# Validation of a 2D/3D shape-matching method for estimating shoulder kinematics after reverse total shoulder arthroplasty using biplane radiographs

Yoann Blache, Sonia Duprey, Sacha Guitteny, Sandrine Bousigues, Raphaël Dumas, Isabelle Rogowski, Florent Moissenet, Nicola Hagemeister, Anthony Viste, Stanislas Gunst, et al.

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To cite this version:

Yoann Blache, Sonia Duprey, Sacha Guitteny, Sandrine Bousigues, Raphaël Dumas, et al. Validation of a 2D/3D shape-matching method for estimating shoulder kinematics after reverse total shoulder arthroplasty using biplane radiographs. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the., 10.46298/mbj.16160. hal-05191712v2

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# Validation of a 2D/3D shape-matching method for estimating shoulder kinematics after reverse total shoulder arthroplasty using biplane radiographs

Yoann Blache<sup>a*</sup>, Sonia Duprey<sup>b</sup>, Sacha Guitteny<sup>b</sup>, Sandrine Bousigues<sup>b</sup>, Raphaël Dumas<sup>b</sup>, Isabelle Rogowski<sup>a</sup>, Florent Moissenet<sup>c</sup>, Nicola Hagemeister<sup>d</sup>, Anthony Viste<sup>b, e</sup>, Stanislas Gunst<sup>f</sup>, Yannick Carrillon<sup>f</sup>, Lionel Neyton<sup>f</sup>

a Université Lyon 1, LIBM UR7424, Lyon, France

b LBMC UMR T_9406, Univ Gustave Eiffel - Université Lyon 1, Lyon, France

c Geneva University Hospitals, Geneva, Switzerland

d Laboratoire d'Innovation Ouverte en technologies de la santé,
École de technologie Supérieure, Canada

e HCL, Hôpital Lyon Sud, Chirurgie Orthopédique et Traumatologique,
Pierre Bénite, France

f Centre Orthopédique Santy, FIFA Medical Center of Excellence, Lyon, France

* Corresponding author: yoann.blache@univ-lyon1.fr

Received date: 31/03/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** shoulder, bone registration, biplane X-Ray, prosthetic implants

© 2025 The Authors

Licence CC-BY 4.0

Published by Société de Biomécanique

## 1. Introduction

Over the last decades, the prevalence of reverse total shoulder arthroplasty (rTSA) has continuously increased. Although rTSA provides substantial functional benefits, multiple complications are also described (Gonzalez et al. 2022). Therefore, a better understanding of rTSA biomechanics and kinematics is crucial to identify how complications can be avoided.

Several approaches have been developed to assess rTSA kinematics (Gonzalez et al. 2022). Marker-based optoelectronic systems are widely used but suffer from inaccuracy because of the soft tissue artifact (Blache et al. 2017). By contrast, current 2D/3D shape-matching approaches based on 3D meshes combined with 2D biplanar radiographs present high accuracy but require the Computer-Aided Design meshes of the prosthetic implants (Matsuki et al. 2012, 2018). These meshes can be obtained from either a post-operative computed tomography (CT) scan or from the surgery planning software, but both solutions have drawbacks, e.g. additional X-ray radiations exposure and the use of an implant reference system limiting outcomes comparisons to data based on more conventional bone reference systems.

This pilot study aimed to 1) assess the accuracy of a 2D/3D shape-matching procedure based solely on

preoperative bone meshes for quantifying the scapular and humeral 3D pose with and without prosthetic implants, and 2) determine the influence of the experimenter expertise on the resulting accuracy.

## 2. Methods

### 2.1 Imaging

A single real full body dry skeleton was used for 2D/3D image registration without prosthetic implants, while radiopaque sawbones of the right scapula and humerus were fixed to the real full body skeleton for analysis with prosthetic implants. In both cases, the bones were fitted with lead beads (Ø 1 mm) to ease bone coordinate system implementation. CT-scans of both real and sawbones scapula and proximal-third of the humerus without prosthetic implant were acquired (140 kVp, 0.6 mm slice thickness, 315 mA, 512×512 resolution). For each bone, a 3D surface mesh was created with 3D Slicer (5.2.1, https://www.slicer.org/) both with (reference) and without (shape-matching) lead beads. Then, the scapula and humerus sawbones received implants simulating a rTSA (Tornier PerformTM humeral system Size 3/4 Ø39; Reversed glenoid eccentric glenosphere CoCr Ø39 +3mm offset). Low dose biplane radiographs (EOS®) of the skeleton without and with
<figure><img src="image_3.png" /><figcaption>**Figure 1.** 2D/3D shape-matching procedure for the skeleton with prosthetic implants</figcaption></figure>

Credit: Blache.

prosthetic implants were finally recorded, while the arm was placed with a pulley at 0°, 30°, 60°, and 90° of humerothoracic elevation in the scapular plane.

## 2.2 2D/3D shape-matching procedure

For the reference, the 2D lead bead coordinates were recorded on each X-ray image and converted to 3D coordinates by using X-ray source intrinsic parameters and location. For the 2D/3D shape-matching procedure,

meshes were manually registered with a custom algorithm (see Data, software, code availability section) based on Laporte et al. (2003). Briefly, it consisted in generating the 2D contours of the 3D meshes (without prosthetic implants) and projecting them on the X-ray images obtained for each elevation angle, both without and with prosthetic implants (Fig. 1).

This procedure was conducted three times by two experienced and two novice experimenters with a minimum interval of four days between repetitions. The bone pose error (translation and helical angle) was calculated at each elevation angle as the difference between the shape-matching and lead bead tracking.

## 3. Results and discussion

For experienced experimenters, the average accuracy of the 2D/3D shape-matching procedure without implants was inferior to 2 mm and 2° for both the scapula and the humerus (Table 1). This accuracy was in the same range than the previous literature (Matsuki et al. 2012). Similar average values were observed for the novice experimenters but with higher extreme values especially for the humerus (up to 7.8°) in comparison to experts.

The average accuracy with implants was inferior to 2 mm and 2° for the scapula for both experienced and novice experimenters (Table 1). These results evidenced that the alterations of both bone meshes (cuts) and X-ray images (occlusions) due to the implants had no impact on the 2D/3D shape-matching procedure for

<table><caption>**Table 1.** Mean [min-max] scapula and humerus mislocation or misorientation</caption><thead><tr><th></th><th></th><th>Scapula mislocation (mm)</th><th>Scapula misorientation (°)</th><th>Humerus mislocation (mm)</th><th>Humerus misorientation (°)</th></tr></thead><tbody><tr><td rowspan="4">Without PI</td><td>Exp #1</td><td>1.1 [0.5-1.8]</td><td>1.7 [0.7-2.4]</td><td>0.8 [0.4-1.4]</td><td>2.0 [1.0-3.7]</td></tr><tr><td>Exp #2</td><td>1.4 [1.0-1.9]</td><td>1.9 [1.5-2.2]</td><td>0.9 [0.2-1.9]</td><td>1.7 [1.0-3.6]</td></tr><tr><td>Nov #1</td><td>1.7 [1.1-2.8]</td><td>2.0 [1.0-2.7]</td><td>1.1 [0.4-1.8]</td><td>2.1 [0.9-4.2]</td></tr><tr><td>Nov #2</td><td>1.6 [0.7-2.6]</td><td>1.9 [0.6-3.6]</td><td>1.2 [0.3-2.3]</td><td>3.0 [0.8-7.8]</td></tr><tr><td rowspan="4">With PI</td><td>Exp #1</td><td>1.6 [1.2-2.1]</td><td>1.1 [0.8-1.4]</td><td>1.3 [0.8-1.6]</td><td>3.2 [1.7-5.1]</td></tr><tr><td>Exp #2</td><td>1.8 [1.3-2.2]</td><td>1.2 [0.8-1.4]</td><td>1.3 [0.2-1.9]</td><td>3.6 [1.0-7.4]</td></tr><tr><td>Nov #1</td><td>1.8 [1.3-2.4]</td><td>1.1 [1.0-1.3]</td><td>1.6 [0.4-2.8]</td><td>5.1 [0.9-10.1]</td></tr><tr><td>Nov #2</td><td>1.5 [1.1-2.1]</td><td>1.1 [0.5-1.5]</td><td>2.1 [0.6-5.0]</td><td>5.2 [3.8-7.1]</td></tr></tbody></table>

PI: Prosthetic Implant; Exp: experienced experimenter; Nov: novice experimenter.

Credit: Blache.
the scapula, likely because key features like the coracoid process, acromion, and lateral margin were not obscured by the implant (Fig. 1).

By contrast, the accuracy decreased for the humerus with implants, with maximal errors up to 1.9 mm and 5.0 mm, and 7.4° and 10.1°, respectively for experienced and novice experimenters. These results can be explained by the absence of the humeral head after rTSA. Nevertheless, the presence of the intertubercular sulcus, even after rTSA, seemed crucial for the 2D/3D shape-matching procedure to ensure the correct rotation along the humeral longitudinal axis. The main limitation of this study was the use of a single full-body skeleton without soft tissues, which may have facilitated the 2D/3D shape matching procedure.

## 4. Conclusions

The main findings of this pilot study are that a 2D/3D shape-matching procedure based on CT-based 3D meshes and low-dose EOS® radiographs following rTSA can be used for an accurate estimation of the scapula's 3D pose, and to a lesser extend that of the humerus. The present approach does not require the Computer-Aided Design meshes of the implant. Additionally, a familiarization to this procedure is advocated to avoid extreme errors.

## Acknowledgements

We would like to thank Stryker for providing the funding for the implant loan used in this study.

## Conflict of Interest Statement

YB, SD, SG, SB, RD, IR, FM, NH, YC declare no conflict of interest.

AV: Stryker - Paid consultant. SG: Lepine - Paid consultant. LN: Stryker - IP royalties and Paid consultant; Tornier - research support.

## Contributor Roles

YB: Conceptualization, Data curation, Investigation, Methodology, Writing-original draft; SD: Conceptualization, Data curation, Investigation, Methodology, Writing-review & editing; SG: Data curation, Investigation, Methodology, Writing-review & editing; SB: Data curation, Investigation, Methodology, Writing-review & editing; RD: Conceptualization, Methodology, Writing-review & editing; IR: Conceptualization, Methodology, Writing-review & editing; FM: Methodology, Writing-review & editing; NH: Methodology, Writing-review & editing; AV: Methodology, Writing-review & editing; SG: Methodology, Writing-review & editing; YC: Methodology, Writing-review & editing; LN: Conceptualization, Methodology, Funding acquisition, Writing-review & editing.

## Funding

This study was supported by Ramsay Santé "COS-RGDS-2022-06-032-P-NEYTON-L".

## Data, software, code availability

https://github.com/yoannBlacheGit/2D-3D-shape-matching.

## References

Blache, Y., Dumas, R., Lundberg, A., & Begon, M. (2017). Main component of soft tissue artifact of the upper-limbs with respect to different functional, daily life and sports movements. *J Biomech, 62*, 39-46. https://doi.org/10.1016/j.jbiomech.2016.10.019

Gonzalez, F. F., Fonseca, R., Leporace, G., Pitta, R., Giordano, M. N., Chahla, J., & Metsavaht, L. (2022). Three-dimensional kinematic evaluation of scapulohumeral rhythm after reverse shoulder arthroplasty: a systematic review and meta-analysis. *JSES Reviews, Reports, and Techniques, 2*, 8-16. https://doi.org/10.1016/j.xrrt.2021.10.009

Laporte, S., Skalli, W., de Guise, J. A., Lavaste, F., & Mitton, D. (2003). A biplanar reconstruction method based on 2D and 3D contours: application to the distal femur. *Comput Methods Biomech Biomed Engin, 6*(1), 1-6. https://doi.org/10.1080/1025584031000065956

Matsuki, K., Matsuki, K. O., Yamaguchi, S., Ochiai, N., Sasho, T., Sugaya, H., ... Banks, S. A. (2012). Dynamic in vivo glenohumeral kinematics during scapular plane abduction in healthy shoulders. *J Orthop Sports Phys Ther, 42*(2), 96-104. https://doi.org/10.2519/jospt.2012.3584

Matsuki, K., Sugaya, H., Hoshika, S., Takahashi, N., Kenmoku, T., & Banks, S. A. (2018). Scaption kinematics of reverse shoulder arthroplasty do not change after the sixth postoperative month. *Clin Biomech, 58*, 1-6. https://doi.org/10.1016/j.clinbiomech.2018.07.005