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. 2020 Apr 29;8(4):2325967120915709.
doi: 10.1177/2325967120915709. eCollection 2020 Apr.

Femoral Tunnel Placement Analysis in ACL Reconstruction Through Use of a Novel 3-Dimensional Reference With Biplanar Stereoradiographic Imaging

Julien Montreuil  1   2 , Joseph Saleh  3 , Thierry Cresson  1 , Jacques A De Guise  1 , Frédéric Lavoie  4
Affiliations

Femoral Tunnel Placement Analysis in ACL Reconstruction Through Use of a Novel 3-Dimensional Reference With Biplanar Stereoradiographic Imaging

Julien Montreuil et al. Orthop J Sports Med. .

Abstract

Background: The femoral-sided anatomic footprint of the anterior cruciate ligament (ACL) has been widely studied during the past decades. Nonanatomic placement is an important cause of ACL reconstruction (ACLR) failure.

Purpose: To describe femoral tunnel placement in ACLR through use of a comprehensive 3-dimensional (3D) cylindrical coordinate system combining both the traditional clockface technique and the quadrant method. Our objective was to validate this technique and evaluate its reproducibility.

Study design: Descriptive laboratory study.

Methods: The EOS Imaging System was used to make 3D models of the knee for 37 patients who had undergone ACLR. We designed an automated cylindrical reference software program individualized to the distal femoral morphology of each patient. Cylinder parameters were collected from 2 observers' series of 3D models. Each independent observer also manually measured the corresponding parameters using a lateral view of the 3D contours and a 2-dimensional stereoradiographic image for the corresponding patient.

Results: The average cylinder produced from the first observer's EOS 3D models had a 30.0° orientation (95% CI, 28.4°-31.5°), 40.4 mm length (95% CI, 39.3-41.4 mm), and 19.3 mm diameter (95% CI, 18.6-20.0 mm). For the second observer, these measurements were 29.7° (95% CI, 28.1°-31.3°), 40.7 mm (95% CI, 39.7-41.8 mm), and 19.7 mm (95% CI, 18.8-20.6 mm), respectively. Our method showed moderate intertest intraclass correlation among all 3 measuring techniques for both length (r = 0.68) and diameter (r = 0.63) but poor correlation for orientation (r = 0.44). In terms of interobserver reproducibility of the automated EOS 3D method, similar results were obtained: moderate to excellent correlations for length (r = 0.95; P < .001) and diameter (r = 0.66; P < .001) but poor correlation for orientation (r = 0.29; P < .08). With this reference system, we were able to describe the placement of each individual femoral tunnel aperture, averaging a difference of less than 10 mm from the historical anatomic description by Bernard et al.

Conclusion: This novel 3D cylindrical coordinate system using biplanar, stereoradiographic, low-irradiation imaging showed a precision comparable with standard manual measurements for ACLR femoral tunnel placement. Our results also suggest that automated cylinders issued from EOS 3D models show adequate accuracy and reproducibility.

Clinical relevance: This technique will open multiple possibilities in ACLR femoral tunnel placement in terms of preoperative planning, postoperative feedback, and even intraoperative guidance with augmented reality.

Keywords: 3D modeling; ACL; knee; stereoradiographic imaging.

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Conflict of interest statement

One or more of the authors has declared the following potential conflict of interest or source of funding: This study was sponsored by grants from the Natural Sciences and Engineering Research Council of Canada, Canada Research Chairs, Mitacs, and MEDTEQ. T.C. and J.A.D.G. have received research support and royalties from EOS Imaging and have licensed patents to EOS Imaging. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Figures

Figure 1.
Figure 1.
EOS Imaging System.
Figure 2.
Figure 2.
EOS 3-dimensional (3D) modeling method.
Figure 3.
Figure 3.
Lateral view of distal femur with knee arthroscopy terminology compared to usual references (anterior-posterior).
Figure 4.
Figure 4.
Cylindrical coordinate system. Cynlindrical reference: from the origin, a radius (R), an angle (θ), and a depth (Z) coordinate allow for the description of any point on the cylinder.
Figure 5.
Figure 5.
Intercondylar notch surface mapping with EOS Imaging System.
Figure 6.
Figure 6.
Automated tridimensional cylinder reference system fitted in the intercondylar notch on (A) frontal and (B) sagittal views.
Figure 7.
Figure 7.
Manual validation measurements on 3-dimensional contours.
Figure 8.
Figure 8.
Manual validation measurements on lateral stereoradiographic image with femoral condyles spacing suggesting suboptimal rotation.
Figure 9.
Figure 9.
Three-dimensional location of anatomic femoral anterior cruciate ligament insertion.
Figure 10.
Figure 10.
Actual tunnel axis (green dots) compared with anatomic (black dot) femoral anterior cruciate ligament insertion.
Figure 11.
Figure 11.
Column graph of intertest cylinder validation mean and 95% CIs. Automatized, automated EOS 3D system; XR, stereoradiographic.
Figure 12.
Figure 12.
Intertest Pearson correlation matrices. Automatized, automated EOS 3D system; EOS, manual 3D; XR, manual stereoradiographic.
Figure 13.
Figure 13.
Actual tunnel aperture placement with the cylindrical reference in the intercondylar notch for both observers. ACLR, anterior cruciate ligament reconstruction.
See this image and copyright information in PMC

References

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