Transgluteal ultrasonography in spica cast in postreduction assessment of developmental dysplasia of the hip.

PURPOSE: The position of the femoral head in spica cast after the reduction of developmental dysplasia of the hip (DDH) should be examined and followed up closely and regularly. The study aimed to use the transgluteal ultrasonography approach for this purpose and compare its accuracy with the results of CT scan, which is the most commonly used modality. METHODS: Twenty-three patients with an average age of 20-21 months were examined for 1 year after the reduction of DDH, both closed and open. Ultrasonography and CT scan were performed on the patients on the same day, and the results were interpreted by different radiologists. Transgluteal ultrasonography in spica cast was performed while the legs were abducted, internally rotated, and flexed. A blanket was placed under the patient to elevate the cast. RESULTS: Thirty cases of proper reduction (81%) and 7 cases of dislocated hip (19%) were reported in transgluteal ultrasonography, and 29 cases of proper reduction (78%) and 8 cases of dislocated hip (22%) were reported in the CT scan. The rate of agreement between the results of ultrasonography and CT scan was 91%. CONCLUSION: Transgluteal ultrasonography can be used as an excellent modality to examine the position of the femoral head in relation to the posterior rim of the acetabulum in spica cast. The position of the femoral head can be viewed properly needless of perineal opening in the cast. Thus, transgluteal ultrasonography can replace the CT scan to assess the position of the femoral head. Sonography does not expose patients to radiation and does not require sedation.