Biomechanical Comparison of Subpectoral Biceps Tenodesis Onlay Techniques

Abstract

Background: Subpectoral biceps tenodesis can be performed with cortical fixation using different repair techniques. The goal of this technique is to obtain a strong and stable reduction of biceps tendon in an anatomic position. Purpose/Hypothesis: The purpose of this study was to compare (1) displacement during cyclic loading, (2) ultimate load, (3) construct stiffness, and (4) failure mode of the biceps tenodesis fixation methods using onlay techniques with an all-suture anchor versus an intramedullary unicortical button. It was hypothesized that fixation with all-suture anchors using a Krackow stitch would exhibit biomechanical characteristics similar to those exhibited by fixation with unicortical buttons. Study Design: Controlled laboratory study. Methods: Ten pairs of fresh-frozen cadaveric shoulders (N = 20) were dissected to the humerus, leaving the biceps tendon-muscle unit intact for testing. A standardized subpectoral biceps cortical (onlay) tenodesis was performed using either an all-suture anchor or a unicortical button. The biceps tendon was initially cycled from 5 to 70 N at a frequency of 1.5 Hz. The force on the tendon was then returned to 5 N, and the tendon was pulled until ultimate failure of the construct. Displacement during cyclic loading, ultimate failure load, stiffness, and failure modes were assessed. Results: Cyclic loading resulted in a mean displacement of 12.5 ± 2.5 mm for all-suture anchor fixation and 29.2 ± 9.4 mm for unicortical button fixation ( P = .005). One all-suture anchor fixation and 2 unicortical button fixations failed during cyclic loading. The mean ultimate failure load was 170.4 ± 68.8 N for the all-suture anchor group and 125.4 ± 44.6 N for the unicortical button group ( P = .074), with stiffness 59.3 ± 11.6 N/mm and 48.6 ± 6.8 N/mm ( P = .091), respectively. For the unicortical button, failure occurred by suture tearing through tendon in 100% of the specimens. For the all-suture anchor, failure occurred by suture tearing through tendon in 56% and knot failure in 44% of the specimens. Conclusion: The all-suture anchor fixation using a Krackow stitch for subpectoral biceps tenodesis provided ultimate load and stiffness similar to unicortical button fixation using a nonlocking whipstitch. The all-suture anchor fixation technique was shown to be superior in terms of displacement during cyclic loading when compared with the unicortical button fixation technique. However, the results of this study help to show that the fixation method used on the humeral side is less implicative of the overall construct strength than stitch location and technique, as the biceps tendon tissue and stitch configuration seem to be the limiting factor in subpectoral onlay tenodesis techniques. Clinical Relevance: All-suture anchors have a smaller diameter than traditional suture anchors, can be inserted through curved guides, and preserve humeral bone stock without compromising postoperative imaging. This study supports use of the all-suture anchor fixation technique for subpectoral biceps tenodesis, with high biomechanical fixation strength and low displacement, as an alternative to the subpectoral onlay biceps tenodesis technique.

Subpectoral Biceps Tenodesis: All-Suture Anchor Onlay Technique

“…15 In a biomechanical comparison of all-suture anchor versus unicortical button fixation for subpectoral biceps tenodesis, the all-suture anchor using a Krackow-type whipstitch provided similar biomechanical strength to unicortical button fixation using a noncontinuous locking whipstitch. 24 The all-suture anchor fixation technique was shown to be superior in terms of displacement during cyclic loading compared with the unicortical button fixation technique. However, the results of this study helped to show that the fixation method used on the humeral side is less implicative of overall construct strength than stitch location and technique, given that the biceps tendon tissue as well as stitch configuration seems to be the limiting factor in subpectoral onlay tenodesis techniques.…”

Editorial Commentary: All-Suture Anchor for Shoulder Biceps Tenodesis Results in Excellent Outcomes

“…5,6 Biomechanical studies also support the use of all-suture anchors for biceps tenodesis due to comparable fixation strengths compared to interference screws, 7,8 conventional suture anchors, 7 and unicortical button fixations. 9 The study "Reliable Clinical and Sonographic Outcomes of Subpectoral Biceps Tenodesis Using an All-Suture Anchor Onlay Technique" by Degenhardt, Pogorzelski, Themessl, Muench, Wechselberger, Woertler, Siebenlist, Imhoff, and Scheiderer further evaluated the clinical outcomes and structural integrity using sonography in patients treated with subpectoral biceps tenodesis using an all-suture anchor onlay technique. 10 The authors demonstrated that their technique provided reliable clinical results for pathology of the biceps long head tendon.…”

Editorial Commentary: All-Suture Anchors Are Evidence-Based and Biomechanically Sound but Require Additional Clinical Outcomes Evaluation

“…So far, ASA have been investigated in multiple biomechanical studies. [3][4][5][6][7][8][9][10][11][12] ASA have shown equal stability with similar load to failure in comparison to current standard implants. [3][4][5][6][7][8][9][10][11][12] In the light of these observations, we should leave the expectation that every new generation of implant should outmatch their predecessor.…”

“…[3][4][5][6][7][8][9][10][11][12] ASA have shown equal stability with similar load to failure in comparison to current standard implants. [3][4][5][6][7][8][9][10][11][12] In the light of these observations, we should leave the expectation that every new generation of implant should outmatch their predecessor. Current standard implants for distal biceps repair already reach adequate primary stability, 13,14 even comparable to the failure load of the native distal biceps tendon.…”