Application of a 3-dimensional printed navigation template in Bernese periacetabular osteotomies: A cadaveric study

Abstract

The aim of the present study was to describe the application of 3D printed templates for intraoperative navigation and simulation of periacetabular osteotomies (PAOs) in a cadaveric model.Five cadaveric specimens (10 sides) underwent thin-slice computed tomographic scans of the ala of ilium downwards to the proximal end of femoral shaft. Bernese PAO was performed. Using Mimics v10.1 software (Materialise, Leuven, Belgium), 3D computed tomographic reconstructions were created and the 4 standard PAO bone cuts-ischial, pubic, anterior, and posterior aspects of the ilium-as well as rotation of the dislocated acetabular bone blocks were simulated for each specimen. Using these data, custom 3D printed bone-drilling templates of the pelvis were manufactured, to guide surgical placement of the PAO bone cuts. An angle fix wedge was designed and printed, to help accurately achieve the predetermined rotation angle of the acetabular bone block. Each specimen underwent a conventional PAO. Preoperative, postsimulation, and postoperative lateral center-edge angles, acetabular indices, extrusion indices, and femoral head coverage were measured and compared; P and t values were calculated for above-mentioned measurements while comparing preoperative and postoperative data, and also in postsimulation and postoperative data comparison.All 10 PAO osteotomies were successfully completed using the 3D printed bone-drilling template and angle fix wedge. No osteotomy entered the hip joint and a single posterior column fracture was observed. Comparison of preoperative and postoperative measurements of the 10 sides showed statistically significant changes, whereas no statistically significant differences between postsimulation and postoperative values were noted, demonstrating the accuracy and utility of the 3D printed templates.The application of patient-specific 3D printed bone-drilling and rotation templates in PAO is feasible and may facilitate improved clinical outcomes, through the use of precise presurgical planning and reduced surgical complications with the precisely guided bone drilling.

Figure 1

(A) 3D surface reconstruction of the proximal end of a pelvis and bilateral femurs; (B) 3D reconstruction of the pelvis showing placement of the 4 PAO bone cuts and full dissociation of the acetabular bone block; and (C) 3D reconstruction of the pelvis showing outward displacement and rotation of the acetabular bone block, centered around the femoral head. PAO = periacetabular osteotomy.

Figure 2

Design of the bone-drilling template. (A) A virtual cast (overlay) of each pelvis was created in order to model the pelvic surface anatomy. (B) The position of the bone cuts determined during simulation was plotted, and the cast was trimmed at the margin of the cuts in order to create a (C) drilling template. (D) The 3D printed bone-drilling template.

Figure 3

Design of the angle fix wedge. (A) Using the rotation of the acetabular bone black determined during simulation, a surface overlay was created on the upper and lower surfaces of the bone opening of the ilium. (B) The 3D printed angle fix wedge.

Figure 4

(A) Surgical placement of the bone-drilling template in a cadaver. After exposure of the hip, the bone-drilling template was placed into position on the superior surface of the ilium and used as a stencil for placement of the bone cuts. (B) Surgical placement of the angle fix wedge in a cadaver. Following displacement of the acetabular bone block, the angle fix wedge was placed into the bone opening of the ilium to ensure accurate rotation of the acetabular bone block into the preplanned fixation position.

Figure 5

Preoperative, postsimulation, and postoperative measurements of cadaver side 1. (A) Preoperative x-ray of a right hip with a LCE angle of 35°, AC angle of 3°, EI of 17.5%, and (B) femoral head coverage of 82.7%. (C) Postsimulation of cadaver 1 with a LCE angle of 60°, AC angle of −15°, EI of 0%, and (D) femoral head coverage of 97.9%. (E) Postoperative x-ray of the same specimen with a LCE angle of 61°, AC angle of −15°, EI of 0%, and (F) femoral head coverage of 100%. AC = acetabular index, EI = extrusion index, LCE = lateral center-edge.