Age is Associated with Level of First-Time Anterior Cervical Discectomy and Fusion: An Ordinal Analysis of Factors Influencing Timing of Cervical Degeneration.

BACKGROUND: Symptomatic cervical spondylosis is often treated with anterior cervical discectomy and fusion (ACDF). However, few factors can predict which cervical level will degenerate and require intervention. This analysis evaluates preprocedural factors associated with level of first-time single-level ACDF. METHODS: We performed a retrospective analysis of patients who underwent single-level ACDF without prior history of spine surgery. Mann Whitney U-tests and Spearman rank-order correlation were performed for analyses of associations between variables of interest and ACDF level. Adjusted odds-ratios were calculated by proportional-odds logistic regression, with age, sex, body mass index, current tobacco use, history of neck trauma, preoperative radicular symptoms, and preoperative myelopathic symptoms as covariates. RESULTS: One hundred forty-one patients met inclusion criteria, and age demonstrated a negative correlation with ACDF level, such that younger patients tended to have ACDF performed at inferior subaxial levels (P = 0.0006, rho = -0.31, moderately strong relationship). Patients with preoperative radicular symptoms and myelopathic symptoms were more likely to have ACDF performed at inferior (P = 0.0001) and superior (P < 0.0001) levels, respectively. Patient sex, body mass index, current tobacco use, and history of neck trauma were not predictive of ACDF level. When adjusting for the above variables in a proportional-odds ordinal logistic regression model, a one-year increase in age conferred a 4% increase in the odds of requiring an ACDF at a given superior level compared to the adjacent inferior level. CONCLUSIONS: Age is correlated with level of first-time single level ACDF. Individual subaxial levels may have unique biomechanical properties that influence degeneration.

3D-Printed Spine Models for Planning Staged Minimally Invasive Transverse Process Resections for Bertolotti Syndrome: Technical Note.

Background: Three-dimensional (3D) printing has enabled numerous advances in spine surgery execution and education. However, few examples exist to outline how this technology can aid the performance of complex spine surgery using minimally invasive surgery (MIS) techniques. Therefore, we present a case that illustrates the benefits of 3D-printed spine model production before and after correction of a congenital lumbosacral anomaly using an MIS approach. Case Report: A 40-year-old woman with Bertolotti syndrome underwent a staged bilateral L6 MIS transverse process resection for the treatment of severe and progressive axial back pain which had repeatedly failed conservative management. 3D-printed spine models were used for pre- and post-operative surgical planning and patient counseling. Conclusion: 3D-printed spine models can aid in the planning of complex spine cases suited for an MIS approach.

The Prevalence of Hip Pathologies in Adolescent Idiopathic Scoliosis.

Background: Adolescent idiopathic scoliosis (AIS) is the most common form of abnormal spine curvature observed in patients age 10 to 18. Typically characterized by shoulder height and waistline asymmetry, AIS may drive uneven distribution of force in the hips, leading to increased rates of concurrent hip diagnoses. The relationship between AIS and concurrent hip diagnoses is underexplored in the literature, and to date, there has been little research comparing rates of hip diagnoses between patients with AIS and those unaffected. Purpose: Assess differences in rates and clusters of hip diagnoses between patients with AIS and those unaffected. Study design: Retrospective review of Healthcare Cost and Utilization Project's (HCUP) Nationwide Inpatient Sample (NIS). Patient sample: 224,504 weighted inpatient discharges. Outcome measures: Rates of hip diagnoses. Methods: Patients in the NIS database (2005-2013) ages 10-18 years were isolated. Patients were grouped by those diagnosed with AIS (ICD-9: 737.30) and those unaffected. Patient groups were propensity score matched (PSM) for age. Means comparison tests assessed differences in demographic, comorbidity, and diagnosis profiles between patient groups for corresponding age categories. ICD-9 codes were used to identify specific hip diagnoses. Results: Following PSM, 24,656 AIS and 24,656 unaffected patients were included. The AIS patient group was comprised of more females (66% vs 59%) and had lower rates of obesity (2.4% vs 3.5%, both p < 0.001). Overall, 1.1% of patients had at least one hip diagnosis: congenital deformity (0.31%), developmental dysplasia (0.24%), recurrent dislocation (0.18%), isolated dislocation (0.09%), osteonecrosis (0.08%), osteochondrosis (0.07%), acquired deformity (0.03%), and osteoarthritis (0.02%). AIS patients had lower rates of osteonecrosis (0.04% vs 0.12%, p = 0.003), but higher rates of all other hip diagnoses, including dysplasia (0.41% vs 0.07%, p < 0.001), recurrent dislocation (0.32% vs 0.03%, p < 0.001), isolated dislocation (0.13% vs 0.06%, p < 0.001), and osteoarthritis (0.04% vs 0.01%, p = 0.084. Co-occurrences of hip diagnoses were relatively rare, with 0.03% patients having more than one hip diagnosis. Rates of co-occurring hip diagnoses did not differ between AIS and unaffected groups (0.04% vs 0.02%, p = 0.225). Conclusions: Compared to unaffected patients of similar ages, patients with AIS had higher overall rates of hip diagnoses, including dysplasia and recurrent dislocation. A higher trend of precocious osteoarthritis was also observed at a higher rate in AIS patients, although this difference was not statistically significant. Our results present an argument for surgical realignment in the coronal and sagittal planes to neutralize asymmetrical forces in the hips, and suggest the need for increased awareness and clinical screening for hip-related disorders in AIS patients. Level of Evidence: III.

Cervical and spinopelvic parameters can predict patient reported outcomes following cervical deformity surgery.

Background: Recent studies have evaluated the correlation of health-related quality of life (HRQL) scores with radiographic parameters. This relationship may provide insight into the connection of patient-reported disability and disease burden caused by cervical diagnoses. Purpose: To evaluate the association between spinopelvic sagittal parameters and HRQLs in patients with primary cervical diagnoses. Methods: Patients ≥18 years meeting criteria for primary cervical diagnoses. Cervical radiographic parameters assessed cervical sagittal vertical axis, TS-CL, chin-to-brow vertical angle, C2-T3, CL, C2 Slope, McGregor's slope. Global radiographic alignment parameters assessed PT, SVA, PI-LL, T1 Slope. Pearson correlations were run for all combinations at baseline (BL) and 1 year (1Y) for continuous BL and 1Y modified Japanese Orthopaedic Association scale (mJOA) scores, as well as decline or improvement in those HRQLs at 1Y. Multiple linear regression models were constructed to investigate BL and 1Y alignment parameters as independent variables. Results: Ninety patients included 55.6 ± 9.6 years, 52% female, 30.7 ± 7kg/m2. By approach, 14.3% of patients underwent procedures by anterior approach, 56% posterior, and 30% had combined approaches. Average anterior levels fused: 3.6, posterior: 4.8, and mean total number of levels fused: 4.5. Mean operative time for the cohort was 902.5 minutes with an average estimated blood loss of 830 ccs. The mean BL neck disability index (NDI) score was 56.5 and a mJOA of 12.81. While BL NDI score correlated with gender (P = 0.050), it did not correlate with BL global or cervical radiographic factors. An increased NDI score at 1Y postoperatively correlated with BL body mass index (P = 0.026). A decreased NDI score was associated with 1Y T12-S1 angle (P = 0.009) and 1Y T10 L2 angle (P = 0.013). Overall, BL mJOA score correlated with the BL radiographic factors of T1 slope (P = 0.005), cervical lordosis (P = 0.001), C2-T3 (P = 0.008), C2 sacral slope (P = 0.050), SVA (P = 0.010), and CL Apex (P = 0.043), as well as gender (P = 0.050). Linear regression modeling for the prior independent variables found a significance of P = 0.046 and an R2 of 0.367. Year 1 mJOA scores correlated with 1Y values for maximum kyphosis (P = 0.043) and TS-CL (P = 0.010). At 1Y, a smaller mJOA score correlated with BL S1 sacral slope (P = 0.014), pelvic incidence (P = 0.009), L1-S1 (P = 0.012), T12-S1 (P = 0.008). The linear regression model for those 4 variables demonstrated an R2 of 0.169 and a P = 0.005. An increased mJOA score correlated with PI-LL difference at 1Y (P = 0.012), L1-S1 difference (P = 0.036), T12-S1 difference (0.006), maximum lordosis (P = 0.026), T9-PA difference (P = 0.010), and difference of T4-PA (P = 0.008). Conclusions: While the impact of preoperative sagittal and cervical parameters on mJOA was strong, the BL radiographic factors did not impact NDI scores. PostOp HRQL was significantly associated with sagittal parameters for mJOA (both worsening and improvement) and NDI scores (improvement). When cervical surgery has been indicated, radiographic alignment is important for postoperative HRQL.

Not Frail and Elderly: How Invasive Can We Go in This Different Type of Adult Spinal Deformity Patient?

STUDY DESIGN: Retrospective review of a single-center spine database. OBJECTIVE: Investigate the intersections of chronological age and physiological age via frailty to determine the influence of surgical invasiveness on patient outcomes. SUMMARY OF BACKGROUND DATA: Frailty is a well-established factor in preoperative risk stratification and prediction of postoperative outcomes. The surgical profile of operative patients with adult spinal deformity (ASD) who present as elderly and not frail (NF) has yet to be investigated. Our aim was to examine the surgical profile and outcomes of patients with ASD who were NF and elderly. METHODS: Patients with ASD 18 years or older, four or greater levels fused, with baseline (BL) and follow-up data were included. Patients were categorized by ASD frailty index: NF, Frail (F), severely frail (SF]. An elderly patient was defined as 70 years or older. Patients were grouped into NF/elderly and F/elderly. SRS-Schwab modifiers were assessed at BL and 1 year (0, +, ++). Logistic regression analysis assessed the relationship between increasing invasiveness, no reoperations, or major complications, and improvement in SRS-Schwab modifiers [Good Outcome]. Decision tree analysis assessed thresholds for an invasiveness risk/benefit cutoff point. RESULTS: A total of 598 patients with ASD included (55.3 yr, 59.7% F, 28.3 kg/m2). 29.8% of patients were older than 70 years. At BL, 51.3% of patients were NF, 37.5% F, and 11.2% SF. Sixty-sis (11%) patients were NF and elderly. About 24.2% of NF-elderly patients improved in SRS-Schwab by 1 year and had no reoperation or complication postoperatively. Binary regression analysis found a relationship between worsening SRS-Schwab, postop complication, and reoperation with invasiveness score (odds ratio: 1.056 [1.01-1.102], P = 0.011). Risk/benefit cut-off was 10 (P = 0.004). Patients below this threshold were 7.9 (2.2-28.4) times more likely to have a Good Outcome. 156 patients were elderly and F/SF with 16.7% having good outcome, with a risk/benefit cut-off point of less than 8 (4.4 [2.2-9.0], P < 0.001). CONCLUSION: Frailty status impacted the balance of surgical invasiveness relative to operative risk in an inverse manner, whereas the opposite was seen amongst elderly patients with a frailty status less than their chronologic age. Surgeons should perhaps consider incorporation of frailty status over age status when determining realignment plans in patients of advanced age.Level of Evidence: 3.

Interactions between mitoNEET and NAF-1 in cells.

The NEET proteins mitoNEET (mNT) and nutrient-deprivation autophagy factor-1 (NAF-1) are required for cancer cell proliferation and resistance to oxidative stress. NAF-1 and mNT are also implicated in a number of other human pathologies including diabetes, neurodegeneration and cardiovascular disease, as well as in development, differentiation and aging. Previous studies suggested that mNT and NAF-1 could function in the same pathway in mammalian cells, preventing the over-accumulation of iron and reactive oxygen species (ROS) in mitochondria. Nevertheless, it is unknown whether these two proteins directly interact in cells, and how they mediate their function. Here we demonstrate, using yeast two-hybrid, in vivo bimolecular fluorescence complementation (BiFC), direct coupling analysis (DCA), RNA-sequencing, ROS and iron imaging, and single and double shRNA lines with suppressed mNT, NAF-1 and mNT/NAF-1 expression, that mNT and NAF-1 directly interact in mammalian cells and could function in the same cellular pathway. We further show using an in vitro cluster transfer assay that mNT can transfer its clusters to NAF-1. Our study highlights the possibility that mNT and NAF-1 function as part of an iron-sulfur (2Fe-2S) cluster relay to maintain the levels of iron and Fe-S clusters under control in the mitochondria of mammalian cells, thereby preventing the activation of apoptosis and/or autophagy and supporting cellular proliferation.