Anatomical study of the C6 pedicle and lateral mass in children aged 0-14 years based on CT imaging.

OBJECTIVE: This study aims to investigate the anatomical structure of the C6 pedicle and lateral mass in children aged 0-14 years using CT imaging, providing detailed insights into their growth and development. METHODS: We conducted a comprehensive measurement of C6. Measurements included width, length, and height of the pedicles, as well as the length, width, and thickness of the lateral masses, and several angular metrics. Regression analysis was performed to understand the growth trends, and statistical analyses were carried out to identify differences between age groups, genders, and sides. RESULTS: In children younger than four years, the pedicle width exceeds its height, influencing the diameter of the pedicle screws. By age two to three, the pedicle height and lateral mass thickness reaches 3.0 mm, allowing for the use of 3.0 mm diameter screws. The pedicle transverse angle remains stable. Most parameters showed no significant differences between the left and right sides. Size parameters exhibited significant larger in males than females at ages 0-1, 3-7, and 10-12 years. Regression analysis revealed that the growth trends of size parameters follow cubic or polynomial curves. Most angular metrics follow cubic fitting curves without a clear trend of change with age. CONCLUSION: This study provides a detailed analysis of the anatomical development of the C6 pedicle and lateral masses in children, offering valuable insights for pediatric cervical spine surgeries. The findings highlight the importance of considering age-specific anatomical variations when planning posterior surgical fixation, specifically at C6. It is necessary for us to perform thin-layer CT scans on children and carefully measure various indicators before surgery.

Efficacy and safety of navigation robot-assisted versus conventional oblique lateral lumbar interbody fusion with internal fixation in the treatment of lumbar degenerative diseases: A retrospective study.

Effective internal fixation with pedicle screw is a key factor in the success of lumbar fusion with internal fixation. Whether navigation robots can improve the efficacy and safety of screw placement is controversial. Thirty-eight patients who underwent oblique lateral lumbar interbody fusion internal fixation from March 2022 to May 2023 were retrospectively analyzed, 16 cases in the navigational robot group and 22 cases in the fluoroscopy group. Using visual analog score (VAS) for the low back and lower limbs, Oswestry Disability Index to compare the clinical efficacy of the 2 groups; using perioperative indexes such as the duration of surgery, intraoperative blood loss, intraoperative fluoroscopy times, and postoperative hospital stay to compare the safety of the 2 groups; and using accuracy of pedicle screws (APS) and the facet joint violation (FJV) to compare the accuracy of the 2 groups. Postoperative follow-up at least 6 months, there was no statistically significant difference between the 2 groups in the baseline data (P > .05). The navigational robot group's VAS-back was significantly lower than the fluoroscopy group at 3 days postoperatively (P < .05). However, the differences between the 2 groups in VAS-back at 3 and 6 months postoperatively, and in VAS-leg and Oswestry Disability Index at 3 days, 3 months, and 6 months postoperatively were not significant (P > .05). Although duration of surgery in the navigational robot group was significantly longer than in the fluoroscopy group (P > .05), the intraoperative blood loss and the intraoperative fluoroscopy times were significantly lower than in the fluoroscopy group (P < .05). The difference in the PHS between the 2 groups was not significant (P > .05). The APS in the navigation robot group was significantly higher than in the fluoroscopy group, and the rate of FJV was significantly lower than in the fluoroscopy group (P < .05). Compared with the traditional fluoroscopic technique, navigation robot-assisted lumbar interbody fusion with internal fixation provides less postoperative low back pain in the short term, with less trauma, less bleeding, and lower radiation exposure, as well as better APS and lower FJV, resulting in better clinical efficacy and safety.

[Application of polyetheretherketone rod semi-rigid pedicle screw internal fixation in lumbar non-fusion surgery].

OBJECTIVE: To investigate the effect of Polyetheretherketone (PEEK) rod semi-rigid pedicle screw fixation system in lumbar spine non-fusion surgery. METHODS: A total of 74 patients with tow-level lumbar degenerative diseases who underwent surgery from March 2017 to December 2019 were divided into PEEK rod group and titanium rod group. In the PEEK rod group, there were 34 patients, including 13 males and 21 females, aged from 51 to 79 years old with an average of (62.4±6.8) years old;There were 1 patient of L1-L3 segments, 7 patients of L2-L4 segments, 20 patients of L3-L5 segments and 6 patients of L4-S1 segments. In the titanium rod group, there were 40 patients, including 17 males and 23 females, aged from 52 to 81 years old with an average of (65.2±7.3) years old;There were 3 patient of L1-L3 segments, 11 patients of L2-L4 segments, 19 patients of L3-L5 segments and 7 patients of L4-S1 segments. The general conditions of operation, such as operation time, intraoperative blood loss, postoperative drainage was recorded. The visual analogue scale (VAS) for low back pain and Oswestry disability index (ODI) were compared in preoperatively and postoperatively(3 months, 12 months and last follow-up) between two groups. The change of range of motion (ROM) was observed by flexion and extension x-ray of lumbar. RESULTS: All patients successfully completed the operation. The follow-up time ranged from 22 to 34 months with an average of(26.8±5.6) months. The operative time (142.2±44.7) min and intraoperative blood loss(166.5±67.4)ml in PEEK group were lower than those in titanium group [(160.7±57.3) min、(212.8±85.4) ml](P<0.05). There was no significant differences in postoperative drainage between the two groups (P>0.05). At the final follow-up visit, in PEEK group and titanium group VAS of low back pain[(0.8±0.4) points vs (1.0±0.5) points], VAS for leg pain [ (0.7±0.4) points vs (0.8±0.5) points] and ODI [(9.8±1.6)% vs (12.1±1.5)%] were compared with preoperative [ (5.8±1.1) points vs (6.0±1.1)points], [ (7.2±1.7) points vs (7.0±1.6) points], [(68.5±8.9)% vs(66.3±8.2)%] were significantly different(P<0.05). There was no significant difference in VAS scores between the two groups at each postoperative time point (P>0.05). At 3 months after surgery, there was no difference in ODI between the two groups (P>0.05). There were significant differences in ODI between PEEK group and titanium rod group at 12 months [(15.5±2.1)% vs (18.4±2.4)%] and at the last follow-up [(9.8±1.6)% vs (12.1±1.5)%] (P<0.05). The total range of motion (ROM) of lumbar decreased in both groups after surgery. At 12 months after surgery and the last follow-up, the PEEK group compared with the titanium rod group, the total range of motion of lumbar was statistically significant (P<0.05). The range of motion (ROM) of the fixed segments decreased in both groups after surgery. The ROM of the fixed segments in PEEK group decreased from (9.5±4.6)° to (4.1±1.9)° at the last follow-up (P<0.05), which in the titanium rod group was decreased from (9.8±4.3)°to (0.9±0.5)° at the last follow-up (P<0.05). The range of motion (ROM) of upper adjacent segment increased in both groups, there was statistical significance in the ROM of upper adjacent segment between the two groups at 12 months after surgery and the last follow-up, (P<0.05). There was no screw loosening and broken rods in both groups during the follow-up period. CONCLUSION: The PEEK rod semi-rigid pedicle screw internal fixation system used in lumbar non-fusion surgery can retain part of the mobility of the fixed segment, showing comparable short-term clinical efficacy to titanium rod fusion. PEEK rod semi-rigid pedicle screw internal fixation system is a feasible choice for the treatment of lumbar spine degenerative diseases, and its long-term efficacy needs further follow-up observation.

Clinical performance of implanted devices used in surgical treatment of patients with spinal tumors: a systematic review.

PURPOSE: Implanted devices used in metastatic spine tumor surgery (MSTS) include pedicle screws, fixation plates, fixation rods, and interbody devices. A material to be used to fabricate any of these devices should possess an array of properties, which include biocompatibility, no toxicity, bioactivity, low wear rate, low to moderate incidence of artifacts during imaging, tensile strength and modulus that are comparable to those of cortical bone, high fatigue strength/long fatigue life, minimal or no negative impact on radiotherapy (RT) planning and delivery, and high capability for fusion to the contiguous bone. The shortcomings of Ti6Al4V alloy for these applications with respect to these desirable properties are well recognized, opening the field for an investigation about novel biomaterials that could replace the current gold standard. Previously published reviews on this topic have exhibited significant shortcomings in the studies they included, such as a small, heterogenous sample size and the lack of a cost-benefit analysis, extremely useful to understand the practical possibility of applying a novel material on a large scale. Therefore, this review aims to collect information about the clinical performance of these biomaterials from the most recent literature, with the objective of deliberating which could potentially be better than titanium in the future, with particular attention to safety, artifact production and radiotherapy planning interference. The significant promise showed by analyzing the clinical performance of these devices warrants further research through prospective studies with a larger sample size also taking into account each aspect of the production and use of such materials. METHODS: The Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines were used to improve the reporting of the review. The search was performed from March 2022 to September 2023. RESULTS: At the end of the screening process, 20 articles were considered eligible for this study. Polyetheretherketone (PEEK), Carbon-fibre reinforced polyetheretherketone (CFR-PEEK), long carbon fiber reinforced polymer (LCFRP), Polymethylmethacrylate (PMMA), and carbon screw and rods were used in the included studies. CONCLUSION: CFR-PEEK displays a noninferior safety and efficacy profile to titanium implanted devices. However, it also has other advantages. By decreasing artifact production, it is able to increase detection of local tumor recurrence and decrease radiotherapy dose perturbation, ultimately bettering prognosis for patients necessitating adjuvant treatment. Nonetheless, its drawbacks have not been explored fully and still require further investigation in future studies. This does not exclude the fact that CFR-PEEK could be a valid alternative to titanium in the near future.

Individualized Design Application of 3-Dimensional Printing Navigational Template for Pedicle Screw Installation: A Training Case Report.

BACKGROUND The proper installation for pedicle screws by the traditional method of surgeons dependent on experience is not guaranteed, and educational solutions have progressed from chalkboards to electronic teaching platforms. We designed a case of 3-dimensional printing drill guide template as a surgical application, which can accurately navigate implantation of pedicle screws, and assessed its effect for simulative training. MATERIAL AND METHODS We randomly selected a set of computed tomography data for spondylolisthesis. A navigational template of pedicles and screws was designed by software Mimics and Pro-E, where trajectories of directions and angles guiding the nail way were manipulated for screwing based on anatomy, and its solid model was fabricated by a BT600 3D printer. The screws were integrated and installed to observe their stability. RESULTS The navigational model and custom spine implants were examined to be compatibly immobilized, because they are tolerant to radiation and stable against hydrolysis. The screw size and template were fit accurately to the vertebrae intraosseously, because the pilot holes were drilled and the trajectories were guided by cannulas with visible routes. During the surgical workflow, the patient reported appreciation and showed substantial compliance, while having few complications with this approach. Compared with fluoroscopy-assisted or free-hand techniques, the effect of simulative training during processing was excellent. CONCLUSIONS The surgical biomodel is practical for the procedural accuracy of surgical guides or as an educational drill. This fostering a style of "practice substituting for teaching" sets a paragon of keeping up with time and is worthy of recommendation.

Injectable bone cement cannulated pedicle screw for lumbar degenerative disease in osteoporosis - clinical follow-up of over 5 years.

OBJECTIVE: The aim of this study is to evaluate the clinical efficacy of injectable cemented hollow pedicle screw (CICPS) in the treatment of osteoporotic lumbar degenerative diseases through a large sample long-term follow-up study. Additionally, we aim to explore the risk factors affecting interbody fusion. METHODS: A total of 98 patients who underwent CICPS for transforaminal lumbar interbody fusion (TLIF) for osteoporotic lumbar degenerative disease from March 2011 to September 2017 were analyzed. X-ray and electronic computed tomography (CT) imaging data were collected during preoperative, postoperative, and follow-up periods. The data included changes in intervertebral space height (ΔH), screw failure, cement leakage (CL), and intervertebral fusion. The patients were divided into two groups based on their fusion status one year after surgery: satisfied group A and dissatisfied group B. Surgical data such as operation time, intraoperative bleeding volume and surgical complications were recorded, and visual analog scale (VAS) and Oswestry disability index (ODI) were used to evaluate the improvement of lumbar and leg pain. RESULTS: The mean follow-up time was 101.29 months (ranging from 70 to 128 months). A total of 320 CICPS were used, with 26 screws (8.13%) leaking, 3 screws (0.94%) experiencing cement augmentation failure, and 1 screw (0.31%) becoming loose and breaking. The remaining screws were not loose or pulled out. Female gender, decreased bone density, and CL were identified as risk factors affecting interbody fusion (P < 0.05). Early realization of interbody fusion can effectively prevent the loss of intervertebral space height (P < 0.05) and maintain the surgical treatment effect. Both VAS and ODI scores showed significant improvement during the follow-up period (P < 0.05). Binary logistic regression analysis revealed that decreased bone density and cement leakage were risk factors for prolonged interbody fusion. CONCLUSIONS: The results of long-term follow-up indicate that PMMA enhanced CICPS has unique advantages in achieving good clinical efficacy in the treatment of osteoporosis lumbar degenerative diseases. Attention should be paid to identify female gender, severe osteoporosis, and CL as risk factors affecting interbody fusion.

Fully automated determination of robotic pedicle screw accuracy and precision utilizing computer vision algorithms.

Historically, pedicle screw accuracy measurements have relied on CT and expert visual assessment of the position of pedicle screws relative to preoperative plans. Proper pedicle screw placement is necessary to avoid complications, cost and morbidity of revision procedures. The aim of this study was to determine accuracy and precision of pedicle screw insertion via a novel computer vision algorithm using preoperative and postoperative computed tomography (CT) scans. Three cadaveric specimens were utilized. Screw placement planning on preoperative CT was performed according to standard clinical practice. Two experienced surgeons performed bilateral T2-L4 instrumentation using robotic-assisted navigation. Postoperative CT scans of the instrumented levels were obtained. Automated segmentation and computer vision techniques were employed to align each preoperative vertebra with its postoperative counterpart and then compare screw positions along all three axes. Registration accuracy was assessed by preoperatively embedding spherical markers (tantalum beads) to measure discrepancies in landmark alignment. Eighty-eight pedicle screws were placed in 3 cadavers' spines. Automated registrations between pre- and postoperative CT achieved sub-voxel accuracy. For the screw tip and tail, the mean three-dimensional errors were 1.67 mm and 1.78 mm, respectively. Mean angular deviation of screw axes from plan was 1.58°. For screw mid-pedicular accuracy, mean absolute error in the medial-lateral and superior-inferior directions were 0.75 mm and 0.60 mm, respectively. This study introduces automated algorithms for determining accuracy and precision of planned pedicle screws. Our accuracy outcomes are comparable or superior to recent robotic-assisted in vivo and cadaver studies. This computerized workflow establishes a standardized protocol for assessing pedicle screw placement accuracy and precision and provides detailed 3D translational and angular accuracy and precision for baseline comparison.

Comparison of robot-assisted versus fluoroscopy-guided transforaminal lumbar interbody fusion (TLIF) for lumbar degenerative diseases: a systematic review and meta-analysis of randomized controlled trails and cohort studies.

BACKGROUND: As an emerging technology in robot-assisted (RA) surgery, the potential benefits of its application in transforaminal lumbar interbody fusion (TLIF) lack substantial support from current evidence. OBJECTIVE: We aimed to investigate whether the RA TLIF is superior to FG TLIF in the treatment of lumbar degenerative disease. METHODS: We systematically reviewed studies comparing RA versus FG TLIF for lumbar degenerative diseases through July 2022 by searching PubMed, Embase, Web of Science, CINAHL (EBSCO), Chinese National Knowledge Infrastructure (CNKI), WanFang, VIP, and the Cochrane Library, as well as the references of published review articles. Both cohort studies (CSs) and randomized controlled trials (RCTs) were included. Evaluation criteria included the accuracy of percutaneous pedicle screw placement, proximal facet joint violation (FJV), radiation exposure, duration of surgery, estimated blood loss (EBL), and surgical revision. Methodological quality was assessed using the Cochrane risk of bias and ROBINS-I Tool. Random-effects models were used, and the standardized mean difference (SMD) was employed as the effect measure. We conducted subgroup analyses based on surgical type, the specific robot system used, and the study design. Two investigators independently screened abstracts and full-text articles, and the certainty of evidence was graded using the GRADE (Grading of Recommendations Assessment, Development and Evaluation) approach. RESULTS: Our search identified 539 articles, of which 21 met the inclusion criteria for quantitative analysis. Meta-analysis revealed that RA had 1.03-folds higher "clinically acceptable" accuracy than FG (RR: 1.0382, 95% CI: 1.0273-1.0493). And RA had 1.12-folds higher "perfect" accuracy than FG group (RR: 1.1167, 95% CI: 1.0726-1.1626). In the case of proximal FJV, our results indicate a 74% reduction in occurrences for patients undergoing RA pedicle screw placement compared to those in the FG group (RR: 0.2606, 95%CI: 0.2063- 0.3293). Seventeen CSs and two RCTs reported the duration of time. The results of CSs suggest that there is no significant difference between RA and FG group (SMD: 0.1111, 95%CI: -0.391-0.6131), but the results of RCTs suggest that the patients who underwent RA-TLIF need more surgery time than FG (SMD: 3.7213, 95%CI: 3.0756-4.3669). Sixteen CSs and two RCTs reported the EBL. The results suggest that the patients who underwent RA pedicle screw placement had fewer EBL than FG group (CSs: SMD: -1.9151, 95%CI: -3.1265-0.7036, RCTs: SMD: -5.9010, 95%CI: -8.7238-3.0782). For radiation exposure, the results of CSs suggest that there is no significant difference in radiation time between RA and FG group (SMD: -0.5256, 95%CI: -1.4357-0.3845), but the patients who underwent RA pedicle screw placement had fewer radiation dose than FG group (SMD: -2.2682, 95%CI: -3.1953-1.3411). And four CSs and one RCT reported the number of revision case. The results of CSs suggest that there is no significant difference in the number of revision case between RA and FG group (RR: 0.4087,95% CI 0.1592-1.0495). Our findings are limited by the residual heterogeneity of the included studies, which may limit the interpretation of the results. CONCLUSION: In TLIF, RA technology exhibits enhanced precision in pedicle screw placement when compared to FG methods. This accuracy contributes to advantages such as the protection of adjacent facet joints and reductions in intraoperative radiation dosage and blood loss. However, the longer preoperative preparation time associated with RA procedures results in comparable surgical duration and radiation time to FG techniques. Presently, FG screw placement remains the predominant approach, with clinical surgeons possessing greater proficiency in its application. Consequently, the integration of RA into TLIF surgery may not be considered the optimal choice. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42023441600.

Adolescent idiopathic scoliosis: a prospective randomised trial protocol comparing clinical and radiological outcomes in minimally invasive surgery versus standard posterior spinal fusion in a single-centre, the Rizzoli Orthopaedic Institute, Bologna, Italy.

INTRODUCTION: Minimally invasive spine surgery (MISS) has been shown to be safe and effective in adolescent idiopathic scoliosis (AIS) correction, even though there is no consensus on which treatment provides the best results. METHODS AND ANALYSIS: The present study will be a randomised controlled trial with allocation 1:1. We will enrol 126 patients with Cobb≤70° undergoing AIS surgery. Patients will be divided into two groups, according to a randomisation list unknown to the surgeons. Group 1 will be treated with posterior spine fusion and group 2 with MISS. MISS technique: two midline noncontiguous skin incisions of 3 cm in length, 3-4 segments (6-8 pedicles screws) instrumented per skin incision, uniplanar and polyaxial pedicle screws inserted bilaterally on each side of the proximal and distal levels, rod translation manoeuvre and C-D manoeuvre performed on the distal part. Clinical and radiological follow-ups will be performed for 5 years. Values of Cobb angles degrees will be collected to study the correction rate of the structural major curve. Postoperative and preoperative anterior-posterior (AP) direct radiography will be compared with the last follow-up examination. Operative time, preoperative haemoglobin (Hb) and second postoperative day Hb, full length of hospitalisation, time to achieve verticalisation and time to remove the drainage will be recorded. Numeric Rating Scale (NRS) medium score will be assessed immediately after surgery and during the whole postoperative rehabilitation treatment to estimate pain reduction. Complications will be collected postoperatively and throughout the whole follow-up period.Moreover, questionnaires will be administered at follow-up (NRS, Scoliosis Research Society-22 and Oswestry Disability Index) for the clinical assessment. ETHICS AND DISSEMINATION: The study protocol has been approved by the local ethic committee Area Vasta Emilia Romagna Centro. Written informed consent will be collected for all the participants. Findings of this study will be disseminated through peer-reviewed publications and conference presentations. TRIAL REGISTRATION NUMBER: NCT05860673.

Pars interarticularis screws for posterior cervical fusion - investigating a new trajectory using a CT-based multiplanar reconstruction: Part I.

BACKGROUND: Lateral mass screw fixation is the standard for posterior cervical fusion between C3 and C6. Traditional trajectories stabilize but carry risks, including nerve root and vertebral artery injuries. Minimally invasive spine surgery (MISS) is gaining popularity, but trajectories present anatomical challenges. RESEARCH QUESTION: This study proposes a novel pars interarticularis screw trajectory to address these issues and enhance in-line instrumentation with cervical pedicle screws. MATERIALS AND METHODS: A retrospective analysis of reformatted cervical CT scans included 10 patients. Measurements of the pars interarticularis morphology were performed on 80 segments (C3-C6). Two pars interarticularis screw trajectories were evaluated: Trajectory A (upper outer quadrant entry, horizontal trajectory) and Trajectory B (lower outer quadrant entry, cranially pointed trajectory). These were compared to standard lateral mass and cervical pedicle screw trajectories, assessing screw lengths, angles, and potential risks to the spinal canal and transverse foramen. RESULTS: Trajectory B showed significantly longer pars lengths (15.69 ± 0.65 mm) compared to Trajectory A (12.51 ± 0.24 mm; p < 0.01). Lateral mass screw lengths were comparable to pars interarticularis screw lengths using Trajectory B. Both trajectories provided safe angular ranges, minimizing the risk to delicate structures. DISCUSSION: and Conclusion. Pars interarticularis screws offer a viable alternative to lateral mass screws for posterior cervical fusion, especially in MISS contexts. Trajectory B, in particular, presents a feasible and safe alternative, reducing the risk of vertebral artery and spinal cord injury. Preoperative assessment and intraoperative technologies are essential for successful implementation. Biomechanical validation is needed before clinical application.

Impact of screw tip design on screw anchorage: mechanical testing and numerical simulation.

BACKGROUND: Screw loosening is a commonly reported issue following spinal screw fixation and can lead to various complications. The initial cause of screw loosening is biomechanical deterioration. Previous studies have demonstrated that modifications in screw design can impact the local biomechanical environment, specifically the stress distribution on bone-screw interfaces. There are several different designs of screw tips available for clinically used pedicle screws; however, it remains unclear whether these variations affect the local stress distribution and subsequent screw anchorage ability. METHODS: This study conducted comprehensive biomechanical research using polyurethane foam mechanical tests and corresponding numerical simulations to investigate this topic. Models of pedicle screw-fixed osteoporotic polyurethane foam were created with two different clinically used screw tip designs (flat and steep) featuring varying tip lengths, taper angles, and diameters, as well as identical flank overlap areas and thread designs. The anchorage ability of the different models was assessed through toggle and pull-out test. Additionally, numerical mechanical models were utilized to compute the stress distributions at the screw and bone-screw interfaces in the different models. RESULTS: Mechanical tests revealed superior anchorage ability in models utilizing flat-tipped screws. Furthermore, numerical modeling indicated improved anchorage ability and reduced stress concentration tendency in these models. CONCLUSION: Changes in screw tip design can significantly impact the biomechanical anchoring capability of screws. Specifically, flatter tip pedicle screws may mitigate the risk of screw loosening by alleviating stress concentration on bone-screw interfaces.

Single-position oblique lumbar interbody fusion with navigation: improved efficiency and screw accuracy compared to dual-position with fluoroscopy.

Dual-position oblique lumbar interbody fusion with fluoroscopy (D-OLIF) requires repositioning the patient to a prone position for pedicle screw insertion. Recently, single-position surgery with navigation has been introduced. However, there are concerns regarding pedicle screw accuracy and achieving appropriate sagittal balance in single-position OLIF with navigation (S-OLIF). The purpose of this study is to evaluate the clinical and radiological outcomes of S-OLIF compared to D-OLIF. A retrospective analysis was conducted on 102 patients who underwent single-level OLIF at a single institution. The patients were divided into two groups: 55 in the S-OLIF group and 47 in the D-OLIF group. The numeric rating scale for back and leg, Oswestry disability index, and walking distance improvements showed no significant difference. However, the EuroQol 5-dimension 5-level index showed higher improvement in the S-OLIF (P = 0.029). The segmental lordosis, lumbar lordosis, and C7 sagittal vertical axis showed no significant difference. S-OLIF had significantly fewer cases of pedicle screw malposition (P = 0.045). Additionally, the surgery time was shorter in the S-OLIF (P = 0.002). In conclusion, S-OLIF exhibited clinical and radiological outcomes comparable to D-OLIF, with the added advantages of reduced surgery time and enhanced accuracy in pedicle screw placement.

Robotic assisted surgery for the treatment of spinal metastases: A case series.

OBJECTIVE: Spinal metastases can significantly affect quality of life in patients with cancer and present complex neurosurgical challenges for surgeons. Surgery with instrumentation is often indicated to alleviate pain, preserve neurological function, and ensure mechanical stability. However, distortions in the bony anatomy due to oncological disease can decrease the accuracy of pedicle screw placement. Robotic-assisted surgery may offer an opportunity to increase screw accuracy and improve navigation of spinal lesions compared to conventional techniques. Therefore, we presented our institutional experience evaluating robotic-assisted surgical fixation for spinal metastases. METHODS: Patients undergoing robotic-assisted surgery at a large tertiary care center between January 2019 - January 2023 for the treatment of spinal metastases were identified. Patient characteristics, including demographics, tumor pathology, surgical complications, and post-operative outcomes were extracted. The Gertzbein Robbins classification system (GRS) was used to assess pedicle screw placement accuracy in patients with post-operative computed tomography. RESULTS: Twenty patients were identified, including 7 females (35 %), with an overall median age of 66 years (range: 39-80 years) and median BMI of 25 kg/m2 (range: 17-34 kg/m2). An average of four spinal levels were instrumented, with metastases located primarily in the thoracic (n=17, 85 %) spine. Common primary tumor types included prostate (n=4), lung (n=2), and plasma cell (n=2) cancers. Most pedicle screws (92 %) were classified as GRS A in patients with postoperative imaging. Post-operative complications were unrelated to the use of the robot, and included pulmonary embolism (n=1), deep vein thrombosis (n=2), and gastric symptoms (n=3). Three patients were readmitted at 30 days, with one reoperation due to tumor recurrence. Four patients were deceased within 6 months of surgery. CONCLUSIONS: Despite the inherent high-risk nature of these surgeries, this study underscores the safety and efficacy of robotic-assisted surgery in the management of spinal metastases. Robots can be helpful in ensuring accuracy of pedicle screw placement in patients with metastatic disease.

Pedicle screw insertion into infected vertebrae reduces operative time and range of fixation in minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis: a multicenter retrospective cohort study.

BACKGROUND: Minimally invasive posterior fixation surgery for pyogenic spondylitis is known to reduce invasiveness and complication rates; however, the outcomes of concomitant insertion of pedicle screws (PS) into the infected vertebrae via the posterior approach are undetermined. This study aimed to assess the safety and efficacy of PS insertion into infected vertebrae in minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis. METHODS: This multicenter retrospective cohort study included 70 patients undergoing minimally invasive posterior fixation for thoracolumbar pyogenic spondylitis across nine institutions. Patients were categorized into insertion and skip groups based on PS insertion into infected vertebrae, and surgical data and postoperative outcomes, particularly unplanned reoperations due to complications, were compared. RESULTS: The mean age of the 70 patients was 72.8 years. The insertion group (n = 36) had shorter operative times (146 versus 195 min, p = 0.032) and a reduced range of fixation (5.4 versus 6.9 vertebrae, p = 0.0009) compared to the skip group (n = 34). Unplanned reoperations occurred in 24% (n = 17) due to surgical site infections (SSI) or implant failure; the incidence was comparable between the groups. Poor infection control necessitating additional anterior surgery was reported in four patients in the skip group. CONCLUSIONS: PS insertion into infected vertebrae during minimally invasive posterior fixation reduces the operative time and range of fixation without increasing the occurrence of unplanned reoperations due to SSI or implant failure. Judicious PS insertion in patients with minimal bone destruction in thoracolumbar pyogenic spondylitis can minimize surgical invasiveness.

Biomechanical analysis of adjacent segments after correction surgery for adult idiopathic scoliosis: a finite element analysis.

The biomechanical aspects of adjacent segment degeneration after Adult Idiopathic Scoliosis (AdIS) corrective surgery involving postoperative changes in motion and stress of adjacent segments have yet to be investigated. The objective of this study was to evaluate the biomechanical effects of corrective surgery on adjacent segments in adult idiopathic scoliosis by finite element analysis. Based on computed tomography data of the consecutive spine from T1-S1 of a 28-year-old male patient with adult idiopathic scoliosis, a three-dimensional finite element model was established to simulate the biomechanics. Two posterior long-segment fixation and fusion operations were designed: Strategy A, pedicle screws implanted in all segments of both sides, and Strategy B, alternate screws instrumentation on both sides. The range of motion (ROM), Maximum von Mises stress value of intervertebral disc (IVD), and Maximum von Mises stress of the facet joint (FJ) at the fixation adjacent segment were calculated and compared with data of the preoperative AdIS model. Corrective surgery decreased the IVD on the adjacent segments, increased the FJ on the adjacent segments, and decreased the ROM of the adjacent segments. A greater decrease of Maximum von Mises stress was observed on the distal adjacent segment compared with the proximal adjacent segment. The decrease of Maximum von Mises stress and increment of Maximum von Mises stress on adjacent FJ in strategy B was greater than that in strategy A. Under the six operation modes, the change of the Maximum von Mises stress on the adjacent IVD and FJ was significant. The decrease in ROM in the proximal adjacent segment was greater than that of the distal adjacent segment, and the decrease of ROM in strategy A was greater than that in strategy B. This study clarified the biomechanical characteristics of adjacent segments after AdIS corrective surgery, and further biomechanical analysis of two different posterior pedicle screw placement schemes by finite element method. Our study provides a theoretical basis for the pathogenesis, prevention, and treatment of adjacent segment degeneration after corrective surgery for AdIS.

Retrieval analysis of PEEK rods pedicle screw system: three cases analysis.

PURPOSE: To analyze the characteristics of PEEK rods retrieved in vivo, specifically their wear and deformation, biodegradability, histocompatibility, and mechanical properties. METHOD: Six PEEK rods were retrieved from revision surgeries along with periprosthetic tissue. The retrieved PEEK rods were evaluated for surface damage and internal changes using Micro-CT, while light and electron microscopy were utilized to determine any histological changes in periprosthetic tissues. Patient history was gathered from medical records. Two intact and retrieved PEEK rods were used for fatigue testing analysis by sinusoidal load to the spinal construct. RESULTS: All implants showed evidence of plastic deformation around the screw-rod interface, while the inner structure of PEEK rods appeared unchanged with no visible voids or cracks. Examining images captured through light and electron microscopy indicated that phagocytosis of macrophages around PEEK rods was less severe in comparison to the screw-rod interface. The results of an energy spectrum analysis suggested that the distribution of tissue elements around PEEK rods did not differ significantly from normal tissue. During fatigue testing, it was found that the retrieved PEEK rods cracked after 1.36 million tests, whereas the intact PEEK rods completed 5 million fatigue tests without any failure. CONCLUSION: PEEK rods demonstrate satisfactory biocompatibility, corrosion resistance, chemical stability, and mechanical properties. Nevertheless, it is observed that the indentation at the junction between the nut and the rod exhibits relatively weak strength, making it susceptible to breakage. As a precautionary measure, it is recommended to secure the nut with a counter wrench, applying the preset torque to prevent overtightening.

Comparative effectiveness of cortical bone trajectory screws and pedicle screws in the treatment of adjacent segment degeneration after lumbar fusion surgery: a systematic review and meta-analysis.

PURPOSE: To compare the efficacy and safety of cortical bone trajectory (CBT) screw and pedicle screw (PS) internal fixation in the treatment of adjacent segment degeneration (ASD) after lumbar fusion. METHODS: This study was registered on International Prospective Register of Systematic Reviews (PROSPERO) (ID: CRD42023484937). We searched PubMed, Embase, Web of Science, Cochrane Library, China National Knowledge Infrastructure (CNKI), Wan Fang Database, and Wei Pu Database by computer to collect controlled clinical studies on the efficacy and safety of cortical bone trajectory (CBT) screw and pedicle screw (PS) internal fixation in the treatment of adjacent segment degeneration (ASD) after lumbar fusion from database establishment to November 2023. Two researchers screened the literature, extracted data and evaluated the risk of bias of the included studies, recorded the authors, and sample size, and extracted the intraoperative blood loss, operation time, Oswestry disability index (ODI), Visual analogue scale (VAS), disc height (DH), hospital length stay and complications in each study. Meta-analysis was performed using Revman 5.4 software provided by Cochrane Library. RESULTS: A total of 6 cohort studies (CS) and 1 randomized controlled study with a total of 420 patients were included in this study, including 188 patients in the CBT group and 232 patients in the PS group. The CBT group had lower intraoperative blood loss than the PS group [mean difference (MD) = -129.38, 95% CI (-177.22, -81.55), P < 0.00001] and operation time was shorter than that of the PS group [MD = -1.42, 95% CI (-2.63, -0.20), P = 0.02]. Early postoperative back and leg pain improved more significantly in the CBT group [MD = -0.77, 95% CI (-1.35, -0.19), P = 0.01; MD = -0.24, 95% CI (-0.37, -0.10), P = 0.0005]. CONCLUSION: Compared with PS, CBT for adjacent segment degeneration after lumbar fusion has the advantages of less intraoperative blood loss, shorter operation time, and less back and leg pain in the early postoperative period.

Accuracy and postoperative assessment of robot-assisted placement of pedicle screws during scoliosis surgery compared with conventional freehand technique: a systematic review and meta-analysis.

STUDY DESIGN: A systematic review and meta-analysis. BACKGROUND: The complexity of human anatomical structures and the variability of vertebral body structures in patients with scoliosis pose challenges in pedicle screw placement during spinal deformity correction surgery. Through technological advancements, robots have been introduced in spinal surgery to assist with pedicle screw placement. METHODS: A systematic search was conducted using PubMed, Cochrane, Embase, and CNKI databases and comparative studies assessing the accuracy and postoperative efficacy of pedicle screw placement using robotic assistance or freehand techniques in patients with scoliosis were included. The analysis evaluated the accuracy of screw placement, operative duration, intraoperative blood loss, length of postoperative hospital stay, and complications. RESULTS: Seven studies comprising 584 patients were included in the meta-analysis, with 282 patients (48.3%) in the robot-assisted group and 320 (51.7%) in the freehand group. Robot-assisted placement showed significantly better clinically acceptable screw placement results compared with freehand placement (odds ratio [OR]: 2.61, 95% confidence interval [CI]: 1.75-3.91, P < 0.0001). However, there were no statistically significant differences in achieving "perfect" screw placement between the two groups (OR: 1.52, 95% CI: 0.95-2.46, P = 0.08). The robot-assisted group had longer operation durations (mean deviation [MD]: 43.64, 95% CI: 22.25-64.74, P < 0.0001) but shorter postoperative hospital stays (MD: - 1.12, 95% CI: - 2.15 to - 0.08, P = 0.03) than the freehand group. There were no significant differences in overall complication rates or intraoperative blood loss between the two groups. There was no significant difference in Cobb Angle between the two groups before and after operation. CONCLUSION: Robot-assisted pedicle screw placement offers higher accuracy and shorter hospital stay than freehand placement in scoliosis surgery; although the robotics approach is associated with longer operative durations, similar complication rates and intraoperative blood loss.

3D Printed Pedicle Screws with Microarc Oxidation Ceramic Interfaces Enhance Osteointegration and Orthopedic Fixation Feasibility.

Effective osteointegration is of great importance for pedicle screws in spinal fusion surgeries. However, the lack of osteoinductive activity of current screws diminishes their feasibility for osteointegration and fixation, making screw loosening a common complication worldwide. In this study, Ti-6Al-4V pedicle screws with full through-hole design were fabricated via selective laser melting (SLM) 3D printing and then deposited with porous oxide coatings by microarc oxidation (MAO). The porous surface morphology of the oxide coating and the release of bioactive ions could effectively support cell adhesion, migration, vascularization, and osteogenesis in vitro. Furthermore, an in vivo goat model demonstrated the efficacy of modified screws in improving bone maturation and osseointegration, thus providing a promising method for feasible orthopedic internal fixation.