The effect of C2 screw type on perioperative outcomes and long-term stability after C2-T2 posterior cervical decompression and fusion.

PURPOSE: To determine if C2 pedicle versus pars screw type predicts change in fusion status, C2 screw loosening, cervical alignment, and patient-reported outcomes measures (PROMs) after C2-T2 posterior cervical decompression and fusion (PDCF). METHODS: All adult patients who underwent C2-T2 PCDF for myelopathy or myeloradiculopathy between 2013-2020 were retrospectively identified. Patients were dichotomized by C2 screw type into bilateral C2 pedicle and bilateral C2 pars screw groups. Preoperative and short- and long-term postoperative radiographic outcomes and PROMs were collected. Univariate and multivariate analysis compared patient factors, fusion status, radiographic measures, and PROMs across groups. RESULTS: A total of 159 patients met the inclusion/exclusion criteria (76 bilateral pedicle screws, 83 bilateral pars screws). Patients in the C2 pars relative to C2 pedicle screw group were on average more likely to have bone morphogenic protein (p = 0.001) and four-millimeter diameter rods utilized intraoperatively (p = 0.033). There were no significant differences in total construct and C2-3 fusion rate, C2 screw loosening, or complication and revision rates between C2 screw groups in univariate and regression analysis. Changes in C2 tilt, C2-3 segmental lordosis, C0-2 Cobb angle, proximal junctional kyphosis, atlanto-dens interval, C1 lamina-occiput distance, C2 sagittal vertical axis, C2-7 lordosis, and PROMs at all follow-up intervals did not vary significantly by C2 screw type. CONCLUSION: There were no significant differences in fusion status, hardware complications, and radiographic and clinical outcomes based on C2 screw type following C2-T2 PCDF. Accordingly, intraoperative usage criteria can be flexible based on patient vertebral artery positioning and surgeon comfort level.

R2 advances in robotic-assisted spine surgery: comparative analysis of options, future directions, and bibliometric analysis of the literature.

Spine surgery has undergone rapid advancements over the past several decades with the emergence of robotic and minimally invasive surgery (MIS). While conventional MIS spine surgery has had relative success, its complication profile has warranted continued efforts to improve clinical outcomes. We discuss the functional, clinical, and financial aspects of four robotic options for spinal pathologies, namely ROSA, Mazor X, Da Vinci, and ExcelsiusGPS, and conduct a bibliometric analysis to better understand current trends and applications of these robots as the field of robotic spine surgery continues to grow. An extensive search of English-language published literature on robotic-assisted spinal surgery was performed in Elsevier's Scopus database. A bibliometric analysis was then performed on the top 100 most cited papers. The search yielded articles regarding robotic-assisted spine surgery application, limitations, and functional outcomes secondary to spine pathology. Accuracy analyses of 1733 screw placements were reviewed. The top 100 papers were published between 1992 and 2020, with a significant increase from 2015 onwards. The top publishing institution was John Hopkins University (n = 8). The top contributing author was Dr. Isador H. Lieberman (n = 6). The USA (n = 34) had the most articles on robotic spinal surgery, followed by Germany (n = 12). This review examines robotic applications in spine surgery, including four available options: ROSA, Mazor X, Da Vinci, and ExcelsiusGPS. Publication output over time, surgical outcomes, screw accuracy, and cost-effectiveness of these technologies have been investigated here. Certain robots have functional, clinical, and financial differences worth noting. Given the dearth of existing literature reporting postoperative complications and long-term comparative outcomes, there is a clear need for further studies on this matter.

Cervical Paraspinal Muscle Fatty Degeneration Is Not Associated with Muscle Cross-sectional Area: Qualitative Assessment Is Preferable for Cervical Sarcopenia.

BACKGROUND: Sarcopenia, defined as decreased skeletal mass, is an independent marker of frailty that is not accounted for by other risk-stratification methods. Recent studies have demonstrated a clear association between paraspinal sarcopenia and worse patient-reported outcomes and complications after spine surgery. Currently, sarcopenia is characterized according to either a quantitative assessment of the paraspinal cross-sectional area or a qualitative analysis of paraspinal fatty infiltration on MRI. No studies have investigated whether the cervical paraspinal cross-sectional area correlates with fatty infiltration of the cervical paraspinal muscles on advanced imaging. QUESTION/PURPOSE: Do patients undergoing anterior cervical discectomy and fusion (ACDF) with increasing paraspinal fatty degeneration on advanced imaging also demonstrate decreased cervical paraspinal cross-sectional area? METHODS: Between 2011 and 2017, 98 patients were prospectively enrolled in a database of patients undergoing one- to three-level ACDF for degenerative conditions at a single institution. To be eligible for this prospective study, patients were required to undergo an MRI before surgery, be older than 18 years, and have no previous history of cervical spine surgery. Two independent reviewers, both surgeons not involved in the patients' care and who were blinded to the clinical outcomes, retrospectively assessed the paraspinal cross-sectional area and Goutallier classification of the right-sided paraspinal muscle complex. We then compared the patients' Goutallier grades with their paraspinal cross-sectional area measurements. We identified 98 patients for inclusion. Using the Fuchs modification of the Goutallier classification, we classified the fatty degeneration of 41 patients as normal (Goutallier Grades 0 to 1), that of 47 patients as moderate (Grade 2), and that of 10 patients as severe (Grades 3 to 4). We used ANOVA to compare all means between groups. RESULTS: There was no difference in the mean paraspinal cross-sectional area of the obliquus capitus inferior (normal 295 ± 81 mm2; moderate 317 ± 104 mm2; severe 300 ± 79 mm2; p = 0.51), multifidus (normal 146 ± 59 mm2; moderate 170 ± 70 mm2; severe 192 ± 107 mm2; p = 0.11), or sternocleidomastoid (normal 483 ± 150 mm2; moderate 468 ± 149 mm2; severe 458 ± 183 mm2; p = 0.85) among patients with mild, moderate, and severe fatty infiltration based on Goutallier grading. There was a slightly greater longus colli cross-sectional area in the moderate and severe fatty infiltration groups (74 ± 22 mm2 and 66 ± 18 mm2, respectively) than in the normal group (63 ± 15 mm2; p = 0.03). CONCLUSION: Because our study demonstrates minimal association between paraspinal cross-sectional area and fatty infiltration of the cervical paraspinals, we recommend that physicians use the proven qualitative assessment of paraspinal fatty infiltration during preoperative evaluation of patients who are candidates for ACDF. Future studies investigating the relationship between cervical paraspinal cross-sectional area and patient-reported outcomes after ACDF are necessary to lend greater strength to this recommendation. LEVEL OF EVIDENCE: Level III, diagnostic study.

Pelvic Tilt and the Pubic Symphysis to Sacrococcygeal Junction Distance: Risk Factors for Hip Dislocation Observed on Anteroposterior Pelvis Radiographs.

BACKGROUND: Dislocation after total hip arthroplasty (THA) is among the most common causes of early revision in contemporary practice. Abnormal spinopelvic alignment increases risk for dislocation, but methods to identify such are limited and can be complex. We sought to determine the effect of pelvic tilt, using a novel radiographic measurement, on dislocation risk by evaluating those with and without a history of dislocation. METHODS: Using our institutional total joint registry, we identified 10,082 primary THAs performed between 2006 and 2015. Postoperatively, 177 dislocated (1.7%). Dislocators were matched 1:1 to control patients who did not dislocate. Pelvic tilt was calculated using the pubic symphysis to sacrococcygeal junction distance (PSCD) from a supine anteroposterior pelvis radiograph both preoperatively and postoperatively. The association between dislocation and both pelvic tilt and PSCD was then evaluated by logistic regression. Mean follow-up was 3 years. RESULTS: Patients who dislocated had more posterior pelvic tilt (mean pelvic tilt of 57° vs 60°; P = .02) and smaller PSCDs (mean 41 mm vs 46 mm; P = .04) than controls. Patients with a PSCD <0 mm (symphysis above sacrococcygeal junction) had 9-fold odds of dislocation compared to those with a PSCD >50 (odds ratio 9; P = .006). CONCLUSION: Patients who dislocated following primary THA had more posterior pelvic tilt. Additionally, those with a PSCD <0 had 9-fold odds of dislocation. Assessing the PSCD can alert a surgeon of increased risk for dislocation and identification of a negative PSCD should encourage further investigation or optimization of the preoperative plan to minimize dislocation risk. LEVEL OF EVIDENCE: Level IV, case-control study.

Primary Total Hip Arthroplasty in Patients With Ankylosing Spondylitis.

BACKGROUND: Ankylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the renewed interest in the hip-spine interplay, this study aimed to define long-term outcomes of primary total hip arthroplasty (THA) in the setting of AS. METHODS: We identified 309 hips (219 patients) with AS treated with primary THA from 1969 to 2018. Mean age was 49 years, 80% were males, and mean body mass index was 28 kg/m2. Cumulative incidences of any revision, reoperation, and dislocation were calculated utilizing a competing risk analysis. Harris Hip Scores and complications were also reported. Mean follow-up was 16 years. RESULTS: The cumulative incidence of any revision after primary THA was 2.3% at 5 years and 17.5% at 20 years. The most common reasons for revision (n = 73) were aseptic loosening (41%), osteolysis/polyethylene (PE) wear (30%, all with conventional PE), and femoral component fracture (8%). The cumulative incidence of dislocation was 1.9% at 5 years and 2.9% at 20 years. Younger age was associated with increased risk of revision (hazard ratio (HR) = 1.3, P < .01) and reoperation (HR = 1.2, P < .01), but not dislocation (HR = 0.7, P = .1). Twenty-eight hips (9%) experienced a postoperative complication not requiring reoperation. The mean Harris Hip Score improved from 51 to 76 after THA (P < .001). CONCLUSION: In this series of 309 primary THAs in patients with AS, the 20-year cumulative incidence of any revision after primary THA was 17.5%. Aseptic loosening, osteolysis/PE wear, and femoral component fracture were the most common reasons for revision. Notably, the cumulative incidence of dislocation at 20 years was only 2.9%. LEVEL OF EVIDENCE: Level IV.

Regional improvements in lumbosacropelvic Hounsfield units following teriparatide treatment.

OBJECTIVE: Opportunistic Hounsfield unit (HU) determination from CT imaging has been increasingly used to estimate bone mineral density (BMD) in conjunction with assessments from dual energy x-ray absorptiometry (DXA). The authors sought to compare the effect of teriparatide on HUs across different regions in the pelvis, sacrum, and lumbar spine, as a surrogate measure for the effects of teriparatide on lumbosacropelvic instrumentation. METHODS: A single-institution retrospective review of patients who had been treated with at least 6 months of teriparatide was performed. All patients had at least baseline DXA as well as pre- and post-teriparatide CT imaging. HUs were measured in the pedicle, lamina, and vertebral body of the lumbar spine, in the sciatic notch, and at the S1 and S2 levels at three different points (ilium, sacral body, and sacral ala). RESULTS: Forty patients with an average age of 67 years underwent a mean of 20 months of teriparatide therapy. Mean HUs of the lumbar lamina, pedicles, and vertebral body were significantly different from each other before teriparatide treatment: 343 ± 114, 219 ± 89.2, and 111 ± 48.1, respectively (p < 0.001). Mean HUs at the S1 level for the ilium, sacral ala, and sacral body were also significantly different from each other: 124 ± 90.1, -10.7 ± 61.9, and 99.1 ± 72.1, respectively (p < 0.001). The mean HUs at the S2 level for the ilium and sacral body were not significantly different from each other, although the mean HU at the sacral ala (-11.9 ± 52.6) was significantly lower than those at the ilium and sacral body (p = 0.003 and 0.006, respectively). HU improvement occurred in most regions following teriparatide treatment. In the lumbar spine, the mean lamina HU increased from 343 to 400 (p < 0.001), the mean pedicle HU increased from 219 to 242 (p = 0.04), and the mean vertebral body HU increased from 111 to 134 (p < 0.001). There were also significant increases in the S1 sacral body (99.1 to 130, p < 0.05), S1 ilium (124 vs 165, p = 0.01), S1 sacral ala (-10.7 vs 3.68, p = 0.04), and S2 sacral body (168 vs 189, p < 0.05). CONCLUSIONS: There was significant regional variation in lumbar and sacropelvic HUs, with most regions significantly increasing following teriparatide treatment. The sacropelvic area had lower HU values than the lumbar spine, more regional variation, and a higher degree of correlation with BMD as measured on DXA. While teriparatide treatment resulted in HUs > 110 in the majority of the lumbosacral spine, the HUs in the sacral ala remained suggestive of severe osteoporosis, which may limit the effectiveness of fixation in this region.

Osteoporosis in spine surgery patients: what is the best way to diagnose osteoporosis in this population?

OBJECTIVE: The goal of this study was to compare different recognized definitions of osteoporosis in patients with degenerative lumbar spine pathology undergoing elective spinal fusion surgery to determine which patient population should be considered for preoperative optimization. METHODS: A retrospective review of patients in whom lumbar spine surgery was planned at 2 academic medical centers was performed, and the rate of osteoporosis was compared based on different recognized definitions. Assessments were made based on dual-energy x-ray absorptiometry (DXA), CT Hounsfield units (HU), trabecular bone score (TBS), and fracture risk assessment tool (FRAX). The rate of osteoporosis was compared based on different definitions: 1) the WHO definition (T-score ≤ -2.5) at total hip or spine; 2) CT HU of < 110; 3) National Bone Health Alliance (NBHA) guidelines; and 4) "expanded spine" criteria, which includes patients meeting NBHA criteria and/or HU < 110, and/or "degraded" TBS in the setting of an osteopenic T-score. Inclusion criteria were adult patients with a DXA scan of the total hip and/or spine performed within 1 year and a lumbar spine CT scan within 6 months of the physician visit. RESULTS: Two hundred forty-four patients were included. The mean age was 68.3 years, with 70.5% female, 96.7% Caucasian, and the mean BMI was 28.8. Fracture history was reported in 53.8% of patients. The proportion of patients identified with osteoporosis on DXA, HUs, NBHA guidelines, and the authors' proposed "expanded spine" criteria was 25.4%, 36.5%, 75%, and 81.9%, respectively. Of the patients not identified with osteoporosis on DXA, 31.3% had osteoporosis based on HU, 55.1% had osteoporosis with NBHA, and 70.4% had osteoporosis with expanded spine criteria (p < 0.05), with poor correlations among the different assessment tools. CONCLUSIONS: Limitations in the use of DXA T-scores alone to diagnose osteoporosis in patients with lumbar spondylosis has prompted interest in additional methods of evaluating bone health in the spine, such as CT HU, TBS, and FRAX, to inform guidelines that aim to reduce fracture risk. However, no current osteoporosis assessment was developed with a focus on improving outcomes in spinal surgery. Therefore, the authors propose an expanded spine definition for osteoporosis to identify a more comprehensive cohort of patients with potential poor bone health who could be considered for preoperative optimization, although further study is needed to validate these results in terms of clinical outcomes.

Revision Total Hip Arthroplasty in Patients With Ankylosing Spondylitis: Long-Term Results.

BACKGROUND: Ankylosing spondylitis (AS) is a common inflammatory spondyloarthropathy with hip involvement in 40% of patients. With the recent interest in the hip-spine interplay, the purpose of this study was to define the long-term outcomes of revision total hip arthroplasty (THA) in the setting of AS. METHODS: 174 hips in patients with AS treated with revision THA from 1969 to 2016 were identified. Mean age at revision THA was 53 years and 76% were male. Cumulative incidences of any re-revision, reoperation, and dislocation were calculated using a competing risk analysis. Mean follow-up was 13 years. RESULTS: The cumulative incidence of any re-revision after index revision THA was 7% at 5 years and 36% at 20 years. Cumulative incidence of any reoperation was 9% at 5 years and 38% at 20 years. Cumulative incidence of dislocation was 6% at 5 years and 8% at 20 years. Revision THAs performed with contemporary implants (2000-2016) had a lower but statistically nonsignificant cumulative incidence of any re-revision when compared with historical implants (before 2000) at 5 years (5% vs 8%), 10 years (11% vs 18%), and 15 years (11% vs 38%) (hazard ratio, 0.47; 95% confidence interval, 0.17-1.33; P = .016). CONCLUSION: In this large series of 174 revision THAs in patients with AS, the cumulative incidence of dislocation was 8% at 20 years. The 20-year cumulative incidence of any re-revision was 36%, which is similar to reported rates in patients with comparable demographic features without AS. LEVEL OF EVIDENCE: Level IV.

Retrospective Analysis of Long-Term Outcomes After Combat Injury: A Hidden Cost of War.

BACKGROUND: During the conflicts in Iraq and Afghanistan, 52,087 service members have been wounded in combat. The long-term sequelae of these injuries have not been carefully examined. We sought to determine the relation between markers of injury severity and the subsequent development of hypertension, coronary artery disease, diabetes mellitus, and chronic kidney disease. METHODS AND RESULTS: Retrospective cohort study of critically injured US military personnel wounded in Iraq or Afghanistan from February 1, 2002 to February 1, 2011. Patients were then followed until January 18, 2013. Chronic disease outcomes were assessed by International Classification of Diseases, 9th edition codes and causes of death were confirmed by autopsy. From 6011 admissions, records were excluded because of missing data or if they were for an individual's second admission. Patients with a disease diagnosis of interest before the injury date were also excluded, yielding a cohort of 3846 subjects for analysis. After adjustment for other factors, each 5-point increment in the injury severity score was associated with a 6%, 13%, 13%, and 15% increase in incidence rates of hypertension, coronary artery disease, diabetes mellitus, and chronic kidney disease, respectively. Acute kidney injury was associated with a 66% increase in rates of hypertension and nearly 5-fold increase in rates of chronic kidney disease. CONCLUSIONS: In Iraq and Afghanistan veterans, the severity of combat injury was associated with the subsequent development of hypertension, coronary artery disease, diabetes mellitus, and chronic kidney disease.

Tick-borne flaviviruses antagonize both IRF-1 and type I IFN signaling to inhibit dendritic cell function.

Tick-borne encephalitis virus (TBEV), a member of the Flaviviridae family, is a leading cause of viral encephalitis in Europe and Asia. Dendritic cells (DCs), as early cellular targets of infection, provide an opportunity for flaviviruses to inhibit innate and adaptive immune responses. Flaviviruses modulate DC function, but the mechanisms underpinning this are not defined. We examined the maturation phenotype and function of murine bone marrow-derived DCs infected with Langat virus (LGTV), a naturally attenuated member of the TBEV serogroup. LGTV infection failed to induce DC maturation or a cytokine response. Treatment with LPS or LPS/IFN-γ, strong inducers of inflammatory cytokines, resulted in enhanced TNF-α and IL-6 production, but suppressed IL-12 production in infected DCs compared with uninfected "bystander" cells or mock-infected controls. LGTV-mediated antagonism of type I IFN (IFN-I) signaling contributed to inhibition of IL-12p40 mRNA expression at late time points after stimulation. However, early suppression was still observed in DCs lacking the IFN-I receptor (Ifnar(-/-)), suggesting that additional mechanisms of antagonism exist. The early IFN-independent inhibition of IL-12p40 was nearly abolished in DCs deficient in IFN regulatory factor-1 (IRF-1), a key transcription factor required for IL-12 production. LGTV infection did not affect Irf-1 mRNA expression, but rather diminished IRF-1 protein levels and nuclear localization. The effect on IRF-1 was also observed in DCs infected with the highly virulent Sofjin strain of TBEV. Thus, antagonism of IRF-1 is a novel mechanism that synergizes with the noted ability of flaviviruses to suppress IFN-α/ß receptor-dependent signaling, resulting in the orchestrated evasion of host innate immunity.

Evaluation of immediate postoperative complications and outcomes among military personnel treated for spinal trauma in Afghanistan: a cohort-control study of 50 cases.

STUDY DESIGN: Retrospective case-control study. OBJECTIVE: The objective of the study was to compare neurological outcomes and complication rates between a series of combat-injured patients treated in Afghanistan (AFG) and those treated at Landstuhl Regional Medical Center (LRMC). SUMMARY OF BACKGROUND DATA: At present, no studies have addressed the ideal timing and setting for surgical stabilization in combat-injured soldiers who sustain spinal trauma. METHODS: Soldiers who sustained spine injuries while deployed to Afghanistan and who underwent surgery in theater or at LRMC between 2010 and 2011 were identified. Demographic information, injury-specific data, neurological status, type of surgical intervention, postoperative complications, and need for additional surgery were abstracted for all patients. Neurological improvement was the primary dependent variable. Secondary variables included the risk of developing complications and the need for additional surgery. Statistical analysis was performed using t tests, and the Fisher exact test was used for categorical variables. RESULTS: Between 2010 and 2011, 30 individuals were treated in AFG, and 20 received surgery at LRMC. Neurological improvement occurred in 10% of AFG patients and 5% of those treated at LRMC. Complications occurred in 40% of AFG patients and in 20% of the LRMC group. Twenty-three percent of AFG patients required additional spine surgery after leaving Afghanistan. There was no statistical difference in neurological improvement between the AFG and LRMC groups (P=0.64). Soldiers who received surgery in AFG were at significantly increased risk of requiring additional procedures (P=0.03). CONCLUSIONS: Soldiers treated in theater did not have statistically higher rates of neurological improvement as compared with those treated at LRMC. Patients treated in-theater were at elevated risk for the need for additional surgery. This study is among the first to evaluate clinical outcomes after surgical intervention for war-related spinal trauma. LEVEL OF EVIDENCE: Level III (case-control).

The combat burst fracture study--results of a cohort analysis of the most prevalent combat specific mechanism of major thoracolumbar spinal injury.

INTRODUCTION: In 2009-2010, military physicians hypothesized that a new pattern of spinal injury had emerged, resulting from improvised explosive device assault on up-armored vehicles, associated with a high rate of point of first contact fracture and neurological injury-the combat burst fracture. We sought to determine the incidence of all thoracolumbar (TL) burst fractures and combat burst fractures in 2009-2010 as compared to two antecedent years. METHODS: A screening process identified all individuals who sustained TL burst fractures in the time-period studied. Demographics, injury-specific characteristics, mechanism of injury, surgical interventions and early complications were recorded. Incidence rates were calculated for the three time periods using total deployed troop-strength and number of LRMC combat admissions as denominators. The incidences of TL burst fractures within each year group and by mechanism were compared, and clinical characteristics and process of care were described. RESULTS: Between 2007-2010, 65 individuals sustained a TL burst fracture. The incidence of these injuries in 2009-2010 was 2.1 per 10,000 soldier-years and accounted for 3.0 % of LRMC combat-casualty admissions, a significant increase from 0.6 % and 1.1 % in 2007-2008 and 2008-2009, respectively (p ≤ 0.001). In 2009-2010, US soldiers were 3.4-4.6 times more likely to sustain a TL burst fracture compared to 2008-2009 and 2007-2008 (p < 0.001), and the most common mechanism of injury was IED vs. vehicle (65 %)-the combat burst fracture mechanism. Neurological deficits were present in 43 % of TL burst fractures and 1/3 were complete injuries. Spinal fixation was performed in 68 % overall and 74 % of combat burst fractures. CONCLUSIONS: There was a 3.4- to 4.6-fold increase in TL burst fractures in 2009-2010 compared to antecedent years. The primary driver of this phenomenon was the marked increased in combat burst fractures. Mitigating/preventing the mechanism behind this major spinal injury is a key research initiative for the US military. Level of Evidence III (Case-control).

Interbody cages versus structural bone grafts in lumbar arthrodesis: a systematic review and meta-analysis.

OBJECTIVE: The role of interbodies in lumbar arthrodesis has been insufficiently supported by evidence, impacting clinical decision-making and occasionally insurance coverage. This study aimed to compare clinical and radiological outcomes between lumbar arthrodesis with a synthetic interbody spacer (cage) versus structural bone graft alone (autograft or allograft) in patients with degenerative spine disease. METHODS: A systematic review of the literature was performed to identify studies directly comparing outcomes of lumbar interbody arthrodesis with and without interbody cage use. The outcomes of individual studies were synthesized in meta-analyses using random-effects models. RESULTS: Twenty studies with 1508 patients (769 with an interbody cage and 739 without an interbody cage) were included. Interbody cage placement was associated with a significantly greater increase in disc height after surgery (4.0 mm vs 3.4 mm, p < 0.01). There was a significantly greater reduction of back pain (visual analog scale [VAS] score) in cases in which an interbody cage was used (5.4 vs 4.7, p = 0.03). Fusion rates were 5.5% higher in the cage group (96.3% vs 90.8%) and reached statistical significance (p = 0.03). No statistically significant differences were identified between the two groups regarding all-cause reoperation rates, complication rates, or improvement in Oswestry Disability Index score or leg pain (VAS score). CONCLUSIONS: These results suggest that implantation of an interbody cage is associated with higher rates of fusion, more effective maintenance of disc height, and greater improvement of back pain. This study underlines the clinical value of interbody cages in lumbar arthrodesis for patients with degenerative spine disease.

Bone morphogenetic protein in subaxial cervical arthrodesis: a meta-analysis of 5828 patients.

OBJECTIVE: Use of bone morphogenetic protein (BMP)-an osteoinductive agent commonly used in lumbar arthrodesis-is off-label for cervical arthrodesis. This study aimed to identify the effect of BMP use on clinical and radiological outcomes in instrumented cervical arthrodesis. METHODS: A comprehensive systematic review of the literature was performed to identify studies directly comparing outcomes between cervical arthrodeses with and without using BMP. Outcomes were analyzed separately for cases of anterior cervical discectomy and fusion (ACDF) and posterior cervical fusion (PCF). RESULTS: A total of 20 studies with 5828 patients (1948 with BMP and 3880 without BMP) were included. In the ACDF cases, BMP use was associated with higher fusion rates (98.9% vs 93.6%, risk difference [RD] 8%; risk ratio [RR] 1.12, p = 0.02), lower reoperation rates (2.2% vs 3.1%, RD 3%; RR 0.48, p = 0.04), and higher risk of dysphagia (24.7% vs 8.1%, RD 11%; RR 1.93, p = 0.02). No significant differences in the Neck Disability Index, neck pain, or arm pain scores were associated with the use of BMP. On subgroup meta-analysis of ACDF cases, older age (≥ 50 years) and higher BMP dose (≥ 0.9 mg/level) were associated with significantly higher fusion rates and relatively lower risk for dysphagia, whereas arthrodesis of fewer segments (< 2 levels) showed significantly higher dysphagia rates without a significant increase in fusion rates. In the PCF cases, the use of BMP was not associated with significant differences in fusion (p = 0.38) or reoperation (p = 0.61) rates but was associated with significantly higher blood loss during surgery (mean difference 146.7 ml, p ≤ 0.01). CONCLUSIONS: Use of BMP in ACDF offers higher rates of augmented fusion and lower rates of all-cause reoperation but with an increased risk of dysphagia. The benefit of fusion outweighs the risk of dysphagia with a higher BMP dose in older patients being operated on for < 2 levels. The use of BMP in PCF seems to have a less important effect on clinical and radiological outcomes.

Transforming Outcomes of Spine Surgery-Exploring the Power of Enhanced Recovery After Surgery Protocol: A Systematic Review and Meta-Analyses of 15 198 Patients.

BACKGROUND AND OBJECTIVES: Enhanced recovery after surgery (ERAS) protocols aim to optimize patient outcomes by reducing the surgical stress response, expediting recovery, and reducing care costs. We aimed to evaluate the impact of implementing ERAS protocols on the perioperative surgical outcomes and financial implications associated with spine surgeries. METHODS: A systematic review and meta-analysis of peer-reviewed studies directly comparing outcome differences between spine surgeries performed with and without utilization of ERAS pathways was conducted along Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS: Of 676 unique articles identified, 59 with 15 198 aggregate patients (7748 ERAS; 7450 non-ERAS) were included. ERAS-treated patients had shorter operative times (mean difference [MD]: 10.2 mins; P < .01), shorter hospitalizations (MD: 1.41 days, P < .01), fewer perioperative complications (relative risk [RR] = 0.64, P < .01), lower postoperative opioid use (MD of morphine equivalent dose: 164.36 mg; P < .01), and more rapid mobilization/time to first out-of-bed ambulation (MD: 0.92 days; P < .01). Spine surgeries employing ERAS were also associated with lower total costs (MD: $1140.26/patient; P < .01), especially in the United States (MD: $2869.11/patient, P < .01) and lower postoperative visual analog pain scores (MD = 0.56, P < .01), without any change in odds of 30-day readmission (RR: 0.80, P = .13) or reoperation (RR: 0.88, P = .60). Subanalyses based on the region of spine showed significantly lower length of stay in both cervical and lumbar surgeries implementing ERAS. Type of procedure showed a significantly lesser time-to-initiate mobilization in fusion surgeries using ERAS protocols compared with decompression. CONCLUSION: The present meta-analysis indicates that current literature supports ERAS implementation as a means of reducing care costs and safely accelerating hospital discharge for patients undergoing spine surgery.

Optimal Implant Sizing Using Machine Learning Is Associated With Increased Range of Motion After Cervical Disk Arthroplasty.

BACKGROUND AND OBJECTIVES: Cervical disk arthroplasty (CDA) offers the advantage of motion preservation in the treatment of focal cervical pathology. At present, implant sizing is performed using subjective tactile feedback and imaging of trial cages. This study aims to construct interpretable machine learning (IML) models to accurately predict postoperative range of motion (ROM) and identify the optimal implant sizes that maximize ROM in patients undergoing CDA. METHODS: Adult patients who underwent CDA for single-level disease from 2012 to 2020 were identified. Patient demographics, comorbidities, and outcomes were collected, including symptoms, examination findings, subsidence, and reoperation. Affected disk height, healthy rostral disk height, and implant height were collected at sequential time points. Linear regression and IML models, including bagged regression tree, bagged multivariate adaptive regression spline, and k-nearest neighbors, were used to predict ROM change. Model performance was assessed by calculating the root mean square error (RMSE) between predicted and actual changes in ROM in the validation cohort. Variable importance was assessed using RMSE loss. Area under the curve analyses were performed to identify the ideal implant size cutoffs in predicting improved ROM. RESULTS: Forty-seven patients were included. The average RMSE between predicted and actual ROM was 7.6° (range: 5.8-10.1) in the k-nearest neighbors model, 7.8° (range: 6.5-10.0) in the bagged regression tree model, 7.8° (range: 6.2-10.0) in the bagged multivariate adaptive regression spline model, and 15.8° (range: 14.3-17.5°) in a linear regression model. In the highest-performing IML model, graft size was the most important predictor with RMSE loss of 6.2, followed by age (RMSE loss = 5.9) and preoperative caudal disk height (RMSE loss = 5.8). Implant size at 110% of the normal adjacent disk height was the optimal cutoff associated with improved ROM. CONCLUSION: IML models can reliably predict change in ROM after CDA within an average of 7.6 degrees of error. Implants sized comparably with the healthy adjacent disk may maximize ROM.

A Standardized Curriculum Improves Trainee Rod Bending Proficiency in Spinal Deformity Surgery. Results of a Prospective Randomized Controlled Educational Study.

INTRODUCTION: Surgical simulation is increasingly being accepted as a training platform to promote skill development and a safe surgical technique. Preliminary investigations in spine surgery show that simulation paired with educational intervention can markedly improve trainee performance. This study used a newly developed thoracolumbar fusion rod bending model to assess the effect of a novel educational curriculum and simulator training on surgical trainee rod bending speed and proficiency. METHODS: Junior (PGY1 to 2) and senior (PGY3-fellow) surgical trainees at a single academic institution were prospectively enrolled in a rod bending simulation using a T7-pelvis spinal fusion model. Participants completed two simulations, with 1 month between first and second attempts. Fifty percent of surgeons in each training level were randomized to receive an educational curriculum (rod bending technique videos and unlimited simulator practice) between simulation attempts. Rod bending simulation proficiency was determined by the percentage of participants who completed the task (conclusion at 20 minutes), time to task completion or conclusion, and number of incomplete set screws at task conclusion. Participants completed a preparticipation and postparticipation survey. Univariate analysis compared rod bending proficiency and survey results between education and control cohorts. RESULTS: Forty trainees (20 junior and 20 senior) were enrolled, with 20 participants randomized to the education and control cohorts. No notable differences were observed in the first simulation rod bending proficiency or preparticipation survey results between the education and control cohorts. In the second simulation, the education versus the control cohort demonstrated a significantly higher completion rate ( P = 0.01), shorter task time ( P = 0.009), fewer incomplete screws ( P = 0.003), and greater experience level ( P = 0.008) and comfort level ( P = 0.002) on postparticipation survey. DISCUSSION: Trainees who participated in a novel educational curriculum and simulator training relative to the control cohort improved markedly in rod bending proficiency and comfort level. Rod bending simulation could be incorporated in existing residency and fellowship surgical skills curricula. LEVEL OF EVIDENCE: I.