Biomechanical comparison of the bioabsorbable RetroScrew system, BioScrew XtraLok with stress equalization tensioner, and 35-mm Delta Screws for tibialis anterior graft-tibial tunnel fixation in porcine tibiae.
BACKGROUND
Achieving effective soft tissue graft-tibial tunnel fixation remains problematic.


OBJECTIVE
No differences would exist for tibialis anterior graft-tibial tunnel fixation when comparing the RetroScrew System (20-mm retrograde screw, 17-mm antegrade screw), the 35-mm tapered Delta Screw (manual tensioning), and the 35-mm BioScrew XtraLok (applied using an instrumented tensioner).


METHODS
Controlled laboratory study.


METHODS
Porcine tibiae (apparent bone mineral density, 1.3 g/cm(2)) and human tendon allografts were divided into 3 matched groups of 6 specimens each before cyclic (500 cycles, 50-250 N, 1 Hz) and load-to-failure (20 mm/min) tests.


RESULTS
The BioScrew XtraLok (210.9 +/- 54.9 N/mm) and the 35-mm Delta Screw (224.3 +/- 43.7 N/mm) displayed superior stiffness to the RetroScrew System (114.1 +/- 23.3 N/mm) (P = .0004) during cyclic testing. The BioScrew XtraLok (1.0 +/- 0.2 mm) and the Delta Screw (0.9 +/- 0.2 mm) also displayed less displacement during cyclic testing than the RetroScrew System (1.8 +/- 0.5 mm) (P = .001). During load-to-failure testing, the BioScrew XtraLok withstood greater loads (1436.3 +/- 331.3 N) (P = .001) and displayed greater stiffness (323.6 +/- 56.8 N/mm) (P = .002) than the 35-mm Delta Screw (load, 1042.2 +/- 214.4 N; stiffness, 257.2 +/- 22.2 N/mm) and the RetroScrew System (load, 778.7 +/- 177.5 N; stiffness, 204.4 +/- 52.9 N/mm).


CONCLUSIONS
The BioScrew XtraLok with instrumented tensioning displayed superior fixation to the RetroScrew System and the 35-mm Delta Screw applied with manual tensioning.


CONCLUSIONS
The BioScrew XtraLok may provide superior soft tissue graft-tibial tunnel fixation. Further in vitro studies using human tissue and in vivo clinical studies are needed.
Chang
Haw Chong
HC
Division of Sports Medicine, Department of Orthopaedic Surgery, University of Louisville, 210 East Gray Street, Suite 1003, Louisville, KY 40202, USA.
Nyland
John
J
Nawab
Akbar
A
Burden
Robert
R
Caborn
David N M
DN
D020341:Absorbable Implants; D000328:Adult; D000818:Animals; D000070598:Anterior Cruciate Ligament Injuries; D001696:Biomechanical Phenomena; D001863:Bone Screws; D019544:Equipment Failure Analysis; D006801:Humans; D008422:Materials Testing; D013552:Swine; D013710:Tendons / Q000637:transplantation*; D013977:Tibia / Q000601:surgery; D014184:Transplantation, Homologous