Application of three dimensional printing in surgery for cam type of femoro-acetabular impingement

Abstract

Surgical treatment of femoroacetabular impingement (FAI) focuses on improving the clearance for hip motion and alleviation of femoral abutment against the acetabular rim. Cam type of impingement is managed by performing an osteochondroplasty to remove the excess impinging bone from the head neck junction, thus improving the head neck offset. This procedure can be done by safe surgical dislocation, arthroscopy assisted mini-open method or all arthroscopy technique. Whatever be the approach, adequate excision of the Cam deformity is necessary to avoid suboptimal results. Under-excision leads to persistent symptoms and progression of disease, while over-excision can lead to weak bone vulnerable to fracture or disturb the labral seal. Various techniques utilized for intra-operative evaluation of amount of excision required described in literature are fluoroscopy, spherometer gauges, intra-operative Computed Tomography (CT) scan, navigation etc. Rapid prototyping, also called as three dimensional (3D) printing, is a technology to create dimensionally accurate model from a computer-assisted design. Accurate physical models can be designed from the medical imaging data like CT scans and 3D printed to aid in various medical applications. Its application in orthopaedic field is on a rise, recently. However, there is no report on utilization of this technique in surgeries for FAI. We have reported a case of Cam type FAI in an eighteen year old boy, which we treated surgically by performing osteochondroplasty using safe surgical dislocation. We did CT based virtual surgical planning to design femoral head and neck jigs, which were 3D printed and used intra-operatively to guide for adequate and optimum excision of bone at head neck junction. We found these customized jigs accurate and useful for the surgery. However, a comparison study with various other techniques is warranted for a detailed research on its usefulness and challenges. The main purpose of this article is to elaborate on the technical steps for designing of jigs for 3D printing to guide in osteochondroplasty surgery for FAI.

MRI-based 3D models of the hip joint enables radiation-free computer-assisted planning of periacetabular osteotomy for treatment of hip dysplasia using deep learning for automatic segmentation

“…In addition, this could be used for 3D printing based on MRI-based 3D-models. 3D Printing is a novel tool for preoperative planning of cam resection [ 54 , 55 ] and can influence the location of the planned osteoplasty [ 56 ].…”

“…preoperative planning of cam resection [54,55] and can influence the location of the planned osteoplasty [56]. This study has the following limitations.…”

Evaluation of Cam Deformity on 3-Dimensional Computed Tomography With the Best-Fit Sphere Technique and the Alpha Angle Marking Method

“…The BFS method was also used to measure the 3D head-neck ratio for quantitative analysis of cam deformity 14 and to fabricate the spherical gauge for interoperative evaluation. 30 In this study, the BFS method was used to mark the border of cam deformity on 3D-CT ( Figure 3) and displayed a larger cam size and distribution range (11:00-03:30) than all views with the AAM method, which indicated that the BFS method can be used on 3D-CT to display the entire cam deformity. As shown in Figure 3, it was noted that the inferior border of cam-r was not as far down as that on cam-bfs, so the radial view of the AAM method showed a smaller portion of the cam deformity.…”

“…21,23 While the AAM method is based on the concept of bestfit circle on 2D images, 19 the best-fit sphere (BFS) method has been used to fabricate a spherical gauge by 3D printing for locating cam deformity during open femoroplasty surgery. 30 Kang et al 11 proposed the BFS method in 2013 to quantify the location and size of cam deformity and indicated that it could be used on 3D-CT to define the cam border. Cam deformity would protrude outside such a BFS of the femoral head on 3D-CT and could then be defined.…”

Three-dimensional-printing Technology in Hip and Pelvic Surgery: Current Landscape

“…Cam-type femoro-acetabular impingement (FAI) can be treated by performing an osteochondroplasty to remove the excess impinging bone from the head neck junction of femur. Verma et al 12) reported a case of Cam-type FAI in an 18 year-old male, who underwent surgical treatment by osteochondroplasty. CT-based virtual surgical planning was conducted to design the femoral head and neck jigs, which were 3D printed and used intra-operatively to guide for adequate and optimum excision of bone at the femoral head neck junction.…”