[Combination surface shaded display with multiplanar reconstruction in the evaluation of acetabular morphologies in patients with developmental dysplasia of the hip before total hip arthroplasty].

OBJECTIVE: To explore the methods and application value of surface shaded display (SSD) and multiplanar reconstruction (MPR) in the evaluation of acetabular morphology in patients with developmental dysplasia of the hip (DDH) before total hip arthroplasty (THA).

METHODS: From October 2003 to November 2006, 17 patients (3 males and 14 females, aging from 35 years to 61 years) with osteoarthritis secondary to DDH were scanned with spiral CT preoperatively. According to the Crowe standard, 19 dysplasia hips were classified as type I in 4 hips, type II in 9 hips, type III in 6 hips. The obtained hip CT data were developed with SSD and MPR to observe spatial position and bone stock of the acetabula.

RESULTS: The dislocated extent was 25%-89% in these dysplasia hips according to the Crowe method and their sharp angles all exceeded 45 degrees. Bone defect occurred to each of the acetabula, among which it was located in anterosuperior acetabulum in 5 hips, in superolateral acetabulum in 11 hips and in posterosuperior acetabulum in 3 hips. The hip images made with MPR showed that the minimum thickness of the medial wall of acetabula ranged from 2.0 mm to 10.9 mm. Among 15 unilateral dysplasia patients, the opening difference and depth difference between the dysplasia acetabulum and the contralateral one ranged from 2.7 mm to 19.1 mm and from 2.3 mm to 13.1 mm, respectively.

CONCLUSION: SSD and MPR of spiral CT are effective methods in evaluating acetabular morphology preoperation and contribute to intraoperative acetabular reconstruction in patients with DDH performed THA.