Rotator cuff repair augmentation in a canine model with use of a woven poly-L-lactide device.
BACKGROUND
Despite advances in surgical treatment options, failure rates of rotator cuff repair have continued to range from 20% to 90%. Hence, there is a need for new repair strategies that provide effective mechanical reinforcement of rotator cuff repair as well as stimulate and enhance the intrinsic healing potential of the patient. The purpose of this study was to evaluate the extent to which augmentation of acute repair of rotator cuff tendons with a newly designed poly-L-lactide repair device would improve functional and biomechanical outcomes in a canine model.


METHODS
Eight adult, male mongrel dogs (25 to 30 kg) underwent bilateral shoulder surgery. One shoulder underwent tendon release and repair only, and the other was subjected to release and repair followed by augmentation with the repair device. At twelve weeks, tendon retraction, cross-sectional area, stiffness, and ultimate load of the repair site were measured. Augmented repairs underwent histologic assessment of biocompatibility. In addition, eight pairs of canine cadaver shoulders underwent infraspinatus injury and repair with and without device augmentation with use of identical surgical procedures and served as time-zero biomechanical controls. Eight unpaired, canine cadaver shoulders were included as normal biomechanical controls.


RESULTS
At time zero, repair augmentation significantly increased the ultimate load (23%) (p = 0.034) but not the stiffness of the canine infraspinatus tendon repair. At twelve weeks, the poly-L-lactide scaffold was observed to be histologically biocompatible, and augmented repairs demonstrated significantly less tendon retraction (p = 0.008) and significantly greater cross-sectional area (137%), stiffness (26%), and ultimate load (35%) than did repairs that had not been augmented (p < 0.001, p = 0.002, and p = 0.009, respectively).


CONCLUSIONS
While limiting but not eliminating tendon repair retraction, the augmentation device provided a tendon-bone bridge and scaffold for host tissue deposition and ingrowth, resulting in improved biomechanical function of the repair at twelve weeks.
Derwin
Kathleen A
KA
Department of Biomedical Engineering, ND2-20, Cleveland Clinic, Cleveland, OH 44122, USA. derwink@ccf.org
Codsi
Michael J
MJ
Milks
Ryan A
RA
Baker
Andrew R
AR
McCarron
Jesse A
JA
Iannotti
Joseph P
JP
D000818:Animals; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D002102:Cadaver; D004146:Dioxanes / Q000627:therapeutic use*; D004285:Dogs; D008297:Male; D017006:Rotator Cuff / Q000502:physiology / Q000601:surgery*; D054457:Tissue Scaffolds; D014945:Wound Healing
D001672:Biocompatible Materials; D004146:Dioxanes; C091880:dilactide