Patients with severe spinal deformities often have small pedicle diameters, and pedicle dimensions vary between segments and individuals. Free-hand pedicle screw placement can be inaccurate. Individualized drill guide templates may be used, but the accuracy of pedicle screw placement in severe scoliosis remains unknown. The accuracy of drill guide templates and free-hand technique for the treatment of adolescent patients with severe idiopathic scoliosis are compared in this study.
Methods
This study included 37 adolescent patients (mean age 16.4 ± 1.3 years) with severe idiopathic scoliosis treated surgically at a single spine center between January 2014 and June 2017. Spinal deformities were corrected using posterior pedicle screw fixation. Patients in group I were treated with rapid prototype drill guide template technique (20 patients; 396 screws) and patients in group II were treated with free-hand technique (17 patients; 312 screws). Outcomes that included operative time, correction rate, and the incidence and distribution of screw misplacement were evaluated.
Results
Operative time in group I was 283 ± 22.7 min compared to 285 ± 25.8 min in group II (p = 0.89). The scoliosis correction rate was 55.0% in group I and 52.9% in group II (p = 0.33). Based on both axial and sagittal reconstruction images, the accuracy rate of pedicle screw placement was 96.7% in group I and 86.9% in group II (p = 0.000).
Conclusion
The drill guide template technique has potential to offer more accurate and thus safer placement of pedicle screws than free-hand technique in the treatment of severe scoliosis in adolescents.
Dorsal spinal instrumentation with pedicle screw constructs is considered the gold standard for numerous spinal pathologies. Screw misplacement is biomechanically disadvantageous and may create severe complications. The aim of this study was to assess the accuracy of patient-specific template-guided pedicle screw placement in the thoracic and lumbar spine compared to the free-hand technique with fluoroscopy.
Methods
Patient-specific targeting guides were used for pedicle screw placement from Th2–L5 in three cadaveric specimens by three surgeons with different experience levels. Instrumentation for each side and level was randomized (template-guided vs. free-hand). Accuracy was assessed by computed tomography (CT), considering perforations of <2 mm as acceptable (safe zone). Time efficiency, radiation exposure and dependencies on surgical experience were compared between the two techniques.
Results
96 screws were inserted with an equal distribution of 48 screws (50 %) in each group. 58 % (n = 28) of template-guided (without fluoroscopy) vs. 44 % (n = 21) of free-hand screws (with fluoroscopy) were fully contained within the pedicle (p = 0.153). 97.9 % (n = 47) of template-guided vs. 81.3 % (n = 39) of free-hand screws were within the 2 mm safe zone (p = 0.008). The mean time for instrumentation per level was 01:14 ± 00:37 for the template-guided vs. 01:40 ± 00:59 min for the free-hand technique (p = 0.013), respectively. Increased radiation exposure was highly associated with lesser experience of the surgeon with the free-hand technique.
Conclusions
In a cadaver model, template-guided pedicle screw placement is faster considering intraoperative instrumentation time, has a higher accuracy particularly in the thoracic spine and creates less intraoperative radiation exposure compared to the free-hand technique.
To assess the accuracy of O-arm-navigation-based pedicle screw insertion in dystrophic scoliosis secondary to NF-1 and compare it with free-hand pedicle screw insertion technique.
Methods
32 patients with dystrophic NF-1-associated scoliosis were divided into two groups. A total of 92 pedicle screws were implanted in apical region (two vertebrae above and below the apex each) in 13 patients using O-arm-based navigation (O-arm group), and 121 screws were implanted in 19 patients using free-hand technique (free-hand group). The postoperative CT images were reviewed and analyzed for pedicle violation. The screw penetration was divided into four grades: grade 0 (ideal placement), grade 1 (penetration <2 mm), grade 2 (penetration between 2 and 4 mm), and grade 3 (penetration >4 mm).
Results
The accuracy rate of pedicle screw placement (grade 0, 1) was significantly higher in the O-arm group (79 %, 73/92) compared to 67 % (81/121) of the free-hand group (P = 0.045). Meanwhile, a significantly lower prevalence of grade 2–3 perforation was observed in the O-arm group (21 vs. 33 %, P < 0.05), and the incidence of medial perforation was significantly minimized by using O-arm navigation compared to free-hand technique (2 vs. 15 %, P < 0.01). Moreover, the implant density in apical region was significantly elevated by using O-arm navigation (58 vs. 42 %, P < 0.001).
Conclusion
We reported 79 % accuracy of O-arm-based pedicle screw placement in dystrophic NF-1-associated scoliosis. O-arm navigation system does facilitate pedicle screw insertion in dystrophic NF-1-associated scoliosis, demonstrating superiorities in the safety and accuracy of pedicle screw placement in comparison with free-hand technique.
The purpose of this study was to evaluate the accuracy of pedicle screw placement, its advantages, and limitations in posterior instrumentation of thoracolumbar and lumbar burst fractures assisted only by lateral fluoroscopic imaging.
Materials and methods
Pre- and postoperative computerized tomographic (CT) scans of 117 patients with thoracolumbar and lumbar burst fractures, who underwent posterior instrumentation with pedicle screw fixation, were prospectively analyzed. Accuracy of screw placement, reconstruction of the vertebral height, and correction of the kyphotic angle were studied. Position of the pedicle screws were determined, and cortical breach was graded on the postoperative axial CT scans. Percentage of vertebral height reconstruction and kyphotic angle correction were calculated from the postoperative midsagittal CT scans.
Results
Four hundred and sixty-eight pedicle screws in 234 motion segments were included in this study. 427 screws were centrally placed with an accuracy rate of 91.24%. Out of the 41 (8.76%) screws that breached the pedicle wall, 32 (6.84%) screws had violated the medial wall, while 9 (1.92%) screws breached the lateral wall. There were no “air-ball” screws. No screw penetrated the anterior wall. Postoperatively, none of the patients deteriorated neurologically, and no screw required revision. Postoperatively, there was significant restoration of vertebral height and correction of kyphosis (P < 0.05).
Conclusion
Pedicle fixation performed on a Relton-Hall frame is relatively simple and, when performed carefully using only lateral fluoroscopic imaging, has a lower potential for complications due to cortical breach.
The free-hand technique carries a higher risk of pedicle weakening and neurovascular injuries in comparison with pedicle screw placement using a drill guide. Due to this evidence and because of some variances in the surgical method, different outcome can be expected. The objective of the study was to evaluate the disability, the back and leg pain before and at least 3 years after the surgery between examined groups.
Materials and methods
Eleven patients in drill guide and 13 in control group were randomly assigned for vertebral fusion in the lumbar and first sacral regions. Pre- and post-operative CT scans, Oswestry disability index (ODI) and visual analogue scale (VAS) for back and leg pain were taken. Post-operative evaluations of cortex perforation and statistical analysis between studied groups have been performed.
Results
Seventy-two screws were inserted in each group. All patients completed a 3-year follow-up. Comparing groups, there was no statistical significant difference in VAS and ODI before or after surgery. Cortex perforation incidence in drill guide group was 6 and in free-hand group 29 (p < 0.05). In each group, pain and disability were significantly lower as before the procedure.
Conclusions
The application of a drill guide template for pedicle screw placement is not more effective in reducing pain and disability after midterm follow-up in comparison with the free-hand technique. However, it reduces the cortex perforation incidence. Concerning this evidence, a drill guide is still an additional tool that could in the future potentially compete with other screw placement techniques.
The goal of this study was to compare the accuracy and cranial facet joint violation rates between percutaneous pedicle screw placements using conventional fluoroscopy and intraoperative 3-D CT (O-arm) computer navigation.
Methods
We reviewed 194 pedicle screw of 28 consecutive patients who underwent minimally invasive lumbar or thoracic spinal stabilization. The accuracy of screw placement was evaluated according to two criteria published by Neo et al. and Upendra et al. Facet joint violation was evaluated according to the classification described by Babu et al.
Results
Upon Neo grading, CFT group had 19.4 % (14/72) pedicle breach rate and CT-IGN group had a 5.7 % (7/122) pedicle breach rate (p < 0.005). The same sets of screws were also assessed using the outcome-based classification established by Upendra. There were no screw caused neurovascular injuries (type 3 = 0) in both groups. The results showed that 87.5 % (63/72) screws had acceptable placements (type I) and 12.5 % (9/72) had unacceptable placements (type II) in CFT group. In contrast, 94.3 % (115/122) screw had acceptable placements (type I) and only 5.7 % (7/122) had unacceptable placements (type II) in CT-IGN group. Additionally, CFT group had a significantly higher facet joint violation rate of 30.5 % (11/36) than CT-IGN group that had a 3.8 % (3/79) violation rate (p < 0.005).
Conclusion
This study indicated the use of intraoperative CT imaging (O-arm) navigation in PPS placement have very beneficial implications for MIS.
To directly compare the safety of fluoroscopic guided percutaneous thoracic pedicle screw placement between Caucasians and Asians.
Methods
This was a retrospective computerized tomography (CT) evaluation study of 880 fluoroscopic guided percutaneous pedicle screws. 440 screws were inserted in 73 European patients and 440 screws were inserted in 75 Asian patients. Screw perforations were classified into Grade 0: no violation; Grade 1: <2 mm perforation; Grade 2: 2–4 mm perforation; and Grade 3: >4 mm perforation. For anterior perforations, the pedicle perforations were classified into Grade 0: no violation, Grade 1: <4 mm perforation; Grade 2: 4–6 mm perforation; and Grade 3: >6 mm perforation.
Results
The inter-rater reliability was adequate with a kappa value of 0.83. The mean age of the study group was 58.3 ± 15.6 years. The indications for surgery were tumor (70.3 %), infection (18.2 %), trauma (6.8 %), osteoporotic fracture (2.7 %) and degenerative diseases (2.0 %). The overall screw perforation rate was 9.7 %, in Europeans 9.1 % and in Asians 10.2 % (p > 0.05). Grade 1 perforation rate was 8.4 %, Grade 2 was 1.2 % and Grade 3 was 0.1 % with no difference in the grade of perforations between Europeans and Asians (p > 0.05). The perforation rate was the highest in T1 (33.3 %), followed by T6 (14.5 %) and T4 (14.0 %). Majority of perforations occurred medially (43.5 %), followed by laterally (25.9 %), and anteriorly (23.5 %). There was no statistical significant difference (p > 0.05) in the perforation rates between right-sided pedicle screws and left-sided pedicle screws (R: 10.0 %, L: 9.3 %).
Conclusions
There were no statistical significant differences in the overall perforation rates, grades of perforations, direction of perforations for implantation of percutaneous thoracic pedicle screws insertion using fluoroscopic guidance between Europeans and Asians. The safety profile for this technique was comparable to the current reported perforation rates for conventional open pedicle screw technique.
We report a single-center, prospective, randomized study for pedicle screw insertion in opened and percutaneous spine surgeries, using a computer-assisted surgery (CAS) technique with three-dimensional (3D) intra-operative images intensifier (without planification on pre-operative CT scan) vs conventional surgical procedure.
Material and method
We included 143 patients: Group C (conventional, 72 patients) and Group N (3D Fluoronavigation, 71 patients). We measured the pedicle screw running time, and surgeon’s radiation exposure. All pedicle runs were assessed according to Heary by two independent radiologists on a post-operative CT scan.
Results
3D Fluoronavigation appeared less accurate in percutaneous procedures (24 % of misplaced pedicle screws vs 5 % in Group C) (p = 0.007), but more accurate in opened surgeries (5 % of misplaced pedicle screws vs 17 % in Group C) (p = 0.025). For one vertebra, the average surgical running time reached 8 min in Group C vs 21 min in Group N for percutaneous surgeries (p = 3.42 × 10?9), 7.33 min in Group C vs 16.33 min in Group N (p = 2.88 × 10?7) for opened surgeries. The 3D navigation device delivered less radiation in percutaneous procedures [0.6 vs 1.62 mSv in Group C (p = 2.45 × 10?9)]. For opened surgeries, it was twice higher in Group N with 0.21 vs 0.1 mSv in Group C (p = 0.022).
Conclusion
The rate of misplaced pedicle screws with conventional techniques was nearly the same as most papers and a little bit higher with CAS. Surgical running time and radiation exposure were consistent with many studies. Our work hypothesis is partially confirmed, depending on the type of surgery (opened or closed procedure).
To assess the pedicle morphology in the lower thoracic and lumbar spine in an Indian population and to determine the causes of pedicle wall violation by pedicle screws.
Methods
Computerised tomographic scans of 135 consecutive patients with thoracolumbar and lumbar spine fractures were prospectively analysed to determine the pedicle morphology. The transverse pedicle angle, pedicle diameter and screw path length at 527 uninjured levels were measured. Post-operative CT scans of 117 patients were analysed to determine the accuracy of 468 pedicle screws at 234 vertebrae.
Results
The lowest (mean ± SD) transverse pedicle width in the lower thoracic spine was 5.4 ± 0.70 mm, whereas in the lumbar spine it was 7.2 ± 0.87 mm. The shortest (mean ± SD) screw path length in lower thoracic pedicles was 35.8 ± 2.10 and 41.9 ± 2.18 mm in the lumbar spine. The mean transverse pedicle angle in the lower thoracic spine was consistently less than 5°, whereas it gradually increased from L1 through L5 from 8.5° to 30°. Forty-one screws violated the pedicle wall, due to erroneous angle of screw insertion.
Conclusions
In the current study, pedicle dimensions were smaller compared to the Western population. In Indian patients, pedicle screws of 5 mm diameter and 30 mm length, and 6 mm diameter and 35 mm length can safely be used in the lower thoracic and lumbar spine, respectively. However, it is important to assess the pedicle morphology on imaging prior to pedicle fixation.
Innovative intraoperative imaging modalities open new horizons to more precise image acquisition and possibly to better results of spinal navigation. Planning of screw entry points and trajectories in this prospective study had been based on intraoperative imaging obtained by a portable 32-slice CT scanner. The authors evaluated accuracy and safety of this novel approach in the initial series of 18 instrumented surgeries in anatomically complex segment of cervico-thoracic junction.
Methods
We report on the single-institution results of assessment of anatomical accuracy of C5–T3 pedicle screw insertion as well as its clinical safety. The evaluation of total radiation dose and of time demands was secondary endpoint of the study.
Results
Out of 129 pedicle screws inserted in the segment of C5–T3, only 5 screws (3.9 %) did not meet the criteria for correct implant positioning. These screw misplacements had not been complicated by neural, vascular or visceral injury and surgeon was not forced to change the position intraoperatively or during the postoperative period. Quality of intraoperative CT imaging sufficient for navigation was obtained at all spinal segments regardless of patient´s habitus, positioning or comorbidity. A higher radiation exposition of the patient and 27 min longer operative time are consequences of this technique.
Conclusions
The intraoperative portable CT scanner-based spinal navigation is a reliable and safe method of pedicle screw insertion in cervico-thoracic junction.
Accurate implantation of pedicle screw in spinal deformity correction surgeries is always challenging. We have developed a method of pedicle screw placement in severe and rigid scoliosis with a multi-level 3D printing drill guide template.
Methods
From November 2011 to March 2015, ten patients (4 males and 6 females) with severe and rigid scoliosis (Cobb angle >70° and flexibility <30%)were included. Multi-level template was designed and manufactured according to the part (two or three levels) of the most severe deformity. The drill template was then placed on the corresponding vertebral surface. Then, pedicle screws were carefully inserted along the trajectories. The other screws were placed in free hand. After surgery, the positions of the pedicle screws were evaluated by CT scan and graded for validation.
Results
48 screws were implanted using templates, other 104 screws in free hand, and the accuracies were 93.8 and 78.8%, respectively, with significant difference. The deformity correction ratio was 67.1 and 41.2% in coronal and sagittal plane post-operatively, respectively. The average operation time was 234.0 ± 34.1 min, and average blood loss was 557 ± 67.4 ml.
Conclusions
With the application of multi-level template, the incidence of cortex perforation in severe and rigid scoliosis decreased and this technology is, therefore, potentially applicable in clinical practice.
The osteoporosis prevalence in population is age related. The aim of this single-center observational study was evaluate the middle- to long-term performance of cement (PMMA) augmented fenestrated pedicle screws in elderly patients with thoraco-lumbar compressive fractures by osteoporosis.
Materials and methods
From 2011 to 2015 we treated 52 patients (20 males and 32 females) suffering from somatic osteoporotic fractures (T10–L2). The average age was 73.4 years, with an age range between 65 and 82 years. The treatment consisted of stabilization with pedicle screw augmentation with PMMA cement. Patients were clinically evaluated with Visual Analyzing System scale (VAS scale) and with low back disability questionnaire Oswestry, in pre and post surgery and during the follow up at 12 and 24 months.
Results
A total of 410 fenestrated pedicle screws with PMMA augmentation were implanted. No cases of loosening or pulling out of screws were recorded. There have been n 3 cases of thrombophlebitis, treated with oral anticoagulant drugs and 1 case of post-operative death due to ventricular fibrillation. No neurological complications occurred during the study. The mean VAS score decreased from 8.5 to 4.8 and the result remained stable during follow up. Oswestry questionnaire showed a mean decrease of low back pain of 24% in post-op period.
Conclusion
Fenestrated screws with PMMA augmentation offers a possibility to treat patients with reduced bone quality due to severe osteoporosis.
Transpedicular screw fixation of the cervical spine provides excellent biomechanical stability. The feasibility of inserting a 3.5-mm screw in the pedicle requires a minimum pedicle diameter of 4.5 mm. This diameter allows at least 0.5 mm bony bridge medially and laterally in order to avoid pedicle violation which can result in neurovascular complications. We aim to evaluate the feasibility of this technique in Arab people since no data are available about this population.
Materials and methods
This cross-sectional study involved a retrospective review of computed tomography scans of normal cervical spines of 99 Arab adults. Ten morphometric measurements were obtained. Data were analyzed using a p value of ≤0.05 as the cut-off level of statistical significance.
Results
Our sample included 63 (63.6 %) males and 36 (36.4 %) females, with a mean age of 35.5 ± 16.5 years. The morphometric parameters of C3–C7 spine pedicles were larger in males than in females. The outer pedicle width (OPW) was <4.5 mm in >25 % of all subjects at C3–C6 vertebrae. Statistically significant differences in the OPW between males and females were noted at C3 (p = 0.032) and C6 (p = 0.004).
Conclusions
Inserting pedicle screws in the subaxial cervical spine is feasible among the majority of Arab people.
To review our experience with robotic guided S2-alar iliac (S2AI) screw placement.
Methods
We retrospectively reviewed patients who underwent S2AI fixation with robotic guidance. Screw placement and deviation from the preoperative plan were assessed by fusing preoperative CT (with the planned S2AI screws) to postoperative CT. The software’s measurement tool was used to compare the planned vs. actual screw placements in axial and lateral views, at entry point to the S2 pedicle and at a 30 mm depth at the screws’ mid-shaft, in a resolution of 0.1 mm. Medical charts were reviewed for technical issues and intra-operative complications.
Results
35 S2AI screws were reviewed in 18 patients. The patients’ mean age was 60 years. No intra-operative complications that related to the placement of S2AI screws were reported and robotic guidance was successful in all 35 screws. Post-operative CT scans showed that all trajectories were accurate. No violations of the iliac cortex or breaches of the anterior sacrum were noted. At the entry point, the screw deviated from the pre-operative plan by 3.0 ± 2.2 mm in the axial plane and 1.8 ± 1.6 mm in the lateral plane. At 30 mm depth, the screw deviated from the pre-operative plan by 2.1 ± 1.3 mm in the axial plane and 1.2 ± 1.1 mm in the lateral plane.
Conclusions
Robotic guided S2AI screw placement is feasible and accurate. No screw malpositions or complications that related to the placement of S2AI screws occurred in this series. Larger studies are needed to assess the long-term clinical outcomes of robotic guided sacral-pelvic fixation.
We evaluated the trajectory and the entry points of anterior transpedicular screws (ATPS) in the cervicothoracic junction (CTJ).
Objective
This study aimed at investigating the feasibility of ATPS fixation in the CTJ.
Summary of background data
Application of an ATPS in the lower cervical spine has been reported; however, there were no reports exploring the feasibility of anterior transpedicular screw fixation in the CTJ.
Methods
CT scans were performed in 50 cases and multiplanar reformation was used to measure the related parameters on pedicle axis view at C6–T2. Transverse pedicle angle, outer pedicle width, pedicle axis length, distance transverse intersection point (DtIP), sagittal pedicle angle, anterior vertebral body height, outer pedicle height, and distance sagittal intersection point (DsIP) were measured. The prozone of CTJ was divided into three different regions, which were named as the “manubrium region”, the region “above” and “below” the manubrium. The distribution of the trajectory of sagittal pedicle axes was recorded in the three regions and the related data were statistically analyzed.
Results
There was no statistical difference in gender (P > 0.05). The transverse pedicle angle decreased from C6 (46.77° ± 2.72°) to T2 (20.62° ± 5.04°). DtIP increased from C6 to T2. DsIP was an average of 7.17 mm. The sagittal pedicle axis lines of the C6 and C7 were located in the region above the manubrium. T1 was mainly in the manubrium region followed by the region above the manubrium. T2 was mainly located in the manubrium region followed by the region below the manubrium.
Conclusion
Implantation of ATPS at C6, C7, and some T1 is feasible through the low anterior cervical approach, while it is almost impossible to approach T2 that way.
To assess and compare the efficacy of two minimally invasive techniques (percutaneous pedicle screw with intermediate screw vs. percutaneous pedicle screw with kyphoplasty) for spinal fracture fixation by comparing the segmental kyphosis and vertebral kyphosis angles after trauma before surgery, after surgery, and at 4-month and 12-month follow-up.
Methods
Data from 49 patients without neurological deficit treated by either percutaneous pedicle screw with intermediate screw or percutaneous pedicle screw with kyphoplasty were retrospectively analysed. The segmental kyphosis and vertebral kyphosis angles over time were calculated and correlated with the type of procedure, AO classification, lumbar or thoracic site and the age and sex of the patients.
Results
After surgery, both techniques were found to be efficacious means of bringing about a significant correction of the segmental kyphosis angle (p = 0.002) and a just significant correction of the vertebral kyphosis angle (p = 0.06), although less effectively in thoracic fractures (p = 0.004). At follow-up, the vertebral kyphosis angle was stable in both groups, while there was a significant loss of segmental kyphosis angle stability in the percutaneous pedicle screw with kyphoplasty group at 1 year (p = 0.004); fractured thoracic vertebrae maintained a greater vertebral kyphosis angle (p = 0.06) and segmental kyphosis angle (p < 0.001), than the lumbar.
Conclusion
At 1 year after surgery, the use of intermediate screws in fractured vertebrae seemed to maintain a more efficacious correction with respect to kyphoplasty, although thoracic fracture sites appear to be associated with greater post-traumatic segmental kyphosis and lesser stability in the long term after both percutaneous surgical techniques.
Despite proven biomechanical superiority and resultant superior clinical outcomes, pedicle instrumentation in cervical spine is not widely practiced due to technical difficulties, steep learning curve, and possible potential catastrophic complications due to screw misplacement. This study was undertaken with the purpose to evaluate the feasibility, accuracy, and complications of cervical pedicle screw instrumentation solely using O-arm-based 3D navigation technology.
Methods
Prospectively maintained data from a single-surgeon case series were retrospectively analyzed. All the patients had undergone cervical pedicle instrumentation under O-arm 3D navigation. Screw placement accuracy was analyzed and compared among different vertebral levels and also between different patient groups.
Results
A total of 241 cervical pedicle screws were inserted in 44 patients. Out of the 241 screws, 197 (81.74%) were inserted at the level of C3–C6 vertebrae with nearly equal distribution among the 4 vertebrae, followed by 32 (13.28%) and 12 (4.98%) screws at C2 and C7 vertebrae, respectively. After the analysis of screw placement as per Gertzbein classification, the overall breach rates were found to be 7.05% (17 screws) with 52.94% (10 screws) Grade I, 47.06% (7 screws) Grade II, and nil Grade III screw breaches.
Conclusion
The use of O-arm-based intra-operative 3D scans for navigation can make cervical pedicle screw placement reliable. High accuracy and better intra-operative control can increase surgeon’s confidence in using cervical pedicle instrumentation on more regular basis.
Graphical abstract
These slides can be retrieved under Electronic Supplementary Material.
To analyse the clinical outcomes of 26 children treated surgically for displaced proximal humerus fracture.
Materials and methods
From January 2008 to December 2012, 26 children/adolescents (14 boys, 12 girls) were treated surgically for displaced fractures at the proximal extremity of the humerus. Ten were grade III and 16 were grade IV according to the Neer–Horowitz classification with a mean age of 12.8 ± 4.2 years. Twenty young patients were surgically treated with a closed reduction and direct percutaneous pinning; six required an open approach. To obtain a proper analysis, we compared the Costant scores with the contralateral shoulder (Δ Costant).
Results
The mean follow-up period was 34 months (range 10–55). Two grade IV patients showed a loss in the reduction after percutaneous treatment. This required open surgery with a plate and screws. On average, the treated fractures healed at 40 days. The mean Δ Costant score was 8.43 (range 2–22). There was a statistically significant improvement in the mean Δ Costant score in grade III patients. In grade IV patients, there was a significant improvement in the mean Δ Costant score in those treated with open surgery versus mini-invasive surgery.
Conclusions
Our study shows excellent results with percutaneous k-wires. This closed surgery had success in these patients, and the excellent outcomes noted here lead us to prefer the mini-invasive surgical approach in NH grade III fractures. In grade IV, the best results were noted in patients treated with open surgery. We suggest an open approach for these patients.
The technique of pedicle screw stabilization is finding increasing popularity for use in the cervical spine. Implementing anterior transpedicular screws (ATPS) in cervical spine offers theoretical advantages compared to posterior stabilization. The goal of the current study was the development of a new setting for navigated insertion of ATPS, combining the advantage of reduced invasiveness of an anterior approach with the technical advantages of navigation.
Methods
20 screws were implanted in levels C3 to C6 of four cervical spine models (SAWBONES® Cervical Vertebrae with Anterior Ligament) with the use of 3D fluoroscopy navigation system [Arcadis Orbic 3D, Siemens and VectorVision fluoro 3D trauma software (BrainLAB)]. The accuracy of inserted screws was analyzed according to postoperative CT scans and following the modified Gertzbein and Robbins classification.
Results
20 anterior pedicle screws were placed in four human cervical spine models. Of these, eight screws were placed in C3, two screws in C4, six screws in C5, and four screws in C6. 16 of 20 screws (80 %) reached a grade 1 level of accuracy according to the modified Gertzbein and Robbins Classification. Three screws (15 %) were grade 2, and one screw (5 %) was grade 3. Grade 4 and 5 positions were not evident. Summing grades 1 and 2 together as “good” positions, 95 % of the screws achieved this level. Only a single screw did not fulfill these criteria.
Conclusion
The setting introduced in this study for navigated insertion of ATPS into cervical spine bone models is well implemented and shows excellent results, with an accuracy of 95 % (Gertzbein and Robbins grade 2 or better). Thus, this preliminary study represents a prelude to larger studies with larger case numbers on human specimens.
