgery

The applications of 3D printing technology in health care, particularly orthopedics, continue to broaden as the technology becomes more advanced, accessible, and affordable worldwide. 3D printed models of computed tomography (CT) and magnetic resonance image (MRI) scans can reproduce a replica of anatomical parts that enable surgeons to get a detailed understanding of the underlying anatomy that he/she experiences intraoperatively. The 3D printed anatomic models are particularly useful for preoperative planning, simulation of complex orthopedic procedures, development of patient-specific instruments, and implants that can be used intraoperatively. This paper reviews the role of 3D printing technology in orthopedic surgery, specifically focusing on the role it plays in assisting surgeons to have a better preoperative evaluation and surgical planning.

Three-dimensional printing educational anatomical model of the patellar luxation in dogs

Background

Few studies are available for assessing the current situation of 3D printing in veterinary medicine, due to the recent popularization of this technology. This study aimed to simulate a 3D model of the femorotibiopatellar joint of dogs based on the medial patellar luxation. The scanning, editing and printing of the femur, tibia, fibula and patella of a dog from the Laboratory of Anatomy of FMVZ USP were performed.

Results

Three femorotibiopatellar joint models were printed: one representing a healthy join without alterations; the second one with the medially deviated tibial tuberosity; and a last one representing the shifted tibial tuberosity and the trochlear sulcus flattened as consequence. The 3D edition consisted of medial rotation of the tibia and tibial tuberosity (22° against the healthy tibia), and the flatten of the medial femoral condyle (0.2 cm) and femoral trochlear groove. After printing, the corresponding measurements were taken with the alterations and the bone models were made with elastics to represent the anatomical components of the dog joint. Finally, the measurements corresponding to the distance from the patellar ligament to the lateral femoral condyle were taken in each specimen, in order to observe the change in position of the ligament according to the occurrence of the bone alterations.

Conclusion

We printed 3D articular anatomical components of the femurotibiopatellar joint that could be valuable educational tools for the study of medial patellar luxation in dogs.

Multi-color and Multi-Material 3D Printing of Knee Joint models

Objective

This study reports on a new method for the development of multi-color and multi-material realistic Knee Joint anatomical models with unique features. In particular, the design of a fibers matrix structure that mimics the soft tissue anatomy.

Methods

Various Computer-Aided Design (CAD) systems and the PolyJet 3D printing were used in the fabrication of three anatomical models wherein fibers matrix structure is mimicked: (i) Anterior cruciate ligament reconstruction (ACL-R) model used in the previous study. (ii) ACL-R model, incorporating orientations, directions, locations, and dimensions of the tunnels, as well as a custom-made surgical guide (SG) for avoiding graft tunnel length mismatch. (iii) Total knee arthroplasty (TKA) model, including custom-made implants. Before models 3D printing, uni-axial tensile tests were conducted to obtain the mechanical behaviors for individual No. 1 (A60-A50), No. 2 (A50-A50), No. 3 (A50-A40), and No. 4 (A70-A60) soft tissue-mimicking polymers. Each material combination represents different shore-hardness values between fiber and matrix respectively.

Results

We correlated the pattern of stress-strain curves in the elastic region, stiffness, and elastic modulus of proposed combinations with published literature. Accordingly, material combinations No. 1 and No. 4 with elastic modules of 0.76-1.82 MPa were chosen for the soft tissues 3D printing. Finally, 3D printing Knee Joint models were tested manually simulating 50 flexo-extension cycles without presenting ruptures.

Conclusion

The proposed anatomical models offer a diverse range of applications. These may be considered as an alternative to replacing cadaver specimens for medical training, pre-operative planning, research and education purposes, and predictive models validation. The soft tissue anatomy-mimicking materials are strong enough to withstand the stretching during the flexo-extension. The methodology reported for the design of the fiber-matrix structure might be considered as a start to develop new patterns and typologies that may mimic soft tissues.

The use of a 3D-printed individualized navigation template to assist in the anatomical reconstruction surgery of the anterior cruciate ligament

Background

To explore the location accuracy and early clinical outcomes of using a 3D-printed individualized navigation template to assist in the reconstruction of the anterior cruciate ligament (ACL).

Methods

A single center randomized control study was conducted. Patients with ACL injury were treated with a conventional operation or an operation assisted by a 3D-printed individualized navigation template (the 3D group). The primary endpoint was the accuracy of the actual reconstruction compared with the planned position.

Results

There were 20 and 23 participants in the conventional group and the 3D group, respectively. There were no differences in the bone tunnel position between the actual postoperative position and the preoperative design in the 3D group (P>0.05). Compared with the 3D group, the positioning of the femoral tunnel was more inferior and shallower in the conventional group (P<0.05). The position of the tibia tunnel was closer to the anterior and medial edge of the tibial platform in the conventional group compared to the 3D group (P<0.05). The intraoperative positioning time was shorter in the 3D group than in the conventional group (3.3±1.0 vs. 5.9±1.8 minutes, P<0.001). The Lysholm and International Knee Documentation Committee scores did not differ between the two groups (P>0.05 for both), and all patients improved after surgery (P<0.001).

Conclusions

The 3D-printed individualized navigation template showed good location accuracy and resulted in reduced intraoperative positioning time compared to the traditional method for ACL reconstruction.

3-Dimensional Printed Models May Be a Useful Tool When Planning Revision Anterior Cruciate Ligament Reconstruction

Purpose

To determine whether using 3-dimensional (3D)-printed models in addition to computed tomography (CT) scans to evaluate the primary femoral and tibial tunnels before revision anterior cruciate ligament (ACL) reconstruction leads to better agreement with the surgical approach than CT alone.

Methods

Fifteen patients who underwent revision ACL reconstruction were retrospectively identified. The mean age was 24.3 years, and 73% were female. Using only CT images, 3 board-certified orthopaedists and 5 sports medicine orthopaedic fellows evaluated whether the existing tibial and femoral tunnels were acceptable for the revision surgery. Subsequently, 3D-printed models were made available in addition to the CT scan, and the same questions were asked.

Results

For the attending orthopaedic physicians, adding the 3D-printed models did not have a significant impact on the tibial or femoral tunnel agreement compared with the surgical approach. With the fellow physicians, however, using the 3D-printed models with tibial tunnel evaluation led to a higher agreement rate (76%) compared with CT images alone (63%) (P = .050). Furthermore, with the fellow physicians, there was a higher overall agreement when evaluating both the tibial and femoral tunnels with the addition of 3D-printed models (74%) compared with CT alone (65%) (P = .049).

Conclusion

Our hypothesis that using 3D-printed models leads to better agreement with the surgical approach was unsupported based on the response of the board-certified orthopaedists. Based on the fellow response, it stands to reason that 3D-printed models may be a useful tool in understanding spatial orientation when planning for revision ACL surgery.

Level of Evidence

IV, retrospective case series.

An ACL reconstruction robotic positioning system based on anatomical characteristics

To improve the positioning accuracy of tunnels for anterior cruciate ligament (ACL) reconstruction, we proposed an ACL reconstruction robotic positioning system based on anatomical characteristics. The system includes a preoperative path planning system, an intraoperative path planning system, and a navigation and positioning system. Brahmet line, anterior, and posterior cortical lines are used for registration of preoperative computed tomography (CT) images and intraoperative X-ray images. A new calibrator of C-arm is applied to establish the mapping between medical images and surgical space. Tunnels for ACL reconstruction can be built anatomically by the robot. The accuracy of the path planning system is 1.73 mm in the four dry bones experiments and 2.17 mm in the two cadaver experiments. The accuracy meets the accuracy requirement of ACL construction surgery.

Patient-Specific Coronary Artery 3D Printing Based on Intravascular Optical Coherence Tomography and Coronary Angiography

Despite the new ideas were inspired in medical treatment by the rapid advancement of three-dimensional (3D) printing technology, there is still rare research work reported on 3D printing of coronary arteries being documented in the literature. In this work, the application value of 3D printing technology in the treatment of cardiovascular diseases has been explored via comparison study between the 3D printed vascular solid model and the computer aided design (CAD) model. In this paper, a new framework is proposed to achieve a 3D printing vascular model with high simulation. The patient-specific 3D reconstruction of the coronary arteries is performed by the detailed morphological information abstracted from the contour of the vessel lumen. In the process of reconstruction which has 5 steps, the morphological details of the contour view of the vessel lumen are merged along with the curvature and length information provided by the coronary angiography. After comparing with the diameter of the narrow section and the diameter of the normal section in CAD models and 3D printing model, it can be concluded that there is a high correlation between the diameter of vascular stenosis measured in 3D printing models and computer aided design models. The 3D printing model has high-modeling ability and high precision, which can represent the original coronary artery appearance accurately. It can be adapted for prevascularization planning to support doctors in determining the surgical procedures.

The Effects of a Functional Three-dimensional (3D) Printed Knee Joint Simulator in Improving Anatomical Spatial Knowledge

In recent decades, three-dimensional (3D) printing as an emerging technology, has been utilized for imparting human anatomy knowledge. However, most 3D printed models are rigid anatomical replicas that are unable to represent dynamic spatial relationships between different anatomical structures. In this study, the data obtained from a computed tomography (CT) scan of a normal knee joint were used to design and fabricate a functional knee joint simulator for anatomical education. Utility of the 3D printed simulator was evaluated in comparison with traditional didactic learning in first-year medical students (n = 35), so as to understand how the functional 3D simulator could assist in their learning of human anatomy. The outcome measure was a quiz comprising 11 multiple choice questions based on locking and unlocking of the knee joint. Students in the simulation group (mean score = 85.03%, ±SD 10.13%) performed significantly better than those in the didactic learning group, P < 0.05 (mean score = 70.71%, ±SD 15.13%), which was substantiated by large effect size, as shown by a Cohen's d value of 1.14. In terms of learning outcome, female students who used 3D printed simulators as learning aids achieved greater improvement in their quiz scores as compared to male students in the same group. However, after correcting for the modality of instruction, the sex of the students did not have a significant influence on the learning outcome. This randomized study has demonstrated that the 3D printed simulator is beneficial for anatomical education and can help in enriching students' learning experience.

Intensity-based 2D-3D registration for an ACL reconstruction navigation system

To improve the positioning accuracy of tunnels for anterior cruciate ligament (ACL) reconstruction, we proposed an intensity-based 2D-3D registration method for an ACL reconstruction navigation system. Methods for digitally reconstructed radiograph (DRR) generation, similarity measurement, and optimization are crucial to 2D-3D registration. We evaluated the accuracy, success rate, and processing time of different methods: (a) ray-casting and splating were compared for DRR generation; (b) normalized mutual information (NMI), Mattes mutual information (MMI), and Spearman's rank correlation coefficient (SRC) were assessed for similarity between registrations; and (c) gradient descent (GD) and downhill simplex (DS) were compared for optimization. The combination of splating, SRC, and GD provided the best composite performance and was applied in an augmented reality (AR) ACL reconstruction navigation system. The accuracy of the navigation system could fulfill the clinical needs of ACL reconstruction, with an end pose error of 2.50 mm and an angle error of 2.74°.