In vivo comparison of a metal versus a biodegradable suture anchor.
OBJECTIVE
This protocol compares an absorbable polylactic acid (PLA) anchor to a similarly sized metallic anchor, comparing the load to failure of the suture anchor construct in vivo in a goat model.


METHODS
Basic science.


METHODS
Thirty-nine goats underwent bilateral implantation of suture anchors at the intra-articular origin of the long digital extensor tendon at the knee (stifle). Each goat randomly received an absorbable anchor in one knee and a metallic anchor in the other. At 0, 6, and 12 weeks after implantation, the suture attached to the implanted anchor was pulled to failure on a materials testing machine, annotating the load at failure and location of failure of the suture anchor construct.


RESULTS
At each time period tested, no difference was found in failure load between metal and PLA suture anchor constructs, nor was there degradation in strength over time of implantation of either anchor. Most failures occurred by suture breakage, and the force required for suture breakage did not differ between anchors. Three absorbable PLA anchors failed, one (1 of 13, 7.7%) at 6 weeks, and 2 (15.4%) at 12 weeks. PLA anchor failure occurred when the suture loop eyelet pulled out of the anchor's PLA body.


CONCLUSIONS
The absorbable PLA suture anchor construct, tested in an in vivo, intra-articular model, had similar strength over a 12-week period of implantation with a comparable metal anchor construct. These absorbable anchors offer a reasonable alternative to metal anchors, with comparable strength and function and advantages unique to an absorbable anchor.


CONCLUSIONS
This study provides the reader with an evaluation of the in vivo function and holding strength over time of implantation of an absorbable suture anchor in comparison with a metal anchor.
Dejong
E Schuyler
ES
Orthopaedic Surgery Services, Brooke Army Medical Center, Fort Sam Houston, Texas, USA. schuyler.dejong@mima.com
DeBerardino
Thomas M
TM
Brooks
Daniel E
DE
Judson
Kurt
K
D020341:Absorbable Implants; D000818:Animals; D004868:Equipment Failure; D006041:Goats; D006614:Hindlimb / Q000601:surgery; D020007:Implants, Experimental; D007596:Joints / Q000601:surgery; D019344:Lactic Acid; D008297:Male; D008422:Materials Testing; D011091:Polyesters; D011108:Polymers; D019736:Prostheses and Implants; D011897:Random Allocation; D013536:Suture Techniques / Q000295:instrumentation*; D013710:Tendons / Q000601:surgery; D013718:Tensile Strength; D014025:Titanium
D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D014025:Titanium