Akhmedov Bekhzad, Ahn Soyeon, Chung Chin Youb, Lee Kyung Min, Sung Ki Hyuk, Kim Tae Won, Lee Seung Yeol, Choi In Ho, Cho Tae-Joon, Yoo Won Joon, Park Moon Seok
Department of Orthopaedic Surgery , Seoul National University Bundang Hospital, Kyungki, Korea.
J Pediatr Orthop. 2013 Jun;33(4):439-45. doi: 10.1097/BPO.0b013e318277093d.
Although previous studies have provided reference values for the lower limb alignment in children with physiological genu varum, those often have methodologic flaws, including problems with assumptions of statistical independence. In this study we intend to use appropriate statistical methods to determine reference values of the recovery of physiological genu varum by using a linear mixed model (LMM).
The database of our institution was searched and teleroentgenograms of patients up to 5 years of age with clinical diagnosis of physiological genu varum were selected. The mechanical tibiofemoral angle (mTFA), mechanical lateral distal femoral angle (mLDFA), and mechanical medial proximal tibial angle (mMPTA) were measured from each radiograph. These measures were then incorporated in LMM. The reference values for mTFA, mLDFA, and mMPTA were calculated by LMMs with age, sex, and side of the limbs, as the fixed effects with each subject as random effects.
A total of 425 teleroentgenograms were evaluated from 161 patients with physiological genu varum. Age, sex, and limb side terms were found to be significant contributing factors to the measures. In the LMM, with the age as quadratic, mTFA was equal to -0.3-degree varus [95% confidence interval (CI), -5.9 to 5.3 degrees] at the age of 3 years. The mLDFA was equal to 87.8 degrees (95% CI, 82.8-92.8 degrees) at the age of 4.5 years. The mMPTA was equal to 88.8 degrees (95% CI, 80.4-97.2 degrees) at the age of 2.5 years.
An LMM fitted well to estimate the natural recovery of physiological genu varum. Age, sex, and side of the limbs were found to be significant factors in the estimation of mTFA, and age and side of limbs were significant in estimation of mLDFA and mMPTA.
Level III-diagnostic study.
尽管先前的研究已经提供了生理性膝内翻儿童下肢对线的参考值，但这些研究往往存在方法学上的缺陷，包括统计独立性假设方面的问题。在本研究中，我们打算使用适当的统计方法，通过线性混合模型（LMM）来确定生理性膝内翻恢复的参考值。
检索了我们机构的数据库，并选择了临床诊断为生理性膝内翻的5岁以下患者的远距X线片。从每张X线片中测量机械性胫股角（mTFA）、机械性股骨远端外侧角（mLDFA）和机械性胫骨近端内侧角（mMPTA）。然后将这些测量值纳入线性混合模型。mTFA、mLDFA和mMPTA的参考值通过以年龄、性别和肢体侧别为固定效应、以每个受试者为随机效应的线性混合模型计算得出。
共评估了161例生理性膝内翻患者的425张远距X线片。发现年龄、性别和肢体侧别是这些测量值的重要影响因素。在该线性混合模型中，年龄为二次项时，3岁时mTFA为内翻-0.3度[95%置信区间（CI），-5.9至5.3度]。4.5岁时mLDFA为87.8度（95%CI，82.8 - 92.8度）。2.5岁时mMPTA为88.8度（95%CI，80.4 - 97.2度）。
线性混合模型非常适合用于估计生理性膝内翻的自然恢复情况。发现年龄、性别和肢体侧别是估计mTFA的重要因素，年龄和肢体侧别在估计mLDFA和mMPTA时具有显著意义。
III级 - 诊断性研究。
