# Ex-vivo biomechanical quasi-static and cyclic loading tests of new implant fixation system for intra-articular cranial cruciate ligament repair in canine cadaver models

Bastien Goin, Michel Massenzio, Yoann Lafon, Antonin Crumière, Philippe Buttin, Eric Viguier, Thibaut Cachon

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Bastien Goin, Michel Massenzio, Yoann Lafon, Antonin Crumière, Philippe Buttin, et al. Ex-vivo biomechanical quasi-static and cyclic loading tests of new implant fixation system for intra-articular cranial cruciate ligament repair in canine cadaver models. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the.., 10.46298/mbj.16256. hal-05191811v2

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# Ex-vivo biomechanical quasi-static and cyclic loading tests of new implant fixation system for intra-articular cranial cruciate ligament repair in canine cadaver models

Bastien Goin<sup>a, b, c*</sup>, Michel Massenzio<sup>b</sup>, Yoann Lafon<sup>b</sup>, Antonin Crumière<sup>a</sup>, Philippe Buttin<sup>d</sup>, Eric Viguier<sup>c</sup>, Thibaut Cachon<sup>c</sup>

a Novetech Surgery, Nice, France

b Univ Eiffel, Univ Lyon 1, LBMC UMR T_9406, F-69622 Lyon, France

c Université de Lyon, VetAgro Sup, Interactions Cellules Environnement (ICE), Marcy l'Etoile, France

d VetEchoChir, Villaz, France

* Corresponding author: b.goin@novetech-surgery.com

Received date: 31/03/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** biomechanical experiment, cranial cruciate ligament, dog, ex-vivo, synthetic reconstruction

© 2025 The Authors

Licence CC-BY 4.0

Published by Société de Biomécanique

## 1. Introduction

Cranial cruciate ligament (CrCL) rupture is the main cause of hindlimb lameness in dogs. Intra-articular CrCL repair with synthetic implants aims to restore stifle stability while preserving the anatomy.

Strong implant fixation is crucial to obtain satisfactory clinical outcomes, and has been investigated by *ex-vivo* studies on an ultra-high molecular weight polyethylene (UHMWPE) implant fixed with interference screws (ISs) (Goin et al., 2022; Rafael et al., 2020). Tibial fixation is the main weakness due to variable bone quality (Rumph et al., 1995), which may cause implant slippage at the bone/IS interface and impair the stability of the reconstruction.

This study compared the pullout strength of a new titanium system, developed to improve tibial fixation, with that of conventional ISs in quasi-static pullout and cyclic tests. The new system was expected to provide greater pullout strength, with lower total displacement and a higher ultimate load.

## 2. Methods

### 2.1 Sample preparation

Large-breed dog cadavers (35 to 45 kg) were used.

Quasi-static tests: 8 tibias were randomly assigned to two fixation groups (n=4 each) (Fig. 1). Group A: A UHMWPE Novalig implant (Novetech Surgery, France)

was fixed by an IS implanted inside-out in a tunnel drilled from the CrCL footprint to the medial metaphysis. Group B: The Novalig implant was locked with NovaFix® fixation system (Novetech Surgery, France). The ‘female’ part of the NovaFix was inserted outside-in in the tunnel, the Novalig was passed through it, and the ‘male’ part was screwed in to lock the construct.

Cyclic tests: 12 stifles (tibia, menisci and femur) were randomly assigned to two fixation groups (n=6 each) (Fig. 1). Group A: 3 tunnels were drilled at the femoral and tibial CrCL footprints and transversely in the proximal tibia. A Novalig-Platine implant (Novetech Surgery, France) was secured in the femur by a cortical button and an IS inserted inside-out, and in the tibia by two ISs inserted outside-in and medially to laterally. Group B: Femoral fixation was identical to Group A. Tibial fixation was achieved using NovaFix.

### 2.2 Biomechanical testing

Quasi-static pullout tests: 10 N preloaded at 20 mm/min followed by maximum traction test at 1 mm/min at 180° until failure using a tensile testing machine (AGSX, Shimadzu, Japan).

Cyclic loading tests: with the stifles at 135°, 50 N preload at 20 mm/min, 50 N for 1 minute, followed by 50,000 cycles at 1 Hz (50 to 250 N) over 14 hours using a tensile testing machine (ElectroPuls E10000,
Instron, France). Quasi-static loading to failure was finally applied at 20 mm/min until failure. Sample humidity was maintained by vaporization every 15 minutes. Cyclic conditions mimicked the expected ground reaction force equal to 65% of the dog's body (Rumph et al., 1995) over 50,000 cycles, corresponding to the primary mechanical fixation of the UHMWPE implant in the immediate postoperative period, before reinforcement by periarticular fibrosis.

## 2.3 Data processing and statistical analyses

Displacement and force in the traction direction were acquired at 100 Hz and analyzed for total displacement, linear stiffness, and ultimate load using Mann-Whitney tests.

## 3. Results and discussion

In quasi-static tests, NovaFix led to a significant +175%-higher ultimate load for a non-significant +67%-higher total displacement compared to ISs (Table 1). NovaFix led to a significant +96%-higher pullout strength for a 3-mm displacement (considered as limit displacement for a functional CrCL reconstruction) and a non-significant +63%-higher linear stiffness. In group A, the failure mode was implant slippage at the bone/IS interface (n=4). In group B, failure modes were (i) breach of the NovaFix within the tibial bone tunnel along the axis of tensile loading (n=3) and (ii) fracture lines observed in the proximal tibial epiphysis (n=2); one sample presented both. No trend suggested that failure modes influenced the biomechanical outcomes of NovaFix.

In cyclic tests, two specimens from group A were excluded due to early implant slippage, resulting in 10 specimens analysed (NovaFix n=6, ISs n=4). Imbalance in group sizes can reduce statistical power or inflate Type I or II error risk. NovaFix had significantly -81%-lower total displacement, below 3 mm, with reduced variability compared to ISs, and non-significant +151%-higher linear stiffness, possibly enhancing stifle stability (Table 1). In the final quasi-static test, NovaFix led to a non-significant +42%-higher ultimate load than ISs, supporting previous results. Failure modes were implant slippage at the bone/IS interface for group A and at the interface of both parts of NovaFix for group B.

NovaFix seems to improve tibial fixation compared to ISs and matches the overall tensile breaking force of

the native CrCL (Rafael et al., 2021). The reduced and more uniform slippage of UHMWPE implants with NovaFix is attributed to the well-managed metal-metal interface, rather than the bone-metal interface used in IS fixation. These promising results should be interpreted cautiously due to the small sample size, which limits statistical power and generalizability, and should be confirmed by a larger set of samples.

<figure><img src="image_2.png" /><figcaption>**Figure 1.** Diagram of fixation for quasi-static and cyclic tests.</figcaption></figure>

## 4. Conclusions

NovaFix may be suitable for the treatment of CrCL rupture across dogs with variable tibial bone quality, as it seems to provide superior fixation than ISs. Clinical trials should help to determine the benefits of NovaFix with usual activity restriction during the first two post-operative months, necessary for the development of periarticular fibrosis and the integration of the prosthesis.
<table><caption>**Table 1.** Summary table of test results and statistical analyses.</caption><thead><tr><th rowspan="2">Quasi-static</th><th colspan="2">Strength at 3-mm displacement (N)</th><th colspan="2">Total displacement at ultimate load (mm)</th><th colspan="2">Ultimate load (N)</th><th colspan="2">Linear stiffness (N/mm)</th></tr><tr><th>Gr.</th><th>Gr.</th><th>Gr.</th><th>Gr.</th><th>Gr.</th><th>Gr.</th><th>Gr.</th><th>Gr.</th></tr><tr><th></th><th>A</th><th>B</th><th>A</th><th>B</th><th>A</th><th>B</th><th>A</th><th>B</th></tr></thead><tbody><tr><td></td><td>353</td><td>466</td><td>12.2</td><td>9.6</td><td>512</td><td>607</td><td>199</td><td>205</td></tr><tr><td></td><td>225</td><td>503</td><td>4.1</td><td>8.0</td><td>286</td><td>979</td><td>72</td><td>235</td></tr><tr><td></td><td>262</td><td>714</td><td>3.2</td><td>12.9</td><td>266</td><td>1293</td><td>135</td><td>300</td></tr><tr><td></td><td>308</td><td>568</td><td>3.2</td><td>7.3</td><td>313</td><td>909</td><td>157</td><td>178</td></tr><tr><td>Mean</td><td>287</td><td>563</td><td>5.7</td><td>9.5</td><td>344</td><td>947</td><td>141</td><td>230</td></tr><tr><td>SD</td><td>56</td><td>109</td><td>4.4</td><td>2.5</td><td>113</td><td>281</td><td>53</td><td>52</td></tr><tr><td>P-value</td><td colspan="2">0.029*</td><td colspan="2">0.171</td><td colspan="2">0.029*</td><td colspan="2">0.057</td></tr><tr><th>Cyclic</th><th colspan="2">Total displacement (mm)</th><th colspan="2">Ultimate load (N)</th><th colspan="2">Linear stiffness at 1<sup>st</sup> cycle (N/mm)</th><th colspan="2"></th></tr><tr><th></th><th>Gr. A</th><th>Gr. B</th><th>Gr. A</th><th>Gr. B</th><th>Gr. A</th><th>Gr. B</th><th></th><th></th></tr><tr><td></td><td>2.21</td><td>1.28</td><td>528</td><td>712</td><td>225.85</td><td>275.56</td><td></td><td></td></tr><tr><td></td><td>3.25</td><td>1.33</td><td>734</td><td>673</td><td>183.11</td><td>472.64</td><td></td><td></td></tr><tr><td></td><td>0.83</td><td>0.29</td><td>581</td><td>901</td><td>614.98</td><td>1059.19</td><td></td><td></td></tr><tr><td></td><td>8.80</td><td>0.51</td><td>401</td><td>698</td><td>200.27</td><td>1126.93</td><td></td><td></td></tr><tr><td></td><td></td><td>0.57</td><td></td><td>989</td><td></td><td>317.28</td><td></td><td></td></tr><tr><td></td><td></td><td>0.25</td><td></td><td>791</td><td></td><td>1356.95</td><td></td><td></td></tr><tr><td>Mean</td><td>3.77</td><td>0.71</td><td>561</td><td>794</td><td>306.05</td><td>768.09</td><td></td><td></td></tr><tr><td>SD</td><td>3.50</td><td>0.48</td><td>138</td><td>127</td><td>206.70</td><td>467.63</td><td></td><td></td></tr><tr><td>P-value</td><td colspan="2">0.038*</td><td colspan="2">0.067</td><td colspan="2">0.067</td><td></td><td></td></tr></tbody></table>

## Acknowledgements

The authors thank Mrs Cooke-Martageix E. for copyediting.

## Conflict of Interest Statement

Bastien Goin and Antonin Crumière are employed by Novetech Surgery.

## Contributor Roles

BG: Conceptualization, Formal analysis, Investigation, Methodology, Writing-original draft, Writing-review & editing. MM: Conceptualization, Formal analysis, Methodology, Supervision, Writing-review & editing. YL: Conceptualization, Data curation, Formal analysis, Investigation, Methodology, Supervision, Writing-review & editing. AC: Formal analysis, Writing-review & editing. PB: Conceptualization, Methodology, Writing-review & editing. EV: Conceptualization, Methodology, Supervision, Writing-review & editing. TC: Conceptualization, Formal analysis, Investigation, Methodology, Supervision, Writing-review & editing.

## Funding

Bastien Goin was funded by Novetech Surgery for this CIFRE thesis work.

## References

* Goin, B., Buttin, P., Lafon, Y., Massenzio, M., Viguier, E., & Cachon, T. (2022). Biomechanical cyclic loading test of a synthetic ligament fixation system used for intra-articular stabilization of deficient canine stifles. *Open Vet. J.*, 12(3), 341–350. https://doi.org/10.5455/OVJ.2022.v12.i3.6

* Rafael, P., Goin, B., Blanc, Q., Buttin, P., Cachon, T., & Viguier, E. (2021). Ex-vivo biomechanical analysis of cranial cruciate ligament in Labrador breed dogs. *Comput Methods Biomech Biomed Engin, 24(sup1)*, S150-S152. https://doi.org/10.1080/10255842.2021.1978758

* Rafael, P., Goin, B., Buttin, P., Cachon, T., & Viguier, E. (2020). Comparison of two methods of fixation with interference screw for cranial cruciate ligament reconstruction in canine cadaver model. *Comput Methods Biomech Biomed Engin, 23(sup1)*, S247–S249. https://doi.org/10.1080/10255842.2020.1812846

* Rumph, P. F., Kincaid, S. A., Visco, D. M., Baird, D. K., Kammermann, J. R., & West, M. S. (1995). Redistribution of vertical ground reaction force in dogs with experimentally induced chronic hind-limb lameness. *Vet Surg, 24*(5), 384–389. https://doi.org/10.1111/j.1532-950X.1995.tb01348.x

<footnote>*significant difference between groups with 5% confidence interval.</footnote>