A novel approach reported by Peter Pijpker and colleagues from the University Medical Center Groningen, Groningen, The Netherlands, outlines the use of 3D virtual planning and 3D-printed models that have the ability to change how complex spinal surgeries are managed. Using this technique, surgeons were able to successfully reduce severe kyphosis in a young girl who suffers from skeletal dysplasia.
Pijpker et al emphasise the need for more precise methods of surgical planning. They state that a major advantage regarding the use of 3D virtual planning is the ability for the preoperative plan to correlate precisely with the actual operation: “This technology can give rise to new possibilities for the surgical planning of spinal deformities,” they wrote.
For patients with thoracic kyphosis, vertebral column resections and pedicle subtraction osteotomies (PSO) are widely indicated. To reduce the risk of injuries occurring during the osteotomy and pedicle screw insertion, computer assisted surgery (CAS) systems are commonly used. However, the procedure remains technically demanding with a risk of major complications.
Furthermore, the authors note that recent research in relation to individualised templating for spine surgery is currently limited to drill guides for accurate pedicle screw placement. Although patient-specific osteotomy templates have been described for knee arthroplasty, the authors report that this is the first paper describing this technique for complex spinal osteotomies.
The report describes the case of a young girl with severe angular thoracolumbar kyphoscoliosis. A closing wedge extended pedicle subtraction osteotomy was first virtually planned using medical computer software. Individualised osteotomy guided templates were then designed for the translation of the planned 3D-wedge towards the surgical procedure.
The authors note that the 3D planning and templates facilitated surgery in various ways. Not only did it allow for a 3D insight into case-specific anatomy and identification of vertebrae levels (as well as malformed vertebrae visualisation) during surgery, but it enabled the direct translation of the planned pedicle subtraction osteotomy into the surgical site using 3D printed individualised osteotomy guided templates. Additionally, the surgeons reported that studying the 3D anatomy in a multidisciplinary team facilitated the surgical procedure due to enhanced spatial orientation.
Speaking to Spinal News International, Pijpker comments: “In these severe kyphoscoliosis cases and other high risk or highly complex spinal procedures, these 3D models help our teams to train and prepare. The templates may, together with patient specific drill guides (another topic we are currently working on), contribute to safer spinal procedures. We believe that the 3D planning and printing technology is going to transform the way complex surgery is managed, whether through onscreen 3D visualisations, patient-specific bone models, individualised guiding templates or custom-made prosthetics.”
In relation to the case, the post-operative period was uneventful and the patient was discharged without any neurological deficit after eight days. The early postoperative X-rays showed a satisfactory correction of the kyphoscoliosis, as the kyphosis angle was reduced from 74° to 22° and her coronal plane was normalised.
Through the successful correction of the kyphoscoliosis in this case, it is clear that the novel use of 3D-virtual planning, 3D-printed spine models and osteotomy guiding templates have facilitated the performance of the osteotomy. In the report, the authors also note that this technique is feasible for the surgery of complex spinal deformities. They write that, from the surgeon’s perspective: “The templates and bone models provide valuable guidance during the osteotomy in the severely deformed anatomy.”
The authors reiterate that this method of spinal correction can be cost-effective, while it may help to reduce surgery time. Furthermore, it may preclude the need for intraoperative radiography—especially when combined with patient drill guides.
However, while the templates provided great directional support for the surgeon, the authors note that the use was nevertheless limited to the first stages of pedicle subtraction osteotomy. For example, when approaching the apex of the wedge, temporary rods had to be placed for stabilisation and safety.
As this is a novel technique, future designs of templates can be optimised by incorporating inlets for rod-positioning. Regarding the future of this method in terms of feasibility, the authors said that current feasibility was limited to describing the technical aspects, as well as the use of this new method in a qualitative manner. Therefore, to move forward with this technique, a comprehensive accuracy study is needed in relation to the clinical outcome; assessing its efficacy in a quantitative manner.
Nonetheless, the authors conclude by saying that, in addition to contributing to safer spinal osteotomy procedures, the novel use of this workflow involving 3D-virtual and 3D-printed models may change how complex surgeries are managed.