The Labral Plicae Entrapment Syndrome Of Hip In Children: An Ultrasonography Study

Objective: Labral plicae entrapment syndrome of hip (LPEH) was an important cause for pain in the hip which was the common reason for pediatric consultation. The objective of this study is to evaluate the features of Ultrasonography (US) for the LPEH in child and the US diagnostic value.Methods: (1) According to double-blind procedure, US were performed in 32 cadaveric specimens. 28 LPEH models and 36 sham models were studied to evaluate diagnostic sensitivity, specificity, positive value, and negative value. (2) A total of 21 consecutive children (age, 5.95±2.67 years) with unilateral LPEH and 21 age matched normal children were recruited. The US was performed in the all hips (21 symptomatic hips, 21 asymptomatic hips and 42 normal hips) to obtain the following parameters: the maximum thicken of the cartilage of femora, the maximum thicken of the anterior and posterior layer of the anterior capsule, the maximum width of the anterior and inferior medial recess. The results were expressed in mean±1SD. Pearson X~2 test and One-way ANOVA test were used. The data analyzed using the SPSS (version 11.5). Results: The sensitivity, specificity, positive and negative value of US for the LPEH model on the children cadaver were 88%, 84%, 79%, 91%, respectively. With regard to the thickness of femora head cartilage, the thickness of the anterior layer or posterior layer, there were no significant differences among three groups. However, the anterior layer was thicker than the posterior layer in three groups. The fluid in hip joint was detected in all of 21 symptomatic hips, which was clear commonly (90%) in early procedure. The amount of fluid in anterior recess showed a positive correlation with age (p <0.05). No fluid was detected in the asymptomatic and normal hips (< 2mm). The mean maximum width of inferomedial recess was significantly larger than that of anterior recess (12.50±4.04mm vs.4.35±0.8mm, p < 0.05) in the symptomatic hip joints. The echogenic entrapped labral plicaes were demonstrated in the inferomedial recess in all of 21 children with LPEH, whose length and width ranged from 5.3mm-25.0mm (mean,15.6±5.6mm) and from 4.0mm-17.0mm (mean,8.9±7.8mm). No color signal of blood flow was demonstrated in 90.5% (19/21) of the entrapped labral plicaes. All of 21 LPEH children had an uneventful recovery and no plicaes and fluid were detected in follow-up by US.Conclusions: The entrapped labral plicae in the inferomedial recess of hip joint could be visualized by US. US could provide useful diagnostic information of LPEH and be considered as a convenient, non-invasive examination for the children with LPEH.