Colebatch Alexandra N, Hart Deborah J, Zhai Guangju, Williams F M, Spector Tim D, Arden Nigel K
MRC Epidemiology Resource Centre, University of Southampton, Southampton General Hospital, Southampton, United Kingdom.
Knee. 2009 Jan;16(1):42-5. doi: 10.1016/j.knee.2008.07.007. Epub 2008 Sep 14.
The gold standard for measuring knee alignment is mechanical axis determined using full-limb radiographs (FLR). Measurement of joint alignment using antero-posterior (AP) knee radiographs is more accessible, economical and involves less radiation exposure to the patient compared with using full-limb radiographs. The aim of this study was to compare and assess the reproducibility of knee joint axial alignment on full-limb radiographs and conventional AP knee radiographs. Knee alignment was measured in 40 subjects (80 knees) from the TwinsUK registry. Measurement of mechanical knee alignment was from FLR, and anatomic knee alignment from weight-bearing AP knee radiographs. Reproducibility was assessed by intra-class correlation coefficients and kappa statistics. Reproducibility of knee alignment for both methods was good, with intra-observer ICC's of 0.99 for both FLR and AP radiographs. The mean alignment angle on FLR was 178.9 degrees (SD 2.1, range 173-183 degrees ), and 179.0 degrees (SD 2.1, range 173-185 degrees ) on AP films. 58.8% of knees on FLR and 66.3% on AP films were of varus alignment. Good correlations were seen between results for FLR and AP radiographs, with ICC ranging from 0.87-0.92 for left and right knees, and kappa statistics of 0.65-0.74. Standard AP knee radiographs can be used to measure knee alignment with good reproducibility, and provide comparable results to those obtained from FLR. This will facilitate measurement of knee alignment in existing cohort studies to assess malalignment as a risk factor of incident OA, and in clinical practice.
测量膝关节对线的金标准是使用全下肢X线片（FLR）确定的机械轴。与使用全下肢X线片相比，使用前后位（AP）膝关节X线片测量关节对线更容易实现、更经济，并且患者所受辐射暴露更少。本研究的目的是比较和评估全下肢X线片和传统AP膝关节X线片上膝关节轴向对线的可重复性。从TwinsUK注册中心选取40名受试者（80个膝关节）测量膝关节对线。机械膝关节对线通过FLR测量，解剖膝关节对线通过负重AP膝关节X线片测量。通过组内相关系数和kappa统计量评估可重复性。两种方法的膝关节对线可重复性都很好，FLR和AP X线片的观察者内ICC均为0.99。FLR上的平均对线角度为178.9度（标准差2.1，范围173 - 183度），AP片上为179.0度（标准差2.1，范围173 - 185度）。FLR上58.8%的膝关节和AP片上66.3%的膝关节为内翻对线。FLR和AP X线片的结果之间存在良好的相关性，左右膝关节的ICC范围为0.87 - 0.92，kappa统计量为0.65 - 0.74。标准AP膝关节X线片可用于测量膝关节对线，具有良好的可重复性，并能提供与FLR相当的结果。这将有助于在现有队列研究中测量膝关节对线，以评估对线不良作为新发骨关节炎危险因素的情况，以及在临床实践中进行测量。
