State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures, Shijiazhuang Tiedao University, Shijiazhuang, 050000, Hebei, People's Republic of China.
Department of Pediatric Orthopedics, Shengjing Hospital of China Medical University, Shenyang, 110004, Liaoning, People's Republic of China.
J Orthop Surg Res. 2020 Jan 31;15(1):34. doi: 10.1186/s13018-020-1564-4.
Management of distal humerus metaphyseal-diaphyseal junction (MDJ) region fractures can be very challenging mainly because of the higher location and characteristics of the fracture lines. Loss of reduction is relatively higher in MDJ fractures treated with classical supracondylar humerus fractures (SHFs) fixation techniques.
Three different fracture patterns including transverse, medial oblique and lateral oblique fractures were computationally simulated in the coronal plane in the distal MDJ region of a pediatric humerus and fixated with Kirschner Wires (K-wires), elastic stable intramedullary nails (ESIN), and lateral external fixation system (EF). Stiffness values in flexion, extension, valgus, varus, internal, and external rotations for each fixation technique were calculated.
In the transverse fracture model, 3C (1-medial, 2-lateral K-wires) had the best stiffness in flexion, varus, internal, and external rotations, while 3L (3-divergent lateral K-wires) was the most stable in extension and valgus. In the medial oblique fracture model, EF had the best stiffness in flexion, extension, valgus, and varus loadings, while the best stiffness in internal and external rotations was generated by 3MC (2-medial, 1-lateral K-wires). In the lateral oblique fracture model, 3C (1-medial, 2-lateral K-wires) had the best stiffness in flexion and internal and external rotations, while ESIN had the best stiffness in extension and valgus and varus loadings.
The best stability against translational forces in lateral oblique, medial oblique, and transverse MDJ fractures would be provided by ESIN, EF, and K-wires, respectively. K-wires are however superior to both ESIN and EF in stabilizing all three fracture types against torsional forces, with both 2-crossed and 3-crossed K-wires having comparable stability. Depending on the fracture pattern, a 3-crossed configuration with either 2-divergent lateral and 1-medial K-wires or 2-medial and 1-lateral K-wires may offer the best stability.
治疗肱骨远端干骺端-骨干交界处（MDJ）区域骨折具有挑战性，主要是因为骨折线位置较高且具有特征性。采用经典的肱骨髁上骨折（SHF）固定技术治疗 MDJ 骨折时，复位丢失的风险相对较高。
在儿童肱骨远端 MDJ 区域的冠状面模拟了 3 种不同的骨折模式，包括横形、内侧斜形和外侧斜形骨折，并分别采用克氏针（K 针）、弹性稳定髓内钉（ESIN）和外侧外固定系统（EF）进行固定。计算了每种固定技术在屈伸、外翻、内翻、内旋和外旋时的刚度值。
在横形骨折模型中，3C（1 枚内侧、2 枚外侧 K 针）在屈伸、内翻和外翻旋转时具有最佳的刚度，而 3L（3 枚发散的外侧 K 针）在外展和伸直时最为稳定。在内侧斜形骨折模型中，EF 在屈伸、外展、内翻和外翻加载时具有最佳的刚度，而 3MC（2 枚内侧、1 枚外侧 K 针）在内外旋转时具有最佳的刚度。在外侧斜形骨折模型中，3C（1 枚内侧、2 枚外侧 K 针）在屈伸和内外旋转时具有最佳的刚度，而 ESIN 在伸展和外翻及内翻加载时具有最佳的刚度。
对于 MDJ 外侧斜形、内侧斜形和横形骨折，ESIN、EF 和 K 针分别提供最佳的抗平移力稳定性。然而，K 针在抗扭转力方面优于 ESIN 和 EF，并且 2 交叉和 3 交叉 K 针具有相似的稳定性。根据骨折类型，采用 3 交叉构型，使用 2 枚发散的外侧和 1 枚内侧 K 针或 2 枚内侧和 1 枚外侧 K 针，可能提供最佳的稳定性。
