Original Article
Using Interconnected Knotless Anchor for Suprapectoral Biceps Tenodesis Could Offer Improved Biomechanical Properties in a Cadaveric Model

https://doi.org/10.1016/j.arthro.2020.03.028Get rights and content

Purpose

To compare the biomechanical characteristics of the interconnected knotless anchor (IKA) fixation with the double knotless anchor (DKA) and interference screw (IS) fixation in the suprapectoral biceps tenodesis.

Methods

In total, 24 fresh-frozen human cadaveric shoulders (mean age, 67.3 ± 6 years) were used for the study. All the specimens were randomly divided into 3 experimental biceps tenodesis groups (n = 8): IKA, DKA, and IS. After tenodesis, each specimen was preloaded at 5 N for 2 minutes, followed by a cyclic loading test from 5 to 70 N for 500 load cycles. Finally, a destructive axial load to failure test (1 mm/s) was performed. All the values, including ultimate failure load, stiffness, cyclic displacement, and mode of failure were evaluated.

Results

The IKA provided the highest construct stiffness (38.9 ± 7.7 N/mm) and ultimate failure load (288.3 ± 47.6 N), the results for which were statistically better than the corresponding results in the IS and DKA groups. In terms of cyclic displacement, there were no statistical differences among the 3 fixation constructs. The most common failure mode was biceps tendon tearing in IS group (7/8) and IKA group (8/8). In the contrast, suture slippage accounted for the most common failure mode in DKA.

Conclusions

In suprapectoral bicep tenodesis, IKA fixation appears to offer improved construct stiffness and ultimate failure load while maintaining comparable suture slippage as compared with IS fixation or DKA fixation in the current biomechanical study.

Clinical Relevance

The IKA fixation compares favorably with other techniques and could be an alternative clinical option for suprapectoral biceps tenodesis.

Section snippets

Specimens

A total of 28 fresh-frozen human cadaveric shoulders obtained from the MedCure (http://medcure.org/) were used for the biomechanical study. Cadaveric shoulders 50 to 75 years of age were included; however, specimens with osteoarthritis, unhealthy biceps tendons, fractures, or other associated soft-tissue pathologies were excluded. Before the biomechanical test, all of the specimens were thawed at the proper temperature (20-22°C) for more than 24 hours, after which a senior author (W-R.S.)

Results

The demographic data indicated no statistical differences related to cadaveric age, bone mineral density, and tendon diameters (P < .05) among the 3 experimental groups. The results for the biomechanical values are listed in Table 1.

All the specimens sustained the entire cyclic loading test without failure. The mean construct stiffness was 38.9 ± 7.7 N/mm in the IKA group, which was significantly greater than that in the IS group (26.6 ± 6.3 N/mm, P = .002) and that in the DKA group (14.1 ± 3.1

Discussion

In our biomechanical study of suprapectoral biceps tenodesis, the IKA fixation technique resulted in statistically greater ultimate failure load and stiffness compared with the other fixation methods. However, in terms of the cyclic displacement, there were no statistically significant differences among the 3 experimental groups. All the specimens exhibited displacement of less than 10 mm after the cyclic loading test, which was regarded as the cutoff point for failure in previous biomechanical

Conclusions

In suprapectoral bicep tenodesis, IKA fixation appears to offer improved construct stiffness and ultimate failure load while maintaining comparable suture slippage as compared with IS fixation or DKA fixation in the current biomechanical study.

Acknowledgments

The authors thank Skeleton Materials and Biocompatibility Core Lab, Research Center of Clinical Medicine, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University and Ministry of Science and Technology, R.O.C (grant No. 106-2314-B-006-067-MY32) for the assistance of this project.

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    See commentary on page 2055

    The authors report no conflicts of interest in the authorship and publication of this article. Full ICMJE author disclosure forms are available for this article online, as supplementary material.

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