3D printing in orthopedics. Part 1

By 6 June 2016Medicine

William Osler, a Canadian physician and one of the four founding professors of Johns Hopkins Hospital once said:

“The good physician treats the disease; the great physician treats the patient who has the disease.”

With an appearance of modern technologies in healthcare, this task is starting to be more easily achievable as they all allow doctors to understand their patients better.

Nowadays orthopedists have access to a variety of diagnostic tests with arthrography, dual-energy X-ray absorptiometry, CT scans, ultrasound, nerve conduction study, MRI, and electromyography just to name a few. All of them widen doctors’ perception and help them better understand patient’s condition before starting treatment. As people vary a lot in their anatomy, overall fitness and even in such basic characteristics as a normal body temperature individual approach is essential. How can 3D printing help doctors respond better to William Osler’s call? Let’s find out.

3D printing in preoperative planning

Recognition of complex anatomical structures can sometimes be difficult to attain from simple 2D radiographic views. 3D models of patients’ anatomy facilitate this task and allow doctors to familiarize themselves with a specific patient. This approach proved to reduce drastically OR time, especially in complex cases[1]. Getting to know patients’ anatomy before entering an OR allows to plan the exact approach, helps to predict bottlenecks and even test procedures beforehand. It very often occurs in neurological applications where maneuvering around delicate nerves and vessels are common but can also be beneficial in orthopedics[2].

An amazing example of 3D models created for surgery planning is separation of Siamese twins. Individual variances and complexities of their anatomy make estimation and planning of the surgery very challenging. Surgeons have to agree on organs distribution between two patients beforehand. Having limited information from 2D imaging and also relying only on one’s experience might have been a not good enough approach, as all cases are unique. Any mistake or oversight might lead to severe complications that could be very hard to control in the OR as the procedure is occurring a simultaneously on two patients. One of such cases was described in BBC’s article on two Chinese twins separation and another one in Imaging Technology News – procedure conducted in Texas Children’s Hospital. In each of them accurate 3D models were created to evaluate complexity and validate surgical approach.

Orthopedics can also benefit from planning on 3D models. Some of the most typical use cases are scoliosis or kyphosis surgeries and quite often evaluation of craniosynostosis cases. Some severe bone fractures may be better assessed with use of 3D models. Complex maxillofacial surgical procedures are also a major application for 3D models. Facial reconstruction is a complex procedure often requiring significant time for contouring titanium plates used to link adjacent bones together. The procedure is performed with a patient under anesthesia, and the plates are formed intraoperatively. Increased OR time can increase trauma to a patient. Having a 3D model of patient’s bony structure allows to shape the plates beforehand and thus reduce time spent in surgery[3]. There is a lot of scientific and popular articles showing usefulness of this technology in facial reconstruction.

There are some other applications of 3D printed models for evaluation of patient’s condition and planning of procedures are presented at Boston’s Children Hospital website.

This technology undoubtedly boosts surgeons’ confidence as it gives them the opportunity to evaluate all aspects of patient’s anatomy without losing time to do this in OR. No standard models nor 2D images can replace 3D printing as the first do not represent the specific case in debate and the latter may hide important details, especially in the spatial relationship between structures[3]. Looking inside patient’s body before inventing 3D printing has never been so detailed and clear.

3D printing in education

Three-dimensional print models can improve understanding of anatomy and pathology for both a surgeon and a patient. They supplement images displayed on a computer screen providing tactile and visual experience. Such models may be created as a reference for complex deformities to be shared along specialists.

Studying anatomy is conducted on cadavers of people who decided to donate their bodies to science or were not claimed by their families after passing away. It is not a secret that medical education facilities often lack cadavers for their classes. It is a serious situation as bodies are indispensable study tools for students of medicine. 3D printing might offer a solution here as complex anatomical structures of real patients can be easily reconstructed from CT or MRI data and saved for presentation to students. Of course, it is not a replacement for studying anatomy on cadavers, but it may supplement this type of teaching by providing accurate replicas of real body parts for study. It is especially essential in countries that do not allow for cadaver tests or for people who find such practice unethical. A Monash University has developed a few of such educational tools[4]It has also been suggested that these models could be kept to build a library or a catalogue of pathology for future educational purposes[5]. What limits their application scope is that one material printing cannot mimic mechanical characteristics of real organs. This can though be overcome by using new multi-material printing as was reported by Waran et al.[6] All types of tissues were separated sequentially resulting in 3D digital models of skin, bone, dura, and tumor. Each model had specific material characteristics assigned and after merging them into one, a 3D multi-material printer was used to create them. It gives hope for the future creation of more adequate training tools that may supersede cadavers.

3D prints may be as well used by a doctor to explain to a patient his or her condition. Such practice is already working. Nicolla Bizotto MD reassures his patients before performing a complex bone fracture surgeries and doctors at Radboud UMC hospital print brain tumors to explain the treatment to their patients. According to these articles, the practice shows high potential in using such tools not only for assessing condition but also to facilitate for a surgeon explanation of the procedure to a patient. An article published at Medscape underlines the importance of using 3D models for explaining ocular pathologies to patients as there are no accurate enough standard models to explain some of these conditions[7]). Offering a patient possibility to understand his case and procedure may be reassuring and produce better treatment outcome by reducing stress and insecurity.

Bibliography

  1. Hammad H. M. et al., (2015), “Three-Dimensional Printing in Surgery: A Review of Current Surgical Applications”, Journal of Surgical Research, 199(2), pp. 512-522
  2. Schubert, C. et al., (2014), “Review Innovations in 3D Printing: a 3D Overview from Optics to Organs”, Br J Ophthalmol, 98(2), pp.159-61
  3. Marro, A. et al., (2016), “Three-Dimensional Printing and Medical Imaging: A Review of the Methods and Applications”, Current Problems in Diagnostic Radiology, 45(1), pp. 2-9
  4. McMenamin, P. G. et al., (2014), “The Production of Anatomical Teaching Resources Using Three-Dimensional (3D) Printing Technology”, Anatomical Sciences Education, Volume 7(6), pp. 479–486

  5. Niikura, T. et al., (2014), “Surgical Navigation System for Complex Acetabular Fracture Surgery” Orthopedics, 37, pp. 237-242

  6. Waran, W. et al., (2014), “Utility of Multimaterial 3D Printers in Creating Models with Pathological Entities to Enhance the Training Experience of Neurosurgeons”, Journal of Neurosurgery, 120(2), pp. 489-492
  7. Hobbs, B. N., (2016), Changing Medical Education With 3D Printing,  Available from: http://www.medscape.com/viewarticle/857065 (accessed 30/04/16)

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