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Background: Local, intrawound use of antibiotic powder, such as vancomycin and tobramycin, in spinal fusion surgery has become an increasingly common prophylactic measure in an attempt to reduce rates of postsurgical infection. However, the effects of localized antibiotic delivery on fusion remain unclear. The objective of this study was to examine the in vivo effects of intraoperative local delivery of 2 antibiotics commonly used in bone-grafting surgery on spinal fusion outcomes in a rat model. Methods: Single-level (L4-L5), bilateral posterolateral intertransverse process lumbar fusion surgery was performed on 60 female Lewis rats (6 to 8 weeks of age) using syngeneic iliac crest allograft mixed with clinical bone-graft substitute and varying concentrations of antibiotics (n = 12 each): (1) control without any antibiotics, (2) low-dose vancomycin (14.3 mg/kg), (3) high-dose vancomycin (71.5 mg/kg), (4) low-dose tobramycin (28.6 mg/kg), and (5) high-dose tobramycin (143 mg/kg). Eight weeks postoperatively, fusion was evaluated via micro-computed tomography ([micro]CT), manual palpation, and histological analysis, with blinding to treatment group. In the [micro]CT analysis, fusion-mass volumes were measured for each rat. Each spine specimen (L4-L5) was rated (manual palpation score) on a scale of 2 to 0 (2 = fused, 1 = partially fused, and 0 = non-fused). Results: The mean fusion-mass volume on [micro]CT (mm3) was as follows: control, 29.3 +/- 6.2; low-dose vancomycin, 26.3 +/- 8.9; high-dose vancomycin, 18.8 +/- 7.9; low-dose tobramycin, 32.7 +/- 9.0; and high-dose tobramycin, 43.8 +/- 11.9 (control versus high-dose vancomycin, p < 0.05; and control versus high-dose tobramycin, p < 0.05). The mean manual palpation score for each group was as follows: control, 1.46 +/- 0.58; low-dose vancomycin, 0.86 +/- 0.87; high-dose vancomycin, 0.68 +/- 0.62; low-dose tobramycin, 1.25 +/- 0.71; and high-dose tobramycin, 1.32 +/- 0.72 (control versus high-dose vancomycin, p < 0.05). The histological analyses demonstrated a similar trend with regard to spinal fusion volume. Conclusions: Intraoperative local application of vancomycin, particularly at a supraphysiological dosage, may have detrimental effects on fusion-mass formation. No inhibitory effect of tobramycin on fusion-mass formation was observed. Clinical Relevance: When spine surgeons decide to use intraoperative intrawound antibiotics in spinal fusion surgery, they should weigh the reduction in surgical site infection against a possible inhibitory effect on fusion. [ABSTRACT FROM AUTHOR]

Study Design: An automatic radiographic labeling algorithm called "LevelCheck" was analyzed as a means of decision support for target localization in spine surgery. The potential clinical utility and scenarios in which LevelCheck is likely to be the most beneficial were assessed in a retrospective clinical data set (398 cases) in terms of expert consensus from a multi-reader study (three spine surgeons).Objective: The aim of this study was to evaluate the potential utility of the LevelCheck algorithm for vertebrae localization.Summary Of Background Data: Three hundred ninety-eight intraoperative radiographs and 178 preoperative computed tomographic (CT) images for patients undergoing spine surgery in cervical, thoracic, lumbar regions.Methods: Vertebral labels annotated in preoperative CT image were overlaid on intraoperative radiographs via 3D-2D registration. Three spine surgeons assessed the radiographs and LevelCheck labeling according to a questionnaire evaluating performance, utility, and suitability to surgical workflow. Geometric accuracy and registration run time were measured for each case.Results: LevelCheck was judged to be helpful in 42.2% of the cases (168/398), to improve confidence in 30.6% of the cases (122/398), and in no case diminished performance (0/398), supporting its potential as an independent check and assistant to decision support in spine surgery. The clinical contexts for which the method was judged most likely to be beneficial included the following scenarios: images with a lack of conspicuous anatomical landmarks; level counting across long spine segments; vertebrae obscured by other anatomy (e.g., shoulders); poor radiographic image quality; and anatomical variations/abnormalities. The method demonstrated 100% geometric accuracy (i.e., overlaid labels within the correct vertebral level in all cases) and did not introduce ambiguity in image interpretation.Conclusion: LevelCheck is a potentially useful means of decision support in vertebral level localization in spine surgery.Level Of Evidence: N/A. [ABSTRACT FROM AUTHOR]

Purpose: Intraoperative imaging plays an increased role in support of surgical guidance and quality assurance for interventional approaches. However, image quality sufficient to detect complications and provide quantitative assessment of the surgical product is often confounded by image noise and artifacts. In this work, we translated a three‐dimensional model‐based image reconstruction (referred to as "Known‐Component Reconstruction," KC‐Recon) for the first time to clinical studies with the aim of resolving both limitations. Methods: KC‐Recon builds upon a penalized weighted least‐squares (PWLS) method by incorporating models of surgical instrumentation ("known components") within a joint image registration–reconstruction process to improve image quality. Under IRB approval, a clinical pilot study was conducted with 17 spine surgery patients imaged under informed consent using the O‐arm cone‐beam CT system (Medtronic, Littleton MA) before and after spinal instrumentation. Volumetric images were generated for each patient using KC‐Recon in comparison to conventional filtered backprojection (FBP). Imaging performance prior to instrumentation ("preinstrumentation") was evaluated in terms of soft‐tissue contrast‐to‐noise ratio (CNR) and spatial resolution. The quality of images obtained after the instrumentation ("postinstrumentation") was assessed by quantifying the magnitude of metal artifacts (blooming and streaks) arising from pedicle screws. The potential low‐dose advantages of the algorithm were tested by simulating low‐dose data (down to one‐tenth of the dose of standard protocols) from images acquired at normal dose. Results: Preinstrumentation images (at normal clinical dose and matched resolution) exhibited an average 24.0% increase in soft‐tissue CNR with KC‐Recon compared to FBP (N = 16, P = 0.02), improving visualization of paraspinal muscles, major vessels, and other soft‐tissues about the spine and abdomen. For a total of 72 screws in postinstrumentation images, KC‐Recon yielded a significant reduction in metal artifacts: 66.3% reduction in overestimation of screw shaft width due to blooming (P < 0.0001) and reduction in streaks at the screw tip (65.8% increase in attenuation accuracy, P < 0.0001), enabling clearer depiction of the screw within the pedicle and vertebral body for an assessment of breach. Depending on the imaging task, dose reduction up to an order of magnitude appeared feasible while maintaining soft‐tissue visibility and metal artifact reduction. Conclusions: KC‐Recon offers a promising means to improve visualization in the presence of surgical instrumentation and reduce patient dose in image‐guided procedures. The improved soft‐tissue visibility could facilitate the use of cone‐beam CT to soft‐tissue surgeries, and the ability to precisely quantify and visualize instrument placement could provide a valuable check against complications in the operating room (cf., postoperative CT). [ABSTRACT FROM AUTHOR]

Background context A persistent challenge in spine surgery is improving screw fixation in patients with poor bone quality. Augmenting pedicle screw fixation with cement appears to be a promising approach. Purpose The purpose of this study was to survey the literature and assess the previous biomechanical studies on pedicle screw augmentation with cement to provide in-depth discussions of the biomechanical benefits of multiple parameters in screw augmentation. Study design/Setting This is a systematic literature review. Methods A search of Medline was performed, combining search terms of pedicle screw, augmentation, vertebroplasty, kyphoplasty, polymethylmethacrylate, calcium phosphate, or calcium sulfate. The retrieved articles and their references were reviewed, and articles dealing with biomechanical testing were included in this article. Results Polymethylmethacrylate is an effective material for enhancing pedicle screw fixation in both osteoporosis and revision spine surgery models. Several other calcium ceramics also appear promising, although further work is needed in material development. Although fenestrated screw delivery appears to have some benefits, it results in similar screw fixation to prefilling the cement with a solid screw. Some differences in screw biomechanics were noted with varying cement volume and curing time, and some benefits from a kyphoplasty approach over a vertebroplasty approach have been noted. Additionally, in cadaveric models, cemented-augmented screws were able to be removed, albeit at higher extraction torques, without catastrophic damage to the vertebral body. However, there is a risk of cement extravasation leading to potentially neurological or cardiovascular complications with cement use. A major limitation of these reviewed studies is that biomechanical tests were generally performed at screw implantation or after a limited cyclic loading cycle; thus, the results may not be entirely clinically applicable. This is particularly true in the case of the bioactive calcium ceramics, as these biomechanical studies would not have measured the effects of osseointegration. Conclusions Polymethylmethacrylate and various calcium ceramics appear promising for the augmentation of pedicle screw fixation biomechanically in both osteoporosis and revision spine surgery models. Further translational studies should be performed, and the results summarized in this review will need to be correlated with the clinical outcomes. [ABSTRACT FROM AUTHOR]

Study Design. A 3-dimensional-2-dimensional (3D-2D) image registration algorithm, "Level Check," was used to automatically label vertebrae in intraoperative mobile radiographs obtained during spine surgery. Accuracy, computation time, and potential failure modes were evaluated in a retrospective study of 20 patients. Objective. To measure the performance of the Level Check algorithm using clinical images acquired during spine surgery. Summary of Background Data. In spine surgery, the potential for wrong level surgery is significant due to the difficulty of localizing target vertebrae based solely on visual impression, palpation, and fluoroscopy. To remedy this difficulty and reduce the risk of wrong level surgery, our team introduced a program (dubbed Level Check) to automatically localize target vertebrae in mobile radiographs using robust 3D-2D image registration to preoperative computed tomographic (CT) scan. Methods. Twenty consecutive patients undergoing thoracolumbar spine surgery, for whom both a preoperative CT scan and an intraoperative mobile radiograph were available, were retrospectively analyzed. A board-certified neuroradiologist determined the "true" vertebra levels in each radiograph. Registration of the preoperative CT scan to the intraoperative radiograph was calculated via Level Check, and projection distance errors were analyzed. Five hundred random initializations were performed for each patient, and algorithm settings (viz, the number of robust multistarts, ranging 50-200) were varied to evaluate the trade-off between registration error and computation time. Failure mode analysis was performed by individually analyzing unsuccessful registrations (> 5 mm distance error) observed with 50 multi-starts. Results. At 200 robust multistarts (computation time of ~ 26 s), the registration accuracy was 100% across all 10,000 trials. As the number of multistarts (and computation time) decreased, the registration remained fairly robust, down to 99.3% registration accuracy at 50 multistarts (computation time ~ 7 s). Conclusion. The Level Check algorithm correctly identified target vertebrae in intraoperative mobile radiographs of the thoracolumbar spine, demonstrating acceptable computation time, compatibility with routinely obtained preoperative CT scans, and warranting investigation in prospective studies. [ABSTRACT FROM AUTHOR]

Comparative effectiveness research has a vital role in health reform and policies. Specialty training is one of these provider-side variables, and surgeons performing the same procedure who were trained in different specialties may have different outcomes. The objective of this study was to investigate the impact of spine surgeon specialty (neurosurgery vs. orthopedic surgery) on early perioperative outcome measures of elective anterior/lateral lumbar interbody fusion (ALIF/LLIF) for degenerative disc diseases. In a retrospective, 1:1 propensity score–matched cohort study, 9070 patients were reviewed from the American College of Surgeons National Surgical Quality Improvement Program database. Propensity score matching and subgroup analysis were used. In both groups (single-level and multilevel ALIF/LLIF), patients operated on by neurosurgeons had longer operative time (188 minutes vs. 172 minutes/239 minutes vs. 221 minutes); shorter total hospital stay (71 hours vs. 90 hours/89 hours vs. 96 hours); and lower rates of return to the operating room (2.1% vs. 4.1%/2.4% vs. 4.2%), nonhome discharge (8.7% vs. 11.1%/10.1% vs. 14.9%), discharge after postoperative day 3 (22.0% vs. 30.0%/38.0% vs. 43.9%), and perioperative blood transfusion (2.1% vs. 5.1%/5.0% vs. 9.9%) (P < 0.05). In multilevel ALIF/LLIF, patients operated on by neurosurgeons had lower readmission rates (3.9% vs. 6.9%) (P < 0.05). Other outcome measures and mortality rates were similar between the single-level and multilevel ALIF/LLIF cohorts regardless of surgeon specialty. Our analysis found significant differences in early perioperative outcomes of patients undergoing ALIF/LLIF by neurosurgeons and orthopedic surgeons. These differences have significant clinical and cost implications for patients, physicians, program directors, payers, and health systems. [ABSTRACT FROM AUTHOR]

Study Design: Rat posterolateral lumbar fusion model.Objective: The aim of this study was to compare the efficacy of freshly isolated adipose tissue-derived stromal vascular fraction (A-SVF) and bone marrow cells (BMCs) cells in achieving spinal fusion in a rat model.Summary Of Background Data: Adipose tissue-derived stromal cells (ASCs) offer advantages as a clinical cell source compared to bone marrow-derived stromal cells (BMSCs), including larger available tissue volumes and reduced donor site morbidity. While pre-clinical studies have shown that ex vivo expanded ASCs can be successfully used in spinal fusion, the use of A-SVF cells better allows for clinical translation.Methods: A-SVF cells were isolated from the inguinal fat pads, whereas BMCs were isolated from the long bones of syngeneic 6- to 8-week-old Lewis rats and combined with Vitoss (Stryker) bone graft substitute for subsequent transplantation. Posterolateral spinal fusion surgery at L4-L5 was performed on 36 female Lewis rats divided into three experimental groups: Vitoss bone graft substitute only (VO group); Vitoss + 2.5 × 106 A-SVF cells/side; and, Vitoss + 2.5 × 106 BMCs/side. Fusion was assessed 8 weeks post-surgery via manual palpation, micro-computed tomography (μCT) imaging, and histology.Results: μCT imaging analyses revealed that fusion volumes and μCT fusion scores in the A-SVF group were significantly higher than in the VO group; however, they were not significantly different between the A-SVF group and the BMC group. The average manual palpation score was highest in the A-SVF group compared with the BMC and VO groups. Fusion masses arising from cell-seeded implants yielded better bone quality than nonseeded bone graft substitute.Conclusion: In a rat model, A-SVF cells yielded a comparable fusion mass volume and radiographic rate of fusion to BMCs when combined with a clinical-grade bone graft substitute. These results suggest the feasibility of using freshly isolated A-SVF cells in spinal fusion procedures.Level of Evidence: N/A. [ABSTRACT FROM AUTHOR]

Frailty has been shown to affect patient outcomes after medical and surgical interventions. The Hospital Frailty Risk Score (HFRS) is a growing metric used to assess patient frailty using International Classification of Diseases, Tenth Revision codes. The goal of this study was to investigate the impact of frailty, assessed by HFRS, on health care resource utilization and outcomes in patients undergoing surgery for spinal meningiomas. A retrospective cohort study was performed using the 2016–2019 National Inpatient Sample database. Adult patients with benign or malignant spinal meningiomas, identified using International Classification of Diseases, Tenth Revision, Clinical Modification codes, were stratified by HFRS: low frailty (HFRS <5) and intermediate-high frailty (HFRS ≥5). Patient demographics, hospital characteristics, comorbidities, procedural variables, adverse events, length of stay (LOS), discharge disposition, and cost of admission were assessed. Multivariate regression analysis was used to identify predictors of increased LOS, discharge disposition, and cost. Of the 3345 patients, 530 (15.8%) had intermediate-high frailty. The intermediate-high cohort was significantly older (P < 0.001). More patients in the intermediate-high cohort had ≥3 comorbidities (P < 0.001). In addition, a greater proportion of patients in the intermediate-high cohort experienced ≥1 perioperative adverse events (P < 0.001). Intermediate-high patients experienced greater mean LOS (P < 0.001) and accrued greater costs (P < 0.001). A greater proportion of intermediate-high patients had nonroutine discharges (P < 0.001). On multivariate analysis, increased HFRS (≥5) was independently associated with extended LOS (adjusted odds ratio [aOR], 3.04; P < 0.001), nonroutine discharge (aOR, 1.98; P = 0.006), and increased costs (aOR, 2.39; P = 0.004). Frailty may be associated with increased health care resource utilization in patients undergoing surgery for spinal meningiomas. [ABSTRACT FROM AUTHOR]

As of May 4, 2020, the coronavirus disease 2019 (COVID-19) pandemic has affected >3.5 million people and touched every inhabited continent. Accordingly, it has stressed health systems worldwide, leading to the cancellation of elective surgical cases and discussions regarding health care resource rationing. It is expected that rationing of surgical resources will continue even after the pandemic peak and may recur with future pandemics, creating a need for a means of triaging patients for emergent and elective spine surgery. Using a modified Delphi technique, a cohort of 16 fellowship-trained spine surgeons from 10 academic medical centers constructed a scoring system for the triage and prioritization of emergent and elective spine surgeries. Three separate rounds of videoconferencing and written correspondence were used to reach a final scoring system. Sixteen test cases were used to optimize the scoring system so that it could categorize cases as requiring emergent, urgent, high-priority elective, or low-priority elective scheduling. The devised scoring system included 8 independent components: neurologic status, underlying spine stability, presentation of a high-risk postoperative complication, patient medical comorbidities, expected hospital course, expected discharge disposition, facility resource limitations, and local disease burden. The resultant calculator was deployed as a freely available Web-based calculator (https://jhuspine3.shinyapps.io/SpineUrgencyCalculator/). We present the first quantitative urgency scoring system for the triage and prioritizing of spine surgery cases in resource-limited settings. We believe that our scoring system, although not all encompassing, has potential value as a guide for triaging spine surgical cases during the COVID pandemic and post-COVID period. [ABSTRACT FROM AUTHOR]

Background The pathogenesis of synovial cysts is largely unknown; however, they have been increasingly thought of as markers of spinal facet instability and typically associated with degenerative spondylosis. We specifically investigated the incidence of concomitant synovial cysts with underlying degenerative spondylolisthesis. Methods A literature search was performed using 4 online databases to assess the association between lumbar synovial cysts and degenerative spinal pathological features. Meta-analyses were performed on the prevalence rates of coexisting degenerative spinal pathological entities and treatment modalities. A random effects model was used to calculate the mean and 95% confidence intervals. Results A total of 17 studies encompassing 824 cases met the inclusion criteria. The pooled prevalence rates of concurrent spondylolisthesis, facet arthropathy, and degenerative disc disease at the same level of the synovial cysts were 42.5% (range, 39.0%–46.1%), 89.3% (range, 79.0%–94.8%), and 48.8% (range, 43.8%–53.9%), respectively. Among these, patients with coexisting spondylolisthesis were more likely to undergo spinal fusion surgery (vs. laminectomy alone) and reoperation than were patients without spondylolisthesis with a pooled odds ratio of 11.5 (95% confidence interval, 4.5–29.1; P < 0.0001) and 2.0 (95% confidence interval, 0.9–4.2; P = 0.088), respectively. Conclusions Patients with a combination of synovial cysts and degenerative spondylolisthesis are more likely to undergo spinal fusion surgery than laminectomy alone compared with patients with synovial cysts and no preoperative spondylolisthesis. Furthermore, patients with synovial cysts and spondylolisthesis are more likely to require additional fusion surgery. The results from the present review lend credence to the argument that synovial cyst herniation might be a manifestation of an unstable spinal level. [ABSTRACT FROM AUTHOR]

Transplantation of adipose-derived mesenchymal stem cells (ADSCs) has become a promising approach for bone regeneration therapies, particularly in elderly patients. However, poor cell survival in vivo after implantation due to the ischemic tissue environment has been one of the major limitations of the effectiveness of this strategy. Hypoxia Inducible Factor-1α (HIF-1α) plays an important role in angiogenic-osteogenic coupling during bone regeneration, as it is a critical mediator of the adaptive cell response to hypoxia. DMOG treatment has been demonstrated to stabilize cellular expression of HIF-1α in cells, as well as enhance osteogenic and angiogenic capacity of MSCs. By therapeutically targeting both osteogenesis and vascularization via DMOG preconditioned MSCs, this tissue-engineering approach sought to yield superior bone quality and integration, thereby increasing rates of spinal fusion. We aimed to demonstrate that preconditioning adipose (ADSC)-derived (AD) MSCs with DMOG prior to implantation will prolong survival in vivo and improve spinal fusion outcomes in a rat model. In vivo study via a rat posterolateral spinal fusion model. Syngeneic 6-8 week old Lewis rats. Manual palpation scoring was performed by blinded researchers as follows: 0 = non-fused; 1 = partial fusion, some motion across operative joint; and, 2 = fused, no motion across the operated joint. MicroCT images were used to assess fusion mass volume (mm^3) via ImageJ software and determine CT fusion score (0 = non-fused; 1 = unilateral fusion; 2 = bilateral fusion). ADSCs were isolated from the inguinal fat pads of syngeneic 6-8 week old Lewis rats and cultured in vitro. When passage 1 (P1) ADSCs reached approximately 80% confluency they were pre-conditioned for 24 hours with 1 ng of DMOG (Fisher Scientific). After pre-conditioning, 2 × 10^6 ADSCs were seeded onto Vitoss (Stryker) bone graft substitute scaffolds for subsequent transplantation. Posterolateral spinal fusion surgery at L4-L5 was performed on 18 female Lewis rats divided into 2 experimental groups: [1] Vitoss+ADSCs pre-conditioned with DMOG; and, [2] Vitoss+non pre-conditioned ADSCs. Fusion was evaluated eight weeks post-surgery. Manual palpation scoring evaluated the motion across the operated joint, and MicroCT images were assessed for fusion mass volume and CT fusion. Preliminary microCT imaging data suggest that DMOG pre-conditioned ADSCs (n=12) yielded significantly higher fusion mass volumes than non-preconditioned ADSCs (n=6) (23.49 mm^3 vs. 15.39 mm^3, respectively, p=.001). DMOG pre-conditioned ADSCs showed a trend towards higher rates of fusion and manual palpation scores compared to non-conditioned ADSCs (1.16 vs. 0.50, respectively, p=.06; and 1.25 vs. 0.66, respectively, p>.05). In our rat posterolateral fusion model, DMOG pre-conditioned ADSCs displayed an increased fusion mass volume, CT fusion rates, and manual palpation score compared to non-conditioned ADSCs. Ongoing histological studies will evaluate whether there are any differences in the quality of bone formed within the fusion masses. Future studies will also compare whether these results are also similar in bone marrow-derived MSCs. Dimethyloxaloylglycine (Investigational/Not approved) [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT With the overall advancement in management of patients with human immunodeficiency virus (HIV) infection/AIDS, especially antiretroviral therapy regimens, HIV infection is now considered as a chronic disease and the longevity of these patients has significantly improved for the last two decades. As such, an increasing number of patients with HIV-infection are now potential candidates for elective surgical procedures such as spine surgery. In 2015, an estimated 1.1million adults and adolescents were living with HIV and 39,782 patients were newly diagnosed with HIV infection annually in 2016 (CDC data). Despite this increasing prevalence and incidence of the disease, the literature regarding clinical outcomes of spine surgery in patients with HIV is surprisingly scarce. As is the same as patients with other concurrent immunocompromising co-morbidities such as steroid use, diabetes mellitus, organ recipients, and/or chemo or radiation therapy, postoperative infection is one of the most concerning complications. Furthermore, bone mineral densities of HIV-infected patients are reported to be lower than noninfected controls, which could have some potential indications for worse long-term outcomes such as pseudoarthrosis. Thus, we aimed to characterize clinical outcomes of spine surgery in patients with HIV infection in order to facilitate judicious patient selection and comprehensive informed consent, which are of paramount importance in surgical decision-making processes for this high-risk cohort. PURPOSE Summarize clinical outcomes of spine surgery in patients with HIV, such as readmission rate, infectious complications, fusion rate, and mortality to address surgical indications for this specific cohort. STUDY DESIGN/SETTING Retrospective, single-center, propensity-matched cohort. PATIENT SAMPLE Patients who underwent spine surgery with HIV infection were included and compared with a matched-cohort without HIV infection OUTCOME MEASURES CD4 absolute count/uL, HIV-1 RNA copy numbers/mL, 30-day readmission rate, 90-day medical complication rate, one-year surgical site infectious complication rate, one-year fusion rate, and one-year mortality METHODS Single-center, retrospective data review from 2010 to 2016 yielded a total of 4,968 patients of spine surgery. Amongst those, 45 patients had HIV infection. Patients from the database were propensity-matched for age, sex, diagnoses, procedures, co-morbidities other than HIV at a 1:2 ratio, which yielded 90 matched-patients. Clinical outcomes of (A) 45 patients with HIV infection and (B) 90 matched-patients were compared and statistically analyzed. Intergroup comparison of binary variables was performed via Fisher's exact test. Intergroup comparison of continuous variables was achieved using unpaired t -tests. All reported p values are 2-sided and p values <.05 were regarded as statistically significant. RESULTS No statistically significant differences were noted for baseline characteristics including age, sex, diagnoses, procedures, and co-morbidities. There were no statistically significant intergroup differences in operative data such as operative time and operated levels. the HIV-infected patient group had higher rates of 30-day readmission (11.1% vs. 2.2%, P=.04), one-year surgical site infectious complication (13.3% vs. 3.3%, P=.06), and one-year pseudoarthrosis (17.8% vs. 4.4%, P=.02) as well as longer hospital stay (6.8days vs. 4.6days, p<.01) when compared with the control matched-cohort. Our post-hoc analysis only on 45 HIV-infected patients revealed that while HIV-1 RNA copy number with any cut-off values failed to predict 90-day medical complication rates, the cut-off value of CD4 absolute count <200/uL at the most recent preoperative encounter allowed us to stratify them into the two groups with regards to 90-day medical complication rates with statistical significance (44.4% (CD4<200) vs. 11.4% (CD4≥200), P=.04). CONCLUSIONS Spinal surgery in HIV-infected patients was associated with worse short- and long-term clinical outcomes, including higher rates of 30-day readmission, one-year infectious complication rate, and one-year pseudoarthrosis rate. Furthermore, CD4 absolute count may have some role in preoperative risk stratification. These results warrant further investigation of this cohort on multicenter, prospective basis, which should facilitate better patient selection for spine surgery and detailed informed consent, thereby potentially benefitting patients with HIV infection in the future. [ABSTRACT FROM AUTHOR]

BACKGROUND CONTEXT Solid organ transplant is the mainstay of treatment for a wide variety of several end-stage organ diseases. The number of patients who will benefit from it is expected to increase due to improvement in distribution system for organs from donors, the discovery of novel immunosuppressive treatment/regimens, and better per- and post-operative management of these patients in general. Hence, an increasing number of these patients are becoming reasonable candidates for subsequent, elective surgeries such as spine surgery. Even though these patients are considered to be a high-risk group for surgery generally, clinical outcomes of spine surgery in patients with solid organ transplantation are not well-documented in the current literature partly due to its substantially rare incidence. Furthermore, prolonged use of steroids as well as immunosuppressant such as cyclosporine is associated with a decrease in bone mineral density. Thus, these outcome data might be of particular importance to consider surgical options for this high-risk cohort and inform them of specific risks and complications associated with spinal surgery after organ transplantation. PURPOSE Summarize clinical outcomes of spine surgery in solid organ recipients, such as readmission rate, infectious complications, and mortality, to facilitate clinical decision-making processes for this specific cohort. STUDY DESIGN/SETTING Retrospective, single-center, propensity-matched cohort. PATIENT SAMPLE Patients who underwent spine surgery at a single institution with previous history of solid organ transplantation were included and compared with a matched-cohort without solid organ transplantation. OUTCOME MEASURES Thirty-day readmission rate, 90-day medical complication rate, one-year infectious complication rate, one-year mortality, and functional outcomes such as ambulatory status, which was rated on a four-point scale (4, independently ambulatory; 3, requiring a cane; 2, requiring a walker; and 1, wheelchair bound). METHODS Single-center, retrospective data review from 2010 to 2016 yielded a total of 4,968 patients who underwent spine surgery. Amongst those, 28 patients had a previous history of solid organ transplantation. Patients from the database were propensity-matched for age, sex, body mass index (BMI), smoking status, diagnoses, procedures, co-morbidities other than diseases which had prompted organ transplantation at 1:2 ratio, which yielded 56 matched-patients. Clinical outcomes of (A) 28 patients with organ transplantation and (B) 56 matched-patients were compared and statistically analyzed. Intergroup comparison of binary variables was performed via Fisher's exact test. Intergroup comparison of continuous variables was achieved using unpaired t -tests. All reported p values are 2-sided and p values <.05 were regarded as statistically significant. RESULTS Baseline characteristics including age, sex, BMI, smoking, diagnoses, procedures, and co-morbidities (ASA scale) were similar between the two groups with no statistically significant difference, which validated our matching methods. There were no statistically significant intergroup differences in operative data such as operative time, estimated blood loss, operated levels, and use of bone morphogenetic protein-2. In terms of functional outcomes, postoperative improvement in ambulatory status was comparable between the two groups (A) 16.7% vs. (B) 18.1%, p>.99). However, the organ-recipient group resulted in longer hospital stays (A) 7.2days vs. (B) 4.3days, p<.01), higher rates of 30-day readmission (A) 14.3% vs. (B) 7.1%, P=.04), 90-day medical complication (A) 42.8% vs. (B) 17.9%, P=.02), one-year infectious complication (A) 14.3% vs. (B) 3.6%, P=.09), one-year reoperation (A) 14.3% vs. (B) 3.6%, P=.09) as compared with the control matched-cohort. CONCLUSIONS Spinal surgery after solid organ transplantation resulted in substantially increased complication rates when compared with the matched-control group, while other variables such as baseline characteristics, operative data, and functional outcomes were similar between the two groups. Careful patient selection, meticulous perioperative care, and thorough informed consent of potential complications would be imperative when performing spine surgery on this cohort. [ABSTRACT FROM AUTHOR]