Effect of pretension and suture needle type on mechanical properties of acellular human dermis patches for rotator cuff repair

doi:10.1016/j.jse.2011.10.028

Journal of Shoulder and Elbow Surgery

Volume 21, Issue 10, October 2012, Pages 1413-1421

https://doi.org/10.1016/j.jse.2011.10.028 Get rights and content

Background

Dermal grafts are used for rotator cuff repair and augmentation. Although the in vitro biomechanical properties of dermal grafts have been reported previously, clinical questions related to their biomechanical performance as a surgical construct and the effect of surgical variables that could potentially improve repair outcomes have not been studied.

Methods

This study evaluated the failure and fatigue biomechanics of acellular dermis constructs tested in a clinically relevant size (4 × 4 cm patches) and manner (loaded via sutures) for rotator cuff repair. Also investigated were the effect of 2 surgical variables: (1) the fixation of grafts under varying magnitudes of pretension (0, 10, 20N), and (2) the use of reverse-cutting vs tapered needles for suturing grafts.

Results

Dermis constructs stretched ∼25% before bearing significant loads in the high stiffness region. Although 91% of the patches withstood 2500 cycles of loading to 150 N, the constructs stretched 13 to 19 mm after fatigue loading. This elongation could be reduced by 20% to 32% when reverse-cutting needles were used to prepare constructs or by applying 20 N of in situ circumferential pretension to the constructs before loading.

Conclusions

Although dermis patches demonstrated robustness for use in rotator cuff repair, the patches underwent significant, substantial, and presumably nonrecoverable elongation, even at low physiologic loads. This study indicates that use of reverse-cutting needles for suture passage, preconditioning (cyclically stretching several times), and/or surgical fixation under at least 20 N of circumferential pretension could be developed as strategies to reduce compliance of dermis for its use for rotator cuff repair.

Section snippets

Study design

Hydrated acellular human dermis patches (4 × 4 cm) were affixed to a custom tension-with-side-constraint test apparatus using 16 peripheral sutures applied with tapered needles and tied in a simple loop configuration (Fig. 1). Failure mechanics of 6 dermis constructs (patch plus simple suture loops) were assessed with the constructs subjected to 10 N of side pretension at the onset of the test. Fatigue mechanics of dermis constructs were studied by cyclic loading after application of varying

Tensile failure test

Dermis patches used for failure testing had a hydrated thickness of 1.7 ± 0.15 mm (n = 6). The tensile failure properties of dermis subjected to 10 N side pretension are demonstrated in Fig. 2 and reported in Table I. During the preconditioning phase of failure testing (preload to 5 N and 10 cycles of 5 to 15 N), the constructs elongated 6.2 ± 1.4 mm. The load-displacement curves had a bilinear profile with an initial toe region and a subsequent stiffer linear region. The toe stiffness (9.9 ±

Discussion

The study evaluated the failure and fatigue biomechanics of hydrated acellular human dermis constructs. The dermis was tested in a physiologic manner (as a construct by way of sutures) and in a geometry and size (4 × 4 cm patches) that is clinically relevant for rotator cuff repair. Further, the tension-with-side-constraint test setup allowed in situ circumferential pretensioning of the dermis patches, modeling the physiologic mode of loading on grafts used for rotator cuff repair. The results

Conclusion

Our study showed that 91% of acellular human dermis patches (21 of 23) could withstand 2500 cycles of loading to 150N, suggesting their robustness for use in rotator cuff repair. However, the patches showed significant elongation even at low physiologic loads, accumulating nonrecoverable elongation on cyclic loading. The use of reverse-cutting needles to prepare constructs and the application of in situ circumferential pretension enhanced fatigue behavior of dermis patches, reducing their

Disclaimer

Funding was provided in part by the Musculoskeletal Transplant Foundation and the Armed Forces Institute of Regenerative Medicine (W81XWH-08-2-0034). The U.S. Army Medical Research Acquisition Activity, 820 Chandler St, Fort Detrick MD 21702-5014, USA, is the awarding and administering acquisition office for the second source of funding listed. The content of the manuscript does not necessarily reflect the position or the policy of the Government, and no official endorsement should be inferred.

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: Investigational Review Board approval was not required for this study.

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Basic ScienceEffect of pretension and suture needle type on mechanical properties of acellular human dermis patches for rotator cuff repair

Background

Methods

Results

Conclusions

Section snippets

Study design

Tensile failure test

Discussion

Conclusion

Disclaimer

Clin Biomech (Bristol, Avon)

Biomaterials

Arthroscopy

Am J Surg

Orthop Clin North Am

J Shoulder Elbow Surg

J Am Coll Surg

J Mech Behav Biomed Mater

Am J Surg

Am J Surg

Arthroscopy

Arthroscopy

J Shoulder Elbow Surg

J Biomech

J Shoulder Elbow Surg

Am J Surg

Arthroscopy

Basic Science
Effect of pretension and suture needle type on mechanical properties of acellular human dermis patches for rotator cuff repair