Augmented Reality-Supported Rod Bending in Multilevel Spinal Fusion Using the ADVISE Software.

BACKGROUND: One of the most common reasons for poor patient outcomes and revision surgery in spinal fusion is hardware failure. Screw loosening or pullout occurs in up to one-quarter of all cases. It is known that even small screw-rod misalignments can cause significant mechanical overloads during rod fixation, which can result in hardware failure. To address this crucial surgical step, a novel augmented reality-assisted software was developed to generate custom rod templates that are precisely adapted to the individual patient. METHODS: The novel software, which runs on a tablet, is used in spinal fusion surgery and is based on the use of a specific pedicle screw system, in which the polyaxial screw heads are connected to detachable guides. These guides can be recognized by the tablet camera and a light detection and ranging scanner. This image information is processed to determine the spatial positions of the screw heads and to calculate an ideally fitting rod template. RESULTS: The calculated rod template is displayed in a 1-to-1 scale on the tablet screen. This template is used to cut and bend the rods of the pedicle screw system. Finally, the custom bent rod can be inserted into the screw heads without tension. CONCLUSIONS: The augmented reality-assisted software is intended to give surgeons access to patient-specific intraoperative real-time data, helping them in bending rods that are more precisely adapted to the individual patient compared with the freehand technique.

Treatment of Scoliosis with One-Stage Posterior Pedicle Screw System by Paraspinal Intermuscular Approach: A Minimum of Two Years of Follow-Up.

OBJECTIVE: To evaluate the clinical efficacy of the treatment of scoliosis with a pedicle screw system through paraspinal intermuscular approach (PIA). METHODS: This is a retrospective case series study. A total of 10 patients diagnosed with scoliosis had surgical indications and treated with a pedicle screw system in one-stage posterior surgery by PIA from March 2013 to April 2015 at the First Hospital of Jilin University were enrolled in this study. The average age of the patients was 14.9 years, including one male and nine females. The operative information and surgical results, including Cobb angle correction, correction loss, global balance (including Frontal Plane Balance [FPB] and Sagittal Plane Balance [SPB]), and fusion rate were reviewed. Functional outcomes including visual analog scale (VAS) back pain score, leg pain score, and Scoliosis Research Society-22 questionnaire (SRS-22) were used to evaluate the quality of life of patients preoperatively and at last follow-up. RESULTS: Each patient was followed up at least six times. The average follow-up time was 43.2 months. Mean scoliosis and kyphosis improved from 68.5° ± 18.1°to 18.7° ± 11.8° and from 34.4° ± 17.9°to 24.0° ± 6.7°, respectively (p < 0.05); at last follow-up, it was 20.1° and 24.7°, respectively (p > 0.05). During the follow-up, mean coronal and sagittal correction loss was 1.4° ± 1.2°and 0.7° ± 0.8°, respectively (p > 0.05). Mean FPB improved from 32.7 to 11.7 mm (p < 0.05); Mean SPB changed from 0.3 to -0.7 mm (p > 0.05). No dural tears were observed during the corrective surgery or wound infection or implant-related complications. No pseudoarthrosis was identified according to the last follow-up three-dimensional (3D) CT scan. All the domains in SRS-22 questionnaire show statistically significant improvement at the last follow-up (p < 0.05). The VAS back pain scores improved from a mean preoperative score of 1.7 to a mean postoperative score of 0.2 (p < 0.05). CONCLUSION: This original one-stage posterior PIA is safe and effective in the treatment of scoliosis, which is characterized with less blood loss, shorter operation time, and satisfactory bony fusion.

Application of a new anatomic hook-rod-pedicle screw system in young patients with lumbar spondylolysis: A pilot study.

BACKGROUND: The pedicle screw-laminar hook system has strong fixation and is conducive to bone graft fusion for lumbar spondylolysis. However, the current pedicle screw-laminar hook fixation system is not specifically designed for lumbar spondylolysis. AIM: To investigate the clinical effects of a new anatomical hook-rod-pedicle screw system in the treatment of lumbar spondylolysis in young adults. METHODS: We designed a new anatomic hook-rod-pedicle screw system for young patients with lumbar spondylolysis. The isthmus and the corresponding pedicle screw entry point were exposed through the intermuscular approach. Autogenous iliac bone graft was obtained to bridge the isthmus defect, and then the anatomic hook-rod-pedicle screw system was used to fix the isthmus in 15 young patients. RESULTS: At 24 mo follow-up, the visual analogue scale score of low back pain decreased from 6.73 ± 0.88 to 0.73 ± 0.59, and the Oswestry disability index score decreased from 58.20 ± 8.99 to 7.87 ± 4.97. Computed tomography showed bilateral isthmic bone healing in 14 cases and unilateral isthmic bone healing in 1 case. Magnetic resonance imaging showed that the lumbar disc signal of diseased segment and adjacent segments had no change compared with that before surgery. The pain visual analogue scale score of the donor site was 0.20 ± 0.41 at the last follow-up. According to the Modified Macnab score, the excellent and good rate was 100%. CONCLUSION: The application of this new anatomical hook-rod-pedicle screw system to treat young patients with lumbar spondylolysis has the advantages of less trauma, a simple operation and satisfactory clinical effects.

Comparison of pedicle screw placement accuracy between two types of imaging support (Artis Zeego versus two-dimensional fluoroscopy): a cross-sectional observational study.

BACKGROUND: The pedicle screw system is widely used in spine surgery, and it provides rigid fixation and leads to successful subsequent deformity correction and bony fusion. The standard imaging technique for pedicle screw insertion is two-dimensional images obtained from C-arm-type X-ray fluoroscopy. Artis Zeego is an emerging intraoperative imaging technique that can provide conventional two-dimensional fluoroscopic images and rapid three-dimensional fluoroscopic computed tomography reconstruction imaging. The aim of this study is to compare the insertion accuracies of PS placement using Artis Zeego and conventional 2D X-ray fluoroscopy. METHODS: In this study, we retrospectively reviewed the postoperative images of thoracolumbar fusion patients who underwent surgery using pedicle screws between 2013 and 2018. Pedicle screw malplacement was assessed using a four-grade classification by Rao et al. Misplacement rates were compared between pedicle screws assisted with Artis Zeego and two-dimensional fluoroscopy. RESULTS: A total of 1107 pedicle screws in 153 patients were inserted using Artis Zeego, and 427 pedicle screws in 80 patients were inserted using fluoroscopy. The overall perforation rate was 4.2% (46 perforations of 1106 pedicle screws) in the Artis Zeego group and 7.7% (33 perforations of 427 pedicle screws) in the fluoroscopy group. In the Artis Zeego group, 43 (3.9%) screws were classified as grade 1, and three (0.3%) screws were classified as grade 2. In the fluoroscopy group, 21 (4.9%) screws were classified as grade 1, 10 (2.3%) screws were classified as grade 2, and 2 (0.5%) screws were classified as grade 3. The use of Artis Zeego was associated with a significantly lower screw malplacement rate than was the use of fluoroscopy (p < 0.001). CONCLUSIONS: Our results demonstrated that pedicle screw placement with Artis Zeego was associated with a lower malplacement rate than was conventional two-dimensional fluoroscopy. No severe malplacement was observed in the Artis Zeego group. Thus, Artis Zeego could be a good option for improving pedicle screw accuracy.

Novel MIS 3D NAV Single Step Pedicle Screw System (SSPSS): Workflow, Accuracy and Initial Clinical Experience.

STUDY DESIGN: Prospective case series. OBJECTIVE: SSPSS (single step pedicle screw system) was developed for minimally invasive spine surgery. We performed this study to report on safety, workflow, and our initial clinical experience with this novel technique. METHODS: The prospective study was conducted on patients who underwent pedicle screw fixation between October 2017 and April 2018 using a novel single step 3D navigated pedicle screw system for MIS. Outcome measurements were obtained from intraoperative computerized tomography. The images were evaluated to determine pedicle wall penetration. We used a grading system to assess the severity of the pedicle wall penetration. Breaches were classified as grade 1 (<2 mm), grade 2 (2-4 mm), or grade 3 (<4 mm),1 and as cranial, caudal, medial, and lateral. RESULTS: Our study includes 135 screws in 24 patients. SSPSS eliminated K-wires and multiple steps traditionally necessary for MIS pedicle screw insertion. The median time per screw was 2.45 minutes. 3 screws were corrected intraoperatively. Pedicle wall penetration occurred in 14 screws (10%). Grade 1 breaches occurred in 4 screws (3%) and grade 2 breaches occurred in 10 screws (7%). Lateral breaches were observed more often than medial breaches. The accuracy rate in our study was 90% (Grade 0 breach). No revision surgeries were needed and no complications occurred. CONCLUSIONS: Our study suggests that SSPSS could be a safe, accurate, and efficient tool. Our accuracy rate is comparable to that found in the literature.

Retrospective Comparative Study of Pedicle Screw Fixation via Quadrant Retractor and Buck's Technique in the Treatment of Adolescent Spondylolysis.

OBJECTIVE: To compare the effectiveness and practicality of pedicle screw fixation via the Quadrant retractor and Buck's technique in the treatment of adolescent spondylolysis. METHODS: A total of 31 patients who underwent pedicle screw fixation or Buck's technique at our hospital from 2012 to 2017 were selected for this retrospective study. The patients were divided into a pedicle screw group (16 patients) and a Buck's technique group (15 patients) according to surgical procedure. Age, sex, disease duration, involved segments, preoperative Oswestry disability index (ODI) scores, visual analogue scale (VAS) scores for low back pain (LBP), intraoperative blood loss, incision length, operative time and length of hospital stay were documented. ODI scores, VAS scores for LBP and fusion rates at 1 month, 6 months, 1 year and 3 years postoperatively were used to evaluate surgical outcomes. RESULTS: The average follow-up period was 32.75 ± 11.99 months in the pedicle screw group and 31.02 ± 9.64 months in the Buck's technique group. No significant differences in demographic data and perioperative data were found between the two groups (P > 0.05). The ODI scores and VAS scores for LBP in both groups were significantly improved at 3 years postoperatively compared with the values before surgery (ODI%: 45.74 ± 2.47 vs 10.99 ± 3.00; 45.29 ± 6.94 vs 15.73 ± 6.89. VAS: 5.94 ± 0.68 vs 1.50 ± 0.52; 6.13 ± 0.74 vs 2.13 ± 0.92, P < 0.05). The ODI scores of the patients in the pedicle screw group at 1 month to 3 years postoperatively were lower than those of the patients in the Buck's technique group (P < 0.05). Moreover, the VAS scores for LBP of the patients in the pedicle screw group at 6 months and 3 years postoperatively were lower than those of the patients in the Buck's technique group (P < 0.05). No significant difference in the VAS scores for LBP was found between the two groups at 1 month postoperatively (3.88 ± 0.50 vs 4.20 ± 0.56, P = 0.10). Three years postoperatively, good fusion of the pars interarticularis was achieved in all patients in the pedicle screw group, but four patients in the Buck's technique group did not achieve good fusion (P = 0.02). CONCLUSION: Both pedicle screw fixation and Buck's technique can achieve good outcomes in the treatment of adolescent spondylolysis. Pedicle screw fixation via the Quadrant retractor for the treatment of spondylolysis is associated with more satisfactory effects in terms of LBP relief and fusion results.

Treatment of Thoracolumbar Fractures Through Different Short Segment Pedicle Screw Fixation Techniques: A Finite Element Analysis.

OBJECTIVE: To compare the von Mises stresses of the pedicle screw system and the displacement of injured vertebrae using 3-D finite element analysis, and to evaluate the curative effect of the pedicle screw system. METHODS: Finite element methods were used for biomechanical comparison of four posterior short segment pedicle screw fixation techniques. The different pedicle screw models are traditional trajectory (TT), Universal Spine System (USS), cortical bone trajectory (CBT), and CBT at the cranial level and pedicle screw (PS) at the caudal level (UP-CBT). The stress distribution of the screws and connecting rods under different working conditions and the displacement of the injured vertebrae were compared and analyzed. RESULTS: After the pedicle screw system was fixed, the stress under vertical compression was mainly concentrated at the proximal end of the screw, while the stress was mainly concentrated on the connecting rod during flexion, extension, lateral flexion, and rotation. The TT group had the greatest stress during the flexion, extension, and left and right rotation. The UP-CBT group was most stressed when the left and right sides were flexed; the stress of the USS screw system was less than that of the other three models during flexion, lateral flexion, and rotation. The maximum von Mises stress values of pedicle screws in all exercise states were 556.2, 340.7, 458.1, and 533.4 MPa, respectively. In the USS group, the displacement of the injured vertebra was small in the flexion, and the left and right lateral flexion and the right rotation were higher than in the TT group and the CBT group. The maximum displacements of the injured vertebrae in all motion states were 1.679, 1.604, 1.752, and 1.777 mm, respectively. CONCLUSION: Universal Spine System pedicle screws are relatively less stressed under different working conditions, the risk of breakage is small, and the model is relatively stable; CBT screws do not exhibit better mechanical properties than conventional pedicle screws and USS pedicle screws.

Biomechanical properties of novel transpedicular transdiscal screw fixation with interbody arthrodesis technique in lumbar spine: A finite element study.

PURPOSE: The purpose of this study was to investigate finite element biomechanical properties of the novel transpedicular transdiscal (TPTD) screw fixation with interbody arthrodesis technique in lumbar spine. METHODS: An L4-L5 finite element model was established and validated. Then, two fixation models, TPTD screw system and bilateral pedicle screw system (BPSS), were established on the validated L4-L5 finite element model. The inferior surface of the L5 vertebra was set immobilised, and moment of 7.5 Nm was applied on the L4 vertebra to test the range of motion (ROM) and stress at flexion, extension, lateral bending and axial rotation. RESULTS: The intact model was validated for prediction accuracy by comparing two previously published studies. Both of TPTD and BPSS fixation models displayed decreased motion at L4-L5. The ROMs of six moments of flexion, extension, left lateral bending, right lateral bending, left axial rotation and right axial rotation in TPTD model were 1.92, 2.12, 1.10, 1.11, 0.90 and 0.87°, respectively; in BPSS model, they were 1.48, 0.42, 0.35, 0.38, 0.74 and 0.75°, respectively. The screws' peak stress of above six moments in TPTD model was 182.58, 272.75, 133.01, 137.36, 155.48 and 150.50 MPa, respectively; and in BPSS model, it was 103.16, 129.74, 120.28, 134.62, 180.84 and 169.76 MPa, respectively. CONCLUSION: Both BPSS and TPTD can provide stable biomechanical properties for lumbar spine. The decreased ROM of flexion, extension and lateral bending was slightly more in BPSS model than in TPTD model, but TPTD model had similar ROM of axial rotation with BPSS model. The screws' peak stress of TPTD screw focused on the L4-L5 intervertebral space region, and more caution should be put at this site for the fatigue breakage. THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE: Our finite element study provides the biomechanical properties of novel TPTD screw fixation, and promotes this novel transpedicular transdiscal screw fixation with interbody arthrodesis technique be used clinically.

Interbody cages combined with pedicle screw system for spondylolisthesis / 中华创伤杂志

Objective To investigate the clinical effect of interbody cages combined with pedicle screw system in treatment of spondylolisthesis. Methods Of 20 patients with spondylolisthesis, interbody cages combined with 10pedicle screw system was performed in 10 patients and spinal decompression combined with intervertebral bone grafting in another 10. Results All the patients were followed up for 8-12 months (average 10 months), which showed significant improvement in the syndrome. Of 10 patients treated with interbody cages combined with pedicle screw system, seven patients were evaluated excellent, two good and one fair. Of 10 patients treated with spinal decompression combined with intervertebral bone grafting, five patients were evaluated excellent, two good and three fair. Conclusion Interbody cages combined with pedicle screw system is an safe and effective surgery for spondylolisthesis.

Long-term results of pedicle screw plus cage fixation for lumbar spondylolithesis / 中国矫形外科杂志

[Objective]To investigate the late results of pedicle screw system and cage fixation for lumbar broken isthmus spondylolisthesis.[Method]Totally 86 patients with broken isthmus spondylolisthesis were collected and analyzed from October 1996 to October 2002,they were all reduced and fixed with pedicle screw system and cage.Group 1,62 patients were put one cage in the interbody at an angle of 45 degree from posterior to anterior,while Group 2,24 patients were put two cages in the interbody vertically from posterior to anterior.The height of interbody and the most proximal interbody' s height were measured,the rate was calculated.These rate were acquired preoperatively,2 weeks postoperatively and follow-up period respectively.[Result]The follow-up period was 24~96 months,averaged 35 months.The excellent and good rates were 80.23 per cent,according to Nakai standard.Ninteen patients with one degree spondylolisthesis were reduced anatomically after surgery.Fifty-one patients with two degree spondylolisthesis were reduced anatomically except 5 patients with one degree spondylolisthesis left.Sixteen patients with three degree spondylolisthesis were reduced anatomically except 4 patients with one degree spondylolisthesis left.There were loss of spondylolisthesis reduction at follow-up period comparing with 2 weeks postoperatively in two groups.However there was no statistical significance between the two groups.[Conclusion]Lumbar spondylolisthesis should be treated with pedicle screw system and cage,which may decrease the complications such as broken screw and spondylolisthesis recurrency postoperatively.One piece of cage is enough to make interbody stable.It is also an ideal procedure for lumbar spondylolisthesis.

Surgical treatment for thoracolumbar fracture with ankylosing spondylitis / 中国矫形外科杂志

[Objective]To investigate surgical protocol for treatment of thoracolumbar fracture with ankylosing spondylitis. [Method]A retrospective study was performed in 8 thoracolumbar-fracture patients with ankylosing spondylitis. Of them, 6 patients were neurological intact and 2 had neurological defect(Frankel grades the C level). Under general anesthesia, all of the 8 patients underwent open reduction and internal fixation with pedicle screws at two segments in both ends of the fracture. Laminectomy for decompression of the nerve tissue was performed in the 2 patients with neurological defect simultaneously.[Result]All of the 8 patients were followed up for 8 to 30 months. Solid bone healing was achieved in all of the patients. Two patients with eurological compromise had improved by two Frankel grades (complete recovery).[Conclusion]Thoracolumbar fracture in ankylosing spondylitis traverse both bone and ligaments, producing an extremely unstable situation similar to a shearing type of fracture. Reduction of the displacement and stabilization is best achieved with a pedicle screw system at two segments in both ends of the fracture.

Comparison of short term outcome in the treatment of degenerative lumbar stenosis with Coflex implant versus laminectomy and posterior interbody fusion along with pedicle screw system / 中国矫形外科杂志

[Objective]To compare the short term outcome in treatment of degenerative lumbar stenosis with Coflex implant versus laminectomy and posterior interbody fusion along with pedicle screw system. [Methods]Thirty patients with degenerative lumbar stenosis were randomly divided into two groups.Fifteen patients in the control group were treated with laminectomy and posterior interbody fusion along with pedicle screw system. The other 15 patients in the experiment group were treated with Coflex implant. The parameters for assessment included operation time,intraoperative blood loss,hospital stay,pre- and postoperative JOA score,improvement rate and complication rate.[Results]Compared to the control,significant reduction was found in terms of operation time,intraoperative blood loss,and hospital stay in the experiment group.No significant difference was found regard to the improvement rate and postoperative JOA score. In addition ,there was no complication in the Coflex group during the follow-up.[Conclusion]Coflex implant is an effective,save and minimally invasive surgical method for the treatment of degenerative lumbar stenosis.

Application of posterior circumferential fusion in the surgery of lumbar spondylolisthesis / 中国矫形外科杂志

[Objective] To evaluate the feasibilitiy,methods and therapeautical effects of the posterior circumferential fusion (PCF) combined with short -segmental pedicle screw system fixation for the treatment of lumbar spondylolisthesis(LSL). [Method] From October 2002 to March 2006, 44 cases of LSL were treated with decompression for spine canal stenosis, circumferential fusion and short-segmental pedicle screw system fixation. There were 15 male and 29 female, average age was 48. 6 (ranged, 31~68) years. The diagnoses of LSL and stenosis were confirmed by X-ray and CT. According to Newman classification, 15 of them were the degenerative type and 29 were isthmic type. According to Meryerding classification of LSL, 17 patients had degree I, 24 patients had degree Ⅱ and 3 patients had degree Ⅲ spondylolisthesis. The levels of LSL was between L4 and L5,in 18 patients and between L5 and S1 in 26 cases.[Result]The follow-up period was 18~36 months , averaged 26 months.Seventeen patients with degree Ⅰ spondylolisthesis were all reduced anatomically after surgery. Twenty-four patients with degree Ⅱ spondylolisthesis were reduced anatomically except for 6 patients with Ⅰ degree residual spondylolisthesis. 3 patients with degree Ⅲ spoadylolisthesis were reduced anatomically except for 2 spatients with Ⅰ degree residual spondylolishesis. The effect was evaluated according to Hou Shuxun's evaluation standard, the results were excellent in 28 cases, good in 13 cases, and fair in 3 cases. The excellent and good rate was 93.2%. No complication such as interfixation failure and nerve pedicle injury or cauda equine injury were found. All cases got bony union in 3 to 10 months (mean 4.2 months) postoperatively. All patients had normal disc height and no loss of spondylolisthesis reduction. [Conclusion] The PCF combined with short-segmental pedicle screw system fixation is reasonable options in treating the LSL. It can improve the fusion rate of the spine and maintain good intervertebral space and good lordosis of the lumbar spine. The satisfactory clinical result is relied on the completely understanding of the characteristics of PCF and short-segmental pedicle screw fixation.

Metal Failure of Pedicle Screw System / 대한척추외과학회지

STUDY DESIGN: The metal failure of pedicle screw system followed by posterolateral or posterior fusion used in variable cases(spine fracture, degenerative disorder of spine, deformity of spine) was analyzed retrospectively. PURPOSE: The goal of this study was to analyze frequency and clinical consequence of pedicle screw fixation system failure in the treatment of different etiology(spine fracture, degenerative disorder, deformity of spine) and to evaluate affected factors in metal failure. MATERIALS AND METHODS: We performed survivorship analysis on 442 patients treated with pedicle screw system from September 1990 to December 1999. The average follow-up period was 54 months(from 18 months to 129 months). As affected factors, some variables such as etiology, kinds of system and extent of fusion were subjected to analyzed their influence on metal failure. We also performed analysis about relationship between metal failure and clinical results. We defined the metal failure as 1) breakage of screw or rod 2) screw bending above 5 degrees 3) dissociation of rod-screw coupling system and 4) screw pull out from vertebral body or pedicle. RESULTS: We found out 33 cases of metal failure: among 2786 screws, 41 screws had a problem. The metal failure rate was different between each etiology ; 12 cases in fracture(10%), 21 cases in degenerative disorder(6.9%). There was also difference between a kinds of implants; 13 cases in side assembling type(5.4%), 20 cases in back open type(10.5%). However, there were no difference according to extent of fusion; 6 cases in one segment(6.9%), 21 cases in two segments(8.1%), 6 cases in more than three segments(6.3%). Among the overall patients with metal failure (33 cases), only eight patients were complaint significant symptoms. And three of this eight patients were improved after reoperation The mean interval to metal failure was 14.4 months from operation. CONCLUSION: The metal failure was more common in spine fracture(p0.05). And metal failure did not significantly affect the clinical results(p>0.05).

A Clinical Study of Postoperative Infection in Posterior Spinal Surgery with Pedicle Screw System / 대한정형외과학회잡지

In the treatment of spinal disorder, the introduction of pedicle screw system is an innovation in modern spinal surgery. This kind of new instrumentation provides correction, adjustment, stabilization, firm fixation and short segment fusion. Everybody should know that these complexities of instrumentation will increase the rated of complications, especially postoperative infection. Postoperative infections continue to be a source of frustration for patients and surgeons, and can lead to significant postoperative difficulties. So we analysed the postoperative infection from the 284 cases we operated on during the September 19S8 to August 1992 and obtained following results: 1. There were 17 cases(6.0%) of postoperative infection. Among them Scases(2.8%) were deep infection. 2. Average fused segments were 3.64 and 2. 96 in deep infection and control group respectively. 3. Staphylococcus aureus was the most frequent organism. Other recurring organisms were St. epidermidis, Enterobacter cloacae and so on. Many patients had multiple organisms. 4. Most significant risk factors for postoperative infection were obestity and prolonged surgery. 5. Just preoperative prophylactic antibiotic administation is more valuable than no prophylaxis and too early administration. 6. Postoperative acute deep infection is is not as easily diagnosed. The clinical manifestation such as sudden increase in pain at the operative site is the most valuable sign. 7. Maintaining the instrumentation in place, continuous irrigation system and the appropriate parenteral antibiotics were the choice of treatment.