Hubbard Elizabeth W, Thompson Rachel M, Jo Chan-Hee, Pierce William A, Riccio Anthony I, Wimberly Robert L
Duke University Medical Center, Durham NC.
University of California Los Angeles, Orthopaedic Institute for Children, Los Angeles, CA.
J Pediatr Orthop. 2019 Apr;39(4):e258-e263. doi: 10.1097/BPO.0000000000001301.
It has been shown that retrograde titanium flexible intramedullary nails (Ti FIN) provide superior resistance to bending compared to antegrade Ti FIN in distal femur fractures. The purpose of this study was to compare resistance to torsional and bending forces of stainless steel (SS) FIN, with or without a locking screw, and Ti FIN in distal third femoral shaft fractures. We hypothesize that locked retrograde SS FIN will demonstrate greater resistance to both bending and torsional forces.
Thirty adolescent synthetic femur models were used to simulate transverse distal femoral fractures at either 60 mm or 90 mm proximal to the distal femoral physis. The femurs were instrumented with antegrade Ti FIN, antegrade SS FIN, retrograde Ti FIN, retrograde SS FIN, or retrograde locked SS FIN. Three models for each construct at both osteotomy levels were tested. Models were analyzed to determine maximum resistance to bending and torsion.
In fractures 60 mm from the physis, retrograde SS FIN demonstrated statistically superior resistance to bending when compared with both antegrade and retrograde Ti FIN (P=0.001 and 0.008, respectively) and antegrade SS FIN (P=0.0001). Locked SS constructs showed a trend towards greater resistance to bending forces when compared with unlocked constructs (P>0.05). No significant difference was seen in resistance to bending when fractures were 90 mm proximal to the distal femoral physis between the five groups. No significant differences were observed in resistance to torsion in either the proximal or distal fracture models, regardless of construct type.
Retrograde SS FIN confer significantly greater resistance to bending forces for fractures 60 mm proximal to the distal femoral physis compared with Ti FIN or antegrade entry SS FIN. In fractures 90 mm from the physis, no differences were noted in our model. Our results support the use of retrograde SS nails in the pediatric patient with distal femoral shaft fractures.
Level II-comparative biomechanical study.
研究表明，在股骨远端骨折中，逆行钛弹性髓内钉（Ti FIN）比顺行Ti FIN具有更好的抗弯曲能力。本研究的目的是比较有或没有锁定螺钉的不锈钢（SS）FIN以及Ti FIN在股骨远端三分之一骨干骨折中对扭转力和弯曲力的抵抗能力。我们假设锁定的逆行SS FIN对弯曲力和扭转力都将表现出更大的抵抗能力。
使用30个青少年合成股骨模型来模拟股骨远端骨骺近端60毫米或90毫米处的横向骨折。股骨分别植入顺行Ti FIN、顺行SS FIN、逆行Ti FIN、逆行SS FIN或逆行锁定SS FIN。在两个截骨水平上，每种植入物构建体设置三个模型进行测试。分析模型以确定对弯曲和扭转的最大抵抗能力。
在距骨骺60毫米处的骨折中，与顺行和逆行Ti FIN（分别为P = 0.001和0.008）以及顺行SS FIN（P = 0.0001）相比，逆行SS FIN在统计学上表现出更好的抗弯曲能力。与未锁定的构建体相比，锁定的SS构建体在抵抗弯曲力方面呈现出更大抵抗能力的趋势（P>0.05）。当骨折位于股骨远端骨骺近端90毫米处时，五组之间在抗弯曲能力上没有显著差异。无论植入物构建体类型如何，在近端或远端骨折模型中，抗扭转能力均未观察到显著差异。
与Ti FIN或顺行进入的SS FIN相比，逆行SS FIN对股骨远端骨骺近端60毫米处的骨折具有显著更强的抗弯曲能力。在距骨骺90毫米处的骨折中，在我们的模型中未发现差异。我们的结果支持在患有股骨远端骨干骨折的儿科患者中使用逆行SS钉。
II级——比较生物力学研究。
