评估下肢对线：标准膝关节X线片与全下肢片的比较
Assessing Lower Limb Alignment: Comparison of Standard Knee Xray vs Long Leg View.
作者信息
Zampogna Biagio, Vasta Sebastiano, Amendola Annunziato, Uribe-Echevarria Marbach Bastian, Gao Yubo, Papalia Rocco, Denaro Vincenzo
机构信息
Dept. of Orthopaedics and Rehabilitation, University of Iowa , Iowa City, IA , United States ; Department of Orthopaedic and Trauma Surgery, Campus Bio-Medico University of Rome , Via Alvaro del Portillo 200, Rome , Italy.
Dept. of Orthopaedics and Rehabilitation, University of Iowa , Iowa City, IA , United States.
出版信息
Iowa Orthop J. 2015;35:49-54.
BACKGROUND
High tibial osteotomy (HTO) is a well-established and commonly utilized technique in medial knee osteoarthritis secondary to varus malalignment. Accurate measurement of the preoperative limb alignment, and the amount of correction required are essential when planning limb realignment surgery. The hip-knee-ankle angle (HKA) measured on a full length weightbearing (FLWB) X-ray in the standing position is considered the gold standard, since it allows for reliable and accurate measurement of the mechanical axis of the whole lower extremity. In general practice, alignment is often evaluated on standard anteroposterior weightbearing (APWB) X-rays, as the angle between the femur and tibial anatomic axis (TFa). It is, therefore, of value to establish if measuring the anatomical axis from limited APWB is an effective measure of knee alignment especially in patients undergoing osteotomy about the knee.
METHODS
Three independent observers measured preoperative and postoperative FTa with standard method (FTa1) and with circles method (FTa2) on APWB X-ray and the HKA on FLWB X-ray at three different time-points separated by a two-week period. Intra-observer and inter-observer reliabilities and the comparison and relationship between anatomical and mechanical alignment were calculated.
RESULTS
Intra- and interclass coefficients for all the three methods indicated excellent reliability, having all the values above 0.80. Using the mean of paired t-student test, the comparison of HKA versus TFa1 and TFa2 showed a statistically significant difference (p<.0001) both for the pre-operative and post-operative sets of values. The correlation between the HKA and FTal was found poor for the preoperative set (R=0.26) and fair for the postoperative one (R=0.53), while the new circles method showed a higher correlation in both the preoperative (R=0.71) and postoperative sets (R=0.79).
CONCLUSIONS
Intra-observer reliability was high for HKA, FTal and FTa2 on APWB x-rays in the pre- and post-operative setting. Inter-rater reliability was higher for HKA and TFa2 compared to FTal. The femoro-tibial angle as measured on APWB with the traditional method (FTal) has a weak correlation with the HKA, and based on these findings, should not be used in everyday practice. The FTa2 showed better correlation with the HKA, although not excellent.
LEVEL OF EVIDENCE
Level III, Retrospective study.
背景
高位胫骨截骨术（HTO）是治疗因内翻畸形继发的内侧膝关节骨关节炎的一种成熟且常用的技术。在规划肢体矫正手术时，准确测量术前肢体对线以及所需的矫正量至关重要。在站立位全长负重（FLWB）X线片上测量的髋-膝-踝角（HKA）被视为金标准，因为它能够可靠且准确地测量整个下肢的机械轴。在一般临床实践中，对线通常在标准前后位负重（APWB）X线片上进行评估，即测量股骨和胫骨解剖轴之间的夹角（TFa）。因此，确定从有限的APWB X线片测量解剖轴是否是评估膝关节对线的有效方法具有重要意义，尤其是对于接受膝关节截骨术的患者。
方法
三名独立观察者在三个不同时间点（间隔两周），采用标准方法（FTa1）和圆圈法（FTa2）在APWB X线片上测量术前和术后的TFa，并在FLWB X线片上测量HKA。计算观察者内和观察者间的可靠性以及解剖对线和机械对线之间的比较与关系。
结果
所有三种方法的组内和组间系数均显示出极好的可靠性，所有值均高于0.80。使用配对t检验的均值，HKA与TFa1和TFa2的比较在术前和术后数据集上均显示出统计学上的显著差异（p<0.0001）。术前数据集HKA与FTa1之间的相关性较差（R = 0.26），术后数据集的相关性一般（R = 0.53），而新的圆圈法在术前（R = 0.71）和术后数据集（R = 0.79）中均显示出更高的相关性。
结论
在术前和术后情况下，观察者内对APWB X线片上的HKA、FTa1和FTa2的可靠性较高。与FTa1相比，HKA和TFa2的观察者间可靠性更高。用传统方法（FTa1）在APWB上测量的股胫角与HKA的相关性较弱，基于这些发现，在日常实践中不应使用。FTa2与HKA的相关性较好，尽管并不完美。
证据水平
III级，回顾性研究。
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