Graft laceration and pullout strength of soft-tissue anterior cruciate ligament reconstruction: in vitro study comparing titanium, poly-d,l-lactide, and poly-d,l-lactide-tricalcium phosphate screws.
OBJECTIVE
The aim of part 1 of this study was to compare the structural properties of tibia-graft-interference screw constructs of soft-tissue graft fixation via the anterior cruciate ligament (ACL) by use of different interference screws. In part 2 the influence of graft laceration as a result of 1 single interference screw insertion on the mechanical properties of the graft was evaluated.


METHODS
In part 1 of the study, in a bovine knee model, soft-tissue graft fixation with titanium, biodegradable poly-D,L-lactide (PLDLA), and PLDLA-tricalcium phosphate (TCP) interference screws was performed, and the structural properties were determined by use of a materials testing machine at a rate of 12.5 mm/s. In part 2 the bone was cut after 1 single insertion of titanium, PLDLA, or PLDLA-TCP interference screws, and the mechanical properties of the graft were determined.


RESULTS
Soft-tissue graft fixation with a biodegradable PLDLA interference screw showed a statistically significantly higher maximum load when compared with PLDLA-TCP and titanium interference screws. PLDLA-TCP screw fixation revealed a significantly higher ultimate load than titanium screw fixation. The mechanical properties of the grafts after 1 single insertion of PLDLA-TCP interference screws showed a statistically significantly higher stiffness, yield load, and maximum load when compared with the PLDLA and titanium interference screw groups.


CONCLUSIONS
The results of this study suggest that the use of a titanium screw to fix a soft-tissue graft in cruciate ligament reconstruction surgery may cause damage to the graft. Soft-tissue ACL reconstruction fixed with a PLDLA interference screw resulted in a significantly higher pullout strength than ACL reconstructions fixed with a PLDLA-TCP or titanium interference screw.


CONCLUSIONS
In contrast to fixation with a biodegradable interference screw, fixation with a titanium interference screw may damage the integrity of a soft-tissue graft in cruciate ligament reconstruction and should therefore be avoided.
Zantop
Thore
T
Department of Trauma, Hand, and Reconstructive Surgery, Wilhelms University, Muenster, Germany. thore.zantop@ukmuenster.de <thore.zantop@ukmuenster.de>
Weimann
Andre
A
Schmidtko
Romana
R
Herbort
Mirco
M
Raschke
Michael J
MJ
Petersen
Wolf
W
D020341:Absorbable Implants; D000818:Animals; D016118:Anterior Cruciate Ligament / Q000601:surgery*; D001672:Biocompatible Materials; D001696:Biomechanical Phenomena; D001863:Bone Screws / Q000009:adverse effects*; D002130:Calcium Phosphates; D002417:Cattle; D022125:Lacerations / Q000209:etiology* / Q000473:pathology; D008422:Materials Testing; D011091:Polyesters; D019651:Plastic Surgery Procedures; D013536:Suture Techniques; D013708:Tendon Injuries / Q000209:etiology* / Q000473:pathology; D013710:Tendons / Q000637:transplantation*; D013718:Tensile Strength; D013977:Tibia / Q000601:surgery; D014025:Titanium
D001672:Biocompatible Materials; D002130:Calcium Phosphates; D011091:Polyesters; C033616:poly(lactide); D014025:Titanium; C018392:tricalcium phosphate