Miles James E, Frederiksen Jane V, Jensen Bente, Kirpensteijn Jolle, Svalastoga Eiliv L, Eriksen Thomas
Department of Small Animal Clinical Sciences, Faculty of Life Sciences, University of Copenhagen, Denmark.
Vet Surg. 2012 Apr;41(3):422-9. doi: 10.1111/j.1532-950X.2011.00936.x. Epub 2012 Jan 12.
To evaluate the effect of measurement technique and limb positioning on quadriceps (Q) angle measurement, intra- and interobserver reliability, potential sources of error, and the effect of Q angle variation.
Cadaveric radiographic study and computer modeling.
Pelvic limbs from red foxes (Vulpes vulpes).
Q angles were measured on hip dysplasia (HD) and whole limb (WL) view radiographs of each limb between the acetabular rim, mid-point (Q1: patellar center, Q2: femoral trochlea), and tibial tuberosity. Errors of 0.5-2.0 mm at measurement landmarks alone and in combination were modeled to identify the effect on Q angle. The effect of measured Q angles on the medial force exerted on the patella (F(MEDIAL)) was calculated.
The HD position yielded significantly (P < .001) more medial Q angles than the WL position. No significant difference was observed between Q1 and Q2, but Bland-Altman plots indicated they were not equivalent. Intra- and interobserver agreement was substantial. Q2 errors were inherently greater than Q1: the mid-point and tibial tuberosity are the most important sources of Q angle variability. Increasing Q angles significantly increased the exerted F(MEDIAL) (P < .0001, gradient 1.7%).
Measurements are reliable, but Q2 is more prone to error than Q1, and the 2 measurement techniques are not interchangeable. Positional errors must be kept below 1.3 mm (Q1) or 0.8 mm (Q2).
评估测量技术和肢体位置对股四头肌（Q）角测量、观察者内和观察者间可靠性、潜在误差来源以及Q角变化影响的作用。
尸体放射学研究和计算机建模。
赤狐（赤狐属）的骨盆四肢。
在每个肢体的髋关节发育不良（HD）和全肢（WL）位X线片上，测量髋臼边缘、中点（Q1：髌骨中心，Q2：股骨滑车）和胫骨结节之间的Q角。单独和联合测量标志点处0.5 - 2.0毫米的误差被建模，以确定对Q角的影响。计算测量的Q角对施加于髌骨的内侧力（F（内侧））的影响。
HD位产生的Q角比WL位明显更偏向内侧（P < .001）。Q1和Q2之间未观察到显著差异，但布兰德 - 奥特曼图表明它们并不等效。观察者内和观察者间的一致性良好。Q2的误差本质上大于Q1：中点和胫骨结节是Q角变异性的最重要来源。Q角增加显著增加了施加的F（内侧）（P < .0001，斜率1.7%）。
测量是可靠的，但Q2比Q1更容易出错，并且两种测量技术不可互换。位置误差必须保持在1.3毫米（Q1）或0.8毫米（Q2）以下。
