ULTRASONOGRAPHIC EVALUATION OF THE ANTERIOR RECESS IN THE NORMAL HIP - A PROSPECTIVE-STUDY ON 166 ASYMPTOMATIC CHILDREN

Purpose. To redefine the ultrasonographic features of the normal hip j oint in children and to establish a normal value for the neck-capsule distance (NCD) of its anterior recess. Materials and methods. 332 hips of 166 asymptomatic children were examined sonographically. In a sagi ttal section plane the maximum distance between the anterior surface o f the femoral neck and the anterior limit of the articular capsule (NC D-A) was measured. Results. The hypoechoic synovial membrane occupying the anterior recess could always be differentiated from the capsule. An additional thin layer of synovial fluid was detected in 12% of prob ands. The configuration of the capsule varied with different rotation positions of the legs. In small children the mean NCD-A increased from 2.5 mm at 65 cm height to 5 mm at 100 cm height. In larger children t he mean NCD-A was 5.5 mm. The mean right-to-left difference was 0.5 mm with a pathological limit of 2 mm. Conclusions. The pathological limi t of the NCD-A increases from 3.5 to 7.5 mm in relation to the height. Sonographic investigation of the pediatric hip joint must include det ailed demonstration of anatomical structures to avoid misinterpretatio ns.