Oh Jong-Keon, Lee Jeong-Joon, Jung Duk-Young, Kim Bong-Ju, Oh Chang-Wug
Department of Orthopedics, Medical Research Institute, College of Medicine, Ewha Womans University, 70 Chongro-6ka, Chongro-ku, 110-783 Seoul, Korea.
Arch Orthop Trauma Surg. 2004 Oct;124(8):542-6. doi: 10.1007/s00402-004-0724-z. Epub 2004 Sep 1.
Impalement of the anterior compartment musculature remains a problem in the hybrid external fixation of distal tibial fractures. The purposes of this study were to develop a tensioned wire configuration which does not violate the anterior compartment and to analyze the biomechanical implications of new wire configuration.
Thirty-seven adult volunteers without known pathology around either tibia were recruited. Axial computed tomography of the distal tibia was performed at 5-mm slices from the plafond to the upper margin of the syndesmosis. The wire convergence angle was measured at the 1-, 2-, and 2.5-cm levels using the following landmarks: tibialis anterior tendon (TA), tibialis posterior tendon (TP), peroneus brevis tendon (PB), anterolateral border of the lateral malleolus (LM). Two straight lines were drawn by connecting TA and PB and connecting TP and LM. The wire convergence angle was defined as an acute angle between these two lines. Then the orientation of the bisector axis of the wires was measured. As a second part of this study, a validated three-dimensional hybrid external fixator model was developed using finite elements modeling to analyze the stiffness of the frames constructed according to the measured wire convergence angle and orientation. Five simulated configurations were tested. The stiffness of each frame was analyzed under four load conditions: torsion, axial compression, side bending, and anteroposterior bending.
The mean convergence angle was 30 degrees irrespective of the level. The bisector axis was oriented towards the anterolateral direction about 20 degrees from the coronal plane. The stiffness of the frame constructed with a wire convergence angle of 30 degrees and an anterolateral wire orientation of 20 degrees was 20-30% less than that of the frame constructed with 60 degrees wires oriented in a coronal plane. The addition of an anteromedial half-pin increased the stiffness significantly.
Two tensioned wires may be placed without violating the anterior compartment by using the above four clinically identifiable landmarks. Addition of a half-pin on the anteromedial surface of the distal articular fragment makes the frame markedly stiffer than is possible using the standard wire configuration.
在胫骨远端骨折的混合外固定中，前侧间室肌肉组织的穿入仍然是一个问题。本研究的目的是开发一种不侵犯前侧间室的张紧钢丝构型，并分析新钢丝构型的生物力学意义。
招募37名双侧胫骨周围无已知病变的成年志愿者。从踝关节面至下胫腓联合上缘以5毫米层厚对胫骨远端进行轴向计算机断层扫描。使用以下标志在1厘米、2厘米和2.5厘米水平测量钢丝汇聚角：胫骨前肌腱（TA）、胫骨后肌腱（TP）、腓骨短肌腱（PB）、外踝前外侧缘（LM）。通过连接TA和PB以及连接TP和LM绘制两条直线。钢丝汇聚角定义为这两条线之间的锐角。然后测量钢丝平分线轴的方向。作为本研究的第二部分，使用有限元建模开发了一个经过验证的三维混合外固定器模型，以分析根据测量的钢丝汇聚角和方向构建的框架的刚度。测试了五种模拟构型。在四种载荷条件下分析每个框架的刚度：扭转、轴向压缩、侧弯和前后弯曲。
无论在哪个水平，平均汇聚角均为30度。平分线轴从前冠状面朝向外侧约20度。钢丝汇聚角为30度且钢丝外侧方向为20度构建的框架的刚度比在冠状面中使用60度钢丝构建的框架低20%至30%。在内侧前方添加一个半针显著增加了刚度。
通过使用上述四个临床可识别的标志，可以放置两根张紧钢丝而不侵犯前侧间室。在远侧关节面碎片的内侧前方表面添加一个半针可使框架明显比使用标准钢丝构型时更坚固。
