Vanhove Frédéric, Noppe Nathalie, Fragomen Austin T, Hoekstra Harm, Vanderschueren Geert, Metsemakers Willem-Jan
Department of Radiology, University Hospitals Leuven, 3000, Leuven, Belgium.
Hospital for Special Surgery, Limb Lengthening & Complex Reconstruction Service, 535 East 70th Street, New York, NY, 10021, USA.
Arch Orthop Trauma Surg. 2019 Jun;139(6):795-805. doi: 10.1007/s00402-019-03139-1. Epub 2019 Feb 8.
Re-establishing anatomic rotational alignment of shaft fractures of the lower extremities remains challenging. Clinical evaluation in combination with radiological measurements is important in pre- and post-surgical assessment. Based on computed tomography (CT), a range of reference values for femoral torsion (FT) and tibial torsion (TT) have historically been reported, which require standardization to optimize the significant intra- and inter-observer variability. The aims of this study were (re-)evaluation of the reference FT and TT angles, determination of the normal intra-individual side-to-side torsional differences to aid the surgical decision-making process for reoperation, and development of a novel 3D measurement method for FT.
In this retrospective study, we included 55 patients, without any known torsional deformities of the lower extremities. Two radiologists, independently, measured the rotational profile of the femora using the Hernandez and Weiner CT methods for FT, and the tibiae using the bimalleolar method for TT. The intra-individual side-to-side difference in paired femora and paired tibiae was determined. A 3D technique for FT assessment using InSpace was designed.
FT and TT demographic values were lower than previously reported, with mean FT values of 5.1°-8.8° and mean TT values of 25.5°-27.7°. Maximal side-to-side differences were 12°-13° for FT and 12° for TT. The Weiner method for FT was less variable than the Hernandez method. The new 3D method was equivocal to the conventional CT measurements.
The results from this study showed that the maximal side-to-side tolerance in asymptomatic normal adult lower extremities is 12°-13° for FT and 12° for TT, which could be a useful threshold for surgeons as indication for revision surgery (e.g., derotational osteotomy). We developed a new 3D CT method for FT measurement which is similar to 2D and could be used in the future for virtual 3D planning.
重建下肢骨干骨折的解剖旋转对线仍然具有挑战性。临床评估与放射学测量相结合在手术前后评估中很重要。基于计算机断层扫描（CT），历史上曾报道过一系列股骨扭转（FT）和胫骨扭转（TT）的参考值，需要进行标准化以优化观察者内和观察者间的显著变异性。本研究的目的是（重新）评估参考FT和TT角度，确定个体内正常的左右扭转差异以辅助再次手术的外科决策过程，并开发一种新的FT三维测量方法。
在这项回顾性研究中，我们纳入了55例无任何已知下肢扭转畸形的患者。两名放射科医生分别使用用于FT的埃尔南德斯（Hernandez）和维纳（Weiner）CT方法测量股骨的旋转轮廓，使用双踝方法测量胫骨的TT。确定配对股骨和配对胫骨的个体内左右差异。设计了一种使用InSpace进行FT评估的三维技术。
FT和TT的人口统计学值低于先前报道的值，平均FT值为5.1° - 8.8°，平均TT值为25.5° - 27.7°。FT的最大左右差异为12° - 13°，TT为12°。用于FT的维纳方法比埃尔南德斯方法的变异性小。新的三维方法与传统CT测量结果相当。
本研究结果表明，无症状正常成年下肢的最大左右耐受性对于FT为12° - 13°，对于TT为12°，这可能是外科医生作为翻修手术（如旋转截骨术）指征的有用阈值。我们开发了一种新的用于FT测量的三维CT方法，该方法与二维方法相似，未来可用于虚拟三维规划。
