Application of computer aided design 3D printed navigation template in Salter pelvic osteotomy for dislocation of hip joint in children

Objective To explore the feasibility of accurate localization for the acetabular direction in Salter pelvic osteotomy for the developmental dislocation of the hip joint in children by using computer aided design and 3D printing technique. Methods The clinical data of 12 patients of unilateral hip dislocation treated with Salter pelvic osteotomy by using 3D printed navigation template in Department of Orthopedics, Children′s Hospital of Nanjing Medical University From October 2016 to April 2017 were retrospectively analyzed.Among the 12 cases, there were 4 males and 8 females, 5 hips on the left and 7 hips on the right, aged 1.5 to 5.0 years old (mean 2.3 years old). According to the CT data, the models of the healthy hip joint were mirrored to the contralateral side by Mimics software.Computer-aided simulations of Salter pelvic osteotomy on models of the affected hip joints were performed.Then, the models of the affec-ted hip joint were rotated to the mirror models of the contralateral hip joint.The navigation templates were designed according to the exposed pelvic surface morphology during the operation.The navigation templates were printed by rapid prototyping technology to guide the operation.Preoperative and postoperative acetabular index (AI) and center edge angle (CEA) of affected side were compared to postoperative AI and CEA of contralateral side respectively. Results A method of making personalized navigation templates for Salter pelvic osteotomy was established in 12 children with developmental dislocation of the hip joint.The operation time ranged from 40.2 to 64.5 min, averaging (50.6±8.5) min.The intraoperative bleeding volume ranged from 35 to 60 mL, averaging 52 mL.No vascular and nerve injury was found in the postoperative examination, and no child had complications such as infection, residual foreign body of the guide plate and so on.There was significant difference in preoperative measurements regarding AI between the affected side [(38.4±2.8)°] and the contralateral side [(21.6±0.8)°](t=-18.77, P 0.05), there was no significant difference in postoperative measurements regarding CEA between the affected side[(21.2±2.6)°] and the contralateral side(t=-0.435, P>0.05). Conclusions The navigation template prepared by computer aided design and 3D printing technology has good accuracy, and is a new approach to accurate acetabular rotation in children with the developmental dislocation of the hip joint for Salter pelvic osteotomy. Key words: Dislocation of hip joint; Osteotomy; 3D printing