RESUMO
Objective To improve diagnosis of straight back syndrome.Methods 21 patients with straight back syndrome include 12 male and 9 female,and aged 15～36 years old(mean 21 years old).The standard P-A and left lateral chest film were taken and the A-P diameter and transverse diameter of the chest were measured,and the ratio between the both was calculated.Results The A-P diameter of the chest were 5.3 cm～8.5 cm(mean 6.6 cm)in male and 4.2 cm～8.1 cm(mean 6.2 cm)in female.the ratio between the A-P diameter and transverse diameter of the chest were 0.22～0.37(mean 0.34)in male,and 0.19～0.366(mean 0.31)in female.Conclusion The ratio between the A-P diameter and transverse diameter of the chest ≤0.37 is the diagnostic basis of the straight back syndrome.