前外侧或后内侧辅助钢板结合髓内钉固定胫骨近端 1 / 3 骨折的生物力学研究

目的 研究髓内钉结合辅助钢板固定胫骨近端1/3骨折的稳定性，比较并观察胫骨近端1/3骨折后内侧辅助钢板与前外侧辅助钢板结合髓内钉固定的生物力学特点。方法 选取Sawbones第4代人工胫骨模型。根据辅助钢板位置分为后内侧钢板组和前外侧钢板组，每组4例，髓内钉远近端均2枚锁定钉固定，钢板远近端各3枚皮钉双层皮质固定。模拟AO分型41-A2型骨折，水平截骨平面位于胫骨髓内钉近端锁定钉远端0.5 cm即近端关节面以远5～6 cm位置。截骨完成后，通过生物力学试验机分别进行轴向压缩、三点弯曲、循环加载及极限应力测试，比较各组轴向刚度、三点弯曲刚度等结果。结果 轴向压缩实验表明，后内侧钢板组平均轴向刚度低于前外侧钢板组，两组间差异无统计学意义。三点弯曲实验表明，后内侧钢板组无论是对抗内翻应力(钢板位于骨折压力侧，t=3.679,P<0.05)还是外翻应力(钢板位于骨折张力侧，t=8.975,P<0.05),其弯曲刚度均优于前外侧钢板组。结论 辅助钢板结合髓内钉固定胫骨近端1/3骨折可以提高近端骨折块固定的稳定性，并允许患者更早负重。钢板置于后内侧或者前外侧均能够提供足够的轴向强度，后...

Anterolateral or Posteromedial Plate-Assisted Intramedullary Nailing for Fixation of Proximal Third Tibia Fractures: A Biomechanical Study

Objective To study the stability of plate-assisted intramedullary nailing for fixing proximal third tibiafractures, compare and observe biomechanical characteristics of anterolateral or posteromedial plate-assisted intramedullary nailing after fixation of proximal third tibia fractures. Methods Eight artificial tibia of 4th-generation sawbones were divided into two groups based on location of the assisted plate, namely, anterolateral plate group and posteromedial plate group, with 4 specimens in each group. Each two locking bolts were fixed to theintramedullary nail proximally and distally, and each three bicortical screws were fixed to the plate proximally and distally. The specimens were osteotomized with a 10-mm defect which located 0. 5 cm to the proximal locking bolt of intramedullary nail or 5-6 cm distally to the knee joint line, in order to simulate an AO/ OTA 41-A2 type proximal third tibia fracture after fixation of intramedullary nail. After osteotomy was finished, axial compression test, threepoint bending test, cyclic loading and overstress test were conducted by mechanical testing machine. The results of axial stiffness and three-point stiffness between two groups were compared and analyzed. Results Axial compression test showed that the average axial stiffness in posteromedial plate group was lower than that in anterolateral plate group, but no significantly statistical differences were found between the two groups. Threepoint bending test showed that the average bending stiffness in posteromedial plate group was significantly higher than that in anterolateral plate group when stimulating either varus stress (plate located at pressure side of the fracture, t = 3. 679, P<0. 05) or valgus stress (plate located at tension side of the fracture, t = 8. 975, P<0. 05). Conclusions Plate-assisted intramedullary nailing for fixation of proximal third tibia fractures can minimize the angulation malalignment, improve the stability of nailed proximal tibial fragment and allow the early weight bearing. Both anterolateral and posteromedial plate-assisted intramedullary nail can provide satisfactory axial stability for proximal third tibia fractures, while posteromedial plate-assisted intramedullary nail shows better bending stability than anterolateral plate in countering varus or valgus stress deformity. This study provides an essential basis for clinical decision making about plate-assisted intramedullary nailing for fixing proximal third tibia fractures.