Basic Science
Improved time-zero biomechanical properties using poly-L-lactic acid graft augmentation in a cadaveric rotator cuff repair model

https://doi.org/10.1016/j.jse.2009.12.008Get rights and content

Hypothesis

Rotator cuff repair failure rates range from 20% to 90%, and failure is believed to occur most commonly by sutures cutting through the tendon due to excessive tension at the repair site. This study was designed to determine whether application of a woven poly-L-lactic acid device (X-Repair; Synthasome, San Diego, CA) would improve the mechanical properties of rotator cuff repair in vitro.

Materials and methods

Eight pairs of human cadaveric shoulders were used to test augmented and non-augmented rotator cuff repairs. Initial stiffness, yield load, ultimate load, and failure mode were compared.

Results

Yield load was 56% to 92% higher and ultimate load was 56% to 76% higher in augmented repairs. No increase in initial stiffness was found. Failure by sutures cutting through the tendon was reduced, occurring in 17 of 20 non-augmented repairs but only 7 of 20 augmented repairs.

Conclusions

Our data show that application of the X-Repair device significantly increased the yield load and ultimate load of rotator cuff repairs in a human cadaveric model and altered the failure mode but did not affect initial repair stiffness.

Section snippets

Experimental design

We used 8 pairs (N = 16) of human cadaveric shoulders (mean age, 51 ± 12 years) in this study (Anatomy Gifts Registry, Hanover, MD). On each shoulder, 3 rotator cuff tendon strips were created corresponding to (1) the anterior half of the supraspinatus, (2) the posterior half of the supraspinatus, and (3) the superior half of the infraspinatus. Tendon strips were released from the proximal humerus and repaired through a transosseous technique. Corresponding tendon strips from paired shoulders

Repair construct mechanical properties

Figure 2 shows a pair of representative load-displacement curves for non-augmented and augmented repair constructs in the anterior supraspinatus region of the rotator cuff. These curves show that in the load-to-failure test, repair constructs were stiffest in the initial phase of loading and became less stiff with progressive loading. The manner in which the biomechanical outcomes (initial stiffness, yield load, and ultimate load) were obtained is shown on these representative curves.

Of the 48

Discussion

The objectives of this study were to determine the extent to which the X-Repair device is capable of improving the mechanical properties (stiffness, yield load, and ultimate load) of a rotator cuff repair in vitro and the extent to which regional differences in the rotator cuff tendons influence these capabilities. The mechanical characteristics of this graft material led us to hypothesize that tendon repairs augmented with the X-Repair device would have significantly increased initial

Conclusion

Our data showed that application of the X-Repair PLLA graft device significantly increases the yield load and ultimate load of a primary rotator cuff repair across all of the supraspinatus tendon and the upper half of the infraspinatus tendon but does not affect initial repair stiffness. The increased ultimate load achieved through graft application is significantly greater in the anterior half of the supraspinatus and upper half of the infraspinatus than that achieved in the posterior

Disclaimer

This work was supported by Synthasome (San Diego, CA) and National Institutes of Health grants T32 AR 050959-01 and R44 AR051260. None of the authors, their family members, or affiliated research institutions have received financial payments or other benefits for the work related to this research.

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