3D Applications in Hip Surgery

Recent studies demonstrated the utility of advanced imaging techniques including 3D CT collision modelling, MRI 3D reconstruction and 3D fluoroscopy in hip surgery. Collision modelling including software based on a CT scan and 3D fluoroscopy are able to predict the specific zone of femoral-acetabular impingement and are useful tools to plan the bone resection in preserving hip surgery. Furthermore, they may be helpful for the evaluation of acetabular coverage in hip dysplasia and may predict the amount of correction needed during a periacetabular reorientation osteotomy. On the other hand, CT based prototyping and the custom 3D-printed implants have emerged as new options to address severe bone loss or compromised anatomy. Although, there is little published literature so far, the interest for this technology in hip arthroplasty is growing. Patient and defect-specific implants are designed from CT images and then may be printed via a 3D model or may generate into a one-piece product. Those solutions may be helpful in primary arthroplasty: first, they may be used in a complex case where a standard implant may not be easy to be performed because of the alteration of the bone structure; eventually, they may be used in oncologic cases where a great amount of bone should be resected. Custom implants find indications also in revision arthroplasty, where the bone loss is important. In fact, the resulting precision-fit of the implant to the remaining patients bonestock minimizes the need for more bone resection to fit an off-the-shelf product. Locking screw configurations may be planned preoperatively to obtain the most efficient purchase in the existing bone. Furthermore, by combining angiography from the planning CT, locking screw trajectory can be planned so as to maximize a fixation whilst minimizing vascular risk.