Davids J R, Blackhurst D W, Allen B L
Motion Analysis Laboratory, Shriners Hospitals for Children, Greenville, South Carolina 29605, USA.
J Pediatr Orthop. 2001 Mar-Apr;21(2):257-63.
Radiographic screening is widely used to distinguish between Blount disease (infantile tibia vara) and physiologic bowing. Thirteen children with Blount disease, evaluated before 3 years of age, with initial radiographs showing no sign of Langenskiold changes, were compared with 50 children with physiologic bowing, also evaluated before 3 years of age with similar radiographic studies. Screening test accuracy was determined retrospectively for measurement of the mechanical axis, the tibial metaphyseal-diaphyseal angle (TDMA), and the epiphyseal-metaphyseal angle (EMA). A radiographic screening method combining the TMDA and the EMA, using cutoff values of 10 degrees and 20 degrees respectively, exhibited the best combination of sensitivity, specificity, and positive predictive value, correctly identifying all cases of Blount disease and 40 of 50 cases of physiologic bowing. Our data suggest that children between 1 and 3 years of age with TMDA <10 degrees, or TMDA > or =10 degrees and EMA < or =20 degrees, are at less risk for development of Blount disease. Children with TMDA > or =10 degrees and EMA >20 degrees are at greater risk for development of Blount disease and should be followed closely.
X线筛查广泛用于区分布朗特病（婴儿型胫骨内翻）和生理性膝内翻。对13例3岁前接受评估且初始X线片未显示朗根斯基öld改变迹象的布朗特病患儿，与50例同样在3岁前接受评估且进行了类似X线检查的生理性膝内翻患儿进行比较。回顾性确定了测量机械轴、胫骨干骺端-骨干角（TDMA）和骨骺-干骺端角（EMA）的筛查试验准确性。一种分别使用10度和20度临界值组合TDMA和EMA的X线筛查方法，显示出敏感性、特异性和阳性预测值的最佳组合，正确识别了所有布朗特病病例以及50例生理性膝内翻病例中的40例。我们的数据表明，1至3岁的儿童，若TDMA<10度，或TDMA≥10度且EMA≤20度，则发生布朗特病的风险较低。TDMA≥10度且EMA>20度的儿童发生布朗特病的风险较高，应密切随访。
