3D printing in orthopedic surgery

Operative planning

Traditional preoperative planning relies on plain X-rays and 2D or 3D CT images. There have been significant advances in image processing technologies; however, 3D anatomy is still viewed as a flat image. 3D printers process these data and build a full-scale physical 3D model. These models provide a tactile impression and a better understanding of the patients' normal and pathological anatomy and pathophysiology. Patient-specific anatomical characteristics and variations are easily visualized. Review of 3D-printed models preoperatively can help surgeons to select the appropriate approach and to forerun potential difficulties or the need for special equipment .

Orthopedic trauma is a suitable field for application of 3D-printed models, especially when regions with complex anatomy are involved (i.e., acetabular or intra-articular fractures). Hurson et al. and Bagaria et al. proved that these models assisted surgeons to meliorate the understanding of individual anatomy and complex acetabular fracture patterns . Since the first utilization of 3D printing in trauma patients, it has proliferated to almost all anatomic areas ( Table 10.2 ).

Providing a multiangle and multidirectional view, it increases reliability and accuracy of diagnosis and classification of the fractures. Surgeons can plan the maneuvers of reduction and fixation. Using the mirror imaging technique and the normal, uninjured side as a template, they can choose the positioning of the reduction clumps, select the appropriate plate and its optimal placement, measure its length, and pre-bend it in order to fit the anatomic region where it will be placed. The number of screws needed, their location and entry points, length, and trajectories can be determined a priori .In particular, 3D printing assistance is considerable when inexperienced surgeons face a complex fracture, while experienced ones find it less useful or even unnecessary when dealing with a simple fracture pattern . 3D models can also be sterilized and brought into the operation room and used as references. Operations can be performed on the printed models at the doctor's desk, transforming virtual stimulation into realistic stimulation, and this “hands-on” approach is appreciated by many surgeons .

As a result, operation time, intraoperative blood loss, and overall fluoroscopies are reduced. Minimally invasive techniques can be used even at complex fractures as the accuracy of reduction and fixation is increased. Complications, such as iatrogenic nerve injuries, are decreased .

Spine surgery is another field of Orthopedics where 3D printing has potentially a wide range of applications. 3D models are used in cases with spinal deformities (i.e., idiopathic scoliosis, kyphosis, meningomyelocele) and help the study of joint inclination, false articulations, and pedicle size. These models were utilized in the preoperative setting for the planning of curve correction and pedicle screw placement, resulting in a safer and more accurate operation .

Pediatric Orthopedic surgeons have used 3D models to manage foot deformities, Perthes or Blount disease. Osteotomies in either pediatric or adult patients can also be planned with the aid of such models. The surgeon can study the deformity, choose the ideal site for the osteotomy, and prepare the angle of correction in all planes providing him with confidence during operation .