Can an expansion device be used in anterior cruciate ligament reconstruction? An in vitro study of soft tissue graft tibial fixation.
BACKGROUND
The purpose of this study was to compare the mechanical properties of an interference screw with an expansion device in anterior cruciate ligament (ACL) reconstruction.


METHODS
A total of 52 porcine tibia and 20 polyurethane foam blocks (0.16g/cm3) were used. Forty pullout tests were carried out to combine the two types of bones - surrogate and porcine - with the two fixation systems: interference screw and expansion device (n=10 per group). Thirty-two cyclic tests (n=8 per group) were carried out with both fixation devices in porcine bone at two different force amplitudes (100N and 200N).


RESULTS
Stiffness and load values (mean±SD) at six millimeters of displacement for the expansion device and the interference screw were 74±33N/mm, 318±135N, and 52±28N/mm, 205±70N, respectively, showing a difference in stiffness (P=0.016) and load at six millimeters of displacement (P=0.001). No correlation between insertion torque and the ultimate failure load was found for both fixation devices tested. In cyclic tests, significantly higher (P<0.001) numbers of cycles (mean±SD) were reached with the expansion device (81,014±30,291 at 100N; 13,462±11,351 at 200N) than with the interference screw (15,100±8623 at 100N; 343±113 at 200N) at six millimeters of displacement.


CONCLUSIONS
The use of an expansion device for ACL reconstructions seemed to be a promising alternative to an interference screw. Insertion torque alone was not a useful predictor of graft fixation strength in ACL reconstructions.
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Las Palmas, Spain. Electronic address: oscar.martel@ulpgc.es.
Oscar
O
Martel
Department of Medical and Surgical Science, University of Las Palmas de Gran Canaria, Las Palmas, Spain.
Gerardo L
GL
Garcés
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Las Palmas, Spain.
Alejandro
A
Yánez
Department of Mathematics, University of Las Palmas de Gran Canaria, Las Palmas, Spain.
Alberto
A
Cuadrado
Department of Mechanical Engineering, University of Las Palmas de Gran Canaria, Las Palmas, Spain.
Juan F
JF
Cárdenes
D000818:Animals; D059549:Anterior Cruciate Ligament Reconstruction / Q000295:instrumentation*; D001863:Bone Screws; D008422:Materials Testing; D013552:Swine; D013710:Tendons / Q000637:transplantation*; D013718:Tensile Strength; D013977:Tibia / Q000601:surgery*; D046509:Tissue Culture Techniques
ACL reconstruction; Anterior cruciate ligament (ACL); Biomechanical testing; Expansion device; Interference screw