All-suture anchor and unicortical button show comparable biomechanical properties for onlay subpectoral biceps tenodesis

All-suture anchor size and drill angle influence load to failure in a porcine model of subpectoral biceps tenodesis, a biomechanical study

BACKGROUND

Tenodesis of the long head of the biceps tendon is frequently performed in shoulder surgery, and all-suture anchors have become more popular as fixation methods. However, uncertainty still exists regarding the ultimate load to failure of all-suture anchors and the best insertion angle at a cortical humeral insertion point.

PURPOSE

The purpose of this study was to compare the biomechanical characteristics of three types of all-suture anchors frequently used for biceps tenodesis. In addition, the influence of two different insertion angles was observed in a porcine humeri model.

METHODS

The ultimate load to failure and failure mode of three types of all-suture anchors (1.6 FiberTak®, 1.9 FiberTak®, 2.6 FiberTak®, Arthrex®) applicable for subpectoral biceps tenodesis were evaluated at 90° and 45° insertion angles in 12 fresh-frozen porcine humeri. The anchors were inserted equally alternated in a randomized manner at three different insertion sites along the bicipital groove, and the suture tapes were knotted around a rod for pullout testing. In total, 36 anchors were evaluated in a universal testing machine (Zwick & Roell).

RESULTS

The 2.6 FiberTak® shows higher ultimate loads to failure with a 90° insertion angle (944.0 N ± 169.7 N; 537.0 N ± 308.8 N) compared to the 1.9 FiberTak® (677.8 N ± 57.7 N; 426.3 N ± 167.0 N, p-value: 0.0080) and 1.6 FiberTak® (733.0 N ± 67.6 N; 450.0 N ± 155.8 N, p-value: 0.0018). All anchor types show significantly higher ultimate loads to failure and smaller standard deviations at the 90° insertion angle than at the 45° insertion angle. The major failure mode was anchor pullout. Only the 2.6 FiberTak® anchors showed suture breakage as the major failure mode when placed with a 90° insertion angle.

CONCLUSIONS

All three all-suture anchors are suitable fixation methods for subpectoral biceps tenodesis. Regarding our data, we recommend 90° as the optimum insertion angle.

CLINICAL RELEVANCE

The influence of anchor size and insertion angle of an all-suture anchor should be known by the surgeon for optimizing ultimate loads to failure and for achieving a secure fixation.

Biomechanical properties of suprapectoral biceps tenodesis with double-anchor knotless luggage tag sutures vs. subpectoral biceps tenodesis with single-anchor whipstitch suture using all-suture anchors

Background

As the use of all-suture anchors continues to increase, limited biomechanical data on the use of these anchors in various configurations for tenodesis of the long head biceps tendon (LHBT) exists. The aim of this study was to compare the biomechanical properties of a 2-anchor luggage tag suprapectoral biceps tenodesis (Sup-BT) vs. a single-anchor whipstitch subpectoral biceps tenodesis (Sub-BT) using all-suture anchors. The hypothesis was that the Sub-BT will have a higher ultimate load to failure and less creep relative to the Sup-BT construct.

Methods

Eighteen fresh frozen cadaveric humeri were used. The specimens were randomly divided into 2 groups of 9; i) The Sup-BT were performed with 2 1.8 mm knotless all-suture anchors using a luggage-tag fixation configuration, ii) The Sub-BT were performed using a single 1.9 mm all-suture anchor and a whipstitch suture configuration with a tied knot. The humeri were tested on a hydraulic MTS machine where the specimens were preloaded at 5 N for 2 minutes and then cyclically loaded from 5 to 50 N for 1000 cycles at 1 Hz while maximum displacement was recorded with a motion system and markers attached to the bone and bicep tendon. The tendon was then tensioned at a rate of 1 mm/s to obtain the ultimate load to failure. CT scans of the specimens were used to calculate the bone mineral density at the site of the anchor/bone interface and video recordings were captured during load to failure to document all modes of failure.

Results

There was no significant difference in the average load to failure of the Sup-BT and Sub-BT groups (197 N ± 45 N (SD), 164 N ± 68 N (SD) respectively; P = .122) or creep under fatigue between the Sup-BT vs. Sub-BT specimens (3.1 mm, SD = 1.5 vs. 2.2 mm, SD = 0.9; P = .162). The bone mineral density was statistically different between the 2 groups (P < .001); however, there were no observed failures at the anchor/bone interface and no correlation between failure load and bone mineral density.

Conclusion

The ultimate load to failure and creep between a Sup-BT with 2 knotless all-suture anchors using a luggage tag suture configuration was equivalent to a Sub-BT with 1 all-suture anchor using a whipstitched suture configuration and a tied knot. Surgeons can perform either technique confidently knowing that they are biomechanically equivalent in a cadaver model at time zero, and they offer similar strength to other fixation methods cited in the literature.

All-Suture Suspensory Button Has Similar Biomechanical Performance to Metal Suspensory Button for Onlay Subpectoral Biceps Tenodesis

Purpose

To evaluate the maximal load at failure, cyclic displacement, and stiffness of onlay subpectoral biceps tenodesis (BT) with an intramedullary unicortical metal button (MB) versus a unicortical all-suture button (ASB).

Methods

Eighteen matched paired human cadaveric proximal humeri were randomly allocated for subpectoral BT with either ASB or MB using a high-strength suture. Specimens were tested on a servohydraulic mechanical testing apparatus under cyclic load for 1,000 cycles and then loaded to failure. The clamp was then adjusted to isolate the suture-anchor point interface and loaded to failure. Maximal load to failure, displacement, and stiffness were compared.

Results

There was no significant difference between groups in stiffness, displacement, or yield load. The maximal load to failure for the MB was greater than the ASB (347.6 ± 74.1N vs 266.5 ± 69.3N, P = .047). Eight specimens in each group failed by suture pull-through on the tendon. When the suture-anchor point interface was isolated, there was no significant difference in maximal load at failure (MB 586.5 ± 215.8N vs ASB 579.6 ± 255.9N, P = .957).

Conclusions

This study demonstrates that the MB and ASB have similar biomechanical performance when used in subpectoral BT. Although the MB showed statistically significant greater maximal load to failure, there was no difference between the MB and ASB when the suture-tendon interface was eliminated. Suture pull-through was the most common mode of failure for both implants, underscoring the importance of the suture-tendon interface.

Clinical Relevance

Fixation techniques for the treatment of long head of the biceps brachii tenodesis continue to evolve. The use of an all-suture suspensory button has advantages, but it is important to understand if this implant is a biomechanically suitable alternative to a metal suspensory button.

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

All-suture anchors (ASA) have gained great interest in our community, and multiple biomechanical studies have investigated their primary stability. Equal stability with similar load to failure has been observed for ASA in comparison to current standard implants. Although important biomechanical observations have been made, clinical outcomes are rare for ASA. Consequently, there is a lack of evidence for the clinical benefits of ASA.

Current Controversies and Decision-Making in the Management of Biceps Pathologies

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Biceps tendon pathologies include a spectrum of injuries that range from mild tendinosis to complete tendon rupture.

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Tendinosis, the most common pathology, occurs more frequently with age and is likely related to chronic degeneration. On the other side of the spectrum of severity lies a rupture of the long head of the biceps tendon (LHBT), which may be accompanied by injury to the glenoid labrum.

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Superior labral anterior-posterior (SLAP) tears are frequently associated with biceps pathology. Surgical management for injuries of the bicipital-labral complex includes biceps tenodesis or tenotomy and SLAP repair. A consensus as to which of these procedures is the optimal choice has not been reached, and management may ultimately depend on patient-specific characteristics.

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Due to the relatively low incidence of distal biceps tendon rupture, agreement on the optimal management strategy has not been reached. Surgical repair, or reconstruction in the case of a chronic rupture, is often chosen. However, nonoperative management has also been utilized in older, less-active patients.

[Acute rupture of the pectoralis major muscle at the musculotendinous junction : Case report of a rare injury and literature review]

Die Pectoralis-major-Ruptur (PMR) ist eine seltene Verletzung, die v. a. beim Kraftsport aufritt. Vorgestellt wird der Fall eines 31-jährigen Profibasketballspielers, der sich beim Bankdrücken eine Komplettruptur am muskulotendinösen Übergang des M. pectoralis major (PM) zugezogen hatte. Drei Wochen nach dem erlittenen Trauma erfolgte bei persistierenden Schmerzen und Kraftdefizit die Refixation des PM. Drei Monate postoperativ konnte der Patient bei vollem Bewegungsumfang schmerzfrei in den Basketballsport zurückkehren. Die Verletzungsentität wird vor dem Hintergrund der aktuellen Literatur diskutiert und das operative Vorgehen im Detail dargestellt.