Analysis Of Anatomical Tibiofemoral Angle In 919 Cases Of Healthy Shanxi Children From 0 To 7 Years Of Age

Objective:The study was aimed at disclosing the development process of anatomical tibiofemoral angle and offering normal reference to clinical diagnosis and follow-up of genu varum,genu valgum and knee diseases.Anatomical tibiofemoral angle was measured on 919 cases of normal the radiograph of the knee or Weight-bearing anteroposterior radiographs of the entire lower extremities from 0 to 7 years of age.The reference ranges of anatomical tibiofemoral angle were obtained and corresponding line charts were drawn.Methods:We retrospectively reviewed the normal the radiograph of the knee or Weight-bearing anteroposterior radiographs of the entire lower extremities taken in children from 0 to 7 years of age from January 2012 to January 2017.In total 1505 limbs(925 boys and 580 girls)in 919 children(554 boys and 365 girls)were enrolled in this study.The subjects in this study were divided into eight groups based on their chronologic age,such as the ones from 0 month to 6 month were grouped into age 0 year and the ones from 2-yr-7-month to 3-yr-6 month were grouped into age 3 year.The anatomical tibiofemoral angle(aTFA)was measured on their antemposterior radiographs.Results:The aTFA was in varus alignment in infancy(-6.02°),and became neutral before age of 2 year.Development into valgus alignment continued until age 3 year when it peaked at 6.52°.It then decreased slowly to plateau at 2.95° at age 7 year.Females showed a larger varus alignment at age 0 year[(-7.89±6.07)° vs(-4.88±7.44)°],and there was a statistically difference between females and males(p<0.05).The aTFA become valgus at age of 2 year for females and males.Females showed a larger peak valgus alignment at age 3 year[(7.40±2.98)°vs(5.97±3.27)°],and there was a statistically difference between them(p<0.05).The aTFA was(2.93±2.11)°(females)and(2.95±2.78)°(males)in those who were 7 years old.There were non-significantly differences between the mean aTFA of boys and girls in the age groups of 2,4,5,6 and 7 years(?0.05).Conclusion:This pattern of knee alignment change is similar to that found previously in other ethnic groups.Genu varum in infancy,neutral before 2 year,increasing genu valgum with a maximum value of 6.52° by 3 year followed by a gradual decrease to 2.95° of genu valgum at 7 year of age.We believe that a varus alignment of the knee in Chinese children after the age of 2 years might be atypical and needs detailed evaluation.There were non-significantly differences between the mean aTFA of boys and girls in the age groups of 2,4,5,6 and 7 years.