Clarke Jon V, Riches Philip E, Picard Frederic, Deakin Angela H
Department of Bioengineering, University of Strathclyde, Glasgow, Scotland.
Comput Aided Surg. 2012;17(1):29-39. doi: 10.3109/10929088.2011.635217. Epub 2011 Nov 30.
The quantification of knee alignment is a routine part of orthopaedic practice and is important for monitoring disease progression, planning interventional strategies, and follow-up of patients. Currently available technologies such as radiographic measurements have a number of drawbacks. The aim of this study was to validate a potentially improved technique for measuring knee alignment under different conditions. An image-free navigation system was adapted for non-invasive use through the development of external infrared tracker mountings. Stability was assessed by comparing the variance (F-test) of repeated mechanical femoro-tibial (MFT) angle measurements for a volunteer and a leg model. MFT angles were then measured supine, standing and with varus-valgus stress in asymptomatic volunteers who each underwent two separate registrations and repeated measurements for each condition. The mean difference and 95% limits of agreement were used to assess intra-registration and inter-registration repeatability. For multiple registrations the range of measurements for the external mountings was 1° larger than for the rigid model with statistically similar variance (p=0.34). Thirty volunteers were assessed (19 males, 11 females) with a mean age of 41 years (range: 20-65) and a mean BMI of 26 (range: 19-34). For intra-registration repeatability, consecutive coronal alignment readings agreed to almost ±1°, with up to ±0.5° loss of repeatability for coronal alignment measured before and after stress maneuvers, and a ±0.2° loss following stance trials. Sagittal alignment measurements were less repeatable overall by an approximate factor of two. Inter-registration agreement limits for coronal and sagittal supine MFT angles were ±1.6° and ±2.3°, respectively. Varus and valgus stress measurements agreed to within ±1.3° and ±1.1°, respectively. Agreement limits for standing MFT angles were ±2.9° (coronal) and ±5.0° (sagittal), which may have reflected a variation in stance between measurements. The system provided repeatable, real-time measurements of coronal and sagittal knee alignment under a number of dynamic, real-time conditions, offering a potential alternative to radiographs.
膝关节对线的量化是骨科临床实践的常规部分，对于监测疾病进展、制定干预策略以及患者随访都很重要。目前可用的技术，如影像学测量，存在许多缺点。本研究的目的是验证一种在不同条件下测量膝关节对线的潜在改进技术。通过开发外部红外跟踪器安装装置，使无图像导航系统适用于非侵入性使用。通过比较志愿者和腿部模型重复机械股骨 - 胫骨（MFT）角度测量的方差（F检验）来评估稳定性。然后在无症状志愿者中测量仰卧位、站立位以及施加内翻 - 外翻应力时的MFT角度，每位志愿者进行两次单独的注册，并针对每种情况进行重复测量。使用平均差异和95%一致性界限来评估注册内和注册间的重复性。对于多次注册，外部安装装置的测量范围比刚性模型大1°，方差在统计学上相似（p = 0.34）。评估了30名志愿者（19名男性，11名女性），平均年龄41岁（范围：20 - 65岁），平均BMI为26（范围：19 - 34）。对于注册内重复性，连续的冠状面对线读数几乎在±1°内一致，在应力操作前后测量冠状面对线时重复性损失高达±0.5°，站立试验后损失±0.2°。矢状面对线测量总体上重复性约低一半。仰卧位冠状面和矢状面MFT角度的注册间一致性界限分别为±1.6°和±2.3°。内翻和外翻应力测量分别在±1.3°和±1.1°内一致。站立位MFT角度的一致性界限为±2.9°（冠状面）和±5.0°（矢状面），这可能反映了测量之间站立姿势的变化。该系统在多种动态实时条件下提供了可重复的、实时的冠状面和矢状面膝关节对线测量，为X线片提供了一种潜在的替代方法。
