Spine Surgery with Electronic Conductivity Device: A Prospectively Multicenter Randomized Clinical Trial and Literature Review

OBJECTIVE

Improving accuracy and safety of pedicle screw placement is of great clinical importance. Electronic conductivity device (ECD) can be a promising technique with features of affordability, portability, and real-time detection capabilities. This study aimed to validate the safety and effectiveness of a modified ECD.

METHODS

The ECD underwent a modification where six lamps of various colors, and it was utilized in a prospectively multicenter randomized controlled clinical trial involving 96 patients across three hospitals from June 2018 to December 2018. The trial incorporated a self-control randomization with an equal distribution of left or right side of vertebral pedicle among two groups: the free-hand group and the ECD group. A total of 496 pedicle screws were inserted, with 248 inserted in each group. The primary outcomes focused on the accuracy of pedicle screw placement and the frequency of intraoperative X-rays. Meanwhile, the secondary indicator measured the time required for pedicle screw placement. Results were presented as means ± SD. Paired samples t-test and χ2 -test were used for comparison. Furthermore, an updated review was conducted, which included studies published from 2006 onwards.

RESULTS

Baseline patient characteristics were recorded. The primary accuracy outcome revealed a 96.77% accuracy rate in the ECD group, compared to a 95.16% accuracy rate in the free-hand group, with no significant differences noted. In contrast, ECD demonstrated a significant reduction in radiation exposure frequency when compared to the free-hand group (1.11 ± 0.32 vs. 1.30 ± 0.53; p < 0.001), resulting in a 14.6% reduction. Moreover, ECD displayed a decrease of 30.38% in insertion time (70.88 ± 30.51 vs. 101.82 ± 54.00 s; p < 0.001). According to the results of the 21 studies, ECD has been utilized in various areas of the spine such as the atlas, thoracic and lumbar spine, as well as sacral 2-alar-iliac. The accuracy of ECD ranged from 85% to 100%.

CONCLUSION

The prospectively randomized trial and the review indicate that the use of ECD presents a secure and precise approach to the placement of pedicle screws, with the added benefit of reducing both procedure time and radiation exposure.

Spinolaminar locking plates improve fixation strength compared to pedicle screws: a biomechanical analysis

INTRODUCTION

Pedicle screw loosening is a significant complication of posterior spinal fixation, particularly among osteoporotic patients and in deformity constructs. In orthopedic trauma surgery, locking plates and screws have revolutionized the fixation of osteoporotic fractures. We have combined the traumatology principle of fixed-angle locking plate fixation with the spine principles of segmental instrumentation.

METHODS

A novel spinolaminar locking plate was designed based on morphometric studies of human thoracolumbar vertebrae. The plates were fixed to cadaveric human lumbar spines and connected to form 1-level L1-L2 or L4-L5 constructs and compared to similar pedicle screw constructs. Pure moment testing was performed to assess range of motion before and after 30,000 cycles of cyclic fatigue. Post-fatigue fixture pullout strength was assessed by applying a continuous axial tensile force oriented to the principal axis of the pedicle until pullout was observed.

RESULTS

Spinolaminar plate fixation resulted in superior pullout strength compared to pedicle screws (1,065 ± 400N vs. 714 ± 284N, p = 0.028). Spinolaminar plates performed equivalently to pedicle screws in range of motion reduction during flexion/extension and axial rotation. Pedicle screws outperformed the spinolaminar plates in lateral bending. Finally, no spinolaminar constructs failed during cyclic fatigue testing, whereas one pedicle screw construct did.

CONCLUSIONS

The spinolaminar locking plate maintained adequate fixation post-fatigue, particularly in flexion/extension and axial rotation compared to pedicle screws. Moreover, spinolaminar plates were superior to pedicle screw fixation with respect to cyclic fatiguing and pullout strength. The spinolaminar plates offer a viable option for posterior lumbar instrumentation in the adult spine.

A New Objective Radiographic Criteria for Diagnosis of Adult Idiopathic Scoliosis: Apical Pedicle Diameter Asymmetry

OBJECTIVE

We sought to test the hypothesis that a difference of ≥1 mm in pedicle diameter between the convex and concave pedicles at the apex of a lumbar curve is a sensitive and/or specific criteria for adult idiopathic scoliosis (AdIS).

METHODS

Thirty-nine operative patients with adult deformity and lumbar major curves were identified. A chart review was performed. Radiographic measurements included lumbar Cobb, curve apex, and Cobb levels involved. Apical pedicle diameter at the concavity and convexity of the curve apex were measured.

RESULTS

Among these 39 patients, the average Cobb angle was 48.3 degrees. Curve apex averaged at L1/2 (range L1-L3). The curves spanned 4.7 levels (range 3-7). Twenty-five curves had the apex to the left, while 14 had the apex to the right. The average pedicle diameter at the apex was 6.1 mm. Fourteen patients had apical pedicle diameter asymmetry (APDA) >1 mm. Most (7 of 8, or 87.5%) of the patients with a history of adult idiopathic scoliosis had APDA >1 mm. A minority (7 of 31, 22.5%) of patients without known history of adult idiopathic scoliosis had APDA >1 mm (P < 0.01).

CONCLUSIONS

Apical pedicle diameter asymmetry is among the sensitive diagnostic criteria for AdIS and may be useful for differentiating lumbar major AdIS from degenerative lumbar scoliosis. The sensitivity of APDA >1 mm is 87.5%, with specificity of 77.4%. We propose a new, sensitive radiographic criterion for adult idiopathic scoliosis. A difference of ≥1 mm in pedicle diameter between the convex and concave pedicles at that apex of a lumbar curve has a sensitivity of 87.5% and specificity of 77.4% for patient-reported history of adolescent scoliosis. It can be a useful tool as exclusion criteria for studies on AdIS.

The Feasibility of Multiple Fixation Points in C2

STUDY DESIGN

Analysis using three-dimensional simulation software for spinal screw placement and computed tomographic scan images.

PURPOSE

To assess the feasibility of achieving multiple (three or four) screw fixation points in C2 vertebra by using a combination of pedicle and laminar screws.

OVERVIEW OF LITERATURE

Secure C2 fixation using multiple screws is required or beneficial in some unique cases. However, to the best of our knowledge, there have been no reports analyzing the feasibility of multiple screw fixation in C2.

METHODS

We used 1.0-mm interval computed tomographic scan images of 100 patients (50 men and 50 women) and screw trajectory simulation software. The diameter of all screws was set at 3.5 mm, considering its common usage in real surgery. The anatomical feasibility of placing both pedicle and laminar screws on the same side was evaluated. For all feasible sides, the three-dimensional distance between the screw entry points was measured.

RESULTS

In 85% of cases, both pedicle and laminar screws could be placed on both sides, allowing for the insertion of 4 screws. In 11% of cases, 2 screws could be placed on one side, while only 1 screw was feasible on the other side, resulting in the placement of 3 screws. In all 181 sides where both types of screws could be inserted, the distance between their entry points exceeded 16.1 mm, which was sufficient to prevent the collision between the screw heads.

CONCLUSIONS

C2 vertebra can accommodate three (11%) or four (85%) screws in 96% of cases.

Does index-level pedicle screw instrumentation affect cage subsidence after vertebral body replacement? - A biomechanical study in human cadaveric osteoporotic specimens

BACKGROUND

Vertebral body replacement is a common surgical procedure for treatment of disorders associated with spinal instability. Therefore, pedicle screws are usually inserted in adjacent vertebrae for stabilization of the posterior column, however, there is lack of evidence whether implantation of index-level pedicle screws is beneficial or not. This biomechanical study aims to investigate the effect of pedicle screw instrumentation on axial stability following vertebral body replacement.

METHODS

Unstable fracture at L3 level was simulated in lumbar spines from six human cadaveric specimens. Then instrumentation was performed one level above / one level below index level in three specimens and further, three specimens were instrumented at index-level (L3) additionaly. Then we used a testing protocol for biomechanical evaluation of axial loading on human cadaveric lumbar spines until cage subsidence occurred.

FINDINGS

Our results show that index-level instrumented spines endured significantly higher load until cage subsidence occurred compared to non-index-level instrumented specimens (p = 0.05).

INTERPRETATION

Our results demonstrate pedicle screw instrumentation at index-level vertebra should be considered when possbile as it may have a protective effect against cage subsidence in patients undergoing vertebral body replacement surgery.

The pedicle screw accuracy using a robotic system and measured by a novel three-dimensional method

Robotics in medicine is associated with precision, accuracy, and replicability. Several robotic systems are used in spine surgery. They are all considered shared-control systems, providing "steady-hand" manipulation instruments. Although numerous studies have testified to the benefits of robotic instrumentations, they must address their true accuracy. Our study used the Mazor system under several situations and compared the spatial accuracy of the pedicle screw (PS) insertion and its planned trajectory. We used two cadaveric specimens with intact spinal structures from C7 to S1. PS planning was performed using the two registration methods (preopCT/C-arm or CT-to-fluoroscopy registration). After planning, the implant spatial orientation was defined based on six anatomic parameters using axial and sagittal CT images. Two surgical open and percutaneous access were used to insert the PS. After that, another CT acquisition was taken. Accuracy was classified into optimal, inaccurate and unacceptable according to the degree of screw deviation from its planning using the same spatial orientation method. Based on the type of spatial deviation, we also classified the PS trajectory into 16 pattern errors. Seven (19%) out of 37 implanted screws were considered unacceptable (deviation distances > 2.0 mm or angulation > 5°), and 14 (38%) were inaccurate (> 0.5 mm and ≤ 2.0 mm or > 2.5° and ≤ 5°). CT-to-fluoroscopy registration was superior to preopCT/C-arm (average deviation in 0.9 mm vs. 1.7 mm, respectively, p < 0.003), and percutaneous was slightly better than open but did not reach significance (1.3 mm vs. 1.7 mm, respectively). Regarding pattern error, the tendency was to have more axial than sagittal shifts. Using a quantitative method to categorize the screw 3D position, only 10.8% of the screws were considered unacceptable. However, with a more rigorous concept of inaccuracy, almost half were non-optimal. We also identified that, unlike some previous results, the O-arm registration delivers more accurate implants than the preopCT/C-arm method.

A finite element study and mathematical modeling of lumbar pedicle screw along with various design parameters

BACKGROUND

Lumbar pedicle screw is one of the most common and important elements in the field of lumbar surgery. It plays a great role in rectifying the spinal alignment and stabilization providing strength and stability to the affected area of spine. In spinal surgery, minimally invasive techniques and minor incisions are made which makes it less painful for the patients than the traditional methods. Moreover, the screws are not needed to be removed after the surgery which is yet another great advantage of the pedicle screw.

METHOD

In this study, 3D Finite Element (FE) model of human L4 vertebrae is taken for analysis using image processing tool. Pedicle screw design with varying mechanical and geometrical properties has been carried out at different applied loads on it along with considering the effect of frictional forces between all contact surfaces.

RESULT

Mathematical relationship among stress, strain, pitch of the screw and diameter have been developed for different thread profiles which will be beneficial for researchers for further development of pedicle screw implants.

CONCLUSION

Results from the different analysis shows that bending stress on the screw for different loads at triangular pitch is higher than the trapezoidal. Hence, trapezoidal thread is efficacious than triangular thread. In case of vertebral bone, the magnitude of stress is less for trapezoidal screw than triangular and stress has a linear relationship with pitch length. In term of strain, triangular thread develops more strain than trapezoidal thread. A set of mathematical relation has been developed for different thread profile based on pitch length, stress and strain which gives the idea about von Mises stress and strain.

Patient-specific guide systems decrease the major perforation rate of pedicle screw placement in comparison to the freehand technique for adolescent idiopathic scoliosis

PURPOSE

This study aimed to compare the accuracy of pedicle screw (PS) placement between a low-profile three-dimensional (3D) printed patient-specific guide system and freehand technique for adolescent idiopathic scoliosis (AIS) surgery.

METHODS

Patients with AIS who underwent surgery between 2018 and 2023 at our hospital were included in the study. The 3D-printed patient-specific guide was used since 2021 (guide group). PS perforation was classified using Rao and Neo's classification (grade 0, no violation; grade 1, < 2 mm; grade 2, 2-4 mm; grade 3, > 4 mm). Major perforations were defined as grades 2 or 3. The major perforation rate of PS, operative time, estimated blood loss (EBL), and correction rate were compared between the two groups.

RESULTS

A total of 576 PSs were inserted in 32 patients (20 patients in the freehand (FH) group and 12 patients in the guide group). The major perforation rate was significantly lower in the guide group than in the FH group (2.1% vs. 9.1%, p < 0.001). Significantly fewer major perforations were observed in the guide group than in the FH group in the upper thoracic (T2-4) region (3.2% vs. 20%, p < 0.001) and lower thoracic (T10-12) region (0% vs. 13.8%, p = 0.001). The operative time, EBL, and correction rate were equivalent between the two groups.

CONCLUSION

The 3D-printed patient-specific guide notably reduced the major perforation rate of PS without increasing EBL and operative time. Our findings indicate that this guide system is reliable and effective for AIS surgery.

Safety and accuracy of cannulated pedicle screw placement in scoliosis surgery: a comparison of robotic-navigation, O-arm-based navigation, and freehand techniques

PURPOSE

To compare the safety and accuracy of cannulated pedicle screw placement using a robotic-navigation technique, O-arm-based navigation technique, or freehand technique.

METHODS

This study analyzed 106 consecutive patients who underwent scoliosis surgery. Thirty-two patients underwent robotic-navigation-assisted pedicle screw insertion (Group 1), 34 patients underwent O-arm-based navigation-guided pedicle screw insertion (Group 2), and 40 patients underwent freehand pedicle screw insertion (Group 3). The primary outcome measure was the accuracy of screw placement. Secondary outcome parameters included operation time, blood loss, radiation exposure, and postoperative stay.

RESULTS

A total of 2035 cannulated pedicle screws were implanted in 106 patients. The accuracy rate of the first pedicle screw placement during operation was significantly greater in Group 1 (94.7%) than in Group 2 (89.2%; P < 0.001). The accuracy rate of pedicle screw placement postoperatively decreased in the order of Group 1 (96.7%) > Group 2 (93.0%) > Group 3 (80.4%; P < 0.01). There were no significant differences in blood loss or postoperative stay among the three groups (P > 0.05). The operation times of Group 1 and Group 2 were significantly longer than that of Group 3 (P < 0.05).

CONCLUSION

The robotic-navigation and O-arm-based navigation techniques effectively increased the accuracy and safety of pedicle screw insertion alternative to the freehand technique in scoliosis surgery. Compared with the O-arm-based navigation technique, the robotic-navigation technique increases the mean operation time, but also increases the accuracy of pedicle screw placement. A three-dimensional scan after insertion of the K-wire may increase the accuracy of pedicle screw placement in the O-arm-based navigation technique.

Cement-augmented pedicle screw for thoracolumbar degenerative diseases with osteoporosis: a systematic review and meta-analysis

BACKGROUND

Cement-augmentation pedicle screws have been widely used in spinal internal fixation surgery combined with osteoporosis in recent years, which can significantly improve the fixation strength, but compared with conventional methods, whether it has more advantages is still inconclusive of evidencebased medicine. To systematically evaluate the efficacy and safety of cement-augmented pedicle screw in the treatment of thoracolumbar degenerative diseases with osteoporosis.

METHODS

We searched PubMed, Embase, and Cochrane Library for studies published from the establishment of the database up until June 2023. We included studies that concerning the cement-augmented pedicle screw and the traditional pedicle screw placement for thoracolumbar degenerative diseases with osteoporosis. We excluded repeated publication, researches without full text, incomplete information or inability to conduct data extraction and animal experiments, case report, reviews and systematic reviews. STATA 15.1 software was used to analyze the data.

RESULTS

A total of 12 studies were included in this meta-analysis. The sample size of patients were totally 881, of which, 492 patients in cement-augmented screw group and 389 patients in conventional screw group. Meta-analysis results showed that Japanese Orthopaedic Association (JOA) score (WMD = 1.69, 95% CI 1.15 to 2.22), intervertebral space height (WMD = 1.66, 95% CI 1.03 to 2.29) and post-operation fusion rate (OR = 2.80, 95% CI 1.49 to 5.25) were higher in the cement-augmented screw group than those in the conventional screw group. Operation time was longer in the cement-augmented screw group than that in the conventional screw group (WMD = 15.47, 95% CI 1.25 to 29.70). Screw loosening rate was lower in the cement-augmented screw group than those in the conventional screw group (OR = 0.13, 95% CI 0.07 to 0.22). However, hospitalization time, intraoperative blood loss and Visual analog scale (VAS) score were not significantly different between the two groups (P > 0.05).

CONCLUSION

Compared with conventional pedicle screw placement, cement-augmented pedicle screw is more effective in the treatment of osteoporotic thoracolumbar degenerative disease by improving fusion rate and interbody height, reducing the incidence of screw loosening, and elevating long-term efficacy.

Comparison of the clinical effects of lamina replantation and screw fixation after laminectomy in the treatment of intraspinal tumours

INTRODUCTION

Intraspinal tumours are common diseases in neurosurgery and spinal surgery. Due to the fact that most of them are benign tumours, surgical resection is usually effective, and it is also the main treatment for these tumours. To maintain the stability of the spine and to reduce the incidence of kyphosis, pedicle screw fixation is required after traditional laminectomy, but there are many complications. In recent years, tumour resection and laminectomy have become increasingly favoured by clinicians. However, the comparison of the clinical effects of lamina complex replantation and pedicle screw fixation after laminectomy in the treatment of intraspinal tumours is still unknown. This paper systematically compared the two methods from many aspects and discussed their advantages and disadvantages to obtain better clinical guidance.

MATERIALS AND METHODS

In this study, a retrospective analysis was conducted to select 58 patients who underwent posterior approach tumour resection in the spinal surgery department of our hospital from January 2017 to January 2020. Among them, 32 patients underwent tumour resection and laminoplasty, and 26 patients underwent tumour resection and screw internal fixation. The age, sex, body mass index (BMI), smoking status, duration of symptoms, operation time, length of hospital stay, postoperative complications, amount of bleeding and other data were summarized, calculated and compared.

RESULTS

1. The age, sex, BMI, smoking status and symptom duration of the two groups were compared. The abovementioned results were not statistically significant. 2. The operation time, hospital stay, postoperative complications, intraoperative bleeding and adjacent segment degeneration (ASD) were counted and compared between the two groups. There was no significant difference in hospital stay or intraoperative bleeding between the two groups; in addition, the operation time, postoperative complications and incidence of ASD were statistically significant. 3. The visual analog scale (VAS) score, Oswestry Disability Index (ODI) score of thoracic and lumbar spines and Neck Disability Index (NDI) score of cervical spine patients in the two groups were counted, and the preoperative and postoperative data, as well as their changes, were counted and compared between groups and within groups. There was no statistical significance between the two groups; moreover, the postoperative scores were all significantly lower than preoperative in the group. 4. According to the spinal cord function ASIA grade, the preoperative, final follow-up and change values of the two groups were counted, and intragroup and intergroup comparisons were made. There was no significant difference between the two groups; in addition, the scores of the final follow-up were significantly higher than preoperative in the group. 5. The spinal mobility was measured and recorded before the operation and at the final follow-up. There was no significant difference between preoperative and postoperative cervical mobility, and there was no statistical significance observed; furthermore, the range of flexion, extension, rotation and lateral bending of the thoracic and lumbar spines in the screw fixation group was significantly lower than that in the lamina replantation group.

CONCLUSIONS

Lamina replantation can be used as splendid methods for the treatment of Intraspinal tumour. Lamina replantation can reduce the operation time, as well as reduce the occurrence of postoperative cerebrospinal fluid leakage, iatrogenic spinal stenosis, posterior soft tissue adhesion and ASD. These complications are reduced in comparison to the other mode of management and better preserve the mobility of the spine.

A novel radiographic analysis system for subaxial cervical spine pedicle screw placement

BACKGROUND

Precise pedicle screw placement of the subaxial cervical spine is difficult. Not every hospital is equipped with a guidance system that can provide effective help. Computed tomography (CT) scanning is almost a routine preoperative examination for cervical spine surgery in all hospitals. Appropriate measurement and analysis of the CT images could assist optimal cervical pedicle screw placement. The purpose of this study is to propose a new and universal method using computed tomography (CT) morphological parameters analysis to assist optimal cervical pedicle screw placement from C3 to C7.

METHODS

A localization system with six parameters was designed based on preoperative CT reconstruction to guide subaxial cervical spine pedicle screw placement. The six parameters were distance from the starting point to the midline [D1], distance from the starting point to the lower edge of the inferior articular process [D2], transverse section angle [TSA], sagittal section angle [SSA], pedicle width [PW], and pedicle height [PH]. The six parameters were analyzed in 53 participants.

RESULTS

Combining D1 and D2 could localize the entrance of the pedicle screw, and we concluded that D1 and TSA and D2 and SSA could be a new standard for determination of the transverse and sagittal orientation of the pedicle screw. The six parameters were closely related to the patient's gender, height, and weight. PH and PW were linearly correlated and could guide selection of the appropriate pedicle screw. SSA was an independent parameter of the relevant vertebral body, and changes in SSA had nothing to do with the curvature or posture of the cervical spine.

CONCLUSIONS

Understanding and applying the six-parameter localization system are essential for achieving accurate and optimal pedicle screw placement in subaxial cervical spine, regardless of cervical sagittal alignment.

Anatomical and imaging measurements of the angle between the axis of the lumbar pedicle and lateral isthmus margin and its clinical significance

BACKGROUND

This study aims to explore the measurement of the angle between the axis of the pedicle and the lateral margin of the isthmus on the lumbar spine, and investigate its clinical significance.

METHODS

The angle was measured on 120 normal adults' X-ray and 25 dry anatomical specimens. 60 screws were placed by junior residents on 6 wet specimens through the freehand technique. 30 screws were placed on one side with their original experience. After learning the techniques mentioned in the study, 30 screws were placed on the other side. The specimens were examined by X-ray and CT, and the angles of the screw paths and the integrity of the pedicle were evaluated.

RESULTS

The angles of 120 subjects and 25 anatomical specimens show a gradually increasing trend. The differences among each segment were statistically significant (P < 0.05), but the difference in the same segment between the X-ray and the anatomical specimens was not statistically significant (P > 0.05). Furthermore, the differences in L1, L2, and L3 between the two genders were not statistically significant (P > 0.05). However, the angles were larger in female group than in male group in L4 and L5, and the differences were statistically significant (P < 0.05). The difference in the deviation rate of screw placement before and after the learning was statistically significant only in the L5 segment (P < 0.05). The difference in overall excellence rate was statistically significant (P < 0.05).

CONCLUSIONS

The measurement of the angle between the axis of the pedicle and the lateral margin of the isthmus on the lumbar can improve the accuracy of the lumbar sagittal screw angle.

"Satellite pedicle screws" - A novel technique of pedicle screw insertion in obese patients undergoing lumbar fusion

The presence of thick sub-cutaneous fat and bulky paraspinal musculature mandates extensive surgical dissection in obese patients undergoing open Transforaminal lumbar interbody fusion surgery. Securing a 'converging' pedicle screw trajectory becomes difficult by the counterforces of the erector spinae muscles and thick sub-cutaneous fat in obese patients, especially at the L5-S1 level. We describe the use of a limited standard posterior midline exposure and a separate, far lateral 'satellite' incision to insert pedicle screws in an optimal trajectory in obese patients. Through proper pre-operative planning of the axial and sagittal MRI, the appropriate entry site is determined which is executed intra-operatively to insert pedicle screws freehand. Through a single 1.5 cm incision, both L5-S1 screws were inserted. Fourteen obese patients (mean BMI was 30.5 ± 1.1) received 56 satellite pedicle screws for TLIF at L5-S1 level. The mean age was 48.3 ± 9.7 years. The mean blood loss was 244.8 ± 114 ml and the mean operative time was 126.7 ± 82.8 min. In all patients, the screws were inserted as per pre-operative planning without any difficulties. All wounds healed well without wound complications. There were no screw related complications, and in the antero-posterior and lateral radiographs, there were no screw breaches. Satellite free-hand pedicle screws are safe and easily reproducible. They enable limited dissection of the main surgical wound and well-medialised converging pedicle screws in obese patients.

Operative Effect Comparison of Flexible Drill Guiding vs. Traditional Drill Guiding Template for Lower Cervical Pedicle Screw Insertion: A Retrospective Analysis

OBJECTIVE

Accurately inserting pedicle screws is the key point of posterior pedicle screw fixation for lower cervical spine (C3-C7) instability. 3D printing technology can improve the accuracy of screw placement. This study compared the safety of 3D-printed flexible drill guiding template vs. traditional rigid drill guiding template for lower cervical pedicle screw insertion.

METHODS

This was a retrospective study. A total of 34 patients who underwent lower cervical pedicle screw fixation from March 2018 to May 2021 were enrolled in this study, and they were divided into the flexible drill flexible drill group and the traditional drill group. A total of 18 patients in the flexible drill flexible drill group underwent pedicle screw fixation assisted by 3D printed flexible drill guiding templates for the lower cervix, and 16 patients in the traditional drill group underwent pedicle screw fixation assisted by 3D printed regular drill guiding templates for the lower cervix. The length of the incision and intraoperative blood loss during surgery were recorded and compared for the two groups. The grade, deviation of the screw entry point, deviation of the screw medial angle and screw length were measured and compared after surgery for the two groups by independent-sample tests.

RESULTS

There was a significant difference in the length of the incision and blood loss between the two groups (P < 0.05). There was a significant difference between the two groups for grade (P = 0.016). The deviation of the screw entry point was 0.65 ± 0.50 mm in the flexible drill group and 0.78 ± 0.83 mm in the traditional drill group. The deviation of the screw medial angle was 2.14 ± 1.78 in the flexible drill group and 4.23 ± 2.51 in the traditional drill group, with a significant difference between the two groups (P < 0.05).

CONCLUSION

Compared with regular guiding techniques, lower cervical pedicle screw placement assisted by multistep navigation templates and flexible K-wires results in less trauma and better safety.

Floor-Mounted Robotic Pedicle Screw Placement in Lumbar Spine Surgery: An Analysis of 1,050 Screws

OBJECTIVE

To analyze the usage of floor-mounted robot in minimally invasive lumbar fusion.

METHODS

Patients who underwent minimally invasive lumbar fusion for degenerative pathology using floor-mounted robot (ExcelsiusGPS) were included. Pedicle screw accuracy, proximal level violation rate, pedicle screw size, screw-related complications, and robot abandonment rate were analyzed.

RESULTS

Two hundred twenty-nine patients were included. Most surgeries were primary single-level fusion. Sixty-five percent of surgeries had intraoperative computed tomography (CT) workflow, 35% had preoperative CT workflow. Sixty-six percent were transforaminal lumbar interbody fusion, 16% were lateral, 8% were anterior, and 10% were a combined approach. A total of 1,050 screws were placed with robotic assistance (85% in prone position, 15% in lateral position). Postoperative CT scan was available for 80 patients (419 screws). Overall pedicle screw accuracy rate was 96.4% (prone, 96.7%; lateral, 94.2%; primary, 96.7%; revision, 95.3%). Overall poor screw placement rate was 2.8% (prone, 2.7%; lateral, 3.8%; primary, 2.7%; revision, 3.5%). Overall proximal facet and endplate violation rates were 0.4% and 0.9%. Average diameter and length of pedicle screws were 7.1 mm and 47.7 mm. Screw revision had to be done for 1 screw (0.1%). Use of the robot had to be aborted in 2 cases (0.8%).

CONCLUSION

Usage of floor-mounted robotics for the placement of lumbar pedicle screws leads to excellent accuracy, large screw size, and negligible screw-related complications. It does so for screw placement in prone/lateral position and primary/revision surgery alike with negligible robot abandonment rates.

Craniocaudal toggling increases the risk of screw loosening in osteoporotic vertebrae

BACKGROUND AND OBJECTIVE

Screw loosening remains a prominent problem for osteoporotic patients undergoing pedicle screw fixation surgeries but its underlying mechanisms are not fully understood. This study sought to examine the interactive effect of craniocaudal or axial cyclic loading (toggling) and osteoporosis on screw fixation.

METHODS

QCT-based finite element models of normal (n = 7; vBMD = 156 ± 13 mg/cm³) and osteoporotic vertebrae (n = 7; vBMD = 72 ± 6 mg/cm³) were inserted with pedicle screws and loaded with or without craniocaudal toggling. Among them, a representative normal vertebra (age: 55; BMD: 140 mg/cm³) and an osteoporotic vertebra (age: 64; BMD: 79 mg/cm³) were also loaded with or without axial toggling. The individual and interactive effects of craniocaudal toggling and osteoporosis on screw fixation strength (the force when the pull-up displacement of the screw head reached 1 mm) and bone tissue failure (characterized by equivalent plastic strain) were examined by repeated measure ANOVA.

RESULTS

A significant interactive effect between craniocaudal toggling and osteoporosis on screw fixation strength was detected (p = 0.008). Specifically, craniocaudal toggling led to a marked decrease in the fixation strength (68%, p < 0.05) and stiffness (83%, p < 0.05) only in the osteoporotic vertebrae but had no effect on screw fixation strength and stiffness of the normal vertebrae (p > 0.05). Likewise, most of the bone tissues around the screw in the osteoporotic vertebrae yielded following craniocaudal toggling whereas this result was not seen in the normal vertebrae. The axial toggling had no significant effect on bone tissue failure as well as pedicle screw fixation in normal or osteoporotic vertebrae.

CONCLUSIONS

Craniocaudal toggling substantially reduces the screw fixation strength of the osteoporotic vertebrae by progressively increasing tissue failure around the screw, and therefore may contribute to the higher rates of screw loosening in osteoporotic compared to normal patients, whereas axial toggling is not a risk factor for pedicle screw loosening in normal or osteoporotic patients.

Complication, fusion, and revision rate in the lumbar cortical bone trajectory and pedicle screw fixation techniques: a systematic review and meta-analysis

BACKGROUND

To obtain the complication rate, fusion rate, and revision rate of the lumbar cortical bone trajectory technique and pedicle screw fixation technique in lumbar interbody fusion surgery by single-arm meta-analysis and lay a basis for orthopedic surgeons to select the fixation techniques and perioperative management.

METHODS

PubMed, Ovid Medline, Web of Science, CNKI, and Wanfang databases were searched comprehensively. Data extraction, content analysis, and quality assessment of the literature were performed by two independent reviewers according to the Cochrane Collaboration guidelines using R and STATA software for single-arm meta-analysis.

RESULTS

The total complication rate of the lumbar cortical bone trajectory technique was 6%, including a hardware complication rate of 2%, ASD (adjacent segment degeneration) rate of 1%, wound infection rate of 1%, dural damage rate of 1%, hematoma rate tending to 0%, fusion rate of 94%, and revision rate of 1%. Lumbar pedicle screw fixation techniques had a total complication rate of 9%, with a hardware complication rate of 2%, ASD rate of 3%, wound infection rate of 2%, dural damage rate of 1%, hematoma rate tending to 0%, fusion rate of 94%, and revision rate of 5%. This study was registered with PROSPERO, CRD42022354550.

CONCLUSION

Lumbar cortical bone trajectory was associated with a lower total complication rate, ASD rate, wound infection rate, and revision rate than pedicle screw fixation. The cortical bone trajectory technique reduces the incidence of intraoperative and postoperative complications and can be an alternative in lumbar interbody fusion surgery.

[Treatment of spinal burst fractures with pedicle screw fixation at high altitude area]

OBJECTIVE

According to the characteristics of spinal burst fractures in high-altitude areas and the local medical conditions, to explore the clinical efficacy of short-segment fixation with pedicle screws combined with screw placement in injured vertebrae in the treatment of thoracolumbar burst fractures.

METHODS

From August 2018 to December 2021, 12 patients with single-vertebral thoracolumbar burst fractures without neurological symptoms were treated with injured vertebral screw placement technique, including 7 males and 5 females;aged 29 to 54 years old, with an average of(42.50±7.95) years old;6 cases of traffic accident injury, 4 cases of high fall injury, 2 cases of heavy object injury;2 cases of T₁₁, 4 cases of T₁₂, 3 cases of L₁, 2 cases of L₂, and 1 case of L₃. In the operation, screws were first placed in the upper and lower vertebrae of the fracture, pedicle screws were placed in the injured vertebra, and connecting rods were installed, and the fractured vertebral body was reset by positioning and distraction. Visual analogue scale (VAS) and Japanese Orthopedic Association (JOA) scoring were used to evaluate the changes in pain and quality of life of patients, and the kyphotic correction rate and correction loss rate of the injured segment were measured by X-ray.

RESULTS

All operations were successful without significant intraoperative complications. All 12 patients were followed up, the duration ranged from 9 to 27 months, with an mean of (17.75±5.79) months. VAS at 3 days after operation was significantly higher than that at admission (t=6.701, P=0.000). There was significant difference in JOA score between 9 months after operation and at admission (t=5.085, P=0.000). Three days after operation, Cobb angle was (4.42±1.16)°, and the correction rate was (82±5)% compared with (25.67±5.71)° at admission. Cobb angle was (5.08±1.24) °at 9 months after operation, with a corrected loss rate of (16±13)%. No loosening or breakage of internal fixation was found.

CONCLUSION

Under the high-altitude hypobaric and hypoxic environment, the effect of the operation should be ensured while reducing the trauma. The application of the technique of placing screws on the injured vertebra can effectively restore and maintain the height of the injured vertebra, with less bleeding and shorter fixed segments, which is an effective method.

Biomechanical evaluation of the hybrid pedicle screw-cortical bone trajectory technique in transforaminal lumbar interbody fusion to adjacent segment degeneration-finite element analysis

BACKGROUND

Transforaminal lumbar interbody fusion is an effective surgical treatment of intervertebral disk herniation. However, its clinical efficacy for adjacent segment disk degeneration (ASDD) after hybrid bilateral pedicle screw - bilateral cortical screw (pedicle screw at L4 and cortical bone trajectory screw at L5) and hybrid bilateral cortical screw - bilateral pedicle screw (bilateral cortical screw at L4 and bilateral pedicle screw at L5) remains undiscovered. Therefore, the aim of this study is to evaluate the effect of the hybrid bilateral pedicle screw - bilateral cortical screw and hybrid bilateral cortical screw - bilateral pedicle screw on the adjacent segment via a 3-dimensional (3D) finite element (FE) analysis.

METHODS

Four human cadaveric lumbar spine specimens were provided by the anatomy teaching and research department of Xinjiang Medical University. Four finite element models of L1-S1 lumbar spine segment were generated. For each of these, four lumbar transforaminal lumbar interbody fusion models at L4-L5 segment with the following instruments were created: hybrid bilateral pedicle screw - bilateral cortical screw, bilateral cortical screw - bilateral cortical screw (bilateral cortical screw at both L4 and L5 segments), bilateral pedicle screw - bilateral pedicle screw (bilateral pedicle screw at both L4 and L5 segments), and hybrid bilateral cortical screw - bilateral pedicle screw. A 400-N compressive load with 7.5 Nm moments was applied for the simulation of flexion, extension, lateral bending, and rotation. The range of motion of L3-L4 and L5-S1 segments and von Mises stress of the intervertebral disc at the adjacent segment were compared.

RESULTS

Hybrid bilateral pedicle screw - bilateral cortical screw has the lowest range of motion at L3-L4 segment in flexion, extension, and lateral bending, and the highest disc stress in all motions, while the range of motion at L5-S1 segment and disc stress was lower than bilateral pedicle screw - bilateral pedicle screw in flexion, extension, and lateral bending, and higher than bilateral cortical screw - bilateral cortical screw in all motions. The range of motion of hybrid bilateral cortical screw - bilateral pedicle screw at L3-L4 segment was lower than bilateral pedicle screw - bilateral pedicle screw and higher than bilateral cortical screw - bilateral cortical screw in flexion, extension, and lateral bending, and the range of motion at L5-S1 segment was higher than bilateral pedicle screw - bilateral pedicle screw in flexion, lateral bending, and axial rotation. The disc stress at L3-L4 segment was lowest and more dispersed in all motions, and the disc stress at L5-S1 segment was higher than bilateral pedicle screw - bilateral pedicle screw in lateral bending and axial rotation, but more dispersed.

CONCLUSION

Hybrid bilateral cortical screw - bilateral pedicle screw decreases the impact on adjacent segments after spinal fusion, reduces the iatrogenic injury to the paravertebral tissues, and provides throughout decompression of the lateral recess.

Multitrack and multianchor point screw technique combined with the Wiltse approach for lesion debridement for lumbar tuberculosis

BACKGROUND

The incidence of lumbar tuberculosis is high worldwide, and effective treatment is a continuing problem.

AIM

To study the safety and efficacy of the multitrack and multianchor point screw technique combined with the contralateral Wiltse approach for lesion debridement to treat lumbar tuberculosis.

METHODS

The C-reactive protein (CRP) level, erythrocyte sedimentation rate (ESR), visual analogue scale (VAS) score, oswestry disability index (ODI) and American Spinal Injury Association (ASIA) grade were recorded and analysed pre- and postoperatively.

RESULTS

The CRP level and ESR returned to normal, and the VAS score and ODI were decreased at 3 mo postoperatively, with significant differences compared with the preoperative values (P < 0.01). Neurological dysfunction was relieved, and the ASIA grade increased, with no adverse events.

CONCLUSION

The multitrack, multianchor point screw fixation technique combined with the contralateral Wiltse approach for debridement is an effective and safe method for the treatment of lumbar tuberculosis.

Comparison of short-term clinical outcomes between robot-assisted and freehand pedicle screw placement in spine surgery: a meta-analysis and systematic review

STUDY DESIGN

Meta-analysis and systematic review.

BACKGROUND

Robot-assisted pedicle screw placement technique offers greater accuracy than the traditional freehand screw placement technique. However, it is controversial whether there is a difference between the two procedures in terms of improved clinical outcomes.

MATERIALS AND METHODS

We systematically searched PubMed, EMBASE, Cochrane, and Web of Science to identify potentially eligible articles. Indispensable data such as the year of publication, study type, age, number of patients, sex distribution, and outcomes were extracted. The outcome indicators of interest included Oswestry disability index (ODI), visual analog scale (VAS) score, operative time, intraoperative blood loss, and post-operative length of stay. RevMan 5.4.1 was used for the meta-analysis.

RESULTS

A total of eight studies with 508 participants were included. Eight were related to ΔVAS, six were related to ΔODI, seven were related to operative time, five were related to intraoperative blood loss, and seven were related to the length of hospitalization. The results showed that, in terms of ΔVAS (95% CI, -1.20 to -0.36, P = 0.0003) and ΔODI (95% CI, -2.50 to -0.48, P = 0.004), robot-assisted pedicle screw placement technique scored higher than traditional freehand technique. Additionally, the intraoperative blood loss (95% CI, -140.34 to -10.94, P = 0.02) and the length of hospitalization (95% CI, -2.59 to -0.31, P = 0.01) for patients who underwent robotic-assisted pedicle screw placement were less than that of those who underwent the conventional freehand screw placement. No significant difference was found between robot-assisted techniques and conventional freehand techniques in pedicle screw placement in surgical time (95% CI, -2.24 to 26.32, P = 0.10).

CONCLUSIONS

Robot-assisted technique helps improve short-term clinical outcomes, reduce intraoperative blood loss and patient suffering, and shorten recovery time compared to the freehand technique.

Fast and versatile platform for pedicle screw insertion planning

PURPOSE

Computer-assisted surgical planning methods help to reduce the risks and costs in transpedicular fixation surgeries. However, most methods do not consider the speed and versatility of the planning as factors that improve its overall performance. In this work, we propose a method able to generate surgical plans in minimal time, within the required safety margins and accounting for the surgeon's personal preferences.

METHODS

The proposed planning module takes as input a CT image of the patient, initial-guess insertion trajectories provided by the surgeon and a reduced set of parameters, delivering optimal screw sizes and trajectories in a very reduced time frame.

RESULTS

The planning results were validated with quantitative metrics and feedback from surgeons. The whole planning pipeline can be executed at an estimated time of less than 1 min per vertebra. The surgeons remarked that the proposed trajectories remained in the safe area of the vertebra, and a Gertzbein-Robbins ranking of A or B was obtained for 95 % of them.

CONCLUSIONS

The planning algorithm is safe and fast enough to perform in both pre-operative and intra-operative scenarios. Future steps will include the improvement of the preprocessing efficiency, as well as consideration of the spine's biomechanics and intervertebral rod constraints to improve the performance of the optimisation algorithm.

The Fusion Rate of Cortical Bone Trajectory Screw Fixation and Pedicle Screw Fixations in L4-5 Interbody Fusion: A Retrospective Cohort Study

OBJECTIVE

Although cortical bone trajectory (CBT) screw fixation has been used for several years, the number of studies on its fusion effects is limited. Furthermore, several studies report conflicting outcomes. We aimed to compare the fusion rates and clinical efficacy of CBT screw fixation and pedicle screw (PS) fixation for L4-L5 interbody fusion.

METHODS

This study was a retrospective cohort control study. Patients with lumbar degenerative disease who underwent L4-L5 oblique lumbar interbody fusion (OLIF) or posterior decompression using CBT screws between February 2016 and February 2019 were included. Patients in whom PS was used were matched for age, sex, height, weight, and BMI. Record the operation time, blood loss. All enrolled patients underwent lumbar CT imaging at one-year follow-up to evaluate the fusion rate. At the two-year follow-up the visual analogue scale (VAS), Oswestry disability index (ODI), and Japanese Orthopaedic Association scores (JOA) were used to identify symptom improvement. Independent t-test was used for the comparison, and score data were analyzed using the χ² and exact probability tests.

RESULTS

A total of 144 patients with were included. All patients were followed-up postoperatively for 25-36 months (average 32.42 ± 10.55 months). Twenty-eight patients underwent OLIF and CBT screw fixation, 36 underwent OLIF and PS fixation, 32 underwent posterior decompression and CBT screw fixation, and 48 underwent posterior decompression and PS fixation. The fusion rates following CBT screw and PS fixations in OLIF were 92.86% (26/28) and 91.67% (33/36), respectively (P = 1). The fusion rates following CBT screw and PS fixations in posterior decompression were 93.75% (30/32) and 93.75% (45/48), respectively (P > 0.05). Regardless of OLIF or posterior decompression, there were no significant differences in the VAS, ODI, and JOA scores between patients treated with CBT and PS (P > 0.05).

CONCLUSION

CBT screw fixation can achieve a satisfactory interbody fusion rate with a clinical efficacy similar to that of PS in patients with lumbar degenerative disease, regardless of whether OLIF or posterior decompression was performed.

Hybrid pedicle screw and modified cortical bone trajectory technique in transforaminal lumbar interbody fusion at L4-L5 segment: finite element analysis

BACKGROUND

Investigate the biomechanical properties of the hybrid fixation technique with bilateral pedicle screw (BPS) and bilateral modified cortical bone trajectory screw (BMCS) in L4-L5 transforaminal lumbar interbody fusion (TLIF).

METHODS

 Three finite element (FE) models of the L1-S1 lumbar spine were established according to the three human cadaveric lumbar specimens. BPS-BMCS (BPS at L4 and BMCS at L5), BMCS-BPS (BMCS at L4 and BPS at L5), BPS-BPS (BPS at L4 and L5), and BMCS-BMCS (BMCS at L4 and L5) were implanted into the L4-L5 segment of each FE model. The range of motion (ROM) of the L4-L5 segment, von Mises stress of the fixation, intervertebral cage, and rod were compared under a 400-N compressive load with 7.5 Nm moments in flexion, extension, bending, and rotation.

RESULTS

 BPS-BMCS technique has the lowest ROM in extension and rotation, and BMCS-BMCS technique has the lowest ROM in flexion and lateral bending. The BMCS-BMCS technique showed maximal cage stress in flexion and lateral bending, and the BPS-BPS technique in extension and rotation. Compared to the BPS-BPS and BMCS-BMCS technique, BPS-BMCS technique presented a lower risk of screw breakage and BMCS-BPS technique presented a lower risk of rod breakage.

CONCLUSION

 The results of this study support that the use of the BPS-BMCS and BMCS-BPS techniques in TLIF surgery for offering the superior stability and a lower risk of cage subsidence and instrument-related complication.