Risks Associated with Surgical Management of Lumbosacral Transitional Vertebrae: Systematic Review of Surgical Considerations and Illustrative Case.

BACKGROUND: Lumbosacral transitional vertebrae (LSTV) are congenital anomalies of the L5-S1 segments characterized by either sacralization of the most caudal lumbar vertebra or lumbarization of the most cephalad sacral vertebra. This variation in anatomy exposes patients to additional surgical risks. METHODS: In order to shed light on surgical considerations reported for lumbar spine cases involving LSTV as described in the extant literature, we performed a systematic review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines. We also present a case example in which wrong level surgery was avoided due to anatomical understanding of LSTV. RESULTS: A 48-year-old female presented with severe back pain after sustaining a fall from ten feet. The patient exhibited full motor function in all extremities but had begun to experience urinary retention. On initial imaging read, the patient was suspected to have an L1 burst fracture. A review of the imaging demonstrated a transitional vertebra. Therefore, based on the last rib corresponding to T12, the fractured level was L2. This case illustrates the risk LSTV carries for wrong site surgery; appropriate levels were then decompressed and instrumented. On systematic review of the literature according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines, a three database literature search identified 39 studies describing 885 patients with LSTV and relevant surgical considerations. The primary indications for surgery were for disc herniation (37%), Bertolotti's syndrome (35%), and spinal stenosis (25%). This cohort displayed a mean follow-up time of 23 months. Reherniation occurred in 12 patients (5.5%). Medical management through steroid injection was 24, 72% (n = 80) for the sample. Wrong level surgery occurred in 1.4% (n = 12) of patients. CONCLUSIONS: LSTV represents a constellation of changes in anatomy beyond just a sacralized or lumbarized vertebra. These anatomical differences expose the patient to additional surgical risks. This case and review of the literature highlight avoidable complications and in particular wrong level surgery.

Endoscopic Anterior Lumbar Interbody Fusion: Systematic Review and Meta-Analysis.

Laparoscopic anterior lumbar interbody fusion (L-ALIF), which employs laparoscopic cameras to facilitate a less invasive approach, originally gained traction during the 1990s but has subsequently fallen out of favor. As the envelope for endoscopic approaches continues to be pushed, a recurrence of interest in laparoscopic and/or endoscopic anterior approaches seems possible. Therefore, evaluating the current evidence base in regard to this approach is of much clinical relevance. To this end, a systematic literature search was performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines using the following keywords: "(laparoscopic OR endoscopic) AND (anterior AND lumbar)." Out of the 441 articles retrieved, 22 were selected for quantitative analysis. The primary outcome of interest was the radiographic fusion rate. The secondary outcome was the incidence of perioperative complications. Meta-analysis was performed using RStudio's "metafor" package. Of the 1,079 included patients (mean age, 41.8±2.9 years), 481 were males (44.6%). The most common indication for L-ALIF surgery was degenerative disk disease (reported by 18 studies, 81.8%). The mean follow-up duration was 18.8±11.2 months (range, 6-43 months). The pooled fusion rate was 78.9% (95% confidence interval [CI], 68.9-90.4). Complications occurred in 19.2% (95% CI, 13.4-27.4) of L-ALIF cases. Additionally, 7.2% (95% CI, 4.6-11.4) of patients required conversion from L-ALIF to open surgery. Although L-ALIF does not appear to be supported by studies available in the literature, it is important to consider the context from which these results have been obtained. Even if these results are taken at face value, the failure of endoscopy to have a role in the ALIF approach does not mean that it should not be incorporated in posterior approaches.

External Validation of the Global Alignment and Proportion Score as Prognostic Tool for Corrective Surgery in Adult Spinal Deformity: A Systematic Review and Meta-Analysis.

BACKGROUND: Since its proposal, the Global Alignment and Proportion (GAP) score has been the topic of several external validation studies, which have yielded conflicting results. Given the lack of consensus regarding this prognostic tool, the authors aim to assess the accuracy of GAP scores for predicting mechanical complications following adult spinal deformity correction surgery. METHODS: A systematic search was performed using PubMed, Embase, and Cochrane Library for the purpose of identifying all studies evaluating the GAP score as a predictive tool for mechanical complications. GAP scores were pooled using a random-effects model to compare patients reporting mechanical complications after surgery versus those reporting no complications. Where receiver operator curves were provided, the area under the curve (AUC) was pooled. RESULTS: A total of 15 studies featuring 2092 patients were selected for inclusion. Qualitative analysis using Newcastle-Ottawa criteria revealed moderate quality among all included studies (5.99/9). With respect to sex, the cohort was predominantly female (82%). The pooled mean age among all patients in the cohort was 58.55 years, with a mean follow-up of 33.86 months after surgery. Upon pooled analysis, we found that mechanical complications were associated with higher mean GAP scores, albeit minimal (mean difference = 0.571 [ 95% confidence interval: 0.163-0.979]; P = 0.006, n = 864). Additionally, age (P = 0.136, n = 202), fusion levels (P = 0.207, n = 358), and body mass index (P = 0.616, n = 350) were unassociated with mechanical complications. Pooled AUC revealed poor discrimination overall (AUC = 0.69; n = 1206). CONCLUSIONS: GAP scores may have a minimal-to-moderate predictive capability for mechanical complications associated with adult spinal deformity correction.

Primary Spinal Infections in Patients With Hematologic Immunocompromising Conditions: A Systematic Literature Review.

PURPOSE: Primary spinal infections (PSIs) are a group of infectious diseases characterized by inflammation of the end plate-disk unit or its surroundings. PSI is considered more prevalent and aggressive among patients with chronic immunocompromised states. Association of PSIs, immunocompromising cancers, and hemoglobinopathies has not been systematically analyzed. We conducted a systematic review to study characteristics, clinical presentation, and mortality of patients with PSI in the setting of hematologic disease. METHODS: A systematic literature search in PubMed, Web of Science, and Scopus was conducted in April 2022 in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. We included retrospective case series and individual case reports. RESULTS: On careful review, 28 articles published between 1970 and 2022 were selected. These studies featured 29 patients who met inclusion criteria (mean age 29 years, age range 1.5 to 67 years; 63.3% male). Lumbar infection was the most common location (65.5%), with Salmonella (24.1%) as the main causative microorganism. Neurologic compromise was present in 41% of patients, and surgical intervention occurred in 48.3%. Average antibiotic duration was 13 weeks. The postoperative complication rate was 21.4%, with a mortality of 6.9%. CONCLUSION: PSI in patients with hematologic disease, while having shorter periods to diagnosis, presents increased rates of neurologic deficit, surgical intervention, and complications.

Resident Training in Spine Surgery: A Systematic Review of Simulation-Based Educational Models.

OBJECTIVE: With the increasing prevalence of spine surgery, ensuring effective resident training is becoming of increasing importance. Training safe, competent surgeons relies heavily on effective teaching of surgical indications and adequate practice to achieve a minimum level of technical proficiency before independent practice. American Council of Graduate Medical Education work-hour restrictions have complicated the latter, forcing programs to identify novel methods of surgical resident training. Simulation-based training is one such method that can be used to complement traditional training. The present review aims to evaluate the educational success of simulation-based models in the spine surgical training of residents. METHODS: Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, the PubMed, Web of Science, and Google Scholar databases were systematically screened for English full-text studies examining simulation-based spine training curricula. Studies were categorized based on simulation model class, including animal-cadaveric, human-cadaveric, physical/3-dimensional, and computer-based/virtual reality. Outcomes studied included participant feedback regarding the simulator and competency metrics used to evaluate participant performance. RESULTS: Seventy-two studies were identified. Simulators displayed high face validity and were useful for spine surgery training. Objective measures used to evaluate procedural performance included implant placement evaluation, procedural time, and technical skill assessment, with numerous simulators demonstrating a learning effect. CONCLUSIONS: While simulation-based educational models are one potential means of training residents to perform spine surgery, traditional in-person operating room training remains pivotal. To establish the efficacy of simulators, future research should focus on improving study quality by leveraging longitudinal study designs and correlating simulation-based training with clinical outcome measures.

Analysis of Current Neurological Surgery Residents and Prior Medical Education: Do Medical School Attributes Matter?

BACKGROUND: With the recent changes to the U.S. Medical Licensing Examination grading system, an understanding of the factors that influence the neurological surgery residency match process is crucial for residency directors. The aim of the present retrospective study was to explore the associations of medical school location, ranking, private school status, size, and presence of an American Association of Neurological Surgeons (AANS) chapter or neurological surgery interest group (NSIG) with the neurosurgery match outcomes. METHODS: An enrollment list of all accredited U.S. neurosurgery residency programs was compiled on June 28, 2021. For the included residents, the residency program, degree, and previously attended medical school were retrieved. The geographic location, ranking, private school status, and size were collected for the residency programs and medical schools attended by the residents at each program. RESULTS: A total of 1437 residents from 101 neurosurgery residency programs (89%) were included. Graduates from the top 25 medical schools were more likely to match into their home residency programs (P < 0.001) and highly ranked residency programs (P < 0.001). Students from larger medical schools were also more likely to match into larger (P < 0.001) and highly ranked (P < 0.001) programs than were applicants from smaller schools. Students from medical schools with an AANS chapter or NSIG were also more likely to match into top ranked programs (P < 0.001 for both). CONCLUSIONS: Medical students from the top 25 medical schools, private medical schools, medical schools with an AANS chapter, and medical schools with an NSIG were more likely to match into a prestigious residency program. These findings suggest that underlying biases might be present for program directors to consider in the resident selection process.

Cost analysis comparison between anterior and posterior cervical spine approaches.

Background: The costs of cervical spine surgery have steadily increased. We performed a 5-year propensity scoring-matched analysis of 276 patients undergoing anterior versus posterior cervical surgery at one institution. Methods: We performed propensity score matching on financial data from 276 patients undergoing 1-3 level anterior versus posterior cervical fusions for degenerative disease (2015-2019). Results: We found no significant difference between anterior versus posterior approaches for hospital costs ($42,529.63 vs. $45,110.52), net revenue ($40,877.25 vs. $34,036.01), or contribution margins ($14,230.19 vs. $6,312.54). Multivariate regression analysis showed variables significantly associated with the lower contribution margins included age (ß = -392.3) and length of stay (LOS; ß = -1151). Removing age/LOS from the analysis, contribution margins were significantly higher for the anterior versus posterior approach ($17,824.16 vs. $6,312.54, P = 0.01). Conclusion: Anterior cervical surgery produced higher contribution margins compared to posterior approaches, most likely because posterior surgery was typically performed in older patients requiring longer LOS.

Association of tranexamic acid with decreased blood loss in patients undergoing laminectomy and fusion with posterior instrumentation: a systematic review and meta-analysis.

OBJECTIVE: Tranexamic acid (TXA) is an antifibrinolytic agent associated with reduced blood loss and mortality in a wide range of procedures, including spine surgery, traumatic brain injury, and craniosynostosis. Despite this wide use, the safety and efficacy of TXA in spine surgery has been considered controversial due to a relative scarcity of literature and lack of statistical power in reported studies. However, if TXA can be shown to reduce blood loss in laminectomy with fusion and posterior instrumentation, more surgeons may include it in their armamentarium. The authors aimed to conduct an up-to-date systematic review and meta-analysis of the efficacy of TXA in reducing blood loss in laminectomy and fusion with posterior instrumentation. METHODS: A systematic review and meta-analysis, abiding by PRISMA guidelines, was performed by searching the databases of PubMed, Web of Science, and Cochrane. These platforms were queried for all studies reporting the use of TXA in laminectomy and fusion with posterior instrumentation. Variables retrieved included patient demographics, surgical indications, involved spinal levels, type of laminectomy performed, TXA administration dose, TXA route of administration, operative duration, blood loss, blood transfusion rate, postoperative hemoglobin level, and perioperative complications. Heterogeneity across studies was evaluated using a chi-square test, Cochran's Q test, and I2 test performed with R statistical programming software. RESULTS: A total of 7 articles were included in the qualitative study, while 6 articles featuring 411 patients underwent statistical analysis. The most common route of administration for TXA was intravenous with 15 mg/kg administered preoperatively. After the beginning of surgery, TXA administration patterns were varied among studies. Blood transfusions were increased in non-TXA cohorts compared to TXA cohorts. Patients administered TXA demonstrated a significant reduction in blood loss (mean difference -218.44 mL; 95% CI -379.34 to -57.53; p = 0.018). TXA administration was not associated with statistically significant reductions in operative durations. There were no adverse events reported in either the TXA or non-TXA patient cohorts. CONCLUSIONS: TXA can significantly reduce perioperative blood loss in cervical, thoracic, and lumbar laminectomy and fusion procedures, while demonstrating a minimal complication profile.

Elective versus nonelective brain tumor resections: a 5-year propensity score matching cost comparison analysis.

OBJECTIVE: Elective surgical cases generally have lower costs, higher profit margins, and better outcomes than nonelective cases. Investigating the differences in cost and profit between elective and nonelective cases would help hospitals in planning strategies to withstand financial losses due to potential pandemics. The authors sought to evaluate the exact cost and profit margin differences between elective and nonelective supratentorial tumor resections at a single institution. METHODS: The authors collected economic analysis data in all patients who underwent supratentorial tumor resection at their institution between January 2014 and December 2018. The patients were grouped into elective and nonelective cases. Propensity score matching was used to adjust for heterogeneity of baseline characteristics between the two groups. RESULTS: There were 143 elective cases and 232 nonelective cases over the 5 years. Patients in the majority of elective cases had private insurance and in the majority of nonelective cases the patients had Medicare/Medicaid (p < 0.01). The total charges were significantly lower for elective cases ($168,800.12) compared to nonelective cases ($254,839.30, p < 0.01). The profit margins were almost 6 times higher for elective than for nonelective cases ($13,025.28 vs $2,128.01, p = 0.04). After propensity score matching, there was still a significant difference between total charges and total cost. CONCLUSIONS: Elective supratentorial tumor resections were associated with significantly lower costs with shorter lengths of stay while also being roughly 6 times more profitable than nonelective cases. These findings may help future planning for hospital strategies to survive financial losses during future pandemics that require widespread cancellation of elective cases.

Second opinion in spine surgery: A scoping review.

BACKGROUND: As a growing number of patients seek consultations for increasingly complex and costly spinal surgery, it is of both clinical and economic value to investigate the role for second opinions (SOs). Here, we summarized and focused on the shortcomings of 14 studies regarding the role and value of SOs before proceeding with spine surgery. METHODS: Utilizing PubMed, Google Scholar, and Scopus, we identified 14 studies that met the inclusion criteria that included: English, primary articles, and studies published in the past 20 years. RESULTS: We identified the following findings regarding SO for spine surgery: (1) about 40.6% of spine consultations are SO cases; (2) 61.3% of those received a discordant SO; (3) 75% of discordant SOs recommended conservative management; and (4) SO discordance applied to a variety of procedures. CONCLUSION: The 14 studies reviewed regarding SOs in spine surgery showed that half of the SOs differed from those given in the initial consultation and that SOs in spine surgery can have a substantial impact on patient care. Absent are prospective studies investigating the impact of following a first versus second opinion. These studies are needed to inform the potential benefit of universal implementation of SOs before major spine operations to potentially reduce the frequency and type/extent of surgery.

Comparison of Minimally Invasive Total versus Subtotal Resection of Spinal Tumors: A Systematic Review and Meta-Analysis.

OBJECTIVE: With the advent of minimally invasive techniques, minimally invasive spine surgery (MISS) has become a realistic option for many spine cases. This study aims to evaluate the operative and clinical outcomes of MISS for total versus subtotal tumor resection from current evidence. METHODS: A literature search was performed using the search term (Minimally invasive surgery OR MIS) AND (spine tumor OR spinal tumor). Studies including both minimally invasive total and subtotal resection cases with operative or clinical data were included. RESULTS: Seven studies describing 159 spinal tumor cases were included. Compared with total resection, subtotal resection showed no significant differences in surgical time (mean difference (MD), 9.44 minutes; 95% confidence interval [CI], -47.66 to 66.55 minutes; P = 0.37), surgical blood loss (MD, -84.72 mL; 95% CI, -342.82 to 173.39 mL; P = 0.34), length of stay (MD, 1.38 days; 95% CI, -0.95 to 3.71 days; P = 0.17), and complication rate (odds ratio, 9.47; 95% CI, 0.34-263.56; P = 0.12). Pooled analyses with the random-effects model showed that neurologic function improved in 89% of patients undergoing total resection, whereas neurologic function improved in 61% of patients undergoing subtotal resection. CONCLUSIONS: Our analyses show that there is no significant difference in operative outcomes between total and subtotal resection. Patients undergoing total resection showed slightly better improvement in neurologic outcomes compared with patients undergoing subtotal resection. Overall, this study suggests that both total and subtotal resection may result in comparable outcomes for patients with spinal tumors. However, maximal safe resection remains the ideal treatment because it provides the greatest chance of long-term benefit.

Effectiveness of Repair Techniques for Spinal Dural Tears: A Systematic Review.

BACKGROUND: Incidental or intentional durotomy in spine surgery is associated with a risk of cerebrospinal fluid (CSF) leakage and reoperation. Several strategies have been introduced, but the incomplete closure is still relatively frequent and troublesome. In this study, we review current evidence on spinal dural repair strategies and evaluate their efficacy. METHODS: PubMed, Web of Science, and Scopus were used to search primary studies about the repair of the spinal dura with different techniques. Of 265 articles found, 11 studies, which specified repair techniques and postoperative outcomes, were included for qualitative and quantitative analysis. The primary outcomes were CSF leakage and postoperative infection. RESULTS: The outcomes of different dural repair techniques were available in 776 cases. Pooled analysis of 11 studies demonstrated that the most commonly used technique was a combination of primary closure, patch or graft, and sealant (22.7%, 176/776). A combination of primary closure and patch or graft resulted in the lowest rate of CSF leakage (5.5%, 7/128). In this study, sealants as an adjunct to primary closure (13.7%, 18/131) did not significantly reduce the rate of CSF leakage compared with primary closure alone (17.6%, 18/102). The rates of infection and postoperative neurologic deficit were similar regardless of the repair techniques. CONCLUSIONS: Although the use of sealants has become prevalent, available sealants as an adjunct to primary closure did not reduce the rate of CSF leakage compared with primary closure. The combination of primary closure and patches or grafts could be effective in decreasing postoperative CSF leakage.

Predictors of Patient Satisfaction in Spine Surgery: A Systematic Review.

BACKGROUND: Recently, there has been increased interest in patient satisfaction measures such as Press Ganey and Hospital Consumer Assessment of Healthcare Providers and Systems (HCAHPS) surveys. In this systematic review, the spine surgery literature is analyzed to evaluate factors predictive of patient satisfaction as measured by these surveys. METHODS: A thorough literature search was performed in PubMed/MEDLINE, Google Scholar, and Cochrane databases. All English-language articles from database inception to July 2020 were screened for study inclusion according to PRISMA guidelines. RESULTS: Twenty-four of the 1899 published studies were included for qualitative analysis. There has been a statistically significant increase in the number of publications across years (P = 0.04). Overall, the studies evaluated the relationship between patient satisfaction and patient demographics (71%), preoperative and intraoperative clinical factors (21%), and postoperative factors (33%). Top positive predictors of patient satisfaction were patient and nursing/medical staff relationship (n = 4; 17%), physician-patient relationship (n = 4; 17%), managerial oversight of received care (n = 3; 13%), same sex/ethnicity between patient and physician (n = 2; 8%), and older age (n = 2; 8%). Top negative predictors of patient satisfaction were high Charlson Comorbidity Index/high disability/worse overall health functioning (n = 7; 29%), increased length of hospital stay (n = 4; 17%), high rating for pain/complications/readmissions (n = 4; 17%), and psychosocial factors (n = 3; 13%). CONCLUSIONS: There is heterogeneity in terms of different factors, both clinical and nonclinically related, that affect patient satisfaction ratings. More research is warranted to investigate the role of hospital consumer surveys in the spine surgical patient population.

The market landscape of online second opinion services for spine surgery.

BACKGROUND: The aim of this study was to identify patient interest in second opinion services online and identify the options patients have in obtaining second opinions from spine surgeons in the United States. METHODS: We utilized Google Trends (i.e., search data since 2010) to ascertain the level of interest in receiving second opinions for spinal surgery. In addition, we contacted the top 30 hospitals for neurology and neurosurgery in the U.S. News rankings by phone to obtain information regarding when/how and at what cost they provide second opinions for spine surgery. RESULTS: The cost of the second surgical opinions averaged $493 (±$343) USD (range $90-$1,300); the time to receive a second opinion averaged 20 (±19) days (range 1 day-5 months). Remote or "online second opinion" programs charged an average of $643 (±$259) USD (range $100-$850), and the time to receive an "online second opinion" averaged 14 (±7) days (range 1-4 weeks). CONCLUSION: Although second opinions have been shown to be beneficial to patients, ambiguous or high costs and long wait times may serve as barriers for certain groups (i.e., uninsured or underinsured) and potentially diminish the quality of care.

Back pain outcomes after minimally invasive anterior lumbar interbody fusion: a systematic review.

OBJECTIVE: Minimally invasive anterior lumbar interbody fusion surgery (MIS ALIF) is a technique that restores disc height and lumbar lordosis through a smaller exposure and less soft-tissue trauma compared to open approaches. The mini-open and laparoscopic assistance techniques are two main forms of MIS ALIF. The authors conducted a systematic review that sought to critically summarize the literature on back pain following MIS ALIF. METHODS: In March 2020, the authors searched the PubMed, Web of Science, and Cochrane Library databases for studies describing back pain visual analog scale (VAS) outcomes after MIS ALIF. The following exclusion criteria were applied to studies evaluated in full text: 1) the study included fewer than 20 patients, 2) the mean follow-up duration was shorter than 12 months, 3) the study did not report back pain VAS score as an outcome measure, and 4) MIS ALIF was not studied specifically. The methodology for the included studies were evaluated for potential biases and assigned a level of evidence. RESULTS: There were a total of 552 patients included from 13 studies. The most common biases were selection and interviewer bias. The majority of studies were retrospective. The mean sample size was 42.3 patients. The mean follow-up duration was approximately 41.8 months. The mean postoperative VAS reduction was 5.1 points. The mean VAS reduction for standalone grafts was 5.9 points, and 5.0 points for those augmented with posterior fixation. The most common complications included bladder or urinary dysfunction, infection, and hardware-related complications. CONCLUSIONS: This was a systematic review of back pain outcomes following MIS ALIF. Back pain VAS score was reduced postoperatively across all studies. The complication rates were low overall. MIS ALIF is safe and effective at reducing back pain in appropriate patient populations.

PIP4K2A as a negative regulator of PI3K in PTEN-deficient glioblastoma.

Glioblastoma (GBM) is the most malignant brain tumor with profound genomic alterations. Tumor suppressor genes regulate multiple signaling networks that restrict cellular proliferation and present barriers to malignant transformation. While bona fide tumor suppressors such as PTEN and TP53 often undergo inactivation due to mutations, there are several genes for which genomic deletion is the primary route for tumor progression. To functionally identify putative tumor suppressors in GBM, we employed in vivo RNAi screening using patient-derived xenograft models. Here, we identified PIP4K2A, whose functional role and clinical relevance remain unexplored in GBM. We discovered that PIP4K2A negatively regulates phosphoinositide 3-kinase (PI3K) signaling via p85/p110 component degradation in PTEN-deficient GBMs and specifically targets p85 for proteasome-mediated degradation. Overexpression of PIP4K2A suppressed cellular and clonogenic growth in vitro and impeded tumor growth in vivo. Our results unravel a novel tumor-suppressive role of PIP4K2A for the first time and support the feasibility of combining oncogenomics with in vivo RNAi screen.

Long-term prospective outcomes after minimally invasive trans-iliac sacroiliac joint fusion using triangular titanium implants.

BACKGROUND: Minimally invasive sacroiliac joint fusion (SIJF) has become an increasingly accepted surgical option for chronic sacroiliac (SI) joint dysfunction, a prevalent cause of unremitting low back/buttock pain. OBJECTIVE: The objective of this study was to report clinical and functional outcomes of SIJF using triangular titanium implants (TTI) in the treatment of chronic SI joint dysfunction due to degenerative sacroiliitis or sacroiliac joint (SIJ) disruption at 3 years postoperatively. METHODS: A total of 103 subjects with SIJ dysfunction at 12 centers were treated with TTI in two prospective clinical trials (NCT01640353 and NCT01681004) and enrolled in this long-term follow-up study (NCT02270203). Subjects were evaluated in study clinics at study start and again at 3, 4, and 5 years. RESULTS: Mean (SD) preoperative SIJ pain score was 81.5, and mean preoperative Oswestry Disability Index (ODI) was 56.3. At 3 years, mean pain SIJ pain score decreased to 26.2 (a 55-point improvement from baseline, p<0.0001). At 3 years, mean ODI was 28.2 (a 28-point improvement from baseline, p<0.0001). In all, 82% of subjects were very satisfied with the procedure at 3 years. EuroQol-5D (EQ-5D) time trade-off index improved by 0.30 points (p<0.0001). No adverse events definitely related to the study device or procedure were reported; one subject underwent revision surgery at year 3.7. SIJ pain contralateral to the originally treated side occurred in 15 subjects of whom four underwent contralateral SIJF. The proportion of subjects who were employed outside the home full- or part-time at 3 years decreased somewhat from baseline (p=0.1814), and the proportion of subjects who would have the procedure again was lower at 3 years compared to earlier time points. CONCLUSION: In long-term (3-year) follow-up, minimally invasive trans-iliac SIJF with TTI was associated with improved pain, disability, and quality of life with relatively high satisfaction rates. LEVEL OF EVIDENCE: Level II. CLINICAL RELEVANCE: SIJF with TTI.

Disc nucleus fortification for lumbar degenerative disc disease: a biomechanical study.

OBJECTIVE Spinal stability is attributed in part to osteoligamentous structures, including the vertebral body, facets, intervertebral discs, and posterior elements. The materials in this study provide an opportunity to augment the degenerated nucleus without removing native disc material, a procedure introduced here as "fortification." The objective of this study was to determine the effect of nucleus fortification on lumbar disc biomechanics. METHODS The authors performed in vitro analysis of human cadaveric functional spinal units (FSUs), along with characterization and quantification of movement of the units using biomechanical data in intact, disc-only, and fortified specimens. The units underwent removal of all posterior elements and annulus and were fortified by injecting a biogel into the nucleus pulposus. Each specimen was subjected to load testing, range of motion (ROM) quantification, and disc bulge measurements. Optoelectric tracking was used to quantify disc bulge. These criteria were assessed in the intact, disc-only, and fortified treatments. RESULTS Disc-only FSUs resulted in increased ROM when compared with intact and fortified conditions. Fortification of the FSU resulted in partial restoration of normal ROM in the treatment groups. Analysis of hysteresis loops showed more linear response in the fortified groups when compared with the intact and disc-only groups. CONCLUSIONS Disc nucleus fortification increases linearity and decreases ROM.

Effect of TLIF Cage Placement on In Vivo Kinematics.

BACKGROUND: The influence of interbody cage positioning on clinical outcomes following lumbar interbody fusion is not well understood, though it has been hypothesized to play a significant role in stability of the treated level. The purpose of this study was to evaluate any correlations between cage placement in TLIF procedures and post-operative kinematics. METHODS: Thirteen patients who had previously undergone a TLIF procedure were evaluated using the Vertebral Motion Analysis (VMA) system, an automated fluoroscopic method of tracking kinematics in vivo. Upright and recumbent bending platforms were used to guide patients through a set range of motion (ROM) standing up and lying down, respectively, in both flexion-extension (FE) and lateral bending (LB). Intervertebral ROM was measured via fluoroscopic images captured sequentially throughout the movement. DICOM images acquired by the VMA system were used to calculate cage positioning. Intra-rater and inter-rater reliability of TLIF cage position were also assessed. RESULTS: Statistically significant correlations were noted between sagittal cage position and lying LB (r = -0.583, p = 0.047), and coronal cage positioning with both standing (r = 0.672, p = 0.012) and lying LB (r = 0.632, p = 0.027). Additionally, the correlation between sagittal cage position and standing FE was trending towards significance (r = -0.542, p = 0.055). CONCLUSIONS: The intuitive correlation between coronal cage position and both standing and lying lateral bending ROM is supported by the data from this study, suggesting placement closer to midline is optimal for stability. Additionally, the VMA system appears to be a sensitive and repeatable means to obtain information on postoperative kinematic outcomes. Further work to establish the relationship between cage placement, these kinematic outcomes and, potentially, functional pain outcomes seems to be warranted based on the results obtained here.