Galal Sherif
Department of Orthopaedic Surgery, Faculty of Medicine, Cairo University, Cairo, 11559, Egypt.
Strategies Trauma Limb Reconstr. 2018 Aug;13(2):109-118. doi: 10.1007/s11751-018-0312-3. Epub 2018 May 24.
Femoral lengthening with or along intramedullary (IM) nails will occur along the axis of the nail coincident with the anatomical axis of the bone. In the femur particularly, such lengthening often creates lateral mechanical axis deviation as the knee is driven medially. In cases where shortening is associated with frontal plane deformity the surgeon needs to correct the deformity intra-operatively, however, subsequent lengthening along the anatomical axis will create deformity. Thus, planning for lengthening of the femur with or along IM nails, whether shortening is associated with frontal plane deformity or not, requires a completely different planning strategy. The author questioned if a resolution anatomical axis can be identified and used for planning when lengthening the femur along or with IM nails while still applying the same classic CORA deformity analysis method.
In a prospective study, the author included eight patients who needed femoral lengthening, five with associated frontal plane deformity and three without. The author identified a method to determine the trajectory of the nail in the lower femoral segment. It was done by calculating the angle enclosed between this resolution anatomical axis and the mechanical axis, also known as the anatomical-mechanical angle.
This new method has proven to be effective in achieving normal alignment after lengthening is completed.
The Resolution Axis Method is a new and alternative method providing a solution for planning when lengthening the femur along the anatomical axis using an IM nail, whether a deformity is present or not.
使用髓内钉或沿髓内钉进行股骨延长会沿着与骨的解剖轴一致的髓内钉轴线发生。特别是在股骨中，由于膝关节被向内推动，这种延长常常会导致外侧机械轴偏差。在缩短与额状面畸形相关的情况下，外科医生需要在术中纠正畸形，然而，随后沿解剖轴延长会导致畸形。因此，无论缩短是否与额状面畸形相关，使用髓内钉或沿髓内钉进行股骨延长的规划都需要完全不同的规划策略。作者质疑在使用经典的CORA畸形分析方法的同时，在沿髓内钉或使用髓内钉延长股骨时，是否可以确定并使用一个解析解剖轴进行规划。
在一项前瞻性研究中，作者纳入了8例需要进行股骨延长的患者，其中5例伴有额状面畸形，3例没有。作者确定了一种确定股骨下段髓内钉轨迹的方法。这是通过计算该解析解剖轴与机械轴之间的夹角来完成的，该夹角也称为解剖-机械角。
这种新方法已被证明在延长完成后实现正常对线方面是有效的。
解析轴方法是一种新的替代方法，为使用髓内钉沿解剖轴延长股骨时的规划提供了解决方案，无论是否存在畸形。
