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.

Unilateral biportal endoscopic versus microscopic transforaminal lumbar interbody fusion for lumbar degenerative disease: a retrospective study.

BACKGROUND: In the past decade, Minimally invasive transforaminal lumbar interbody fusion (MIS-TLIF) with a microscopic tubular technique has become a surgical procedure that reduces surgical-related morbidity, shortens hospital stays, and expedites early rehabilitation in the treatment of lumbar degenerative diseases (LDD). Unilateral biportal endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) has emerged as a novel surgical technique. The present study aims to compare the clinical outcomes and postoperative complications of MIS-TLIF and Endo-TLIF for treating LDD. METHODS: A retrospective analysis of LLD patients undergoing either Endo-TLIF or MIS-TLIF was performed. Patient demographics, operative data (operation time, estimated blood loss, length of hospitalization), and complications were recorded. The visual analog scale (VAS) score for leg and back pain and the Oswestry Disability Index (ODI) score were used to evaluate the clinical outcomes. RESULTS: This study involved 80 patients, 56 in the MIS-TLIF group and 34 in the Endo-TLIF group. The Endo-TLIF group showed a more substantial improvement in the VAS for back pain at 3 weeks post-surgery compared to the MIS-TLIF group. However, at the 1-year mark after surgery, there were no significant differences between the groups in the mean VAS for back pain and VAS for leg pain. Interestingly, the ODI at one year demonstrated a significant improvement in the Endo-TLIF group compared to the MIS-TLIF group. Additionally, the MIS-TLIF group exhibited a shorter operative time than the Endo-TLIF group, with no notable differences in estimated blood loss, length of hospitalization, and complications between the two groups. CONCLUSION: Endo-TLIF and MIS-TLIF are both safe and effective for LDD. In surgical decision-making, clinicians may consider nuances revealed in this study, such as lower early postoperative back pain with Endo-TLIF and shorter operative time with MIS-TLIF.

The hemostatic and anti-inflammatory effects of intravenous single-dose of tranexamic acid in double-segment posterior lumbar interbody fusion: a case control study.

This study aims to observe the hemostatic and anti-inflammatory effects of intravenous administration of tranexamic acid (TXA) in dual segment posterior lumbar interbody fusion (PLIF). The data of 53 patients with lumbar disease treated with double-segment PLIF were included in this study. The observation group was received a single-dose intravenous of TXA (1 g/100 mL) 15 min before skin incision after general anesthesia. The control group was not received TXA. The observation indicators included postoperative activated partial prothrombin time (APTT), thrombin time (PT), thrombin time (TT), fibrinogen (FIB), platelets (PLT), and postoperative deep vein thrombosis in the lower limbs, surgical time, intraoperative bleeding volume, postoperative drainage volume, transfusion rate, postoperative hospital stay, red blood cell (RBC), hemoglobin (HB), hematocrit (HCT), C-reactive protein (CRP), and erythrocyte sedimentation rate (ESR) on the 1st, 4th, 7th, and last tested day after surgery. All patients successfully completed the operation, and there was no deep vein thrombosis after operation. There was no statistically significant difference in postoperative APTT, PT, TT, FIB, PLT, surgical time, and postoperative hospital stay between the two groups (p > 0.05). The intraoperative bleeding volume, postoperative drainage volume, and transfusion rate in the observation group were lower than those in the control group, and the differences were statistically significant (p < 0.05). There was no statistically significant difference in RBC, HB, HCT, CRP, and ESR between the two groups on the 1st, 4th, 7th, and last tested day after surgery (p > 0.05). Intravenous administration of TXA in dual segment PLIF does not affect coagulation function and can reduce bleeding volume, postoperative drainage volume, and transfusion rate. Moreover, it does not affect the postoperative inflammatory response.

Survey of major complications after prone transpsoas surgery: an analysis of early adopters' practice.

INTRODUCTION: The prone transpsoas technique (PTP) is a modification of the traditional lateral lumbar interbody fusion approach, which was first published in the literature in 2020. The technique provides several advantages, such as lordosis correction and redistribution, single-position surgery framework, and ease of performing posterior techniques when needed. However, the prone position also leads to the movement of some retroperitoneal, vascular, and neurological structures, which could impact the complication profile. Therefore, this study aimed to investigate the occurrence of major complications in the practice of early adopters of the PTP approach. METHODS: A questionnaire containing 8 questions was sent to 50 participants and events involving early adopters of the prone transpsoas technique. Of the 50 surgeons, 32 completed the questionnaire, which totaled 1963 cases of PTP surgeries. RESULTS: Nine of the 32 surgeons experienced a major complication (28%), with persistent neurological deficit being the most frequent (7/9). Of the total number of cases, the occurrence of permanent neurological deficits was approximately 0,6%, and the rate of vascular and visceral injuries were both 0,05% (1/1963 for each case). CONCLUSION: Based on the analysis of the questionnaire responses, it can be concluded that PTP is a safe technique with a very low rate of serious complications. However, future studies with a more heterogeneous group of surgeons and a more rigorous linkage between answers and patient data are needed to support the findings of this study.

Buck technique supplemented by temporary intersegmental pedicle screw fixation to repair lumbar spondylolysis in youth.

BACKGROUND: Lumbar spondylolysis is a bone defect in the pars interarticularis of the lumbar vertebral, which is a common cause of low back pain in youth. Although non-surgical treatment is a mainstream option, surgery is necessary for patients with persistent symptoms. Buck technique is widely used as a classical direct repair technique, but it cannot achieve reduction of low-grade spondylolisthesis and reconstruction of lumbosacral sagittal balance. We have described a novel surgical procedure based on Buck technique with temporary intersegmental pedicle screw fixation, and report a series of clinical outcomes in 5 patients to provide a reference for the clinical treatment of young lumbar spondylolysis. METHODS: Five young patients with symptomatic lumbar spondylolysis with a mean age of 19.20 ± 5.41 years underwent surgical treatment after an average of 7.60 ± 1.52 months of failure to respond to conservative treatment, using a new surgical procedure based on Buck technique combined with temporary intersegmental pedicle screw fixation. RESULTS: Five patients were successfully operated without serious complications such as nerve and vascular injury. The average operation time was 109.00 ± 7.42 min, the interpretative average blood loss was 148.00 ± 31.14 ml, and the average fusion time was 11.20 ± 1.64 months. All patients were followed up for 2 years after surgery, and the visual analogue score (VAS) of low back pain and Oswestry disability index (ODI) scores were significantly improved compared with those before surgery, and the Henderson's evaluation were rated excellent or good. After the removal of the internal fixation, it was observed that temporary intersegmental fixation could repair the isthmus, reduce lumbar spondylolisthesis, and reconstruct the sagittal balance of the lumbosacral vertebrae while preserving lumbar motion and preventing intervertebral disc degeneration. Postoperative MRI indicated the Pfirrmann classification of the affected discs: 1 case from grade III to grade II, 3 cases from grade II to grade I, and 1 case remained grade II. CONCLUSIONS: Buck technique supplemented by temporary intersegmental pedicle screw fixation is a highly applicable and effective method for the treatment of adolescent lumbar spondylolysis. The isthmic fusion is accurate, and temporary intersegmental fixation can effectively prevent disc degeneration and reconstruct the sagittal balance of lumbosacral vertebra.

Transforaminal posterior lumbar interbody fusion microscopic safe operating area: a three-dimensional model study based on computed tomography imaging.

BACKGROUND: Endoscopic spine lumbar interbody fusion (Endo-LIF) is well-regarded within the academic community. However, it presents challenges such as intraoperative disorientation, high rates of nerve damage, a steep learning curve, and prolonged surgical times, often occurring during the creation of the operative channel. Furthermore, the undefined safe operational zones under endoscopy continue to pose risks to surgical safety. We aimed to analyse the anatomical data of Kambin's triangle via CT imaging to define the parameters of the safe operating area for transforaminal posterior lumbar interbody fusion (TPLIF), providing crucial insights for clinical practice. METHODS: We selected the L4-L5 intervertebral space. Using three-dimensional (3D), we identified Kambin's triangle and the endocircle within it, and recorded the position of point 'J' on the adjacent facet joint as the centre 'O' of the circle shifts by angle 'ß.' The diameter of the inscribed circle 'd,' the abduction angle 'ß,' and the distances 'L1' and 'L2' were measured from the trephine's edge to the exiting and traversing nerve roots, respectively. RESULTS: Using a trephine with a diameter of 8 mm in TPLIF has a significant safety distance. The safe operating area under the TPLIF microscope was also clarified. CONCLUSIONS: Through CT imaging research, combined with 3D simulation, we identified the anatomical data of the L4-L5 segment Kambin's triangle, to clarify the safe operation area under TPLIF. We propose a simple and easy positioning method and provide a novel surgical technique to establish working channels faster and reduce nerve damage rates. At the same time, according to this method, the Kambin's triangle anatomical data of the patient's lumbar spine diseased segments can be measured through CT 3D reconstruction of the lumbar spine, and individualised preoperative design can be conducted to select the appropriate specifications of visible trephine and supporting tools. This may effectively reduce the learning curve, shorten the time operation time, and improve surgical safety.

Can zoledronic acid reduce the risk of cage subsidence after oblique lumbar interbody fusion combined with bilateral pedicle screw fixation in the elderly population? A retrospective study.

BACKGROUND: The objective of this study was to evaluate the potential of zoledronic acid for reducing the incidence of cage subsidence and enhancing interbody fusion rates following oblique lumbar interbody fusion (OLIF) surgery, particularly as the first reported evidence of the role of zoledronic acid combined with OLIF. METHODS: A retrospective analysis was conducted on data from 108 elderly patients treated for degenerative lumbar diseases using OLIF combined with bilateral pedicle screw fixation from January 2018 to December 2021. Patients were divided into the zoledronic acid (ZOL) group (43 patients, 67 surgical segments) and the control group (65 patients, 86 surgical segments). A comparative analysis of the radiographic and clinical outcomes between the groups was performed, employing univariate and multivariate regression analyses to explore the relationships between cage subsidence and the independent variables. RESULTS: Radiographic outcomes, including anterior height, posterior height, disc height, coronal disc angle, foraminal height, and lumbar lordosis, were not significantly different between the two groups. Similarly, no statistically significant differences were noted in the back visual analog scale (VAS) scores and Oswestry Disability Index (ODI) scores between the groups. However, at the 1-year follow-up, the leg VAS score was lower in the ZOL group than in the control group (P = 0.028). The ZOL group demonstrated a notably lower cage subsidence rate (20.9%) than did the control group (43.0%) (P < 0.001). There was no significant difference in the interbody fusion rate between the ZOL group (93.0%) and the control group (90.8%). Non-use of zoledronic acid emerged as an independent risk factor for cage subsidence (OR = 6.047, P = 0.003), along with lower bone mineral density, lower postoperative anterior height, and concave endplate morphology. The model exhibited robust discriminative performance, with an area under the curve (AUC) of 0.872. CONCLUSION: The administration of zoledronic acid mitigates the risk of cage subsidence following OLIF combined with bilateral pedicle screw fixation in elderly patients; however, it does not improve the interbody fusion rate.

High Strength and Shape Memory Spinal Fusion Device for Minimally Invasive Interbody Fusions.

Introduction: Lumbar interbody fusion is widely employed for both acute and chronic spinal diseases interventions. However, large incision created during interbody cage implantation may adversely impair spinal tissue and influence postoperative recovery. The aim of this study was to design a shape memory interbody fusion device suitable for small incision implantation. Methods: In this study, we designed and fabricated an intervertebral fusion cage that utilizes near-infrared (NIR) light-responsive shape memory characteristics. This cage was composed of bisphenol A diglycidyl ether, polyether amine D-230, decylamine and iron oxide nanoparticles. A self-hardening calcium phosphate-starch cement (CSC) was injected internally through the injection channel of the cage for healing outcome improvement. Results: The size of the interbody cage is reduced from 22 mm to 8.8 mm to minimize the incision size. Subsequent NIR light irradiation prompted a swift recovery of the cage shape within 5 min at the lesion site. The biocompatibility of the shape memory composite was validated through in vitro MC3T3-E1 cell (osteoblast-like cells) adhesion and proliferation assays and subcutaneous implantation experiments in rats. CSC was injected into the cage, and the relevant results revealed that CSC is uniformly dispersed within the internal space, along with the cage compressive strength increasing from 12 to 20 MPa. Conclusion: The results from this study thus demonstrated that this integrated approach of using a minimally invasive NIR shape memory spinal fusion cage with CSC has potential for lumbar interbody fusion.

Successful Treatment of Cervical Spondylolysis with Grade-II Spondylolisthesis using Single-Level ACDF: A Case Report.

BACKGROUND Cervical spondylolysis with spondylolisthesis is a rare disorder. According to previous reports, the spondylolisthesis is usually Meyerding Grade I, with only a limited number of cases receiving surgical treatment. We hereby report a special case of cervical spondylolysis with Grade-II spondylolisthesis, treated with single-level anterior cervical discectomy and fusion (ACDF), and present a literature review related to this problem. CASE REPORT Here, we report the case of a 52-year-old man who complained of posterior neck pain and numbness of the bilateral upper limbs. Radiological examination showed bilateral spondylolysis of the C6 and Meyerding Grade-II spondylolisthesis of C6 on C7 with instability. The patient underwent a single-level C6/C7 ACDF surgery. The symptoms of neck pain and bilateral upper-limb numbness were relieved immediately after surgery. The immediate postoperative radiological examination showed successful restoration of sagittal alignment. At 3-month follow-up, the patient had returned to normal life without any symptoms. At 2-year follow-up, computed tomography showed that C6-C7 fusion had been achieved and alignment was maintained. CONCLUSIONS Cervical spondylolysis, as an uncommon spinal disorder, has been regarded as a congenital abnormity, and has unique radiological characteristics. For most of the cases with cervical spondylolysis, even with Grade-II spondylolisthesis, single-level ACDF can achieve good clinical and radiological outcomes.

Impact of surgical risk factors for non-union on lumbar spinal fusion outcomes using cellular bone allograft at 24-months follow-up.

BACKGROUND: The current report investigates fusion rates and patient-reported outcomes following lumbar spinal surgery using cellular bone allograft (CBA) in patients with risk factors for non-union. METHODS: A prospective, open label study was conducted in subjects undergoing lumbar spinal fusion with CBA (NCT02969616) to assess fusion success rates and patient-reported outcomes in subjects with risk factors for non-union. Subjects were categorized into low-risk (≤ 1 risk factors) and high-risk (> 1 risk factors) groups. Radiographic fusion status was evaluated by an independent review of dynamic radiographs and CT scans. Patient-reported outcome measures included quality of life (EQ-5D), Oswestry Disability Index (ODI) and Visual Analog Scales (VAS) for back and leg pain. Adverse event reporting was conducted throughout 24-months of follow-up. RESULTS: A total of 274 subjects were enrolled: 140 subjects (51.1%) were categorized into the high-risk group (> 1 risk factor) and 134 subjects (48.9%) into the low-risk group (≤ 1 risk factors). The overall mean age at screening was 58.8 years (SD 12.5) with a higher distribution of females (63.1%) than males (36.9%). No statistical difference in fusion rates were observed between the low-risk (90.0%) and high-risk (93.9%) groups (p > 0.05). A statistically significant improvement in patient-reported outcomes (EQ-5D, ODI and VAS) was observed at all time points (p < 0.05) in both low and high-risk groups. The low-risk group showed enhanced improvement at multiple timepoints in EQ-5D, ODI, VAS-Back pain and VAS-Leg pain scores compared to the high-risk group (p < 0.05). The number of AEs were similar among risk groups. CONCLUSIONS: This study demonstrates high fusion rates following lumbar spinal surgery using CBA, regardless of associated risk factors. Patient reported outcomes and fusion rates were not adversely affected by risk factor profiles. TRIAL REGISTRATION: NCT02969616 (21/11/2016).

Precise execution of personalized surgical planning using three-dimensional printed guide template in severe and complex adult spinal deformity patients requiring three-column osteotomy: a retrospective, comparative matched-cohort study.

BACKGROUND: The surgical treatment of severe and complex adult spinal deformity (ASD) commonly required three-column osteotomy (3-CO), which was technically demanding with high risk of neurological deficit. Personalized three dimensional (3D)-printed guide template based on preoperative planning has been gradually applied in 3-CO procedure. The purpose of this study was to compare the efficacy, safety, and precision of 3D-printed osteotomy guide template and free-hand technique in the treatment of severe and complex ASD patients requiring 3-CO. METHODS: This was a single-centre retrospective comparative cohort study of patients with severe and complex ASD (Cobb angle of scoliosis > 80° with flexibility < 25% or focal kyphosis > 90°) who underwent posterior spinal fusion and 3-CO between January 2020 to January 2023, with a minimum 12 months follow-up. Personalized computer-assisted three-dimensional osteotomy simulation was performed for all recruited patients, who were further divided into template and non-template groups based on the application of 3D-printed osteotomy guide template according to the surgical planning. Patients in the two groups were age- and gender- propensity-matched. The radiographic parameters, postoperative neurological deficit, and precision of osteotomy execution were compared between groups. RESULTS: A total of 40 patients (age 36.53 ± 11.98 years) were retrospectively recruited, with 20 patients in each group. The preoperative focal kyphosis (FK) was 92.72° ± 36.77° in the template group and 93.47° ± 33.91° in the non-template group, with a main curve Cobb angle of 63.35° (15.00°, 92.25°) and 64.00° (20.25°, 99.20°), respectively. Following the correction surgery, there were no significant differences in postoperative FK, postoperative main curve Cobb angle, correction rate of FK (54.20% vs. 51.94%, P = 0.738), and correction rate of main curve Cobb angle (72.41% vs. 61.33%, P = 0.101) between the groups. However, the match ratio of execution to simulation osteotomy angle was significantly greater in the template group than the non-template group (coronal: 89.90% vs. 74.50%, P < 0.001; sagittal: 90.45% vs. 80.35%, P < 0.001). The operating time (ORT) was significantly shorter (359.25 ± 57.79 min vs. 398.90 ± 59.48 min, P = 0.039) and the incidence of postoperative neurological deficit (5.0% vs. 35.0%, P = 0.018) was significantly lower in the template group than the non-template group. CONCLUSION: Performing 3-CO with the assistance of personalized 3D-printed guide template could increase the precision of execution, decrease the risk of postoperative neurological deficit, and shorten the ORT in the correction surgery for severe and complex ASD. The personalized osteotomy guide had the advantages of 3D insight of the case-specific anatomy, identification of osteotomy location, and translation of the surgical planning or simulation to the real surgical site.

Long-term efficacy of Waveflex semi-rigid-dynamic-internal-fixation system in delaying intervertebral disc degeneration at adjacent segments and improving spinal sagittal imbalance.

The Waveflex semi-rigid-dynamic-internal-fixation system shows good short-term effects in the treatment of lumbar degenerative diseases, but there are few long-term follow-up studies, especially for recovery of sagittal balance. Fifty patients with lumbar degenerative diseases treated from January 2016 to October 2017 were retrospectively analysed: 25 patients treated with Waveflex semi-rigid-dynamic-internal-fixation system (Waveflex group) and 25 patients treated with double-segment PLIF (PLIF group). Clinical efficacy was evaluated by Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI). Imaging data before surgery and at 3 months, 1 year, and 5 years postoperatively was used for imaging indicator assessment. Local disc degeneration of the cephalic adjacent segment (including disc height index (DHI), intervertebral foramen height (IFH), and range of motion (ROM)) and overall spinal motor function (including lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), pelvic tilt (PT), and |PI-LL|) were analysed. Regarding clinical efficacy, comparison of VAS and ODI scores between the Waveflex and PLIF groups showed no significant preoperative or postoperative differences. The comparison of the objective imaging indicators showed no significant differences in the DHI, IFH, LL, |PI-LL|, and SS values between the Waveflex and PLIF groups preoperatively and 3 months postoperatively (P > 0.05). These values were significantly different at 1 and 5 years postoperatively (P < 0.05), and the Waveflex group showed better ROM values than those of the PLIF group (P < 0.05). PI values were not significantly different between the groups, but PT showed a significant improvement in the Waveflex group 5 years postoperatively (P < 0.05). The Waveflex semi-rigid dynamic fixation system can effectively reduce the probability of intervertebral disc degeneration in upper adjacent segments. Simultaneously, patients in the Waveflex group showed postoperative improvements in LL, spinal sagittal imbalance, and quality of life.

Enhancing spinal bone anchor pull-out resistance with an L-shaped anchor.

The success rate of spinal fusion surgery is mainly determined by the fixation strength of the spinal bone anchors. This study explores the use of an L-shaped spinal bone anchor that is intended to establish a macro-shape lock with the posterior cortical layer of the vertebral body, thereby increasing the pull-out resistance of the anchor. The performance of this L-shaped anchor was evaluated in lumbar vertebra phantoms (L1-L5) across four distinct perpendicular orientations (lateral, medial, superior, and inferior). During the pull-out experiments, the pull-out force, and the displacement of the anchor with respect to the vertebra was measured which allowed the determination of the maximal pull-out force (mean: 123 N ± 25 N) and the initial pull-out force, the initial force required to start motion of the anchor (mean: 23 N ± 16 N). Notably, the maximum pull-out force was observed when the anchor engaged the cortical bone layer. The results demonstrate the potential benefits of utilising a spinal bone anchor featuring a macro-shape lock with the cortical bone layer to increase the pull-out force. Combining the macro shape-lock fixation method with the conventional pedicle screw shows the potential to significantly enhance the fixation strength of spinal bone anchors.

Feasibility and safety report on robotic assistance for cervical pedicle screw fixation: a cadaveric study.

This cadaveric study aimed to evaluate the safety and usability of a novel robotic system for posterior cervical pedicle screw fixation. Three human cadaveric specimens and C2-T3 were included. Freshly frozen human cadaver specimens were prepared and subjected to robot-assisted posterior cervical pedicle screw fixation using the robotic system. The accuracy of screw placement, breach rate, and critical structure violations were evaluated. The results were statistically compared with those of previous studies that used different robotic systems for cervical pedicle screw fixation. The robotic system demonstrated a high accuracy rate in screw placement. A significant number of screws were placed within predetermined safe zones. The total entry offset was 1.08 ± 0.83 mm, the target offset was 1.86 ± 0.50 mm, and the angle offset was 2.14 ± 0.77°. Accuracy rates comparable with those of previous studies using different robotic systems were achieved. The system was also feasible, allowing precise navigation and real-time feedback during the procedure. This cadaveric study validated the safety and usability of the novel robotic system for posterior cervical pedicle screw fixation. The system exhibited high precision in screw placement, and the results support the extension of the indications for robot-assisted pedicle screw fixation from the lumbar spine to the cervical spine.

Comparison of No Tap (two-step) and tapping robotic assisted cortical bone trajectory screw insertion.

Workflow for cortical bone trajectory (CBT) screws includes tapping line-to-line or under tapping by 1 mm. We describe a non-tapping, two-step workflow for CBT screw placement, and compare the safety profile and time savings to the Tap (three-step) workflow. Patients undergoing robotic assisted 1-3 level posterior fusion with CBT screws for degenerative conditions were identified and separated into either a No-Tap or Tap workflow. Number of total screws, screw-related complications, estimated blood loss, operative time, robotic time, and return to the operating room were collected and analyzed. There were 91 cases (458 screws) in the No-Tap and 88 cases (466 screws) in the Tap groups, with no difference in demographics, revision status, ASA grade, approach, number of levels fused or diagnosis between cohorts. Total robotic time was lower in the No-Tap (26.7 min) versus the Tap group (30.3 min, p = 0.053). There was no difference in the number of malpositioned screws identified intraoperatively (10 vs 6, p = 0.427), screws converted to freehand (3 vs 3, p = 0.699), or screws abandoned (3 vs 2, p = 1.000). No pedicle/pars fracture or fixation failure was seen in the No-Tap cohort and one in the Tap cohort (p = 1.00). No patients in either cohort were returned to OR for malpositioned screws. This study showed that the No-Tap screw insertion workflow for robot-assisted CBT reduces robotic time without increasing complications.

Comparison of minimally invasive transforaminal lumbar interbody fusion and midline lumbar interbody fusion in patients with spondylolisthesis.

BACKGROUND: This study aimed to compare surgical outcomes, clinical outcomes, and complications between minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) and midline lumbar interbody fusion (MIDLIF) in patients with spondylolisthesis. METHODS: This study retrospectively compared the patients who underwent MIS TLIF (n = 37) or MIDLIF (n = 50) for spinal spondylolisthesis. Data of surgical outcomes (postoperative one-year fusion rate and time to bony fusion), clinical outcomes (visual analog scale [VAS] for pain and Oswestry Disability Index [ODI] for spine function), and complications were collected and analyzed. RESULTS: There was more 2-level fusion in MIDLIF (46% vs. 24.3%, p = 0.038). The MIS TLIF and MIDLIF groups had similar one-year fusion rate and time to fusion. The MIDLIF group had significantly lower VAS at postoperative 3-months (2.2 vs. 3.1, p = 0.002) and postoperative 1-year (1.1 vs. 2.1, p = < 0.001). ODI was not significantly different. The operation time was shorter in MIDLIF (166.1 min vs. 196.2 min, p = 0.014). The facet joint violation is higher in MIS TLIF (21.6% vs. 2%, p = 0.009). The other complications were not significantly different including rate of implant removal, revision, and adjacent segment disease. CONCLUSION: In this study, postoperative VAS, operation time, and the rate of facet joint violation were significantly higher in the MIS TLIF group. Comparable outcomes were observed between MIDLIF and MIS TLIF in terms of fusion rate, time to fusion, and postoperative ODI score.

Mesenchymal Stem Cell Exosomes Enhance Posterolateral Spinal Fusion in a Rat Model.

Spinal fusion, a common surgery performed for degenerative lumbar conditions, often uses recombinant human bone morphogenetic protein 2 (rhBMP-2) that is associated with adverse effects. Mesenchymal stromal/stem cells (MSCs) and their extracellular vesicles (EVs), particularly exosomes, have demonstrated efficacy in bone and cartilage repair. However, the efficacy of MSC exosomes in spinal fusion remains to be ascertained. This study investigates the fusion efficacy of MSC exosomes delivered via an absorbable collagen sponge packed in a poly Ɛ-caprolactone tricalcium phosphate (PCL-TCP) scaffold in a rat posterolateral spinal fusion model. Herein, it is shown that a single implantation of exosome-supplemented collagen sponge packed in PCL-TCP scaffold enhanced spinal fusion and improved mechanical stability by inducing bone formation and bridging between the transverse processes, as evidenced by significant improvements in fusion score and rate, bone structural parameters, histology, stiffness, and range of motion. This study demonstrates for the first time that MSC exosomes promote bone formation to enhance spinal fusion and mechanical stability in a rat model, supporting its translational potential for application in spinal fusion.

Spine Surgery in a Geriatric Population. Is it Really Different?

OBJECTIVES: Spinal degenerative disorders are a major cause of morbidity in the elderly resulting in high dependency. Most of them have a trend to be managed conservatively considering age, comorbidities, and apprehensions of surgical complications. Surgical intervention at early stage with appropriate indications can have better outcomes rather than conservative management in fit patients. The objective of the study is to evaluate the functional outcome in geriatric patients > 60 years who have undergone various spinal procedures for degenerative spine. METHODS: The study is retrospective, which includes all cases of spinal degenerative disease operated between 2014 and 2016. They were divided into geriatric (>60 years) and non-geriatric cohorts. These include all patients undergoing spinal decompression and/or instrumentation for degenerative disorders of the spine. Patients were interviewed for their functional outcomes in the follow-up period. RESULTS: A total of 184 spine cases were operated upon by a single surgeon, out of which a total of 139 cases were operated for the spinal degenerative condition. Forty-eight patients underwent lumbar spinal fusion procedures, 67 underwent non-instrumented lumbar decompression, and 24 patients underwent cervical procedures. These were further divided into 65 geriatric cases and 74 non-geriatric cases. The outcome was assessed with improvement and functional outcomes for spinal disability. Statistical analysis was performed using SPSS 20. CONCLUSION: It is concluded that surgical intervention for spinal problems in geriatric patients is not different from the general population. The outcome is also satisfactory provided, the choice of surgical procedure as per its indication is appropriate. The usual preoperative evaluation for the geriatric age group is very important. The performance status before surgery and the comorbidities have a direct bearing on the outcome in these patients.

In vivo study of a novel 3D-printed motion-preservation artificial cervical corpectomy construct: short-term imaging and biocompatibility evaluations in a goat model.

BACKGROUND: Nonfusion technologies, such as motion-preservation devices, have begun a new era of treatment options in spine surgery. Motion-preservation approaches mainly include total disc replacement for anterior cervical discectomy and fusion. However, for multisegment fusion, such as anterior cervical corpectomy and fusion, the options are more limited. Therefore, we designed a novel 3D-printed motion-preservation artificial cervical corpectomy construct (ACCC) for multisegment fusion. The aim of this study was to explore the feasibility of ACCC in a goat model. METHODS: Goats were treated with anterior C3 corpectomy and ACCC implantation and randomly divided into two groups evaluated at 3 or 6 months. Radiography, 3D CT reconstruction and MRI evaluations were performed. Biocompatibility was evaluated using micro-CT and histology. RESULTS: Postoperatively, all goats were in good condition, with free neck movement. Implant positioning was optimal. The relationship between facet joints was stable. The range of motion of the C2-C4 segments during flexion-extension at 3 and 6 months postoperatively was 7.8° and 7.3°, respectively. The implants were wrapped by new bone tissue, which had grown into the porous structure. Cartilage tissue, ossification centres, new blood vessels, and bone mineralization were observed at the porous metal vertebrae-bone interface and in the metal pores. CONCLUSIONS: The ACCC provided stabilization while preserving the motion of the functional spinal unit and promoting bone regeneration and vascularization. In this study, the ACCC was used for anterior cervical corpectomy and fusion (ACCF) in a goat model. We hope that this study will propel further research of motion-preservation devices.

TRANSPEDICULAR SCREW FIXATION IN DEGENERATIVE LUMBOSACRAL SPINE DISEASE SURGICAL OUTCOME.

Highlighting the prospective evaluation of the surgical outcome of pedicle screw usage in the treatment of degenerative lumbar spine disease in fifty-five patients who were treated consecutively via a posterior surgical approach with pedicle screw fixation. A total of 55 consecutive patients with degenerative lumbosacral spine disease were treated at AL Mosul Teaching Hospital. Patients were included if they were between the ages of 25 and 60 years, they were admitted to the hospital with chronic back pain and or radicular pain and had a pedicle anatomy (based on a preoperative X-ray) that could accommodate surgical stabilization with PS instrumentation and fusion. Posterior surgical stabilization of the degenerative lumbar spine disease with pedicular screws was done and before discharge, each patient underwent a postoperative X-ray of the lumbosacral spine. In this series 55 patients were operated on for pedicular screw fixation with connecting bar, all patients underwent decompression except 2 cases, 47 patients with 2-level fixation and 8 patients with 3-level fixation. All patients' pain disappeared or became less, as well as paraesthesia.10 patients with lower limb neurological deficits improved. Only 5 of all patients are re-operated (three due to displacement, one due to a broken screw, and one due to a loose screw), 3 patients developed Dural tears and were treated by suturing with muscle patch, no vascular injury, no post-operative infection seen but one patient developed DVT post-operatively treated conservatively. Pedicle screw fixation facilitates the bone-fusion process, and its use is associated with a relatively low complication rate. The application of pedicle screws can be technically demanding; a thorough working knowledge of spinal anatomy and the principles of pedicle screw insertion will greatly contribute to their safe and accurate placement. These devices should be used when there is any feature of instability or due to iatrogenic instability after wide bone removal or after the destruction of facet joints.