Analysis of Risk Factors for Urinary Tract Infection after Lumbar Interbody Fusion.

OBJECTIVE: Urinary tract infection (UTI) is a common postoperative complication, so exploring its risk factors is helpful to provide a basis for clinical prevention. This study aims to analyse the risk factors for UTI after lumbar interbody fusion (LIF). METHODS: A single-centre retrospective study was conducted on the clinical data of 358 patients treated with LIF from April 2020 to April 2023. In accordance with the results of postoperative urine culture, the patients were divided into UTI group (n = 19, those with UTI after LIF) and control group (n = 332, those without UTI after LIF). Binary logistic regression analysis was carried out through collecting the medical records of the two groups to probe into the risk factors for UTI after LIF. RESULTS: After seven patients were excluded, the remaining 351 patients were included in the analysis. In this study, 19 patients (5.41%) developed postoperative UTI, whereas 332 patients (94.59%) had no UTI. Regression analysis results showed drinking (odds ratio (OR) = 16.193, 95% confidence interval (CI): 1.017-257.860) and high preoperative C-reactive protein (CRP) level (OR = 3.237, 95% CI: 1.213-8.636) as risk factors for UTI after LIF. A high professional title of main surgeon (OR = 0.095, 95% CI: 0.010-0.932) and preoperative red blood cell (RBC) count (OR = 0.001, 95% CI: 0.000-0.198) were protective factors for UTI after LIF (p < 0.05). CONCLUSIONS: This study advocated strengthening the prevention and treatment of UTI in patients who had drinking history, high preoperative CRP level and low preoperative RBC count, and received LIF based on the study results. Attention should be paid to the training of physicians with low professional title.

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.

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.

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.

Pseudarthrosis risk factors in lumbar fusion: a systematic review and meta-analysis.

This study presents a systematic literature review and meta-analysis of pseudarthrosis risk factors following lumbar fusion procedures. The odds ratio (OR) and 95% confidence interval (95% CI) were used for outcome measurements. The objective of this study was to identify the independent risk factors for pseudarthrosis after lumbar spinal fusion, which is crucial for mitigating morbidity and reoperation. Systematic searches in PubMed, Embase, and Scopus (1990-July 2021) were conducted using specific terms. The inclusion criteria included prospective and retrospective cohorts and case‒control series reporting ORs with 95% CIs from multivariate analysis. The quality assessment utilized the Newcastle-Ottawa scale. Meta-analysis, employing OR and 95% CI, assessed pseudarthrosis risk factors in lumbar fusion surgery, depicted in a forest plot. Of the 568 abstracts identified, 12 met the inclusion criteria (9 retrospective, 2006-2021). The 17 risk factors were categorized into clinical, radiographic, surgical, and bone turnover marker factors. The meta-analysis highlighted two significant clinical risk factors: age (95% CI 1.02-1.11; p = 0.005) and smoking (95% CI 1.68-5.44; p = 0.0002). The sole significant surgical risk factor was the number of fused levels (pooled OR 1.35; 95% CI 1.17-1.55; p < 0.0001). This study identified 17 risk factors for pseudarthrosis after lumbar fusion surgery, emphasizing age, smoking status, and the number of fusion levels. Prospective studies are warranted to explore additional risk factors and assess the impact of surgery and graft type.

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.

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.

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.

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.

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.

Comparison of the Outcomes of Anterior Cervical Discectomy and Fusion and Cervical Disc Replacement for Cervical Disc Disease.

OBJECTIVE: To compare the radiological outcome and development of heterotopic ossification (HO) following single-segment anterior cervical discectomy and fusion (ACDF) and cervical disc replacement (CDR) for cervical disc herniation and evaluate their impact on surgical success. STUDY DESIGN: Descriptive comparative study. Place and Duration of the Study: Neurosurgery Department at Bozyaka Education and Research Hospital, Izmir, Turkiye, between January 2020 and June 2022. METHODOLOGY: Patients aged 18-70 years with radicular neck pain unresponsive to conventional medical treatment and an MRI-confirmed diagnosis were included. Patients with osteoporosis (OP) were excluded. Patients were randomised into two treatment groups (ACDF and CDR) and stratified by age and symptom severity. Radiographic assessments and HO classification according to McAfee were performed. RESULTS: Among the included patients, 56 underwent ACDF and 45 underwent CDR. The mean patient age was 48.29 ± 9.530 and 41.84 ± 7.239 years in the ACDF and CDR groups, respectively (p <0.001). The postoperative disc height increased in both groups. The T1 slope was significantly higher preoperatively and in the early postoperative period in the CDR group than in the ACDF group (p = 0.001). HO was graded as 1, 2, 3, and 4 in 28 (27.7%), 6 (5.9%), 7 (6.9%), and 4 (3%) patients, respectively. CONCLUSION: ACDF and CDR provided similar improvements in radiological measurements and pain relief. Although both procedures significantly enhanced the patient's quality of life and disability scores, HO was more prevalent following CDR during long-term follow-up. KEY WORDS: Cervical disc replacement, Anterior cervical discectomy and fusion, Spinal surgery techniques, Heterotopic ossification.

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.

Biomechanical comparison of polyetheretherketone rods and titanium alloy rods in transforaminal lumbar interbody fusion: a finite element analysis.

BACKGROUND: Whether polyetheretherketone (PEEK) rods have potential as an alternative to titanium alloy (Ti) rods in transforaminal lumbar interbody fusion (TLIF) remains unclear, especially in cases with insufficient anterior support due to the absence of a cage. The purpose of this study was to investigate biomechanical differences between PEEK rods and Ti rods in TLIF with and without a cage. METHODS: An intact L1-L5 lumbar finite element model was constructed and validated. Accordingly, four TLIF models were developed: (1) Ti rods with a cage; (2) PEEK rods with a cage; (3) Ti rods without a cage; and (4) PEEK rods without a cage. The biomechanical properties were then compared among the four TLIF constructs. RESULTS: With or without a cage, no obvious differences were found in the effect of PEEK rods and Ti rods on the range of motion, adjacent disc stress, and adjacent facet joint force. Compared to Ti rods, PEEK rods increase the average bone graft strain (270.8-6055.2 µE vs. 319.0-8751.6 µE). Moreover, PEEK rods reduced the stresses on the screw-rod system (23.1-96.0 MPa vs. 7.2-48.4 MPa) but increased the stresses on the cage (4.6-35.2 MPa vs. 5.6-40.9 MPa) and endplates (5.7-32.5 MPa vs. 6.6-37.6 MPa). CONCLUSIONS: Regardless of whether a cage was used for TLIF, PEEK rods theoretically have the potential to serve as an alternative to Ti rods because they may provide certain stability, increase the bone graft strain, and reduce the posterior instrumentation stress, which might promote bony fusion and decrease instrumentation failure.

Projections of Single-level and Multilevel Spinal Instrumentation Procedure Volume and Associated Costs for Medicare Patients to 2050.

BACKGROUND: Instrumented spinal fusions can be used in the treatment of vertebral fractures, spinal instability, and scoliosis or kyphosis. Construct-level selection has notable implications on postoperative recovery, alignment, and mobility. This study sought to project future trends in the implementation rates and associated costs of single-level versus multilevel instrumentation procedures in US Medicare patients aged older than 65 years in the United States. METHODS: Data were acquired from the Centers for Medicare & Medicaid Services from January 1, 2000, to December 31, 2019. Procedure costs and counts were abstracted using Current Procedural Terminology codes to identify spinal level involvement. The Prophet machine learning algorithm was used, using a Bayesian Inference framework, to generate point forecasts for 2020 to 2050 and 95% forecast intervals (FIs). Sensitivity analyses were done by comparing projections from linear, log-linear, Poisson and negative-binomial, and autoregressive integrated moving average models. Costs were adjusted for inflation using the 2019 US Bureau of Labor Statistics' Consumer Price Index. RESULTS: Between 2000 and 2019, the annual spinal instrumentation volume increased by 776% (from 7,342 to 64,350 cases) for single level, by 329% (from 20,319 to 87,253 cases) for two-four levels, by 1049% (from 1,218 to 14,000 cases) for five-seven levels, and by 739% (from 193 to 1,620 cases) for eight-twelve levels (P < 0.0001). The inflation-adjusted reimbursement for single-level instrumentation procedures decreased 45.6% from $1,148.15 to $788.62 between 2000 and 2019, which is markedly lower than for other prevalent orthopaedic procedures: total shoulder arthroplasty (-23.1%), total hip arthroplasty (-39.2%), and total knee arthroplasty (-42.4%). By 2050, the number of single-level spinal instrumentation procedures performed yearly is projected to be 124,061 (95% FI, 87,027 to 142,907), with associated costs of $93,900,672 (95% FI, $80,281,788 to $108,220,932). CONCLUSIONS: The number of single-level instrumentation procedures is projected to double by 2050, while the number of two-four level procedures will double by 2040. These projections offer a measurable basis for resource allocation and procedural distribution.

[Prospective comparative study of unilateral biportal endoscopic transforaminal lumbar interbody fusion and endoscopic transforaminal lumbar interbody fusion for treatment of single-segment degenerative lumbar spinal stenosis with lumbar spondylolisthesis].

Objective: To compare the effectiveness of unilateral biportal endoscopic transforaminal lumbar interbody fusion (UBE-TLIF) and endoscopic transforaminal lumbar interbody fusion (Endo-TLIF) in the treatment of single-segment degenerative lumbar spinal stenosis with lumbar spondylolisthesis. Methods: Between November 2019 and May 2023, a total of 81 patients with single-segment degenerative lumbar spinal stenosis with lumbar spondylolisthesis who met the selection criteria were enrolled. They were randomly divided into UBE-TLIF group (39 cases) and Endo-TLIF group (42 cases). There was no significant difference in baseline data between the two groups ( P>0.05), including gender, age, body mass index, surgical segment, and preoperative visual analogue scale (VAS) scores for low back and leg pain, Oswestry Disability Index (ODI), and serum markers including creatine kinase (CK) and C reactive protein (CRP). Total blood loss (TBL), intraoperative blood loss, hidden blood loss (HBL), postoperative drainage volume, and operation time were recorded and compared between the two groups. Serum markers (CK, CRP) levels were compared between the two groups at 1 day before operation and 1, 3, and 5 days after operation. Furthermore, the VAS scores for low back and leg pain, and ODI at 1 day before operation and 1 day, 3 months, 6 months, and 12 months after operation, and intervertebral fusion rate at 12 months after operation were compared between the two groups. Results: All surgeries were completed successfully without occurrence of incision infection, vascular or nerve injury, epidural hematoma, dural tear, or postoperative paraplegia. The operation time in UBE-TLIF group was significantly shorter than that in Endo-TLIF group, but the intraoperative blood loss, TBL, and HBL in UBE-TLIF group were significantly more than those in Endo-TLIF group ( P<0.05). There was no significant difference in postoperative drainage volume between the two groups ( P>0.05). The levels of CK at 1 day and 3 days after operation and CRP at 1, 3, and 5 days after operation in UBE-TLIF group were slightly higher than those in the Endo-TLIF group ( P<0.05), while there was no significant difference in the levels of CK and CPR between the two groups at other time points ( P>0.05). All patients were followed up 12 months. VAS score of low back and leg pain and ODI at each time point after operation significantly improved when compared with those before operation in the two groups ( P<0.05); there was no significant difference in VAS score of low back and leg pain and ODI between the two groups at each time point after operation ( P>0.05). There was no significant difference in the intervertebral fusion rate between the two groups at 12 months after operation ( P>0.05). Conclusion: UBE-TLIF and Endo-TLIF are both effective methods for treating degenerative lumbar spinal stenosis with lumbar spondylolisthesis. However, compared to Endo-TLIF, UBE-TLIF requires further improvement in minimally invasive techniques to reduce tissue trauma and blood loss.

[Application of self-stabilizing zero-profile three-dimensional printed artificial vertebral bodies for treatment of cervical spondylotic myelopathy].

Objective: To evaluate the safety and effectiveness of applying self-stabilizing zero-profile three-dimensional (3D) printed artificial vertebral bodies in anterior cervical corpectomy and fusion (ACCF) for cervical spondylotic myelopathy. Methods: A retrospective analysis was conducted on 37 patients diagnosed with cervical spondylotic myelopathy who underwent single-level ACCF using either self-stabilizing zero-profile 3D-printed artificial vertebral bodies ( n=15, treatment group) or conventional 3D-printed artificial vertebral bodies with titanium plates ( n=22, control group) between January 2022 and February 2023. There was no significant difference in age, gender, lesion segment, disease duration, and preoperative Japanese Orthopedic Association (JOA) score between the two groups ( P>0.05). Operation time, intraoperative bleeding volume, hospitalization costs, JOA score and improvement rate, incidence of postoperative prosthesis subsidence, and interbody fusion were recorded and compared between the two groups. Results: Compared with the control group, the treatment group had significantly shorter operation time and lower hospitalization costs ( P<0.05); there was no significant difference in intraoperative bleeding volume between the two groups ( P>0.05). All patients were followed up, with a follow-up period of 6-21 months in the treatment group (mean, 13.7 months) and 6-19 months in the control group (mean, 12.7 months). No dysphagia occurred in the treatment group, while 5 cases occurred in the control group, with a significant difference in the incidence of dysphagia between the two groups ( P<0.05). At 12 months after operation, both groups showed improvement in JOA scores compared to preoperative scores, with significant differences ( P<0.05); however, there was no significant difference in the JOA scores and improvement rate between the two groups ( P>0.05). Radiographic examinations showed the interbody fusion in both groups, and the difference in the time of interbody fusion was not significant ( P>0.05). At last follow-up, 2 cases in the treatment group and 3 cases in the control group experienced prosthesis subsidence, with no significant difference in the incidence of prosthesis subsidence ( P>0.05). There was no implant displacement or plate-screw fracture during follow-up. Conclusion: The use of self-stabilizing zero-profile 3D-printed artificial vertebral bodies in the treatment of cervical spondylotic myelopathy not only achieves similar effectiveness to 3D-printed artificial vertebral bodies, but also reduces operation time and the incidence of postoperative dysphagia.

[Treatment of cervical ossification of posterior longitudinal ligament with titanium alloy trabecular bone three-dimensional printed artificial vertebral body].

Objective: To evaluate the effectiveness of using titanium alloy trabecular bone three-dimensional (3D) printed artificial vertebral body in treating cervical ossification of the posterior longitudinal ligament (OPLL). Methods: A retrospective analysis was conducted on clinical data from 45 patients with cervical OPLL admitted between September 2019 and August 2021 and meeting the selection criteria. All patients underwent anterior cervical corpectomy and decompression, interbody bone graft fusion, and titanium plate internal fixation. During operation, 21 patients in the study group received titanium alloy trabecular bone 3D printed artificial vertebral bodies, while 24 patients in the control group received titanium cages. There was no significant difference in baseline data such as gender, age, disease duration, affected segments, or preoperative pain visual analogue scale (VAS) score, Japanese Orthopaedic Association (JOA) score, Neck Disability Index (NDI), vertebral height, and C 2-7Cobb angle ( P>0.05). Operation time, intraoperative blood loss, and occurrence of complications were recorded for both groups. Preoperatively and at 3 and 12 months postoperatively, the functionality and symptom relief were assessed using JOA scores, VAS scores, and NDI evaluations. The vertebral height and C 2-7 Cobb angle were detected by imaging examinations and the implant subsidence and intervertebral fusion were observed. Results: The operation time and incidence of complications were significantly lower in the study group than in the control group ( P<0.05), while the difference in intraoperative blood loss between the two groups was not significant ( P>0.05). All patients were followed up 12-18 months, with the follow-up time of (14.28±4.34) months in the study group and (15.23±3.54) months in the control group, showing no significant difference ( t=0.809, P=0.423). The JOA score, VAS score, and NDI of the two groups improved after operation, and further improved at 12 months compared to 3 months, with significant differences ( P<0.05). At each time point, the study group exhibited significantly higher JOA scores and improvement rate compared to the control group ( P<0.05); but there was no significantly difference in VAS score and NDI between the two groups ( P>0.05). Imaging re-examination showed that the vertebral height and C 2-7Cobb angle of the two groups significantly increased at 3 and 12 months after operation ( P<0.05), and there was no significant difference between 3 and 12 months after operation ( P>0.05). At each time point, the vertebral height and C 2-7Cobb angle of the study group were significantly higher than those of the control group ( P<0.05), and the implant subsidence rate was significantly lower than that of the control group ( P<0.05). However, there was no significant difference in intervertebral fusion rate between the two groups ( P>0.05). Conclusion: Compared to traditional titanium cages, the use of titanium alloy trabecular bone 3D-printed artificial vertebral bodies for treating cervical OPLL results in shorter operative time, fewer postoperative complications, and lower implant subsidence rates, making it superior in vertebral reconstruction.