. 2021 Nov 26:9:797389.

doi: 10.3389/fbioe.2021.797389. eCollection 2021.

The Femoral Tunnel Drilling Angle at 45° Coronal and 45° Sagittal Provided the Lowest Peak Stress and Strain on the Bone Tunnels and Anterior Cruciate Ligament Graft

Rongshan Cheng^{1

2}, Huizhi Wang^{1

2}, Ziang Jiang^{1

2}, Dimitris Dimitriou³, Cheng-Kung Cheng^{1

2}, Tsung-Yuan Tsai^{1

2}

Affiliations

¹ School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai, China.
² Shanghai Key Laboratory of Orthopaedic Implants & Clinical Translation R&D Center of 3D Printing Technology, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
³ Department of Orthopedics Balgrist University Hospital, Forchstrasse, Zürich, Switzerland.

PMID: 34900975
PMCID: PMC8661475
DOI: 10.3389/fbioe.2021.797389

The Femoral Tunnel Drilling Angle at 45° Coronal and 45° Sagittal Provided the Lowest Peak Stress and Strain on the Bone Tunnels and Anterior Cruciate Ligament Graft

Rongshan Cheng et al. Front Bioeng Biotechnol. 2021.

. 2021 Nov 26:9:797389.

doi: 10.3389/fbioe.2021.797389. eCollection 2021.

Authors

Rongshan Cheng^{1

2}, Huizhi Wang^{1

2}, Ziang Jiang^{1

2}, Dimitris Dimitriou³, Cheng-Kung Cheng^{1

2}, Tsung-Yuan Tsai^{1

2}

Affiliations

¹ School of Biomedical Engineering & Med-X Research Institute, Shanghai Jiao Tong University, Engineering Research Center of Digital Medicine and Clinical Translation, Ministry of Education, Shanghai, China.
² Shanghai Key Laboratory of Orthopaedic Implants & Clinical Translation R&D Center of 3D Printing Technology, Department of Orthopaedic Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, Shanghai, China.
³ Department of Orthopedics Balgrist University Hospital, Forchstrasse, Zürich, Switzerland.

PMID: 34900975
PMCID: PMC8661475
DOI: 10.3389/fbioe.2021.797389

Abstract

Purpose: The aims of this study were to 1) investigate the effects of femoral drilling angle in coronal and sagittal planes on the stress and strain distribution around the femoral and tibial tunnel entrance and the stress distribution on the graft, following anterior cruciate ligament reconstruction (ACLR), 2) identify the optimal femoral drilling angle to reduce the risk of the tunnel enlargement and graft failure. Methods: A validated three-dimensional (3D) finite element model of a healthy right cadaveric knee was used to simulate an anatomic ACLR with the anteromedial (AM) portal technique. Combined loading of 103.0 N anterior tibial load, 7.5 Nm internal rotation moment, and 6.9 Nm valgus moment during normal human walking at joint flexion of 20° was applied to the ACLR knee models using different tunnel angles (30°/45°/60° and 45°/60° in the coronal and sagittal planes, respectively). The distribution of von Mises stress and strain around the tunnel entrances and the graft was calculated and compared among the different finite element ACLR models with varying femoral drilling angles. Results: With an increasing coronal obliquity drilling angle (30° to 60°), the peak stress and maximum strain on the femoral and tibial tunnel decreased from 30° to 45° and increased from 45° to 60°, respectively. With an increasing sagittal obliquity drilling angle (45° to 60°), the peak stress and the maximum strain on the bone tunnels increased. The lowest peak stress and maximum strain at the ACL tunnels were observed at 45° coronal/45° sagittal drilling angle (7.5 MPa and 7,568.3 μ-strain at the femoral tunnel entrance, and 4.0 MPa and 4,128.7 μ-strain at the tibial tunnel entrance). The lowest peak stress on the ACL graft occurred at 45° coronal/45° sagittal (27.8 MPa) drilling angle. Conclusions: The femoral tunnel drilling angle could affect both the stress and strain distribution on the femoral tunnel, tibial tunnel, and graft. A femoral tunnel drilling angle of 45° coronal/ 45° sagittal demonstrated the lowest peak stress, maximum strain on the femoral and tibial tunnel entrance, and the lowest peak stress on the ACL graft.

Keywords: anterior cruciate ligament reconstruction; bone tunnel enlargement; femoral and tibial tunnel; femoral tunnel drilling angle; finite element analysis; graft failure.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

**FIGURE 1**
A three dimensional **(3D)** finite element model of the knee joint was reconstructed using Abaqus/CAE 6.14.

**FIGURE 2**
Right knee flexed at 110°, demonstrating the femoral tunnel created by the. anteromedial portal technique at **(A)** a coronal obliquity angle of 30° (green arrow), 45° (orange arrow) and 60° (red arrow), **(B)** a sagittal obliquity angle of 45° (yellow arrow) and 60° (blue arrow), starting at the native femoral ACL center (green circle).

**FIGURE 3**
Femoral and tibial tunnel entrances divided into four zones. The two white lines divided the femoral tunnel entrance into four zones: anterior and posterior (A and Po), proximal and distal (Pr and D) zone for the femoral tunnel entrance, and anterior and posterior (A and P), medial and lateral (M and L) zone for the tibial tunnel entrance.

**FIGURE 4**
Stress distribution around femoral tunnel entrance following ACLR.

**FIGURE 5**
Strain distribution around femoral tunnel entrance following ACLR.

**FIGURE 6**
Stress distribution around tibial tunnel entrance following ACLR.

**FIGURE 7**
Strain distribution around tibial tunnel entrance following ACLR.

**FIGURE 8**
Stress distribution around the ACL graft following ACLR.

See this image and copyright information in PMC

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The Femoral Tunnel Drilling Angle at 45° Coronal and 45° Sagittal Provided the Lowest Peak Stress and Strain on the Bone Tunnels and Anterior Cruciate Ligament Graft

Affiliations

The Femoral Tunnel Drilling Angle at 45° Coronal and 45° Sagittal Provided the Lowest Peak Stress and Strain on the Bone Tunnels and Anterior Cruciate Ligament Graft

Authors

Affiliations

Abstract

Conflict of interest statement

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