3D-printed Navigation Template Research Articles

Comparative study of 3D printed navigation template-assisted atlantoaxial pedicle screws versus free-hand screws for type II odontoid fractures

The objective of the study was to compare the safety, efficacy, and accuracy of the pedicle screws with the three-dimensional (3D) printed navigation template to the free-hand screws for type II odontoid fractures. A total of 60 patients with type II odontoid fractures, treated with either template guiding pedicle screws or free-hand screws, were retrospectively assessed. The guiding group was treated with pedicle screws with the assistance of a virtual reality (VR) software-designed, 3D printed navigation template with two guide tubes. The safety rate and treatment efficacy of the screw placement, as well as the trajectory accuracy, were evaluated by respective measures and compared between two surgical groups. There were reduced surgical time (P < 0.05), blood loss (P < 0.01), and C-arm shots (P < 0.01) with 3D printed template guiding screws. The rates of safe pedicle screws in both C1 and C2 were significantly higher in 3D guiding group (P < 0.01) compared to the free-hand group, and the scores of visual analogue scale (VAS) and impairment scale (ASIA) were improved in guiding group at 1week post-surgery (P < 0.01 and P < 0.05, respectively). Postoperative CT and image reconstruction showed the 3D guiding group had better horizontal screw accuracy on both sides of C1 (L: P < 0.001, R: P < 0.01) and C2 (L: P < 0.001, R: P < 0.01) than free-hand group. The herein screw technique using 3D printed navigation template leads to greater improvement in the screw safety, efficacy, and accuracy, which may be a promising alternative to free-hand surgery for the treatment of odontoid fractures.

3D-printed navigation template in cervical spine fusion: a systematic review and meta-analysis.

To explore the effectiveness and advantage of three-dimensional (3D)-printed navigation templates (3DPN-template) assisted in cervical spine fusion (CSF) surgery as compared to conventional surgery. An electronic literature search in PubMed, Scopus, Web of Science, and Cochrane was conducted for studies of 3DPN-templates in CSF up to May 2020. Outcome measures as the accuracy rate, operation time, intra-operative blood loss, and fluoroscopy used, associated with CSF were extracted. Mean difference based on changes was quantified using Hedges' g. From 4414 potentially relevant studies, 61 full-text publications were screened. Thirteen studies comprising 330 cases with 1323 screw placements were eligible for inclusion. For template group, pooled estimates were as follows: 97.3% accuracy rate for screw placement, 144.7min for operating time, 273.6ml for blood loss, and 3.2min for fluoroscopic times. A significantly positive difference was observed between the template group compared to control group in terms of accuracy rate of screw placement (Z = 5.3), operation time (Z = 2.41), intra-operative blood loss (Z = 2.64), and fluoroscopic times (Z = 3.64) (all, P value < 0.0001). Risk of bias for studies under review was assessed using the Newcastle-Ottawa Scale (NOS), and 11 studies were found as having high quality. Overall, funnel plot and Begg's test did not indicate obvious publication bias. The 3D-printed navigation template in the cervical surgery can improve accuracy of pedicle screw placement and consequently improve outcomes. In future, multi-center efforts are needed to validate the relationships found in this review.

Progress in clinical application of 3D printed navigational template in orthopedic surgery

Orthopedic 3D printed surgical navigational template is an instrument that is prepared by 3D reconstruction based on preoperative radiological data of the patient using computer-aided design (CAD) and 3D printing techniques. The 3D printed navigational template allows accurate intra-operative assessment of the relative spatial distance, angular relationship, direction and depth. The application of 3D printed navigational template technique in orthopedics surgeries achieves the conversion of preoperative planning from 2/3D graphics to 3D models, and provides a new method for individualized and precise treatment. Herein we review the evolution, clinical application, and basic classification of 3D printed navigation template technique, analyze its advantages and disadvantages, and discuss the current problems and the future development of this technique.

Comparison of the Accuracy and Safety of Pedicle Screw Placement in Thoracic Spine Between 3D Printed Navigation Templates and Free Hand Technique

Relevance. Transpedicular spine fixation is considered the gold standard for posterior stabilization of the spine in various pathological processes. The most common implantation technique is the free hand method. But today the implantation with 3D printed individual navigation templates is gaining popularity. Purpose — to compare results of the pedicle screw placement in thoracic spine with application of 3D printed navigation templates by various design and free hand technique. Materials and Methods. Results of the three group of patients were analyzed based on postoperative CT. In group 1 (free hand) 112 screws were placed to 23 patients. In group 42 screws were placed to 11 patients using bilateral monosegmental navigation templates, in group 3 (13 patients, 42 screws) — using bilateral monosegmental templates with additional support on the spinous process. The safety of implantation was assessed and compared in all groups. In groups 2 and 3 the accuracy was also evaluated based on the difference between the planned and actual screws trajectory. Results. In group 1 safety grade 0 was registered in 66,96%, safety grade 1 in 18,75%, safety grade 2 — in 9,82%, safety grade 3 — in 4,46%. In group 2 grade 0 was registered in 85,71%, safety grade 1 — in 14,29%. In group 3 grade 0 — in 90,74%, safety grade 1 — in 9,26%. There were no cases of the cortical bone perforation for more than the half of the screw diameter in groups 2 and 3. The differences in the safety parameters are significant between free hand and both groups with application of the navigation templates. Assessment of the deviation hasn’t revealed significant difference depending on the type of the templates. Conclusion. The use of the individual navigation templates for pedicular screws implantation in the thoracic spine is safer than the free hand method (p0.05). Single-level bilateral matrices made by FDM technology from polylactide with support on a part of the dorsal vertebral structures make it possible to achieve the high implantation accuracy. Additional support on the spinous process does not lead to a statistically significant improvement in accuracy and safety indicators (p0.05), while requiring extended dissection and resection of the ligamentous elements.

3D Printing Navigation Template Used in Total Hip Arthroplasty for Developmental Dysplasia of the Hip.

The purpose of our study was to explore the feasibility of 3D printing navigation template used in total hip arthroplasty (THA) for adult developmental dysplasia of the hip (DDH). 25 patients who received THA for DDH from February 2014 to May 2018 were randomized into the control or intervention group. Of these patients, 12 received THAs assisted with 3D printing navigation templates, 13 THAs underwent THAs without navigation templates. The mean follow-up was 1.6 (range, 1.2-3.8) years. Clinical scores and radiographic results were evaluated for two groups. Operating time, intra- and postoperative hemorrhage and Harris Hip Score (HHS) at 6 months postoperatively in the 3D printing group were better than those for patients in the conventional hip replacement group, while infection and implant loosening were 0 in the two groups. There were no significant differences in anteversion angle, abduction angle and the distance from rotation center to the ischial tuberosity line in 3D printing group as compared to the normal side. The abduction angle and the distance from rotation center to the ischial tuberosity line were significantly different between the two sides in the traditional group. Application of the 3D printing template for THA with DDH can facilitate the surgical procedure and create an ideal artificial acetabulum placement.

Application of computer aided design 3D printed navigation template in Salter pelvic osteotomy for dislocation of hip joint in children

Objective To explore the feasibility of accurate localization for the acetabular direction in Salter pelvic osteotomy for the developmental dislocation of the hip joint in children by using computer aided design and 3D printing technique. Methods The clinical data of 12 patients of unilateral hip dislocation treated with Salter pelvic osteotomy by using 3D printed navigation template in Department of Orthopedics, Children′s Hospital of Nanjing Medical University From October 2016 to April 2017 were retrospectively analyzed.Among the 12 cases, there were 4 males and 8 females, 5 hips on the left and 7 hips on the right, aged 1.5 to 5.0 years old (mean 2.3 years old). According to the CT data, the models of the healthy hip joint were mirrored to the contralateral side by Mimics software.Computer-aided simulations of Salter pelvic osteotomy on models of the affected hip joints were performed.Then, the models of the affec-ted hip joint were rotated to the mirror models of the contralateral hip joint.The navigation templates were designed according to the exposed pelvic surface morphology during the operation.The navigation templates were printed by rapid prototyping technology to guide the operation.Preoperative and postoperative acetabular index (AI) and center edge angle (CEA) of affected side were compared to postoperative AI and CEA of contralateral side respectively. Results A method of making personalized navigation templates for Salter pelvic osteotomy was established in 12 children with developmental dislocation of the hip joint.The operation time ranged from 40.2 to 64.5 min, averaging (50.6±8.5) min.The intraoperative bleeding volume ranged from 35 to 60 mL, averaging 52 mL.No vascular and nerve injury was found in the postoperative examination, and no child had complications such as infection, residual foreign body of the guide plate and so on.There was significant difference in preoperative measurements regarding AI between the affected side [(38.4±2.8)°] and the contralateral side [(21.6±0.8)°](t=-18.77, P 0.05), there was no significant difference in postoperative measurements regarding CEA between the affected side[(21.2±2.6)°] and the contralateral side(t=-0.435, P>0.05). Conclusions The navigation template prepared by computer aided design and 3D printing technology has good accuracy, and is a new approach to accurate acetabular rotation in children with the developmental dislocation of the hip joint for Salter pelvic osteotomy. Key words: Dislocation of hip joint; Osteotomy; 3D printing

Clinical application of individualized 3D-printed navigation template to children with cubitus varus deformity

BackgroundCubitus varus deformity is a common sequela of elbow fractures in children. Cubitus varus deformity treatment is tending toward 3D correction, which is challenging for orthopedic surgeons. This study aims to explore whether individualized 3D-printed navigation templates can assist with accurate and effective corrective treatment of children with cubitus varus deformity.MethodsThirty-five patients were treated for cubitus varus deformity from June 2015 to April 2017, including 21 boys and 14 girls, aged 4.6–13.2 years (average, 7.5 years). Of these cases, 17 deformities were on the left side and 18 were on the right side. All were treated with wedge osteotomy of the lateral distal humerus. 3D-printed navigation templates were used in 16 cases, while traditional surgery was used in 19 cases. All patients underwent computed tomography scans before surgery. Computer software was used to analyze the measurements and design and print individualized navigation templates. The navigation templates were matched, and surgery was initially simulated. Intraoperative individualized navigation templates were used to assist with accurate osteotomy and Kirschner wire fixation. Operation times were recorded in all cases, the carrying angles before and after surgery were assessed by computer, and postoperative elbow joint function was evaluated using Bellemore criteria. All measurement data were presented as means ± SD, and Student’s t test was used to examine differences between groups. All count data between both groups were compared using the chi-square test or Fisher’s exact test analysis.ResultsAll individualized navigation templates matched well with the corresponding anatomical markers and were consistent with preoperative planning, simulated surgery, and intraoperative procedures. Average operation times from clear exposure to fixed Kirschner wire were 11.69 min (9.6–13.5 min) for the individualized navigation template group and 22.89 min (17.7–26.8 min) for the traditional operation group (p < 0.001). Average differences in postoperation carrying angles between affected and healthy sides were 1.13° (0–2.0°) and 4.21° (0–7.5°), respectively (p < 0.001). Follow-up 6–12 months postoperation showed that elbow function did not differ significantly between groups using the Bellemore criteria (p > 0.05).ConclusionsIndividualized navigation templates simplify procedures, reduce operation time, and improve accuracy when used in orthopedic surgery to treat children with cubitus varus deformity.

Determination of optimal design of navigation templates for transpedicular implantation in the cervical and thoracic spine: results of cadaveric studies

Objective. To perform comparative analysis of safety and accuracy of pedicle screw placement in the cervical and thoracic vertebrae using custom-made 3D-printed navigation templates of various designs. Material and Methods . The study was performed on three cadaver preparations. A total of 60 pedicle screws were placed in C2–T4 using navigation templates of different designs. Three types of templates were used to install 20 screws in each group: monolateral templates in group A, bilateral templates in group B, and bilateral three-point templates supported by the spinous process in group C. The safety and accuracy of screw placement were evaluated by CT with following comparative evaluation. Results. Three-point templates (group C) demonstrated the highest implantation safety, only one screw (5 %) perforated pedicle’s wall with grade 1, 19 screws (95 %) were completely surrounded by bone tissue. In group A, three screws (15%) were placed with grade 1, two screws (10 %) with grade 2, and one screw (5 %) with grade 3. In group B, two screws (10 %) were placed with grade 1, and one screw (5 %) – with grade 2.The average deviation at the screw entry point was 5.0 ± 0.5 mm in group A, 1.7 ± 0.3 mm in group B, and 0.35 ± 0.05 mm in group C. The average deviation at the end point was 5.1 ± 0.7 mm in group A, 3.5 ± 0.6 mm in group B, and 0.53 ± 0.05 mm in group C. Differences between groups in terms of implantation safety and accuracy are statistically significant (p < 0.05). Conclusion. Bilateral three-point navigation templates supported by spinous process are recommended for pedicle screw placement in the cervical and thoracic spine.

3D printed navigation template-guided minimally invasive percutaneous plate osteosynthesis for distal femoral fracture: A retrospective cohort study

ObjectiveTo evaluate functional and radiological outcomes in distal femoral fracture patients (distal femoral shaft fractures or metaphyseal fractures) receiving indirect reduction and internal fixation with the minimally invasive percutaneous plate osteosynthesis (MIPPO) assisted by 3D printing navigation templates. MethodsThis retrospective study included all adult (≥18 years) patients who underwent MIPPO for distal femoral fracture (AO32/33) at PLA 960 Hospital, Jinan, China between January 1, 2013 and December 31, 2016. 3D printed navigation templates were used to assist surgery. Functional assessment was performed using the Knee Society Score (KSS) and the Functional Knee Society Score (FKSS). Postoperative deformity was assessed with 3D-CT reconstruction using contralateral (non-fracture) side as the reference. ResultsA total of 54 patients underwent MIPPO for distal femoral fracture during the review period (34 and 20 for conventional and template-guided MIPPO, respectively). At 10–14 months, the KSS score was 160.6 ± 18.1 and 167.5 ± 17.2 in the conventional and template-guided MIPPO groups, respectively (p = 0.18). The FKSS was 77.6 ± 9.4 in the conventional MIPPO group vs. 81.0 ± 8.5 in the template-guided MIPPO group (p = 0.15). Femoral length difference was smaller in template-guided MIPPO group (3.31 ± 1.53 vs. 9.50 ± 4.49 mm in the control; p < 0.01). Template-guided MIPPO group also had smaller anatomic lateral distal femoral angle (aLDFA) difference (1.57° ± 0.72° vs. 3.89° ± 1.72° in the control; p < 0.01), anatomic posterior distal femoral angle (aPDFA) difference (1.95° ± 0.78° vs. 5.04° ± 1.78°; p < 0.01), and anteversion angle difference (2.52° ± 1.00° vs. 8.23° ± 4.07°; p < 0.01). The rate of length discrepancy (>20 mm), coronal angulation deformity (aLDFA difference >5°), sagittal angulation deformity (aPDFA difference >10°), and rotational malalignment (anteversion angle >10°) was 5.9%, 20.5%, 2.9%, and 32.4% in the control group. No patients in the template-guided MIPPO group had deformity of any type. ConclusionsMIPPO assisted by 3D printing navigation templates could practically improve surgical accuracy and eliminate postoperative rotational deformity in patients with distal femoral fractures.

Gait analysis after total knee arthroplasty assisted by three-dimensional printing navigation template

To explore the gait trajectory characteristics of patients after total knee arthroplasty (TKA) assisted by three-dimensional (3D) printing navigation template. Twenty female patients (20 knees) with knee osteoarthritis who were treated with TKA assisted by 3D printing navigation template between February 2017 and February 2018 were selected as the 3D printing group. The patients were 50-69 years old, with an average age of 57.2 years. The disease duration was 4-7 years, with an average of 5.6 years. The osteoarthritis was classified as Kellgren-Lawrence Ⅲ level in 5 cases and Ⅳ level in 15 cases. The preoperative hip-knee-ankle angle (HKA) was (170.8±5.6)°. All patients were varus deformity. According to age and affected side, 20 healthy female volunteers were selected as the control group. The volunteers were 51-70 years old, with an average age of 56.7 years. Preoperative HKA was (178.8±0.6)°. There was significant difference in HKA between the two groups ( P>0.05). The HKA, Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and visual analogue scale (VAS) scores of the 3D printing group before and after operation were compared. At 6 months after operation, the gait trajectory characteristics of 3D printing group and control group were analyzed by Vicon gait capture system. The kinematics parameters included velocity, cadence, stride length, maximum knee flexion angle (stance), minimum knee flexion angle (stance), maximum knee flexion angle (swing), mean hip rotation angle (stance), mean ankle rotation angle (stance). The incisions of 3D printing group healed by first intention, with no complications. All patients were followed up 7-12 months (mean, 9.0 months). The WOMAC and VAS scores at 6 months after operation were significant lower than those before operation ( P<0.05). The HKA was (178.8±0.8)° at 4 weeks after operation and the difference was significant when compared with that before operation ( t=39.203, P=0.000). The position of the prosthesis was good. The femoral posterior condyle osteotomy line, surgical transepicondylar axis, and patella transverse line were parallel, varus deformity was corrected, and lower limb alignment was restored to neutral position. Gait analysis at 6 months after operation showed that the differences in all kinematics parameters between the two groups were significant ( P<0.05). Assisted by 3D printing navigation template, TKA can alleviate pain symptoms and correct deformity, with satisfactory early effectiveness. Compared with healthy people, the early postoperative gait of the patients were characterized by decreasing velocity, cadence, stride length, knee flexion range, and increasing compensatory hip and ankle rotation range.

3D printed navigation template assists pedicle lag-screw placement for atypical Hangman’s fracture

Objectives To evaluate the 3D printed navigation template used to assist axis pedicle lag-screw placement in the treatment of atypical Hangman’s fracture (AHF). Methods From May 2015 to January 2017, 12 patients with AHF were treated at Department of Orthopedics, The Fourth People’s Hospital of Zigong.In their operation, the axis pedicle lag-screw placement was assisted by a 3D printed navigation template.They were 8 men and 4 women, aged from 27 to 53 years (average, 45.6 years).There were 7 cases of type Ⅰ, 4 cases type Ⅱ and one case of type ⅡA according to the Levine-Edwards classifi-cation.There were 2 cases of grade D and 12 cases of grade E according to the assessment of America Spinal Injury Association (ASIA).Their preoperative and postoperative neck pain was evaluated by visual analogue scale (VAS); their preoperative and postoperative ranges of cervical motion were recorded and compared.To evaluate the postoperative safety of screws, the insertion point, position within the pedicle, axial angle and sagittal angle of the screws and maximum fracture displacement were compared between actual operation and simulative operation. Results A total of 12 guide plates were designed and printed; a total of 24 lag-screws were placed.All patients underwent surgery uneventfully.They were followed up for 12 to 20 months, with an average of 14.7 months.Two patients with ASIA grade D recovered to ASIA grade E at the last follow-up.All patients showed a significant improvement in neck pain.Their VAS score at 5 days after surgery (5.86±2.02) was significantly lower than their preoperative score (8.29±1.88) (P 0.05).Their postoperative X-ray and CT images showed that the dislocation was all corrected.The last follow-up showed no obvious vertebral in-stability, screw breakage or loosening.Postoperative CT showed that the 24 screws had been located com-pletely in the pedicle (grade 0), indicating that the screw placement was 100% accurate.The postoperative deviation at insertion point (0.70±0.78 mm), deviation within the pedicle (1.3±0.82 mm), axial angle (8.26°±0.88°) and sagittal angle (22.62°±0.86°) of the screws showed no significant differences from the preoperative simulative data (P>0.05).There was a significant difference in the maximum fracture dis-placement between the preoperative data (3.94±0.38 mm) and the postoperative data (2.21±0.39 mm) (P<0.05). Conclusion The 3D printed navigation template can be used to better assist axis pedicle lag-screw placement in the treatment of AHF, because it ensures safe screw placement, leading to good re-duction and fixation and precise match with the preoperative plan. Key words: Axis; Fracture; Fractures fixation, internal; Bone screw; 3D printing tech-nology

Preliminary application of 3D printing navigation template in the screw insertion of the suprapubic fracture

Objective To introduce the method of using hollow pull screw insertion for the suprapubic fracture with 3D printing navigation template and to evaluate its clinical effect. Methods From March 2016 to August 2017, eighteen cases of suprapubic ramus fractures treated with hollow lag screw fixation in the Department of Orthopedics of Yanan University Affiliated Hospital were retrospectively collected was collected.Before operation, the thin slice CT scan of pelvis was used to get raw data, and the mimics17.0 software was used to reconstruction the model, to design and make the personalized navigation template assisting the suprapubic fractures surgery.The navigation template was printed out pre-operatively, and the nail was inserted via the assisted by the template intra-operatively.After the operation, the fracture reduction was evaluated by Matta imaging scores and the pelvis function was evaluated by Majeed scores. Results All the operations were successfully completed.The Matta scores were excellent in 11 cases, good in 6 cases, and fair in 1 case.The Majeed scores were excellent in 13 cases, good in 3 cases, and fair in 2 cases. Conclusion 3D Printing navigation template assisted the placement of the hollow screw on the suprapubic fracture could provide personalized treatment, reduce the difficulty of operation and satisfy the clinical effect. Key words: 3D printing navigation template; suprapubic fracture; Retrospectively study

One-Stage treatment for maxillofacial asymmetry with orthognathic and contouring surgery using virtual surgical planning and 3D-printed surgical templates

Asymmetry is one of the most common maxillofacial deformities. One-stage treatment for maxillofacial asymmetry with orthognathic and contouring surgery has been rarely reported. This retrospective study aims to investigate the feasibility of simultaneous orthognathic and facial bone contouring surgery with the help of virtual surgical planning and 3D-printed navigation templates for facial asymmetry. From January 2012 to December 2015, 51 patients diagnosed with maxillofacial asymmetry received treatment of combined orthognathic and contouring surgery under the guidance of virtual surgical planning and 3D-printed templates. Photographs and measurements were taken before and after operation to evaluate the effectiveness of the treatment. Photographs and cephalometric analysis showed the asymmetry was effectively corrected. All patients were satisfied with the aesthetic results. This study suggested the clinical feasibility of simultaneous orthognathic and contouring surgery for the treatment of maxillofacial asymmetry. Virtual surgical planning and 3D-printed surgical templates enable the surgeons to plan and carry out the procedure more predictably and achieve satisfactory outcomes.

Clinical study of three-dimensional printed navigation template assisted Ludloff osteotomy in treatment of moderate and severe hallux valgus

To explore the effectiveness and advantage of three-dimensional (3D) printed navigation templates assisted Ludloff osteotomy in treatment of moderate and severe hallux valgus. Between April 2013 and February 2015, 28 patients (28 feet) with moderate and severe hallux valgus who underwent Ludloff osteotomy were randomly divided into 2 groups ( n=14). In group A, the patients were treated with Ludloff osteotomy assissted with a 3D printed navigation template. In group B, the patients were treated with traditional Ludloff osteotomy. There was no significant difference in gender, age, affected side, and clinical classification between 2 groups ( P>0.05). The operation time and intraoperative blood loss were recorded. The ankle function of the foot at preoperation, immediate after operation, and last follow-up were assessed by the American Orthopedic Foot and Ankle Society (AOFAS) score. Besides, the X-ray film were taken to assess the hallux valgus angle (HVA), intermetatarsal angle (IMA), and the first metatarsal length shortening. All patients were followed up 18-40 months (mean, 26.4 months). The operation time and intraoperative blood loss in group A were significantly less than those in group B ( P<0.05). The HVA, IMA, and AOFAS scores in groups A and B at immediate after operaton and last follow-up were sinificantly improved when compared with preoperative values ( P<0.05); but no significant difference was found between at immediate after operation and at last follow-up ( P>0.05). No significant difference was found in HVA and IMA between group A and group B at difference time points ( P>0.05). There were significant differences in AOFAS score and the first metatarsal length shortening at immediate after operation and at last follow-up between 2 groups ( P<0.05). Except 1 case of metastatic metatarsalgia in group B, there was no other operative complications in both groups. 3D printed navigation template assisted Ludloff osteotomy can provide accurate preoperative planning and intraoperative osteotomy. It is an ideal method for moderate and severe hallux valgus.

Clinical Application of Atlantoaxial Pedicle Screw Placement Assisted by a Modified 3D-Printed Navigation Template

OBJECTIVES:To investigate the primary clinical value of atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template.METHODS:We retrospectively analyzed the cases of 17 patients treated from June 2015 to September 2016 with atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template. All procedures were performed prior to surgery, including thin-slice CT scanning, medical image sampling and computerized 3D modeling of the atlantoaxial joint, optimal pedicle screw trajectory determination, and anatomical trait acquisition for the atlantoaxial pedicle, spinous process of the axis, vertebral lamina and posterior lateral mass, and design of a reverse template. During surgery, a navigation template was tightly attached to the atlantoaxial joint to assist in pedicle screw placement. Surgeons subsequently used an electric drill to remove the template through a guide channel and then placed the atlantoaxial pedicle screw. Observed indexes included the VAS score, JOA improvement rate, surgery duration, and blood loss.RESULTS:Surgery was successful in all 17 patients, with an average operation duration of 106±25 min and an average blood loss of 220±125 ml. Three days postoperatively, the VAS score decreased from 6.42±2.21 to 3.15±1.26. Six months postoperatively, the score decreased to 2.05±1.56. The postoperative JOA score increased significantly from 7.68±2.51 to 11.65±2.72 3 d after surgery and to 13.65±2.57 after 6 months. Sixty-eight pedicle screws were inserted successfully, with 34 in the atlas and 34 in the axis. According to the Kawaguchi standard, 66 screws were in grade 0 (97.06%), and 2 were in grade 1 (2.94%). The pre- and postoperative transverse and sagittal screw angles showed no significant differences.CONCLUSIONS:Atlantoaxial pedicle screw placement assisted by a modified 3D-printed navigation template is worth recommending due to the improved accuracy in screw placement, improved patient safety and beneficial clinical effects.

Research on application of advanced 3D printing navigation templates in assisting placement of atlantoaxial pedicle screw

Objective To explore the accuracy and clinical efficacy of advanced 3D printing navigation templates in assisting placement of atlantoaxial pedicle screw. Methods A retrospective analysis was carried out on 49 cases of patients with atlanto-axial vertebral fractures and dislocations between June 2013 and June 2016, and all of them were given posterior incision, reduction and internal fixation of atlantoaxial pedicle screw. The patients were divided into advanced 3D printing navigation template group (14 cases), early 3D printing navigation template group (16 cases), and routine pedicle screw placement group (19 cases). Atlantoaxial CT data of patients in advanced 3D printing navigation template group and early 3D printing navigation template group were input into Mimics 17.0, then advanced 3D printing navigation template group and early 3D printing navigation which were used in clinic surgery were designed and printed. The relationship between positions of pedicle screw with the pedicle and bone cortex in plain CT image was observed after operation. The quality of the screw position was assessed and the accuracy of three kinds of screwing methods was compared. The accuracy of the screwing angle was assessed by comparing with the differences between the preoperative designed channel inclination angle and postoperative actual screwing angle. Three groups were compared for differences between operation time, intraoperative blood loss, and scores of cervical nerve scale and visual analogue scale (VAS) of neck and shoulder pain by Japanese Orthopaedic Association (JOA). Results All 49 cases of patients successfully completed the surgery. Patients of the routine pedicle screw placement group, early 3D group and advanced 3D group correspond operation time for 141.2±20.7 min, 112.5±12.1 min and 103.1±10.4 min, intraoperative blood loss for 314.0±81.4 ml, 243.6±71.2 ml and 181.0+59.1 ml; total accuracy of screwing for 75.0%(54/72), 93.75%(60/64) and 96.43%(54/56). There were statistically significant differences among the routine group, 3D group and advanced 3D group in the mentioned programs. There were no statistical differences between advanced 3D group and 3D group in the inclination angle and head tilt angle with the pre-designed values, while there was statistically significant difference between the routine group and the pre-designed value. The accuracy of the inclination angle and head tilt angle screwing angle were obviously superior in the advanced 3D group and early 3D group to that of the routine group. There were statistically significant differences between preoperative with postoperative VAS scores and JOA scores in the same group, while there were no statistically significant differences among groups in JOA. But there was statistically significant difference between the routine group and the advanced 3D in VAS, and there was no statistically significant difference between the routine pedicle screw placement group and the early 3D in VAS. All three groups of patients had bony fusion of atlanto-axial vertebral body, without loosening, dislocation and fracture of the internal fixators. Conclusion Advanced 3D printing templates in assisting the surgical treatment for atlantoaxial fracture and dislocation can improve the accuracy of pedicle screwing and safety of the surgery, reduce the surgery risk, and obtain satisfied clinical curative effects. Key words: Cervical atlas; Axis; Spinal fusion; Bone screws; Surgery, computer-assisted

3D-printed navigation template in proximal femoral osteotomy for older children with developmental dysplasia of the hip

To explore the feasibility of 3D-printed navigation template in proximal femoral varus rotation and shortening osteotomy for older children with developmental dysplasia of the hip (DDH). Between June 2014 and May 2015, navigation templates were designed and used for 12 DDH patients. Surgical information and outcomes were compared to 13 patients undergoing the same surgery but without navigation template. In template-guided patient group, operation time (21.08 min vs. 46.92 min), number of X-ray exposures (3.92 vs. 6.69), and occurrence of femoral epiphysis damage (0 vs. 0.92) were significantly decreased (P < 0.05). Furthermore, after 12–18 months follow-up, 66.7% and 16.7% of the hips in template-guided group were rated as excellent or good, respectively, according to the McKay criteria; 83.3% and 16.7% by using the Severin criteria respectively. By contrast, 46.2% and 23.1% of the hips in traditional operation group were classed as excellent or good, respectively, using the McKay criteria; 46.2% and 30.8% by using the Severin criteria respectively. The template-guided group achieved a better outcome; however, there was no significant difference. Application of the navigation template for older DDH children can reduce the operation time, radiation exposure, and epiphysis damage, which also simplifies surgery and improves precision.

Application of computer-aided design and 3D-printed navigation template in Locking Compression Pediatric Hip PlateΤΜ placement for pediatric hip disease.

To investigate the feasibility and accuracy of a drill template based on computer-aided design (CAD) and 3D printing technology for the placement of screws in Locking Compression Pediatric Hip Plate (LCP-PHP). LCP-PHP was used in 11 children [5 with femoral neck fracture and 6 with development dysplasia of hip (DDH)]. Using the CT data, the proximal femur model was created by a 3D printer. Fracture reduction and the placement of the screw in the femoral neck and the LCP-PHP were simulated by the computer. The navigation template was designed by the software to match the proximal femur. After the feasibility of the 3D model operation was demonstrated before the operation, the guide pins and the screws were inserted with the help of the navigate template in the operation. During surgery, the navigation template for each case was matched to the bony markers of the proximal femur. With the help of the template, in femoral neck fracture cases, three screws could be accurately inserted into the femoral neck to implant the LCP-PHP and stabilize the fracture. The template for DDH includes all operation parameters and steps for proximal femoral varus rotation and shortening osteotomy, which made the surgery much easier to perform. Radiographs taken after surgery showed that the postoperative results closely corresponded to the preoperative computer simulation. The average time taken for LCP-PHP placement was 26.5min; radiography was used during surgery only for an average of 6.0 times. Postoperative radiographs showed good results. With the use of CAD and 3D printing technology, accurate placement of individualized navigation template of LCP-PHP can be achieved. This technology can reduce intraoperative damage to the femoral neck epiphysis, decrease operation time, reduce intraoperative hemorrhage, and decrease radiation exposure to patients and personnel during the surgery.

Individualized 3D printing navigation template for pedicle screw fixation in upper cervical spine.

PurposePedicle screw fixation in the upper cervical spine is a difficult and high-risk procedure. The screw is difficult to place rapidly and accurately, and can lead to serious injury of spinal cord or vertebral artery. The aim of this study was to design an individualized 3D printing navigation template for pedicle screw fixation in the upper cervical spine.MethodsUsing CT thin slices data, we employed computer software to design the navigation template for pedicle screw fixation in the upper cervical spine (atlas and axis). The upper cervical spine models and navigation templates were produced by 3D printer with equal proportion, two sets for each case. In one set (Test group), pedicle screws fixation were guided by the navigation template; in the second set (Control group), the screws were fixed under fluoroscopy. According to the degree of pedicle cortex perforation and whether the screw needed to be refitted, the fixation effects were divided into 3 types: Type I, screw is fully located within the vertebral pedicle; Type II, degree of pedicle cortex perforation is <1 mm, but with good internal fixation stability and no need to renovate; Type III, degree of pedicle cortex perforation is >1 mm or with the poor internal fixation stability and in need of renovation. Type I and Type II were acceptable placements; Type III placements were unacceptable.ResultsA total of 19 upper cervical spine and 19 navigation templates were printed, and 37 pedicle screws were fixed in each group. Type I screw-placements in the test group totaled 32; Type II totaled 3; and Type III totaled 2; with an acceptable rate of 94.60%. Type I screw placements in the control group totaled 23; Type II totaled 3; and Type III totaled 11, with an acceptable rate of 70.27%. The acceptability rate in test group was higher than the rate in control group. The operation time and fluoroscopic frequency for each screw were decreased, compared with control group.ConclusionThe individualized 3D printing navigation template for pedicle screw fixation is easy and safe, with a high success rate in the upper cervical spine surgery.

Intelligentized surgery based on 3D printing technology for personalized total knee arthroplasty

Objective To investigate the application of 3D printed navigation template in personalized total knee arthroplasty (TKA) based on three-dimensional reverse engineering and computer-aided technology. Methods From August 2014 to September 2015, 16 patients (18 knees, 3D group) underwent personalized TKA aided by 3D printed navigation template and the other 18 patients (18 knees, control group) received conventional TKA. In the 3D group, 16-slice spiral CT was performed preoperatively for data collection. The DICOM format data obtained were imported into 3D design software in-house developed software Arigin3D Pro. After pre-processing and 3D reconstruction, 3D models of the patients' knees were generated and surgery navigation models designed in Arigin Surgical Templating. The model data of surgery navigation templates were then converted into STL format and fabricated by a 3D printer. At last, the surgery navigation templates were applied in the personalized TKA. The 2 groups were compared in terms of osteotomy time, postoperative drainage, blood clotting, alignment of the lower limb, prosthetic position, Hospital for Special Surgery (HSS) scores, and rage of motion (ROM). Results All the patients were followed up for an average of 9 months (from 5 to 15 months). In the 3D group, the navigation templates all contacted closely the bony structures of femoral condyle and tibial plateau, with no displacement, and all the deviations in alignment of the lower limb 0.05). Comparisons between the preoperation and the last follow-up showed that in the 3D group the HSS score sig-nificantly increased from 27.3±4.8 to 86.5±4.5, and the ROM from 72.5°±9.1° to 105.4°±6.8° (P< 0.05). Conclusion Application of 3D printed navigation template in personalized TKA based on three-dimensional reverse engineering and computer-aided technology can precisely reconstruct the three-dimensional models of the bony structures of the lower limb, precisely localize the mechanical axis of the lower limb, and make the alignment of the implanted prosthesis maximally meet the biomechanical requirements of human body. Key words: Knee, prosthesis; Arthroplasty, replacement, knee; Prothrombin time; 3D printing; Navigation template