不同接骨板组合治疗干骺端粉碎股骨远端骨折的动物实验

Lateral anatomic locking plate in combination with different medial plates in the treatment of comminuted metaphyseal distal femoral fractures:an animal experiment

目的初步探讨单钢板和不同组合的双钢板治疗干骺端粉碎股骨远端骨折的疗效,为大样本量实验提供研究方向,为临床治疗提供指导。方法健康实验猪(巴马小型猪)5头,建立双侧股骨远端粉碎性骨折模型[国际内固定研究学会(AO/ASIF)分型为33-C2.3型]。分为5组,对照组1头双侧后肢予单纯外侧解剖锁定钢板固定;锁定重建钢板组和普通重建钢板组共2头,每头猪一侧后肢予外侧解剖锁定钢板+内侧锁定重建钢板固定,对侧后肢予外侧解剖锁定钢板+内侧普通重建钢板固定,左右侧随机;锁定加压钢板组和普通加压组共2头,每头猪一侧后肢予外侧解剖锁定钢板+内侧锁定加压钢板固定,对侧后肢予外侧解剖锁定钢板+内侧普通加压钢板固定,左右侧随机。术后4、8、12周分别行X线摄片观察骨折愈合和内固定松动情况。术后12周处死实验猪,在股骨远端侧位X线片上测量骨痂最大前后径。所有股骨标本去除内固定后行垂直压缩实验,记录最大轴向压缩位移,计算平均轴向刚度。结果术后5头猪均存活,骨折均愈合,未出现感染、内固定失效。在大体标本中,各双钢板组实验猪双侧后肢的骨痂最大前后径的均值均大于单钢板组,且锁定重建钢板组最大(5.02cm),锁定加压钢板组最小(4.16cm)。在垂直压缩实验中,各双钢板组实验猪双侧后肢的最大轴向压缩位移的均值均小于单钢板组,平均轴向刚度的均值均大于单钢板组。在双钢板组中,锁定重建钢板组实验猪双侧后肢的最大轴向压缩位移的均值最小(2.50mm),平均轴向刚度的均值最大(1 200.71N/mm);普通加压钢板组实验猪双侧后肢的最大轴向压缩位移最大(2.91 mm),平均轴向刚度的均值最小(1 032.76N/mm)。结论双钢板固定是治疗干骺端粉碎股骨远端骨折较理想的方法之一,外侧使用解剖锁定钢板、内侧使用锁定重建钢板可能最有利于骨折的愈合。

Objective To evaluate the efficacy of single lateral plate and different combinations of double plates in the treatment of distal femoral fractures with comminuted metaphysis. Methods A model of bilateral distal femoral comminuted fractures （AO/ASIF 33-C2.3 type） was established in five healthy experimental pigs （Bama mini-pig）. Then they were divided into five groups randomly： bilateral hind limbs were fixed by the lateral anatomic locking plate in one pig （control group） ; one side was fixed by the anatomic locking plate laterally and locking reconstruction plate medially, and the contralateral was fixed by the anatomical locking plate laterally and unlocking reconstruction plate medially in two pigs （locking reconstruction plate group and unlocking reconstruction plate group） ; one side was fixed by the anatomic locking plate laterally and locking compression plate medially, and the contralateral fracture was fixed by the anatomical locking plate laterally and unlocking compression plate medially in the other pigs （locking compression plate group and unlocking compression plate group）. At 4, 8 and 12 weeks after fixation, X-ray radiography was taken to observe the fracture healing and the stability of internal fixations. All animals were sacrificed at 12 weeks postoperatively. The diameter of the callus was measured on the lateral distal femur radiograph. All femoral specimens were subjected to vertical compression test after removal of the plates. The maximum axial displacement was recorded to calculate the mean axial stiffness. Results All animals survived and all fractures were healed. There was no infection or fixation failure. The maximum diameters of the callus of four double-plate groups were greater than that of single-plate group. Among double-plate groups, the locking reconstruction plate group had the greatest callus diameter （mean 5. 02 cm）, and the locking compression plate group was the least one （mean 4. 16 cm）. The maximum axial displacements of four double-plate groups were less than that of single-plate group, but the axial stiffness of four double-plate groups were greater than that of single-plate group. Among double-plate groups, the locking reconstruction plate group had the least maximum axial displacement （mean 2.50 mm） and the greatest axial stiffness （mean 1 200.71 N/mm）; the unlocking compression plate group had the greatest maximum axial displacement （mean 2.91 mm） and the least axial stiffness （mean 1 032.76 N/mm）. Conclusion Double plates are one of the ideal fixation for comminuted metaphyseal distal femoral fracture. Lateral anatomic locking plate combined with medial locking reconstruction plate may be the most effective fixation for fracture healing.