Adjustable loop ACL suspension devices demonstrate less reliability in terms of reproducibility and irreversible displacement

Ahmad, Sufian S.; Hirschmann, Michael T.; Voumard, Benjamin; Kohl, Sandro; Zysset, Philippe; Mukabeta, Takura; Evangelopoulos, Dimitrios Stergios; Ateschrang, Atesch

doi:10.1007/s00167-017-4769-2

Cited by 30 publications

(43 citation statements)

References 11 publications

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“…Adjustable CFDs based on the sling lock mechanism, however, have exhibited unsatisfactory mechanical performance even when subjected to moderately high-cyclic forces. 1 The present study describes an adjustable-length fixation device based on a modified sling lock mechanism. The device comprises 1 loading suture with a stopper knot and a titanium suspension button with 6 holes.…”

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confidence: 99%

Biomechanical Evaluation of a Novel Loop Retention Mechanism for Cortical Graft Fixation in ACL Reconstruction

Götschi

Rosenberg

et al. 2020

Orthopaedic Journal of Sports Medicine

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Background: Implant fixation by means of a cortical fixation device (CFD) has become a routine procedure in anterior cruciate ligament reconstruction. There is no clear consensus whether adjustable-length CFDs are more susceptible to loop lengthening when compared with pretied fixed-length CFDs.Purpose: To assess biomechanical performance measures of 3 types of CFDs when subjected to various loading protocols.Study Design: Controlled laboratory study.Methods: Three types of CFDs underwent biomechanical testing: 1 fixed length and 2 adjustable length. One of the adjustablelength devices is based on the so-called finger trap mechanism, and the other is based on a modified sling lock mechanism. A device-only test of 5000 cycles (n ¼ 8 per group) and a tendon-device test of 1000 cycles (n ¼ 8 per group) with lower and upper force limits of 50 and 250 N, respectively, were applied, followed by ramp-to-failure testing. Adjustable-length devices then underwent further cyclic testing with complete loop unloading (n ¼ 5 per group) at each cycle, as well as fatigue testing (n ¼ 3 per group) over a total of 1 million cycles. Derived mechanical parameters were compared among the devices for statistical significance using Kruskal-Wallis analysis of variance followed by post hoc Mann-Whitney U testing with Bonferroni correction.Results: All CFDs showed elongation <2 mm after 5000 cycles when tested in an isolated manner and withstood ultimate tensile forces in excess of estimated peak in vivo forces. In both device-only and tendon-device tests, differences in cyclic performance were found among the devices, favoring adjustable-length fixation devices over the fixed-length device. Completely unloading the suspension loops, however, led to excessive loop lengthening of the finger trap device, whereas the modified sling lock device remained stable throughout the test. The fixed-length device displayed superior ultimate strength over both adjustable-length devices. Both adjustable-length devices showed adequate fatigue behavior during high-cyclic testing.Conclusion: All tested devices successfully prevented critical construct elongation when tested with constant tension and withstood ultimate loads in excess of estimated in vivo forces during the rehabilitation phase. The finger trap device gradually lengthened excessively when completely unloaded during cyclic testing.Clinical Relevance: Critical loop lengthening may occur if adjustable-length devices based on the finger trap mechanism are repeatedly unloaded in situ.

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confidence: 99%

Biomechanical Evaluation of a Novel Loop Retention Mechanism for Cortical Graft Fixation in ACL Reconstruction

Götschi

Rosenberg

et al. 2020

Orthopaedic Journal of Sports Medicine

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“…Some mechanical studies that compared adjustable-loop devices and fixed-loop devices reported that the latter showed higher breaking strength and less displacement Takahashi and Takahashi Journal of Experimental Orthopaedics (2020) 7:17 [18][19][20][21][22][23][24][25]. On the other hand, other studies reported no difference in either parameter [26,27].…”

Section: Discussionmentioning

confidence: 99%

The improved cortical button shows better breaking strength of sutures compared with 10 original cortical button after cyclic loading

Takahashi

2020

J EXP ORTOP

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Background: Suspensory cortical buttons are widely used for fixation of reconstructed ligaments during anterior cruciate ligament (ACL) reconstruction because they have high usability and a favorable fixing force. However, it is not always easy to fix a reconstructed ACL while maintaining appropriate ligament tension. Therefore, we developed an improved cortical button that provides temporary tension until suturing is completed. Methods: Button holes of our improved EndoButton are not perpendicular to the bone surface on which the button is placed, but have an angle of 45 degrees so that the button can be temporarily fixed by applying tension to the suture. The improved EndoButton and the original EndoButton (Smith & Nephew Inc., Andover, Massachusetts) were each tied to FiberWire 5/7 metric (5 M) (manufactured by Arthrex). Ten cycles of preliminary loading (0-50 N) were applied to each suture, followed by test loading (0-250 N) for 500 or 1000 cycles. Then, a tensile test was performed at a displacement velocity of 20 mm/min. Results: The breaking strength of the sutures of the improved EndoButton were tend to higher than those of the sutures of the original EndoButton after 1000 loading cycles (p = 0.067, d = 0.883). The moduli of rigidity of the sutures of the improved EndoButton were higher than those of the sutures of the original EndoButton after 500 loading cycles (p = 0.027) and remained almost the same regardless of the number of loading cycles. Conclusion: We found that compared with the original cortical button, the improved cortical button was better able to retain suture breaking strength and modulus of rigidity, regardless of the number of load cycles.

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“…The maximum load level of 300 N was chosen according to previously performed studies [9,10]. Barrow et al [9] and Ahmad et al [11] defined an absolute displacement of 3 mm as clinical failure, this value was considered as failure criterion for the tested samples. For the single device test (see figure 3A) the ALDs and FLDs were fixed in the setup between two metallic components to apply loads on the device.…”

Section: Stability Test Seriesmentioning

confidence: 99%

Evaluation of Adjustable Loop Suspensory Anterior Cruciate Ligament Fixation Devices

Dreier

Bachmayer

Baumgartner

et al. 2019

Current Directions in Biomedical Engineering

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Along with increasing enthusiasm for sports comes an increase of sport related injuries. One of the most common injuries in the human knee is the tear of the anterior cruciate ligament (ACL). The selection of a graft fixation device is an important factor that determines the outcome of an anterior cruciate ligament reconstruction. Before the healing process is completed, the graft is dependent on tibial and femoral fixation devices to maintain normal ACL graft tension. Among various devices, the use of an adjustable loop suspensory fixation device (ALD) in soft-tissue graft reconstruction attracts current interest. An advantage of the ALD is the ability to draw the graft to the depth of the bone tunnel to achieve adequate graft tension while minimizing the empty space in the tunnel. In this study a comprehensive controlled laboratory investigation is performed to examine the biomechanical properties of commonly used cortical fixation devices, with the aim of implementing a standard testing procedure for adjustable loop devices. The procedure consists of three test series, a loop shortening test and two different stability test series (singe device and tendon device test). Those test series are used to compare the performance of a new ALD from Arthrex (Naples, USA) with five competitor devices already on the market. In order to obtain representative results eight samples of each device are tested. In comparison to the previously performed studies, a complete unloading is applied in the stability tests, which allows for a detailed examination of the ALDs locking mechanisms in dynamically loaded test situations. Furthermore, the performed loop shortening tests reveal important aspects, such as the shortening accuracy and settling effects of the loops, that are not found in previous studies. Therefore, the used test protocol can be recommended for further testing.

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Adjustable loop ACL suspension devices demonstrate less reliability in terms of reproducibility and irreversible displacement

Cited by 30 publications

References 11 publications

Biomechanical Evaluation of a Novel Loop Retention Mechanism for Cortical Graft Fixation in ACL Reconstruction

Biomechanical Evaluation of a Novel Loop Retention Mechanism for Cortical Graft Fixation in ACL Reconstruction

The improved cortical button shows better breaking strength of sutures compared with 10 original cortical button after cyclic loading

Evaluation of Adjustable Loop Suspensory Anterior Cruciate Ligament Fixation Devices

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