Augmented reality in minimally invasive spine surgery: early efficiency and complications of percutaneous pedicle screw instrumentation

BACKGROUND CONTEXTAugmented reality (AR) employs an optical projection directly onto the user's retina, allowing complex image overlay on the natural visual field. In general, pedicle screw accuracy rates have improved with increasingly use of technology, with navigation-based instrumentation described as accurate in 89%–100% of cases. Emerging AR technology in spine surgery builds upon current spinal navigation to provide 3-dimensional imaging of the spine and powerfully reduce the impact of inherent ergonomic and efficiency difficulties.PURPOSEThis publication describes the first known series of in vivo pedicle screws placed percutaneously using AR technology for MIS applications.STUDY DESIGN / SETTINGAfter IRB approval, 3 senior surgeons at 2 institutions contributed cases from June, 2020 – March, 2022. 164 total MIS cases in which AR used for placement of percutaneous pedicle screw instrumentation with spinal navigation were identified prospectively.PATIENT SAMPLE155 (94.5%) were performed for degenerative pathology, 6 (3.6%) for tumor and 3 (1.8%) for spinal deformity.  These cases amounted to a total of 606 pedicle screws; 590 (97.3%) were placed in the lumbar spine, with 16 (2.7%) thoracic screws placed.OUTCOME MEASURESPatient demographics and surgical metrics including total posterior construct time (defined as time elapsed from preincision instrument registration to final screw placement), clinical complications and instrumentation revision rates were recorded in a secure and de-identified database.METHODSThe AR system used features a wireless headset with transparent near-eye display which projects intra-operative 3D imaging directly onto the surgeon's retina. After patient positioning, 1 percuntaneous and 1 superficial reference marker are placed. Intra-operative CT data is processed to the headset and integrates into the surgeon's visual field creating a “see-through” 3D effect in addition to 2D standard navigation images. MIS pedicle screw placement is then carried out percutaneously through single line of sight using navigated instruments.RESULTSTime elapsed from registration and percutaneous approach to final screw placement averaged 3 minutes and 54 seconds per screw.  Analysis of the learning curve revealed similar surgical times in the early cases compared to the cases performed with more experience with the system.  No instrumentation was revised for clinical or radiographic complication at final available follow-up ranging from 6–24 months. A total of 3 screws (0.49%) were replaced intra-operatively. No clinical effects via radiculopathy or neurologic deficit postoperatively were noted.CONCLUSIONSThis is the first report of the use of AR for placement of spinal pedicle screws using minimally invasive techniques.   This series of 164 cases confirmed efficiency and safety of screw placement with the inherent advantages of AR technologies over legacy enabling technologies.     

Single-position prone transpsoas fusion for the treatment of lumbar adjacent segment disease: early experience of twenty-four cases across three tertiary medical centers

Purpose

Prone transpsoas fusion (PTP) is a minimally invasive technique that maximizes the benefit of lateral access interbody surgery and the prone positioning for surgically significant adjacent segment disease. The authors describe the feasibility, reproducibility and radiographic efficacy of PTP when performed for cases of lumbar ASD.

Methods

Adult patients undergoing PTP for treatment of lumbar ASD at three institutions were retrospectively enrolled. Demographic information was recorded, as was operative data such as adjacent segment levels, operative time, blood loss, laterality of approach, open versus percutaneous pedicle screw instrumentation and need for primary decompression. Radiographic measurements including segmental and global lumbar lordosis, pelvic incidence, pelvic tilt, sacral slope and sagittal vertical axis were recorded both pre- and immediately post-operatively.

Results

Twenty-four patients met criteria for inclusion. Average age was 60.4 ± 10.4 years and average BMI was 31.6 ± 5.0 kg/m². Total operative time was 204.7 ± 83.3 min with blood loss of 187.9 ± 211 mL. Twenty-one patients had pedicle screw instrumentation exchanged percutaneously and 3 patients had open pedicle screw exchange. Two patients suffered pulmonary embolism that was treated medically with no long-term sequelae. One patient had transient lumbar radicular pain and all patients were discharged home with an average length of stay of 3.0 days (range 1–6). Radiographically, global lumbar lordosis improved by an average of 10.3 ± 9.0 degrees, segmental lordosis by 10.1 ± 13.3 degrees and sagittal vertical axis by 3.2 ± 3.2 cm.

Conclusion

Single-position prone transpsoas lumbar interbody fusion is a clinically reproducible minimally invasive technique that can effectively treat lumbar adjacent segment disease.

     

Accuracy of percutaneous pedicle screws for thoracic and lumbar spine fractures: a prospective trial

Purpose

The percutaneous insertion technique requires surgical skill and experience. However, there have been few clinical reports evaluating the accuracy of minimally invasive pedicle screw placement using the conventional fluoroscopy method. The purpose of this study was to evaluate the accuracy of percutaneous pedicle screw placement in the treatment of thoracic and lumbar spine fractures using two-plane conventional fluoroscopy.

Methods

A prospective clinical trial was performed. A total of 502 percutaneous pedicle screws in 111 patients, all inserted with the assistance of conventional fluoroscopy, were evaluated. The safety and accuracy of pedicle screw placement were based on the evaluation of postoperative axial 3-mm slice computed tomography scans using the scoring system described by Zdichavsky et al. [Eur J Trauma 30:234–240, 2004; Eur J Trauma 30:241–247, 2004].

Results

427/502 pedicle screws (85 %) were classified as good and excellent concerning the best possible screw length and 494/502 (98 %) were found to have good or excellent position. One screw had to be revised due to medial position with a neurological deficit.

Conclusions

This study demonstrates the feasibility of placing percutaneous posterior thoracolumbar pedicle screws with the assistance of conventional fluoroscopy. Minimally invasive transpedicular instrumentation is an accurate, reliable and safe method to treat a variety of spinal disorders, including thoracic and lumbar spine fractures.     

Robot assisted navigated drilling for percutaneous pedicle screw placement: A preliminary animal study

Background:There is much more radiation exposure to the surgeons during minimally invasive pedicle screws placement. In order to ease the surgeon''s hand-eye coordination and to reduce the iatrogenic radiation injury to the surgeons, a robot assisted percutaneous pedicle screw placement is useful. This study assesses the feasibility and clinical value of robot assisted navigated drilling for pedicle screw placement and the results thus achieved formed the basis for the development of a new robot for pedicle screw fixation surgery.Results:Assisted by spine robot system, the average time for system registration was (343.4 ± 18.4) s, the average time for procedure of drilling one pedicle screw trajectory was (89.5 ± 6.1) s, times of fluoroscopy for drilling one pedicle screw were (2.9 ± 0.8) times. Overall, 12 (15.0%) of the 80 K-wires violated the pedicle wall. Four screws (5.0%) were medial to the pedicle and 8 (10.5%) were lateral. The number of K-wires wholly within the pedicle were 68 (85%).Conclusions:The preliminary study supports the view that computer assisted pedicle screw fixation using spinal robot is feasible and the robot can decrease the intraoperative fluoroscopy time during the minimally invasive pedicle screw fixation surgery. As spine robotic surgery is still in its infancy, further research in this field is worthwhile especially the accuracy of spine robot system should be improved.     

Incidence and risk factors associated with superior-segmented facet joint violation during minimal invasive lumbar interbody fusion

BACKGROUND CONTEXTThe trend of minimally invasive lumbar interbody fusion is increasing, and adjacent segmental degeneration (ASD) is one of the complications of the procedures in which facet joint violation (FJV) is a cause. FJVs can occur during percutaneous instrumentation. This study aimed to identify the risk factors that affect FJV during minimally invasive lumbar interbody fusion.PURPOSETo identify the risk factors for FJVs and the factors that have a strong impact on the violation.STUDY DESIGNRetrospective study.PATIENT SAMPLEPatients who underwent minimally invasive lumbar interbody fusion with percutaneous screw fixation between June 2018 and December 2019.OUTCOME MEASURESPrevalence of the FJV was reviewed by CT scans which obtained within 6 months after surgery, and the axial, coronal, and sagittal cuts of the scans were evaluated. The FJV was defined as the screw being visible in the facet joint in at least one plane of the CT scan. Radiographic parameters were measured using CT scans including diameters of the facet joints in the axial, coronal, and sagittal planes defined by the facet diameter. The facet angle (FA), the pedicle angle (PA), the screw-facet angle (SFA), the screw-endplate angle (SEA), and the superior margin of the facet joint in the sagittal plane (SD) differed from the head of the screw. At Last, the depth of back muscle was measured in the axial cut of the MRI.METHODSThis study analyzed 119 patients who underwent minimally invasive lumbar interbody fusion between June 2018 and December 2019. Facet joint violation at the uppermost level was examined using CT in all dimensions. Radiographic parameters (facet diameter, facet angle, pedicle angle, screw-facet angle, screw-endplate angle, and distance between the head of the screws and the facet) were measured. BMI, age, diagnosis, and navigation assistance were included in the study. Risk factors were analyzed to determine which factors had an effect on FJV, and the cut-off was calculated for each parameter.RESULTSThis study included 119 patients, with a mean age of 63 years. FJV occurred in 13/119 (10.9%) patients and 15/238 (6.3%) joints, respectively. No FJV occurred in 120 joints operated with navigation-assistance and 15/178 (8.4%) joints operated without navigation (p=.01). We found an increasing proportion of violations at more caudal levels: no violations occurred in eight patients with lumbar at L1 or L2, and 1/40 (2.5%), 7/158 (4.4%), and 7/32 (21.9%) of violations occurred at L3, L4, and L5, respectively (p=.01). The diameter of the facet in the axial cut, facet angle, screw facet angle, and distance between the head of the screw and facet were statistically significant in determining the increasing rate of FJV after multivariate analysis was performed (AROC=0.9486, p≤.05). The cutoff point for each radiographic parameter were diameter of facet in the axial ≥17.5 mm, diameter of facet in coronal plane ≥19.5 mm, facet angle ≥41.5^o, screw-facet angle ≥39^o, and distance between facet and the screw ≥-2.6 mm. The estimated probability of FJV was 96.9% when every parameter was greater than the cut-off point.CONCLUSIONSAn increase in the facet diameter in the axial plane, coronal plane, facet angle, screw facet angle, and the distance between the dome of the screw and facet are risk factors for FJV. Surgeons can avoid violations when radiographic considerations are done. Careful screw placement and good entry points for instrumentation may decrease the rate of facet violation.     

Percutaneous pedicle screw instrumentation

Minimally invasive fusion techniques for degenerative lumbar pathology commonly involve the placement of pedicle screws. Percutaneous placement of these screws allows the surgeon to minimize soft tissue trauma, improving postoperative recovery for patients. This review will cover the indications and techniques for percutaneous pedicle screw instrumentation of the lumbar spine, and will highlight the advantages and potential contraindications to using percutaneous instrumentation.     

Accuracy of upper thoracic pedicle screw placement using three-dimensional image guidance

Background contextPedicle screw malposition rates using conventional techniques have been reported to occur with a frequency of 6% to 41%. The upper thoracic spine (T1–T3) is a challenging area for pedicle screw placement secondary to the small size of the pedicles, the inability to visualize this area with lateral fluoroscopy, and significant consequences for malpositioned screws. We describe our experience placing 150 pedicle screws in the T1–T3 levels using three-dimensional (3D) image guidance.PurposeThe aim of this study was to assess the accuracy of 3D image guidance for placing pedicle screws in the first three thoracic vertebrae.Study designThe accuracy of pedicle screw placement in the first three thoracic vertebrae was evaluated using postoperative thin-section computed tomography (CT) scans of the cervicothoracic region.Patient sampleThirty-four patients who underwent cervicothoracic fusion were included.Outcome measuresRadiological investigation with CT scans was performed during the postoperative period.MethodsThirty-four consecutive patients underwent cervicothoracic instrumentation and fusion for a total of 150 pedicle screws placed in the first three thoracic vertebrae. All screws were placed using 3D image guidance. Medical records and postoperative imaging of the cervicothoracic junction for each patient were retrospectively reviewed. An independent radiologist reviewed the placement of the pedicle screws and assessed for pedicle breach. All cortical violations were reported as Grade 1, 0 to 2 mm; Grade 2, 2 to 4 mm; and Grade 3, greater than 4 mm.ResultsOverall, 140 (93.3%) out of 150 screws were contained solely in the desired pedicle. All 10 pedicle violations were Grade 1. The direction of pedicle violation included three medial, four inferior, two superior, and one minor anterolateral vertebral body. No complication occurred as a result of screw placement or the use of image guidance.ConclusionsUpper thoracic pedicle screw placement is technically demanding as a result of variable pedicle anatomy and difficulty with two-dimensional visualization. This study demonstrates the accuracy and reliability of 3D image guidance when placing pedicle screws in this region. Advantages of this technology in our practice include safe and accurate placement of spinal instrumentation with little to no radiation exposure to the surgeon and operating room staff.     

CT-navigation versus fluoroscopy-guided placement of pedicle screws at the thoracolumbar spine: single center experience of 4,500 screws

Purpose

Single center evaluation of the placement accuracy of thoracolumbar pedicle screws implanted either with fluoroscopy or under CT-navigation using 3D-reconstruction and intraoperative computed tomography control of the screw position. There is in fact a huge variation in the reported placement accuracy of pedicle screws, especially concerning the screw placement under conventional fluoroscopy most notably due to the lack of the definition of screw misplacement, combined with a potpourri of postinstrumentation evaluation methods.

Methods

The operation data of 1,006 patients operated on in our clinic between 1995 and 2005 is analyzed retrospectively. There were 2,422 screws placed with the help of CT-navigation compared to 2,002 screws placed under fluoroscopy. The postoperative computed tomography images were reviewed by a radiologist and an independent spine surgeon.

Results

In the lumbar spine, the placement accuracy was 96.4 % for CT-navigated screws and 93.9 % for pedicle screws placed under fluoroscopy, respectively. This difference in accuracy was statistically significant (Fishers Exact Test, p = 0.001). The difference in accuracy became more impressing in the thoracic spine, with a placement accuracy of 95.5 % in the CT-navigation group, compared to 79.0 % accuracy in the fluoroscopy group (p < 0.001).

Conclusion

This study underlines the relevance of CT-navigation-guided pedicle screw placement, especially when instrumentation of the middle and upper thoracic spine is carried out.     

CT accuracy of percutaneous versus open pedicle screw techniques: a series of 1609 screws

Introduction

Traditional open exposure for posterior instrumentation requires significant soft tissue mobilization and causes significant blood loss and increased recovery time. Mal-placed screws can injure nerve roots, the spinal cord, viscera, vasculature and the cardiopulmonary system. Placement of pedicle screws using a minimally invasive technique can decrease bleeding risk, damage to soft tissues, and post-operative pain. The purpose of this study is to compare the radiographic accuracy of open free-hand versus percutaneous technique for pedicle screw placement.

Methods

Consecutive patients undergoing thoracolumbar surgery from September 2006 to October 2011 with post-operative CT imaging were included in this study. Three-dimensional screw positioning within the pedicle and the vertebral body was assessed on CT. The magnitude and location of violations were measured and recorded. Facet breaches at the cephalad and caudad ends of the construct were documented and graded.

Results

Two-hundred and twenty-three patients met the inclusion criteria for a total of 1609 pedicle screws. Seven-hundred and twenty-four screws were placed using a standard open free-hand technique and 885 were placed percutaneously. There was a significant difference in overall pedicle breach rates: 7.5 % for open and 4.7 % for percutaneous techniques. The magnitude of breach was greater for the percutaneous technique compared to the open technique: 5.4 versus 3.7 mm, respectively. The difference in vertebral body breaches was also significant: 11.3 % for open and 3.6 % for percutaneous. The rates of facet breach did not significantly differ.

Discussion and conclusion

This is the largest series comparing the accuracy of percutaneous to open pedicle screw placement. The rates of pedicle, vertebral body, and facets breaches in the percutaneous group were similar to the rates in the open technique group as well as rates reported in the literature. This demonstrates that the percutaneous technique described here is an accurate alternative to standard open free-hand technique.

     

Accuracy of augmented reality surgical navigation for minimally invasive pedicle screw insertion in the thoracic and lumbar spine with a new tracking device

BACKGROUND CONTEXTMinimally invasive approaches are increasingly used in spine surgery. The purpose of navigation systems is to guide the surgeon and to reduce intraoperative x-ray exposure.PURPOSEThis study aimed to determine the feasibility and clinical accuracy of a navigation technology based on augmented reality surgical navigation (ARSN) for minimally invasive thoracic and lumbar pedicle screw instrumentation compared with standard fluoroscopy-guided minimally invasive technique.STUDY DESIGN/SETTINGCadaveric laboratory study.METHODSARSN was installed in a hybrid operating room, consisting of a flat panel detector c-arm with two dimensional/three dimensional imaging capabilities and four integrated cameras in its frame. The surface-referenced navigation device does not require a bony reference but uses video cameras and optical markers applied to the patient's skin for tracking. In four cadavers, a total of 136 pedicle screws were inserted in thoracic and lumbar vertebrae. The accuracy was assessed by three independent raters in postoperative conventional computed tomography.RESULTSThe overall accuracy of ARSN was 94% compared with an accuracy of 88% for fluoroscopy. The difference was not statistically significant. In the thoracic region, accuracy with ARSN was 92% compared with 83% with fluoroscopy. With fluoroscopy, unsafe screws were observed in three normal cadavers and one with scoliosis. Using ARSN, unsafe screws were only observed in the scoliotic spine. No significant difference in the median of time for K-wire placement was recorded. As no intraoperative fluoroscopy was necessary in ARSN, the performing surgeon was not exposed to radiation.CONCLUSIONSIn this limited cadaveric study minimally invasive screw placement using ARSN was demonstrated to be feasible and as accurate as fluoroscopy. It did not require any additional navigation time or use of any intraoperative x-ray imaging, thereby potentially permitting surgery in a protective lead garment-free environment. A well-powered clinical study is needed to demonstrate a significant difference in the accuracy between the two methods.CLINICAL SIGNIFICANCEARSN offers real-time imaging of planned insertion paths, instrument tracking, and overlay of three dimensional bony anatomy and surface topography. The referencing procedure, by optical recognition of several skin markers is easy and does not require a solid bony reference as necessary for conventional navigation which saves time. Additionally, ARSN may foster the reduction of intraoperative x-ray exposure to spinal surgeons.     

Percutaneous instrumentation of the cervical and cervico-thoracic spine using pedicle screws: preliminary clinical results and analysis of accuracy

The pedicle screw instrumentation represents the most rigid construct of the cervical and cervicothoracic spine and in spite of the risks to neurovascular structures clinical relevant complications do not occur frequently. The steep angles of the cervical pedicles result in a wide surgical exposure with extensive muscular trauma. The objective of this study was the evaluation of the accuracy of cervical pedicle screw insertion through a minimally invasive technique to reduce access-related muscular trauma. Therefore, percutaneous transpedicular instrumentation of the cervical and cervicothoracic spine was performed in 15 patients using fluoroscopy. All instrumentations from C2 to Th4 were inserted bilaterally through 2 to 3-cm skin and fascia incisions even in multilevel procedures and the rods were placed by blunt insertion through the incision. Thin-cut CT scan was used postoperatively to analyze pedicle violations. 76.4% of 72 screws were placed accurately. Most pedicle perforations were seen laterally towards the vertebral artery. Critical breaches >2 mm or narrowing of the transversal foramen occurred in 12.5% of screws; however, no revision surgery for screw displacement was needed in the absence of clinical symptoms. No conversion from percutaneous to open surgery was necessary. It was concluded that percutaneous transpedicular instrumentation of the cervical spine is a surgically demanding technique and should be reserved for experienced spine surgeons. The indications are limited to instrumentation-only procedures or in combination with anterior treatment, but with the potential to minimize access-related morbidity.     

Fluoroscopy-based percutaneous posterior screw placement in the lateral position using the tunnel view technique: technical note

Purpose

Lumbar fusion using lateral single position surgery (LSPS) gained popularity during the last few years. While prone percutaneous pedicle screw placement is well described, placing percutaneous pedicle screws with the patient in the lateral position is considered the most complicated part of LSPS. In this article we describe the fluoroscopy navigated technique for lateral percutaneous screw placement using the tunnel view technique.

Methods

The radiologic background and principles of the tunnel view technique are described. In addition, the special positioning of the patient, the C-arm and the surgical technique is discussed in detail.

Results

This technique is used as the standard for percutaneous screw placement in the prone or lateral positions in our department since 2017. Since the introduction of this technique we have had 0% reoperation rate for symptomatic malpositioned pedicle screws.

Conclusion

The tunnel view technique simplifies pedicle screw placement while allowing for permanent observation of pedicle walls and the superior joint surface during placement of the Jamshidi needle. It also allows for confirmation of intrapedicular position of the screw after its implantation. This technique is safe and feasible in our clinical experience.

     

Minimally invasive percutaneous transpedicular screw fixation: increased accuracy and reduced radiation exposure by means of a novel electromagnetic navigation system

Background  

Minimally invasive percutaneous pedicle screw instrumentation methods may increase the need for intraoperative fluoroscopy, resulting in excessive radiation exposure for the patient, surgeon, and support staff. Electromagnetic field (EMF)-based navigation may aid more accurate placement of percutaneous pedicle screws while reducing fluoroscopic exposure. We compared the accuracy, time of insertion, and radiation exposure of EMF with traditional fluoroscopic percutaneous pedicle screw placement.     

Does the accuracy of pedicle screw placement differ between the attending surgeon and resident in navigated robotic-assisted minimally invasive spine surgery?

Robotic assistance with integrated navigation is an area of high interest for improving the accuracy of minimally invasive pedicle screw placement. This study analyzes the accuracy of pedicle screw placement between an attending spine surgeon and a resident by comparing the left and right sides of the first 101 consecutive cases using navigated robotic assistance in a private practice clinical setting. A retrospective, Institutional Review Board-exempt review of the first 106 navigated robot-assisted spine surgery cases was performed. One attending spine surgeon and one resident performed pedicle screw placement consistently on either the left or right side (researchers were blinded). A CT-based Gertzbein and Robbins system (GRS) was used to classify pedicle screw accuracy, with grade A or B considered accurate. There were 630 consecutive lumbosacral pedicle screws placed. Thirty screws (5 patients) were placed without the robot due to surgeon discretion. Of the 600 pedicle screws inserted by navigated robotic guidance (101 patients), only 1.5% (9/600) were repositioned intraoperatively. Based on the GRS CT-based grading of pedicle breach, 98.67% (296/300) of left-side screws were graded A or B, 1.3% (4/300) were graded C, and 0% (0/300) were graded D. For the right-side screws, 97.67% (293/300) were graded A or B, 1.67% (5/300) were graded C, and 0.66% (2/300) were graded D. This study demonstrated a high level of accuracy (based on GRS) with no significant differences between the left- and right-side pedicle screw placements (98.67% vs. 97.67%, respectively) in the clinical use of navigated, robot-assisted surgery.

     

Perioperative course and accuracy of screw positioning in conventional, open robotic-guided and percutaneous robotic-guided, pedicle screw placement

Robotic-guided and percutaneous pedicle screw placement are emerging technologies. We here report a retrospective cohort analysis comparing conventional open to open robotic-guided and percutaneous robotic-guided pedicle screw placement. 112 patient records and CT scans were analyzed concerning the intraoperative and perioperative course. 35 patients underwent percutaneous, 20 open robotic-guided and 57 open conventional pedicle screw placement. 94.5% of robot-assisted and 91.4% of conventionally placed screws were found to be accurate. Percutaneous robotic and open robotic-guided subgroups did not differ obviously. Average X-ray exposure per screw was 34 s in robotic-guided compared to 77 s in conventional cases. Subgroup analysis indicates that percutaneously operated patients required less opioids, had a shorter hospitalization and lower rate of adverse events in the perioperative period. The use of robotic guidance significantly increased accuracy of screw positioning while reducing the X-ray exposure. Patients seem to have a better perioperative course following percutaneous procedures.     

改良金属网格定位器经皮微创椎弓根螺钉内固定术治疗无神经症状胸腰椎骨折

目的　比较改良金属网格定位器经皮微创和传统后路开放椎弓根螺钉内固定术治疗无神经症状的单椎体胸腰椎骨折的临床疗效。方法回顾性分析2014年1月—2017年12月收治的50例无神经症状的单椎体胸腰椎骨折患者临床资料,其中采用改良金属网格定位器经皮微创椎弓根螺钉内固定术治疗25例(微创组),采用传统后路开放椎弓根螺钉内固定术治疗25例(开放组)。记录2组切口总长度、手术时间、术中出血量、置钉准确率及并发症发生情况,测量X线片上伤椎前缘高度及Cobb角,评估恢复及矫正情况,采用改良MacNab标准评价疗效。结果所有手术顺利完成,患者随访12 ～ 21(16.1±2.4)个月。微创组切口总长度、手术时间、术中出血量均明显优于开放组,差异均有统计学意义(P 0.05);微创组置钉准确率为95%,开放组置钉准确率为94%,组间差异无统计学意义(P 0.05)。2组患者术后1周、末次随访时伤椎前缘相对高度及Cobb角均较术前明显改善,差异有统计学意义(P 0.05),组间比较差异无统计学意义(P 0.05)。末次随访时改良MacNab疗效评定:微创组优15例,良8例,可2例,优良率为92%;开放组优13例,良9例,可3例,优良率为88%;组间差异无统计学意义(P 0.05)。微创组1例腰背部出现皮下血肿,嘱患者仰卧位并对症治疗后血肿自行吸收;其余患者未发生类似情况及其他相关并发症。结论改良金属网格定位器经皮微创椎弓根螺钉内固定术治疗无神经症状的单椎体胸腰椎骨折疗效与传统后路开放手术相当,且具有创伤小、手术时间短、出血量少的优点,改良金属网格术中定位准确率高,值得临床推广。     

Percutaneous pedicle screw placement under single dimensional fluoroscopy with a designed pedicle finder—a technical note and case series

Background Context

Minimally invasive spine surgery has become increasingly popular in clinical practice, and it offers patients the potential benefits of reduced blood loss, wound pain, and infection risk, and it also diminishes the loss of working time and length of hospital stay. However, surgeons require more intraoperative fluoroscopy and ionizing radiation exposure during minimally invasive spine surgery for localization, especially for guidance in instrumentation placement. In addition, computer navigation is not accessible in some facility-limited institutions.

Pedicle screw diameter selection for safe insertion in the thoracic spine

Objective

Many thoracic pedicles are too small for the safe acceptance of a transpedicular screw. However, few studies have so far reported on the methods to select a proper pedicle screw size and to confirm the morphologic changes for such a small thoracic spine pedicle. The objective of this work was to determine the potential limits of a pedicle screw diameter for transpedicular screw placement in the thoracic spine.

Methods

T2–T9 vertebrae from eleven patients that underwent posterior thoracic instrumentation with the use of fluoroscopically assisted insertion method were analyzed. The outcome measures were the pedicle widths, the gap between the outer pedicle width and the selected pedicle screw diameter, and the penetration length of the pedicle screws using computed tomography. The screws were distributed into two groups according to the pedicle width and screw diameter, and the screw perforation rate of the two groups was compared. The relationships of the gap and the distance of the screw penetration were compared and investigated in regard to the pedicle screw diameter selection.

Results

A total of 16 screws demonstrated a smaller diameter than the inner pedicle widths, while 22 screws had a larger diameter than the inner pedicle widths. One screw (6.3%) perforated the pedicle cortex in the smaller screw group, and twelve screws (54.5%) perforated the pedicle cortex in the larger screw group (P?=?0.006). A linear regression analysis in the larger screw group revealed that when the gap was less than 0.5?mm, a risk of a pedicle wall violation was observed.

Conclusions

When the screws with a larger diameter than the inner pedicle width are selected, the screw perforation rate increases. Therefore, the size of the screw diameter must be at least 0.5?mm less than the outer pedicle width to ensure safe transpedicular screw placement.     

Hybrid Technique for Posterior Lumbar Interbody Fusion: A Combination of Open Decompression and Percutaneous Pedicle Screw Fixation

The authors describe a hybrid technique that involves a combination of open decompression and posterior lumbar interbody fusion (PLIF) and percutaneously inserted pedicle screws. This technique allows performance of PLIF and decompression via a midline incision and approach without compromising operative time and visualization. Furthermore, compared to standard open decompression, this approach reduces post‐operative wound pain because the small midline incision significantly reduces muscle trauma by obviating the need to dissect the paraspinal muscles off the facet joint complex and by avoiding posterolateral fusion, thus requiring limited lateral muscle dissection off the transverse processes. A series of patients with Grade I‐II spondylolisthesis at L_4–5 and moderate–severe canal/foraminal stenosis underwent midline PLIF at L_4–5, with closure of the midline incision. Percutaneous pedicle screws were inserted, thereby minimizing local muscle trauma, reduction of the spondylolisthesis being performed by using a pedicle screw construct. Rods were inserted percutaneously to link the L₄ and L₅ pedicle screws. Image intensification was used to confirmed satisfactory screw placement and reduction of spondylolisthesis. The results of a prospective study comparing a standard open decompression and fusion technique for spondylolisthesis versus the minimally invasive hybrid technique are discussed. The minimally invasive technique resulted in shorter hospital stay, earlier mobilization and reduced postoperative narcotic usage. The long‐term clinical outcomes were equivalent in the two groups.     

基于术中三维影像的经皮枢椎椎弓根螺钉内固定治疗Hangman骨折

目的探讨基于术中三维影像的经皮枢椎椎弓根螺钉内固定治疗Hangman骨折的精准性和可行性。方法2015年11月—2016年11月,在O形臂X线机引导下采用经皮椎弓根螺钉内固定治疗Hangman骨折患者12例(微创组),其中4例行单侧C2椎弓根螺钉内固定,8例行双侧C2椎弓根螺钉内固定;同期在C形臂X线机引导下开放手术治疗Hangman骨折患者10例(开放组),均行C2椎弓根螺钉和C3侧块螺钉内固定植骨融合术。记录手术时间、术中辐射剂量、出血量、螺钉精准度、术前和术后6个月颈部疼痛视觉模拟量表(VAS)评分及颈椎功能障碍指数(NDI)。结果所有手术顺利完成,所有患者随访 6个月。微创组手术时间及术中出血量均低于开放组,但术中透视辐射剂量明显高于开放组,差异均有统计学意义(P 0.05)。微创组术后6个月VAS评分及NDI均优于开放组,差异均有统计学意义(P 0.05)。2组共置入螺钉60枚,其中C2椎弓根螺钉40枚,C3侧块螺钉20枚,均无螺钉相关的神经、血管损伤。术后1级螺钉,微创组有85%(17/20),开放组有80%(32/40),组间比较差异无统计学意义(P 0.05),且2组均无3级螺钉。结论联合微创和术中三维成像技术,可以安全精准地治疗Hangman骨折,并可降低软组织剥离损伤和术中出血量,可以作为Hangman骨折微创治疗的选择之一。