Minimally Invasive Transforaminal Lumbar Interbody Fusion: Strategies for Creating Lordosis with a Posterior Approach.

The purpose of this article is to review the outcomes concerning lumbar lordosis restoration after the MIS-TLIF and to present strategies to create lumbar lordosis by using this MIS posterior approach. MIS-TLIF is an effective MIS lumbar interbody fusion that can achieve lumbar lordosis restoration. Several crucial steps aid in this sagittal profile correction during the MIS-TLIF, including the appropraite prone positioning, optimizing disc space preparation, maximizing disc space height, anterior interbody cage placement, and reducing the spondylolisthesis.

Selective thoracolumbar fusion in adult spinal deformity double curves with circumferential minimally invasive surgery: 2-year minimum follow-up.

OBJECTIVE: Selection of the upper instrumented vertebra (UIV) level for adult spinal deformity (ASD) remains controversial. Although selective fusion attempts have been described for fractional curves or adolescent curves, no authors have described selective thoracolumbar fusion performance for ASD with double curves. This study evaluated the clinical impact of selective fusion constructs within the lower thoracic and/or lumbar spine on ASD with double curves. METHODS: A retrospective review was performed on an ASD (Cobb angle > 20°, sagittal vertical axis [SVA] > 50 mm, and pelvic incidence minus lumbar lordosis mismatch [PI-LL] > 10°) database consisting of 438 patients who underwent correction with circumferential minimally invasive surgery (CMIS) between 2007 and 2020. The inclusion criteria were ASD double curves (lumbar Cobb angle > 35° and thoracic Cobb angle > 30°), 4 or more levels fused, and minimum 2-year follow-up. Analyses were performed on spinopelvic data and clinical outcome scores. Complications were recorded, specifically the need for revision surgery and hardware-related complications. RESULTS: Twenty-one ASD double curve patients underwent selective correction with a mean ± SD (range) follow-up of 91 ± 43 (24-174) months. A total of 141 levels were fused with a mean of 6.7 ± 1.3 (4-8) levels. T10 was the most proximal and most common UIV (10/21 [48%]). Pelvic fixation was performed in 12 patients (57%). Significant improvements in lumbar Cobb angle, thoracic Cobb angle, coronal balance, lumbar lordosis, thoracic kyphosis, SVA, and PI-LL were achieved. The uninstrumented thoracic spine demonstrated 14.5° of mean coronal correction and a mean increase of 9.4° in kyphosis. Significant improvements in visual analog scale (VAS) and Oswestry Disability Index (ODI) scores were observed. Four patients required revision for the following reasons: 1) superficial wound infection requiring irrigation and debridement; 2) bilateral L5 pars fractures requiring L5-S1 anterior lumbar interbody fusion and pelvic fixation; 3) adjacent-segment degeneration at L5-S1 requiring anterior lumbar interbody fusion and pelvic fixation; and 4) proximal junctional kyphosis requiring revision fusion to include the entire thoracic curve. There were no instances of hardware failure such as rod breakage or screw loosening. CONCLUSIONS: Selective thoracolumbar fusion with CMIS for ASD double curves can provide significant clinical improvements. Despite limiting fusion constructs to within the lower thoracic and/or lumbar spine, significant correction can be observed in the uninstrumented thoracic curve. The rate of mechanical complications was low, and the 2-year follow-up results suggested that limited fusion constructs are viable options for ASD double curve patients.

Do peri-operative parathyroid hormone (PTH) analogues improve bone density and decrease mechanical complications in spinal deformity correction?-a minimum 2-year radiological study measuring Hounsfield units.

OBJECTIVE: To delineate whether use of a PTH analogue in the 1-year peri-operative period improves lumbar bone density. METHODS: A prospectively collected data registry of 254 patients who underwent CMIS correction of ASD (Cobb angle > 20 or SVA > 50 mm or (PI-LL) > 10) from Jan 2011 to Jan 2020 was analysed. Patients who were placed on PTH analogues for one year in conjunction with surgery were included in the study. Ultimately, 41 patients who had pre- and two-year post-operative CT scans for review were included in this study. Hounsfield units were measured off of the L1-L3 levels for all patients before and after surgery on pre-op and post-op CT scans. RESULT: The mean age of patients in this study was 70 (52-84, SD 7). Mean follow-up was 66 (24-132, SD 33) months. Twenty-three patients met criteria for severe deformity (Cobb angle > 50 degrees or SVA > 95 mm or PI/LL mismatch > 20 or PT > 30). Based off 2-year post-op CT scan, there were significant improvements in L1 Hounsfield units when comparing pre-op values (96; SD 55) to post-op values (185 SD 102); p. < 0.05. There was no screw loosening or screw pull out. There were 2 patients with PJF (4.8%). Both these patients had not completed their PTH treatment: one only took PTH for 3 months (PJF at 2-year post-op) and the other one took it only for 1 month (PJF at 1-year post-op). No increase in bone density was noted (based off of Hounsfield units) in five patients (12%) despite completion of their PTH therapy. Only one patient experienced nausea from PTH therapy. There were no other PTH related adverse events. CONCLUSION: The incidence of PTH analogues failing to increase bone density in our series was low at 12%. This study shows that PTH analogues may be a powerful adjunct for increasing bone density and may help to mitigate the risk of mechanical complications in patients undergoing deformity correction with minimally invasive techniques. Future comparative studies are warranted to confirm these latter findings and to potentially protocolize the ideal peri-operative bone health optimization strategy.

Spinal Deformity Complexity Checklist for Minimally Invasive Surgery: Expert Consensus from the Minimally Invasive International Spine Study Group.

BACKGROUND: We developed a spinal deformity complexity checklist (SDCC) to assess the difficulty in performing a circumferential minimally invasive surgery (MIS) for adult spinal deformity. METHODS: A modified Delphi method of panel experts was used to construct an SDCC checklist of radiographic and patient-related characteristics that could affect the complexity of surgery via MIS approaches. Ten surgeons with expertise in MIS deformity surgery were queried to develop and refine the SDCC with 3 radiographic categories (x-ray, magnetic resonance imaging, computed tomography) and 1 patient-related category. Within each category, characteristics affecting MIS complexity were identified by initial roundtable discussion. Second-round discussion determined which characteristics substantially impacted complexity the most. RESULTS: Thirteen characteristics within the x-ray category were determined. Spinopelvic characteristics, endpoints of instrumentation, and prior hardware/fusion were associated with increased complexity. Vertebral body rotation-as reflected by the Nash-Moe grade-added significant complexity. Psoas anatomy and spinal stenosis added the most complexity for the 5 magnetic resonance imaging characteristics. There were 3 characteristics in the CT category with pre-exisiting fusion, being the variable most highly selected. Of the 5 patient-related characteristics, osteoporosis and BMI were found to most affect complexity. CONCLUSIONS: The SDCC is a comprehensive list of pertinent radiographic and patient-related characteristics affecting complexity level for MIS deformity surgery. The value of the SDCC is that it allows rapid assessment of key factors when determining whether MIS surgery can be performed effectively and safely. Patients with scores of 4 in any characteristic should be considered challenging to treat with MIS; open surgery may be a better alternative.

Does the Global Alignment and Proportion score predict mechanical complications in circumferential minimally invasive surgery for adult spinal deformity?

OBJECTIVE: The Global Alignment and Proportion (GAP) score was developed to serve as a tool to predict mechanical complication probability in patients undergoing surgery for adult spinal deformity (ASD), serving as an aid for setting surgical goals to decrease the prevalence of mechanical complications in ASD surgery. However, it was developed using ASD patients for whom open surgical techniques were used for correction. Therefore, the purpose of this study was to assess the applicability of the score for patients undergoing circumferential minimally invasive surgery (cMIS) for correction of ASD. METHODS: Study participants were patients undergoing cMIS ASD surgery without the use of osteotomies with a minimum of four levels fused and 2 years of follow-up. Postoperative GAP scores were calculated for all patients, and the association with mechanical failure was analyzed. RESULTS: The authors identified 182 patients who underwent cMIS correction of ASD. Mechanical complications were found in 11.1% of patients with proportioned spinopelvic states, 20.5% of patients with moderately disproportioned spinopelvic states, and 18.8% of patients with severely disproportioned spinopelvic states. Analysis with a chi-square test showed a significant difference between the cMIS and original GAP study cohorts in the moderately disproportioned and severely disproportioned spinopelvic states, but not in the proportioned spinopelvic states. CONCLUSIONS: For patients stratified into proportioned, moderately disproportioned, and severely disproportioned spinopelvic states, the GAP score predicted 6%, 47%, and 95% mechanical complication rates, respectively. The mechanical complication rate in patients undergoing cMIS ASD correction did not correlate with the calculated GAP spinopelvic state.

A novel scoring system concept for de novo spinal infection treatment, the Spinal Infection Treatment Evaluation Score (SITE Score): a proof-of-concept study.

OBJECTIVE: De novo infections of the spine are an increasing healthcare problem. The decision for nonsurgical or surgical treatment is often made case by case on the basis of physician experience, specialty, or practice affiliation rather than evidence-based medicine. To create a more systematic foundation for surgical assessments of de novo spinal infections, the authors applied a formal validation process toward developing a spinal infection scoring system using principles gained from other spine severity scoring systems like the Spine Instability Neoplastic Score, Thoracolumbar Injury Classification and Severity Score, and AO Spine classification of thoracolumbar injuries. They utilized an expert panel and literature reviews to develop a severity scale called the "Spinal Infection Treatment Evaluation Score" (SITE Score). METHODS: The authors conducted an evidence-based process of combining literature reviews, extracting key elements from previous scoring systems, and obtaining iterative expert panel input while following a formal Delphi process. The resulting basic SITE scoring system was tested on selected de novo spinal infection cases and serially refined by an international multidisciplinary expert panel. Intra- and interobserver reliabilities were calculated using the intraclass correlation coefficient (ICC) and Fleiss' and Cohen's kappa, respectively. A receiver operating characteristic analysis was performed for cutoff value analysis. The predictive validity was assessed through cross-tabulation analysis. RESULTS: The conceptual SITE scoring system combines the key variables of neurological symptoms, infection location, radiological variables for instability and impingement of neural elements, pain, and patient comorbidities. Ten patients formed the first cohort of de novo spinal infections, which was used to validate the conceptual scoring system. A second cohort of 30 patients with de novo spinal infections, including the 10 patients from the first cohort, was utilized to validate the SITE Score. Mean scores of 6.73 ± 1.5 and 6.90 ± 3.61 were found in the first and second cohorts, respectively. The ICCs for the total score were 0.989 (95% CI 0.975-0.997, p < 0.01) in the first round of scoring system validation, 0.992 (95% CI 0.981-0.998, p < 0.01) in the second round, and 0.961 (95% CI 0.929-0.980, p < 0.01) in the third round. The mean intraobserver reliability was 0.851 ± 0.089 in the third validation round. The SITE Score yielded a sensitivity of 97.77% ± 3.87% and a specificity of 95.53% ± 3.87% in the last validation round for the panel treatment decision. CONCLUSIONS: The SITE scoring concept showed statistically meaningful reliability parameters. Hopefully, this effort will provide a foundation for a future evidence-based decision aid for treating de novo spinal infections. The SITE Score showed promising inter- and intraobserver reliability. It could serve as a helpful tool to guide physicians' therapeutic decisions in managing de novo spinal infections and help in comparison studies to better understand disease severity and outcomes.

An Assessment of the Safety of Surgery and Hardware Placement in de-novo Spinal Infections. A Systematic Review and Meta-Analysis of the Literature.

OBJECTIVES: Primary objectives were outcomes comparison of instrumented surgery used for de-novo spinal infections in terms of infection recurrence, reoperations, primary failure, mortality, and length of stay relative to non-instrumented surgery. Secondary objectives were outcomes for surgical and non-surgical treatment of de-novo spinal infections regarding recurrence of infection, mortality, quality of life, and length-of-stay. METHODS: A systematic literature review was performed using the PubMed database. Studies comparing outcome variables of patients with de-novo spinal infections (DNSI) treated with and without instrumentation and surgical versus non-surgical treatment were included. Studies primarily focusing on epidural abscesses or non-de-novo infections were excluded. A meta-analysis was performed for infection recurrence, reoperation, primary treatment failure, mortality, and quality-of-life parameters. RESULTS: A total of 17 retrospective studies with 2.069 patients met the inclusion criteria. 1.378 patients received surgical treatment with or without instrumentation; 676 patients were treated non-surgically. For the comparison of instrumented to non-instrumented surgery Odds-Ratios were .98 (P = .95) for infection recurrence, .83 (P = .92) for primary failure, .53 (P = .02) for mortality and .32 (P = .05) for reoperation. For the comparison of non-surgical to surgical treatment, Odds-Ratios were .98 (P = .95) for infection recurrence, and 1.05 (P = .89) for mortality. CONCLUSION: Available data support that instrumented surgery can be performed safely without higher rates of infection recurrence or primary failure and lower reoperation and mortality rates compared to nonsurgical treatment for DNSI. Furthermore, spine surgical treatment may generally be performed without higher risk of infection recurrence and mortality and better quality-of-life outcomes compared to generic non-surgical treatment.