Development of a novel customized cutting and rotating template for Bernese periacetabular osteotomy

Abstract

Background Bernese periacetabular osteotomy (PAO) has been shown to be applicable as a hip-preserving technique for the treatment of developmental dysplasia of the hip (DDH). The approach could be designed preoperatively using various types of reverse-engineering software and finite element analysis, but how to implement it in the actual PAO remains a challenge. This study examines and evaluates a solution to achieve higher accuracy when performing a PAO. Methods A patient-specific cutting and rotating template was predesigned through computer-aided design (CAD) with three-dimensional (3D) modeling programs. The templates were then reproduced with rapid prototyping (RP) technology and used in the actual PAO. Finally, the clinical and radiographic effects were assessed and compared between the newly developed PAO and conventional PAO groups. Results The customized cutting template fit well with the bone surface and served as a guide for surgeons as they slid the osteotome to the precise location that had been determined prior to surgery. A very similar acetabular fragment was reproduced, and no major complications occurred when performing the osteotomy along the edge of the cutting template. The acetabular fragment was then corrected to the predetermined position through one-off manipulation with the customized rotating template. The final position of the acetabular fragment in the new developed PAO group was highly consistent with the planned position, and the postoperative morphological parameters were consistent with the preoperative planned data compared to the conventional PAO group. The duration of the operation and the number of irradiation decreased significantly. The Harris hip score (HHS) and visual analogue scale (VAS) score improved significantly with the use of the new developed PAO. Conclusions We demonstrate that our system, which was based on CAD-RP technology, is feasible and could realize the predicted results accurately during the actual PAO.

Three-Dimensional Digital Surgical Planning and Rapid Prototyped Surgical Guides in Bernese Periacetabular Osteotomy

“…In our case, we only used the 3D virtual plan and the quantitative data derived from that plan to implement the correction during surgery. In that study, the corrections obtained in five different radiographic projections were accurate varying from 1°to 4°on average, which was significantly superior to the traditional method (that varied from 6°to 13°, p < 0:01) [11]. In our case, the difference between the planned and actual center edge angle was 0°, and the Tönnis angle was 2°.…”

“…The differences between the guides produced by Wang et al [11] and ours include the printing method, the presence of slots in our guide, and the fact that our guide does not extend to the quadrilateral surface. One potential advantage 7 Case Reports in Orthopedics of our method is that with the slots, the osteotomes are less likely to deviate from course both rotationally and inclination wise, thereby adding accuracy and safety to the procedure.…”

“…Additionally, as the guide does not extend to the quadrilateral surface, less intrapelvic dissection is needed, which tends to produce less bleeding. In fact, in the study of Wang et al [11], the hips operated using the newly developed guide bled more compared with the traditional method, on average. However, the authors of that study reported decreased bleeding with experience, and we understand that creating an ischium osteotomy through the window originally described by Ganz [1] in the outer aspect of the pelvis would be less problematic; thus, we did not include this cut in our guide.…”

“…In 2019, Wang et al [11] published the first report of the clinical application of RP guides for PAO in 20 patients. The cases managed with this new technique had no complications, and the authors reported good accuracy, less radiation exposure during surgery, and decreased surgical time.…”

“…In 2016, a cadaveric study reported good accuracy and utility of RPgenerated guides in simulated PAO [10]. In 2019, the first series of 20 patients undergoing surgery with RP-generated plastic guides reported viability of this approach as well as good accuracy and reproducibility [11].…”