Why are 3D models of patient-specific anatomy so useful for operative planning?
Perhaps the most obvious answer is that the models provide surgeons with an opportunity to understand the complex anatomy unique to each case in the dimension they will be operating in. These 3D printed anatomic models based on patient-specific anatomy can be used for surgical planning both in and out of the operating room.
The use of 3D printing for treatment planning usually under three buckets:
- Fracture Fixation
- Resection of Renal Tumours
- Cardiovascular Applications
Treatment planning is a multistep process where clinical and imaging information is integrated to determine the best therapeutic options while saving operative time. With 3D printing, this can be creation of haptic models to plan the surgical approach along with cross-sectional imaging or, alternatively, creating custom prosthetics based on patient specific anatomy.
For more than a decade, additive manufacturing techniques have been used to improve surgical planning.
Orthopaedic, Maxillofacial, and Cardiothoracic surgeons were among the first to use 3D printing techniques to design custom prosthetics.
Chung et al. used 3D-printed calcaneal models in patients with intra-articular fractures to plan internal fixation and plating. Preoperatively, the models were used to determine an appropriate approach for fracture reduction. In some patients, the models were also sterilized and used intraoperatively.
Huang et al. used 3D printing to plan screw trajectories before internal fixation of tibial plateau fractures.
Pacione et al. reported on a case of a complex deformity of the skull base, requiring surgery. The 3D model of the skull base and upper cervical spine was used preoperatively to plan the surgical approach and then placed on a stand in the operating room to help guide surgery.
The use of 3D-printed models for operative planning has been implemented in a number of orthopaedic and fracture fixation applications. For example, Mao et al. used 3D models in 22 patients with hip arthroplasty requiring revision surgery.
The 3D models were used to fit the surgically altered acetabulum with commercially available cages or custom acetabular cages.
Resection of renal tumors
Wake et al. retrospectively identified 10 renal cancers that were characterized with magnetic resonance (MR) imaging before resection and fashioned 3D-printed models based on T1- weighted post-contrast fat-suppressed gradient-echo sequences. Using these models, they conducted a faux preoperative planning session (the session was conducted after the patients underwent surgery) with three urologists both with imaging alone then subsequently with the 3D-printed model and imaging. They administered a questionnaire concerning the surgical approach and understanding of the tumor’s anatomy (relationship with the native kidney). When compared to the initial session without the 3D-printed model, the session that incorporated both the model and the imaging data led to a change in at least one aspect of the surgical approach in all 10 patients. Although these models were not used in the actual planning, the surveyed surgeons did report increased confidence in their understanding of the tumor’s anatomy.
3D-printed heart and aortic models have been used for treatment planning in both cardiothoracic surgery and percutaneous cardiology applications.
In cardiothoracic surgery, 3D-printed anatomic models have been used intraoperatively to help guide the surgical approach, to perform the resection, and to guide tissue reconstruction.
Pepper et al. reported on a cohort of 34 patients with Marfan syndrome who had surgically implemented aortic root support from 3D-printed models. From preoperative CT and MR data, personalized aortic roots were manufactured along with an externalized mesh atop of the model. This conglomeration was sterilized and used intraoperatively with good technical success.
The 3D-printed contours were crucial in ensuring a proper fit and providing a surface for cutting branching points for branch arteries.
Hossien et al. used 3D printing in patients with aortic dissections to help determine treatment: open surgery versus endovascular intervention. After surgery, 3D printing can be used to help follow patients’ progress. For example, 3D-printed heart model derived from cardiac CT has been used to evaluate the integration of an atrial septal defect occlusion device.
- Wake N, Rude T, Kang SK, et al. 3D printed renal cancer models derived from MRI data: application in pre-surgical planning. Abdom Radiol 2017; 42:1501–1509. doi:10.1007/s00261-016-1022-2.
- Hossien A, Gesomino S, Maessen J, et al. The interactive use of multidimensional modeling and 3D printing in preplanning of type A aortic dissection. J Card Surg 2016; 31:441–445. doi:10.1111/jocs.12772.
- Pepper J, Petrou M, Rega F, et al. Implantation of an individually computer-designed and manufactured external support for the Marfan aortic root. Multimed Man Cardiothorac Surg 2013; 2013:mmt004. doi:10.1093/mmcts/mmt004.
- Pacione D, Tanweer O, Berman P, et al. The utility of a multimaterial 3D printed model for surgical planning of complex deformity of the skull base and craniovertebral junction. J Neurosurg 2016; 125:1194–1197. doi:10.3171/2015.12.JNS151936.
- Chung KJ, Hong DY, Kim YT, et al. Preshaping plates for minimally invasive fixation of calcaneal fractures using a real-size 3D-printed model as a preoperative and intraoperative tool. Foot Ankle Int 2014; 35:1231–1236. doi:10.1177/1071100714544522.
- Huang H, Hsieh M-F, Zhang G, et al. Improved accuracy of 3Dprinted navigational template during complicated tibial plateau fracture surgery. Australas Phys Eng Sci Med 2015; 38:109–117. doi:10.1007/ s13246-015-0330-0.1.