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

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.