A biomechanical research into different internal fixations for ACL avulsion fractures of tibial eminence / 中华创伤骨科杂志

ABSTRACT

Objective To conduct a hiomechanical comparison of the four common internal fixation methods for the anterior eruciate ligament(ACL)avulsion fractures of displaced tibial eminence.Methods Sixteen fresh cadaver knee joints were used and randomized into four equal groups of four fixation methods:antegrade wiring group, retrograde wiring group,suturation group,and intramedullary screw group.The knee joint specimens were fixed at flexion of 30?and subject to continuous stretch stresses of 30 N,60 N and 90 N respectively on a material testing machine(MTS 858 Bionix test system,USA)which conducted a simulated Lachman test.The specimens were scanned at different angles by a three dimensional laser scanner.Data were recorded and processed by image software to es- tablish three-dimensional structure models of femur,tibia and knee joint.The test results were analyzed statistically on a computer.Results There were no obvious differences between each fixation group in the length change of ACL when the stresses were 30 N and 60 N(P＞0.05).Under 90 N stress,however,the mean length change between the femoral and tibial attachments of ACL was the smallest(4.8?1.7)mm(2.5 to 6.2 mm)in the suturation group(P＜0.05). There were no distinct differences between the intramedullary screw group and the retrograde wiring group in the changes of A CL shift(P=0.214).The average front shift in the retrograde wiring group was(6.2?1.2)mm(4.8 to 8.2 mm) and significantly smaller than that in the antegrade wiring group(P＜0.05).The antegrade wiring group made the largest average front shift under different stresses and its average front shift was(7.2?1.3)mm(5.6 to 8.7 mm). Conclusions The knee joint stability provided by the suturation fixation is distinctly better than that by the other three fixation methods.The antegrade wire fixation provides the poorest knee joint stability.There is hardly any difference between intramedullary screw fixation and retrograde wiring fixation.