Utility of a custom screw insertion guide and a full-scale, color-coded 3D plaster model for guiding safe surgical exposure and screw insertion during spine revision surgery

Abstract

<jats:p>Several articles have described the use of screw insertion guides during primary spine surgery; however, the use of such a guide during revision surgeries has not been described. The purpose of this study is to describe the utility of a custom screw insertion (CSI) guide assembled using a novel method and a full-scale, color-coded 3D plaster (FCTP) model for safe and accurate revision surgery.</jats:p> <jats:p>The authors applied the CSI guide and the FCTP model in 3 cases. In the first case, a patient with multiple failed cervical spine surgeries underwent occipitocervicothoracic fusion. After a successful result for this patient, the authors applied the CSI guide in 2 other patients who underwent revision lumbar fusion surgeries to confirm the accuracy and the efficacy of the CSI guides in such cases. The models and guides were fabricated using rapid prototyping technology. The effectiveness of these methods was examined.</jats:p> <jats:p>The FCTP model was designed using CT data. During model assembly, implants inserted during previous surgery were removed virtually, and for the cervical spine, vertebral arteries were colored red for planning. The CSI guide was designed with 5 or 6 arms to fit the bone surface precisely after removing artifacts. Surgery was performed by referring to the FCTP model. Because the actual structure of the bone surface was almost identical to that of the FCTP model, surgical exposure around the complex bone shape proceeded smoothly. The CSI guides were positioned accurately to aid the successful insertion of a pedicle screw into the C-2 vertebra in the case of cervical revision surgery, and 4 pedicle screws for lumbar vertebrae in the 2 other patients. Postoperative CT scans showed that all screw positions closely matched those predicted during the preoperative planning. In conclusion, the FCTP models and the novel CSI guides were effective for safe and accurate revision surgery of the spine.</jats:p>

Accuracy Assessment of Pedicle and Lateral Mass Screw Insertion Assisted by Customized 3D-Printed Drill Guides: A Human Cadaver Study

“…Otsuki et al described a design that uses several small contact points connected by cylindrical primitives to deal with iatrogenic bone damage during revision surgery. 20 For our guide design, additional contact areas should be introduced to achieve a good fit after laminectomy (e.g., lateral mass border, osteotomy surfaces, transverse processes). Another challenge for the clinical adoption of drillguides is the lead time for spine fixation procedures.…”

Current status of 3D printing in spine surgery

“…Various authors, including ourselves, have described the use of 3D printed screw guides for inserting screws in cervical spine 20,21,22 complex spinal deformity such as scoliosis 23,24 and in revision surgeries where anatomical landmarks are more likely to be distorted. 25 A number of benefits of using these 3D printed guides have been described such as decreased operative time, lesser blood loss, greater accuracy, lower screw misplacement rate, simplicity of use, decreased radiation exposure and relative cost-effectiveness compared to the other techniques. 20,21,22,24,25 Figs.…”

“…25 A number of benefits of using these 3D printed guides have been described such as decreased operative time, lesser blood loss, greater accuracy, lower screw misplacement rate, simplicity of use, decreased radiation exposure and relative cost-effectiveness compared to the other techniques. 20,21,22,24,25 Figs. 1e6 are illustrative of how the 3DP technology is used to fabricate patientspecific pedicle screw drill guides.…”

Systematic review of 3D printing in spinal surgery: the current state of play

“…The use of intra-operative imaging increases harmful radiation exposure for both doctors and patients (30,(34)(35)(36). 3DP guides may offer an alternative as a simple, convenient, low cost and complexequipment free way to improve the accuracy of pedicle screw placement (30)(31)(32)(33)(34)(35)(36)(37)(39)(40)(41)(42)(43).…”

“…Next, a 3D model is generated by specialist software from which the optimal screw trajectory and size can be determined, often in consultation with the surgeon. Finally, a navigational template is designed and built with optimal screw trajectory, the surface of which is the inverse of the posterior vertebral surface to ensure a good fit and accuracy of screw insertion (30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)55). Numerous studies demonstrated that the guides help to lower operation time, with Deng et al (37) suggesting this may decrease complications related to operative time (e.g., infection) (30,35,37,43).…”