Deuel Christopher R, Wolinsky Philip, Shepherd Eric, Hazelwood Scott J
Department of Mechanical and Aeronautical Engineering, University of California, Davis, California, USA.
J Orthop Trauma. 2007 May;21(5):323-9. doi: 10.1097/BOT.0b013e31804ea479.
To assess improvements in fixation stability when a hinged unilateral external fixator is used to supplement compromised internal fixation for distal humerus fractures.
Removing a 1-cm section of the distal humerus in cadaveric whole-arm specimens created a comminuted distal humerus fracture model (AO type 13-A3). Fixation was then performed using different constructs representing optimal, compromised, or supplemented internal fixation. Internal fixation consisted of either 2 reconstruction plates with 1, 2, or 3 (optimal) distal attachment screws, or crossing medial and lateral cortical screws. A hinged external fixator was applied in combination with compromised internal fixation. The stability of the different constructs was then evaluated using 3-point bending stiffness and distal fragment displacement measurements during flexion and extension testing.
Addition of the external fixator increased the stiffness of all constructs. Stiffness of the compromised reconstruction plate constructs with supplemented fixation was similar to or significantly greater than that of optimal internal fixation. Addition of the fixator to the reconstruction plates with 1 screw or the crossing screws produced displacements of the distal fragment that were similar to those of the compromised constructs alone. However, medial/lateral and anterior/posterior displacements of the distal fragment during flexion and extension of the elbow for supplemented fixation were found to be greater than those for optimal internal fixation.
The use of a hinged external fixator for supplemental fixation of distal humerus fractures may be effective in cases where internal fixation is severely compromised, although displacements may increase above optimal fixation.
评估使用铰链式单侧外固定器辅助固定肱骨干骺端骨折时，固定稳定性的改善情况。
在尸体全臂标本上切除1cm的肱骨干骺端，建立粉碎性肱骨干骺端骨折模型（AO 13-A3型）。然后使用不同的固定方式，分别代表最佳、受损或辅助内固定。内固定包括使用2块重建钢板，每块钢板有1、2或3枚（最佳）远端附着螺钉，或使用内侧和外侧皮质交叉螺钉。将铰链式外固定器与受损的内固定联合应用。然后在屈伸测试中，通过三点弯曲刚度和远端骨折块位移测量来评估不同固定方式的稳定性。
增加外固定器可提高所有固定方式的刚度。辅助固定的受损重建钢板固定方式的刚度与最佳内固定相似或显著更高。在使用1枚螺钉的重建钢板或交叉螺钉上增加固定器，产生的远端骨折块位移与单独的受损固定方式相似。然而，在肘关节屈伸过程中，辅助固定时远端骨折块的内外侧和前后位移大于最佳内固定时的位移。
对于严重受损的内固定，使用铰链式外固定器辅助固定肱骨干骺端骨折可能有效，尽管位移可能会高于最佳固定时的位移。
