Computer-assisted pelvic osteotomy and 3D printing guide plate for developmental dislocation of hip surgery / 中华骨科杂志

ABSTRACT

Objective:To explore the scheme of accurate pelvic osteotomy parameters and to analyze the feasibility and efficacy of 3D printing navigation plate in developmental dysplasia of the hip surgery.Methods:From January 2015 to December 2017, a total of 18 children with DDH underwent computer-assisted Salter pelvic osteotomy (computer-assisted osteotomy group) and 25 children with DDH who underwent conventional Salter pelvic osteotomy (conventional osteotomy group) were selected for retrospective analysis. There were 11 males and 32 females with an average age of 3.2±2.5 (range 1-11) years. According to International Hip Dysplasia Institute (IHDI) classification, there were 20 cases of type 1, 9 of type 2, 12 of type 3 and 2 of type 4. All patients were unilateral dislocation, including 18 cases on the left and 25 on the right. All children underwent pelvic CT examination before operation. Further, the proximal femur was surgically corrected during the operation. According to the acetabular rotation angle (ATA) and bony acetabular index (BAI), the computer-assisted osteotomy group simulated the operation with Mimics software made 3D printing navigation plate through which an accurate osteotomy scheme was developed. The two groups were compared in operative duration, intraoperative blood loss, Japanese Orthopaedic Association (JOA) hip joint score. Acetabular index (AI), central edge (CE) angle, and acetabulum head index (AHI) were compared between the two groups by using postoperative X-ray. The acetabular tilt angle (ATA) changes before and after operation in the computer-assisted osteotomy group were compared through 3D CT.Results:The follow-up duration was 2.3±0.2 (2.0 to 2.5) years in the computer-assisted osteotomy group and 2.8±0.15 (2.5 to 3.0) years in the conventional osteotomy group. The operative duration in the computer-assisted osteotomy group was 127±20.6 min, which was significantly longer ( t=4.657, P<0.001) than that in the conventional osteotomy group (103±13.2 min). Intraoperative bleeding was 157±17.5 ml in the computer-assisted osteotomy group and 151±15.3 ml in the conventional osteotomy group without significant difference between the two groups ( t=1.195, P=0.239). At 2 years after surgery, the JOA score of the hip joint in the computer-assisted osteotomy group (86.7±8.5 points) was like that (84.8±10.0 points) in the conventional osteotomy group ( t=0.628, P=0.533). At the last follow-up, the CE angle in the computer-assisted osteotomy group (36.8°±5.2°) was significantly larger than that (31.8°±4.4°) in the conventional osteotomy group ( t=3.414, P<0.001). There was statistically significant difference in term of AHI between the computer-assisted osteotomy group (85.8%±6.6%) and the conventional osteotomy group (80.4%±8.3%, t=2.284, P=0.028). AI was 23.5°±5.5° in the computer-assisted osteotomy group and 25.2°±4.2° in the conventional osteotomy group without significant difference ( t=-1.150, P=0.257). The ATA of the affected side was 12.3°±1.4° in the computer-assisted osteotomy group which was similar ( t=0.614, P=0.547) to that of the healthy side (11.8°±2.8°). Conclusion:Based on specific anatomical parameters, computer-assisted preoperative planning can not only directly simulate the process of osteotomy, but also produce individualized 3D printed guide plates. Compared with conventional Salter pelvic osteotomy, computer-assisted osteotomy can achieve accurate radiographic correction of the hip joint in children with DDH, resulting in a better matching relationship between the femoral head and acetabulum.