The normal width of anterior hip synovial recess in children

To establish the diagnostic criteria for hip joint effusion, the normal wid th of the anterior hip synovial recess in children and the difference betwe en both hips of the same child were examined in this study. Eight kindergar ten schools were randomly selected for study in Kaohsiung City. The width o f anterior hip synovial recess of 1,568 hips in 784 children (421 boys, 363 girls) was measured by ultrasound scanner with 7.5-MHz linear probe. The a ge of children ranged from 2.5 to 6.6 years old. During measurement, the ch ildren were put in supine position with hips and knees in extension and pat ella facing up. The results revealed that the mean width of the anterior sy novial recess was 7.29 +/- 1.15 mm. Linens correlation of the width of syno vial recess to age and height was disclosed and expressed as follows: width (millimeters) equal to 6.52 + 0.013 x age (months), or width (millimeters) equal to 3.97 + 0.030 x height (centimeters). The mean difference between both hips of the same child was 0.611 +/- 0.523 mm, and the difference was independent from the factors of age, gender, height, or weight (p > 0.05). Ninety-five percent of the differences should be less than or equal to 1.46 mm, so that if the difference between hips is >1.46 mm, hip joint effusion should be suspected.