Development and validation of a point-of-care clinical risk score to predict surgical site complication-associated readmissions following open spine surgery.

Background: Surgical site complications (SSCs) contribute to increased healthcare costs. Predictive analytics can aid in identifying high-risk patients and implementing optimization strategies. This study aimed to develop and validate a risk-assessment score for SSC-associated readmissions (SSC-ARs) in patients undergoing open spine surgery. Methods: The Premier Healthcare Database (PHD) of adult patients (n=157,664; 3,182 SSC-ARs) between January 2019 and September 2020 was used for retrospective data analysis to create an SSC risk score using mixed effects logistic regression modeling. Full and reduced models were developed using patient-, facility-, or procedure-related predictors. The full model used 37 predictors and the reduced used 19. Results: The reduced model exhibited fair discriminatory capability (C-statistic =74.12%) and demonstrated better model fit [Pearson chi-square/degrees of freedom (DF) =0.93] compared to the full model (C-statistic =74.56%; Pearson chi-square/DF =0.92). The risk scoring system, based on the reduced model, comprised the following factors: female (1 point), blood disorder [2], congestive heart failure [2], dementia [3], chronic pulmonary disease [2], rheumatic disease [3], hypertension [2], obesity [2], severe comorbidity [2], nicotine dependence [1], liver disease [2], paraplegia and hemiplegia [3], peripheral vascular disease [2], renal disease [2], cancer [1], diabetes [2], revision surgery [2], operative hours ≥5 [4], emergency/urgent surgery [2]. A final risk score (sum of the points for each surgery; range, 0-40) was validated using a 1,000-surgery random hold-out sample (C-statistic =85.16%). Conclusions: The resulting SSC-AR risk score, composed of readily obtainable clinical information, could serve as a robust predictive tool for unplanned readmissions related to wound complications in the preoperative setting of open spine surgery.

Development and validation of a point-of-care clinical risk score to predict surgical site infection following open spinal fusion.

Background: Surgical site infection (SSI) after open spine surgery increases healthcare costs and patient morbidity. Predictive analytics using large databases can be used to develop prediction tools to aid surgeons in identifying high-risk patients and strategies for optimization. The purpose of this study was to develop and validate an SSI risk-assessment score for patients undergoing open spine surgery. Methods: The Premier Healthcare Database of adult open spine surgery patients (n = 157,664; 2,650 SSIs) was used to create an SSI risk scoring system using mixed effects logistic regression modeling. Full and reduced multilevel logistic regression models were developed using patient, surgery or facility predictors. The full model used 38 predictors and the reduced used 16 predictors. The resulting risk score was the sum of points assigned to 16 predictors. Results: The reduced model showed good discriminatory capability (C-statistic = 0.75) and good fit of the model ([Pearson Chi-square/DF] = 0.90, CAIC=25,517) compared to the full model (C-statistic = 0.75, [Pearson Chi-square/DF] =0.90, CAIC=25,578). The risk scoring system, based on the reduced model, included the following: female (5 points), hypertension (4), blood disorder (8), peripheral vascular disease (9), chronic pulmonary disease (6), rheumatic disease (16), obesity (12), nicotine dependence (5), Charlson Comorbidity Index (2 per point), revision surgery (14), number of ICD-10 procedures (1 per procedure), operative time (1 per hour), and emergency/urgent surgery (12). A final risk score as the sum of the points for each surgery was validated using a 1,000-surgery random hold-out (independent from the study cohort) sample (C-statistic = 0.77). Conclusions: The resulting SSI risk score composed of readily obtainable clinical information could serve as a strong prediction tool for SSI in preoperative settings when open spine surgery is considered.

Resident assistant training level is not associated with patient spinal fusion outcomes.

OBJECTIVE: A hallmark of surgical training is resident involvement in operative procedures. While resident-assisted surgeries have been deemed generally safe, few studies have rigorously isolated the impact of resident post-graduate year (PGY) level on post-operative outcomes in a neurosurgical patient population. The objective of this study is to evaluate the relationship between resident training level and outcomes following single-level, posterior-only lumbar fusion, after matching on key patient demographic/clinical characteristics and attending surgeon. PATIENTS AND METHODS: This coarsened-exact matching (CEM) study analyzed 2338 consecutive adult patients who underwent single-level lumbar fusion with a resident assistant surgeon at a multi-hospital university health system from 2013 to 2019. Primary outcomes were 30-day and 90-day readmissions, Emergency Department (ED) visits, reoperations, surgical complications, and mortality. First, univariate logistic regression examined the relationship between PGY level and outcomes. Then, CEM was used to control for key patient characteristics - such as race and comorbid status - and supervising attending surgeon, between the most junior (PGY-2)-assisted cases and the most senior (PGY-7)-assisted cases, thereby isolating the relationship between training level and outcomes. RESULTS: Among all patients, resident training level was not associated with risk of adverse post-surgical outcomes. Similarly, between exact-matched cohorts of PGY-2- and PGY-7-assisted cases, no significant differences in adverse events or discharge disposition were observed. Patients with the most senior resident assistant surgeons demonstrated longer length of stay (mean 100.5 vs. 93.8 h, p = 0.022) and longer duration of surgery (mean 173.5 vs. 159.8 min, p = 0.036). CONCLUSION: Training level of the resident assistant surgeon did not impact adverse outcomes provided to patients in the setting of single-level, posterior-only lumbar fusion. These findings suggest that attending surgeons appropriately manage cases with resident surgeons at different levels of training.

Incidental Durotomy Following Surgery for Degenerative Lumbar Disease and the Impact of Minimally Invasive Surgical Technique on the Rate and Need for Surgical Revision: A Case Series.

BACKGROUND: Incidental durotomy (ID) is a common complication during lumbar spine surgery. A paucity of literature has studied the impact of minimally invasive surgery (MIS) on durotomy rates and strategies for repair as compared to open surgery. OBJECTIVE: To examine the impact that MIS techniques have on the durotomy rate, repair techniques, and need for surgical revision following surgery for degenerative lumbar disease as compared to open technique. METHODS: A single-center retrospective review of consecutive cases between 2013 and 2016 was performed. All patients underwent lumbar decompression with or without instrumented fusion for degenerative pathology using either open posterior or MIS techniques. ID rate, closure technique, and need for surgical revision related to the durotomy were recorded. RESULTS: A total of 1,196 patients were included with an overall ID rate of 6.8%. There was no difference between open or minimally invasive surgical techniques (P = .14). There was a higher durotomy rate with open technique in patients that underwent decompression with fusion (P = .03) as well as in revision cases (P = .02). Primary repair was feasible more frequently in the open group (P = .001), whereas use of dural substitute (P < .001) was more common in the MIS group. Fibrin sealant was used routinely in both groups (P = .34). There were no failed repairs, regardless of technique used. CONCLUSION: MIS techniques may reduce durotomies in cases involving instrumentation or revisions. Use of dural substitute onlay and fibrin sealant was effective at preventing reoperation. Both MIS and open techniques result in a low rate of future surgical revision when a durotomy occurs.

Does minimally invasive spine surgery improve outcomes in the obese population? A retrospective review of 1442 degenerative lumbar spine surgeries.

OBJECTIVE: The effect of obesity on outcomes in minimally invasive surgery (MIS) approaches to posterior lumbar surgery is not well characterized. The authors aimed to determine if there was a difference in operative variables and complication rates in obese patients who underwent MIS versus open approaches in posterior spinal surgery, as well as between obese and nonobese patients undergoing MIS approaches. METHODS: A retrospective review of all consecutive patients who underwent posterior lumbar surgery from 2013 to 2016 at a single institution was performed. The primary outcome measure was postoperative complications. Secondary outcome measures included estimated blood loss (EBL), operative time, the need for revision, and hospital length of stay (LOS); readmission and disposition were also reviewed. Obese patients who underwent MIS were compared with those who underwent an open approach. Additionally, obese patients who underwent an MIS approach were compared with nonobese patients. Bivariate and multivariate analyses were carried out between the groups. RESULTS: In total, 423 obese patients (57.0% decompression and 43.0% fusion) underwent posterior lumbar MIS. When compared with 229 obese patients (56.8% decompression and 43.2% fusion) who underwent an open approach, patients in both the obese and nonobese groups who underwent MIS experienced significantly decreased EBL, LOS, operative time, and surgical site infections (SSIs). Of the nonobese patients, 538 (58.4% decompression and 41.6% fusion) underwent MIS procedures. When compared with nonobese patients, obese patients who underwent MIS procedures had significantly increased LOS, EBL, operative time, revision rates, complications, and readmissions in the decompression group. In the fusion group, only LOS and disposition were significantly different. CONCLUSIONS: Obese patients have poorer outcomes after posterior lumbar MIS when compared with nonobese patients. The use of an MIS technique can be of benefit, as it decreased EBL, operative time, LOS, and SSIs for posterior decompression with or without instrumented fusion in obese patients.

Minimally invasive posterior lumbar surgery in the morbidly obese, obese and non-obese populations: A single institution retrospective review.

BACKGROUND: There is a paucity of information regarding outcomes in minimally invasive surgical (MIS) approaches to posterior lumbar surgery in morbidly obese patients. We seek to determine if there are differences in operative variables and early complication rates in morbidly obese patients undergoing MIS posterior lumbar surgery compared to obese and non-obese patients. METHODS: A single institution retrospective review of patients undergoing MIS posterior lumbar surgery (decompression and/or fusion) between 2013 and 2016 was performed. Morbidly obese patients (BMI ≥ 40) were compared to obese (BMI 30-39.9) and non-obese (BMI < 30) cohorts. Postoperative complication rates and perioperative variables including estimated blood loss, operative time, and outcome measures including length of stay (LOS), in-hospital complications, readmission, and disposition were assessed. RESULTS: 47 morbidly obese, 135 obese and 224 non-obese patients underwent posterior MIS instrumented fusion. 59 morbidly obese, 182 obese and 314 non-obese patients underwent posterior MIS decompression. The morbidly obese group experienced a greater rate of deep vein thrombosis and had an increased hospital LOS (p < 0.05). Morbidly obese patients who underwent MIS decompression experienced increased postoperative complications (p < 0.01), and increased LOS (p < 0.0001) compared to obese and non-obese patients. There were no differences in revision rates, readmissions, and other complications including surgical site infection. Morbid obesity was an independent predictor of overall complications and increased LOS on multivariate analysis. CONCLUSION: Morbidly obese patients undergoing posterior MIS fusion had a higher rate of complications and increased LOS. While weight loss should be encouraged, complication rates remains acceptably low in morbidly obese patients and MIS posterior lumbar surgery should still be offered.

The Utility of Prolonged Prophylactic Systemic Antibiotics (PPSA) for Subfascial Drains After Degenerative Spine Surgery.

STUDY DESIGN: Retrospective cohort study. OBJECTIVE: The aim of the current investigation was to evaluate the impact of prolonged prophylactic systemic antibiotics (PPSA) on the development of surgical site infection rate (SSIR) in degenerative spine surgery. SUMMARY OF BACKGROUND DATA: Surgical drains are utilized postoperatively in posterior spine surgery to help minimize the risk of seroma formation. Prophylactic antibiotics while drains are in place are frequently used to reduce SSIR, though the practice remains controversial. METHODS: We performed a single center, retrospective review of all patients that underwent posterior spinal surgery for cervical and lumbar degenerative pathology over a 3.5 year period (January 2016-July 2019). Patients underwent a traditional open posterior midline procedure with postoperative placement of a subfascial surgical drain. Antibiotics were administered for the duration of the drain (PPSA group) or for 24 hours postoperatively (non-PPSA group). The number of surgical site infections, organism, and Clostridium difficile infections was recorded. RESULTS: Three hundred thirty six patients were identified, 168 patients in the PPSA group and 168 in the non-PPSA groups. The overall SSIR was 5.36% (18/336). The SSIR for the non-PPSA and PPSA groups were 7.14% (12/168) and 3.57% (6/168), respectively (P = 0.146). While difference of SSIR between the groups was two-fold, it was not statistically significant. For the non-PPSA and PPSA groups, the SSIR for cervical (5.95% [5/84] vs. 2.38% [2/84], P = 0.443) and lumbar (8.33% [7/84], vs. 4.76% [4/84], P = 0.535) regions were not significantly different. C. difficile cases in the PPSA and non-PPSA groups were 1/168 and 0/168 respectively (P = 1.00). CONCLUSION: Our series demonstrate a two-fold reduction of SSI with implementation of PPSA regimen. This benefit was demonstrated separately for both cervical and lumbar regions. Randomized trials and increase in sample size are warranted to elucidate the significance of PPSA in posterior spinal surgery.Level of Evidence: 3.

Effect of Incisional Negative Pressure Wound Therapy vs Standard Wound Dressing on the Development of Surgical Site Infection after Spinal Surgery: A Prospective Observational Study.

BACKGROUND: Use of a closed-incisional negative pressure therapy (ci-NPT) dressing is an emerging strategy to reduce surgical site infections (SSIs) in spine surgery that lacks robust data. OBJECTIVE: To determine the impact of a ci-NPT, as compared with a standard dressing, on the development of SSIs after spine surgery. METHODS: This was a prospective observational study over a 2-yr period. Indications for surgery included degenerative disease, deformity, malignancy, and trauma. Exclusion criteria included anterior and lateral approaches to the spine, intraoperative durotomy, or use of minimally invasive techniques. SSIs up to 60 d following surgery were recorded. RESULTS: A total of 274 patients were included. SSI rate was significantly lower with ci-NPT dressing (n = 118) as compared with the standard dressing (n = 156) (3.4 vs 10.9%, P = .02). There was no statistical difference in infection rate for decompression alone procedures (4.2 vs 9.1%, P = .63), but there was a statistically significant reduction with the use of a negative-pressure dressing in cases that required instrumentation (3.2 vs 11.4%, P = .03). Patients at higher risk (instrumentation, deformity, and malignancy) had less SSIs with the use of ci-NPT, although this did not reach statistical significance. There were no complications in either group. CONCLUSION: SSI rates were significantly reduced with a ci-NPT dressing vs a standard dressing in patients who underwent spinal surgery. The higher cost of a ci-NPT dressing might be justified with instrumented cases, as well as with certain high-risk patient populations undergoing spine surgery, given the serious consequences of an infection.

Management of Intracranial Hemorrhage in Patients with a Left Ventricular Assist Device: A Systematic Review and Meta-Analysis.

BACKGROUND: Intracranial hemorrhage (ICH) has been reported to occur in up to 23% of patients with left ventricular assist devices (LVADs). Currently, limited data exists to guide neurosurgical management strategies to optimize outcomes in patients with an LVAD who develop ICH. METHODS: A systematic review and meta-analysis of the literature was performed to evaluate the mortality rate in these patients following medical and/or surgical management and to evaluate antithrombotic reversal and resumption strategies after hemorrhage. RESULTS: 17 studies reporting on 3869 LVAD patients and 545 intracranial hemorrhages spanning investigative periods from 1996 to 2019 were included. The rate of ICH in LVAD patients was 10.6% (411/3869) with 58.6% (231/394) being intraparenchymal hemorrhage (IPH), 23.6% (93/394) subarachnoid hemorrhage (SAH), and 15.5% (61/394) subdural hemorrhage (SDH). Total mortality rates for surgical management 65.6% (40/61) differed from medical management at 45.2% (109/241). There was an increased relative risk of mortality (RR=1.45, 95% CI: 1.10-1.91, p = 0.01) for ICH patients undergoing surgical intervention. The hemorrhage subtype most frequently managed with anticoagulation reversal was IPH 81.8% (63/77), followed by SDH 52.2% (12/23), and SAH 39.1% (18/46). Mean number of days until antithrombotic resumption ranged from 6 to 10.5 days. CONCLUSION: Outcomes remain poor, specifically for those undergoing surgery. As experience with this population increases, prospective studies are warranted to contribute to management and prognostication .

Resection of a Large Thoracic Schwannoma: 2-Dimensional Operative Video.

Spinal schwannomas most likely occur at the thoracic level and within the intradural extramedullary compartment. They are benign, typically slow-growing, peripheral nerve sheath tumors that produce symptoms by displacing or compressing the nerve roots and spinal cord. There is an association with patients that have neurofibromatosis type 2. Surgical pearls including the utilization of intraoperative ultrasound for localization, D wave monitoring, and microsurgical dissection are demonstrated. Pertinent high-yield radiographic and histological features of schwannomas are reviewed.1-4 We report the case of a 59-yr-old female who presented with progressively worsening gait instability that was associated with lower extremity numbness progressing to weakness. She had myelopathic findings on examination, which included brisk patellar reflexes and persistent clonus with sensory changes to the umbilicus and mild leg weakness. Full body examination revealed no stigmata of neurofibromatosis. Magnetic resonance imaging of the neuroaxis demonstrated a large, intradural extramedullary mass with peripheral enhancement that spanned the T9 to T11 vertebral levels with severe compression of the spinal cord. There were no intracranial, cervical, or lumbar findings. Surgical intervention was planned with the following objectives: decompression of the neural elements, curative resection, and diagnosis. Patient consent for the procedure was obtained. Institutional Review Board approval for solitary case reports are not needed at our institution.

Reoperation, Readmission, and Discharge Disposition for Patients With Degenerative Lumbar Pathology Treated With Either Open or Minimally Invasive Techniques: A Single-Center Retrospective Review of 1435 Cases.

BACKGROUND: Spine surgery has been transformed by the growth of minimally invasive surgery (MIS) procedures. Previous studies agree that MIS has shorter hospitalization and faster recovery time when compared to conventional open surgery. However, the reoperation and readmission rates between the 2 techniques have yet to be well characterized. OBJECTIVE: To evaluate the rate of subsequent revision between MIS and open techniques for degenerative lumbar pathology. METHODS: A total of 1435 adult patients who underwent lumbar spine surgery between 2013 and 2016 were included in this retrospective analysis. The rates of need for subsequent reoperation, 30- and 90-d readmission, and discharge to rehabilitation were recorded for both MIS and traditional open techniques. Groups were divided into decompression alone and decompression with fusion. RESULTS: The rates of subsequent reoperation following MIS and open surgery were 10.4% and 12.2%, respectively (P = .32), which were maintained when subdivided into decompression and decompression with fusion. MIS and open 30-d readmission rates were 7.9% and 7.2% (P = .67), while 90-d readmission rates were 4.3% and 3.6% (P = .57), respectively. Discharge to rehabilitation was significantly lower for patients under 60 yr of age undergoing MIS (1.64% vs 5.63%, P = .04). CONCLUSION: The use of minimally invasive techniques for the treatment of lumbar spine pathology does not result in increased reoperation or 30- and 90-d readmission rates when compared to open approaches. Patients under the age of 60 yr undergoing MIS procedures were less likely to be discharged to rehab.

Biomechanical analysis of occipitocervical stabilization techniques: emphasis on integrity of osseous structures at the occipital implantation sites.

OBJECTIVE: The objective of the current study was to quantify and compare the multidirectional flexibility properties of occipital anchor fixation with conventional methods of occipitocervical screw fixation using nondestructive and destructive investigative methods. METHODS: Fourteen cadaveric occipitocervical specimens (Oc-T2) were randomized to reconstruction with occipital anchors or an occipital plate and screws. Using a 6-degree-of-freedom spine simulator with moments of ± 2.0 Nm, initial multidirectional flexibility analysis of the intact and reconstructed conditions was performed followed by fatigue loading of 25,000 cycles of flexion-extension (x-axis, ± 2.0 Nm), 15,000 cycles of lateral bending (z-axis, ± 2.0 Nm), and 10,000 cycles of axial rotation (y-axis, ± 2.0 Nm). Fluoroscopic images of the implantation sites were obtained before and after fatigue testing and placed on an x-y coordinate system to quantify positional stability of the anchors and screws used for reconstruction and effect, if any, of the fatigue component. Destructive testing included an anterior flexural load to construct failure. Quantification of implant, occipitocervical, and atlantoaxial junction range of motion is reported as absolute values, and peak flexural failure moment in Newton-meters (Nm). RESULTS: Absolute value comparisons between the intact condition and 2 reconstruction groups demonstrated significant reductions in segmental flexion-extension, lateral bending, and axial rotation motion at the Oc-C1 and C1-2 junctions (p < 0.05). The average bone mineral density at the midline keel (1.422 g/cm3) was significantly higher compared with the lateral occipital region at 0.671 g/cm3 (p < 0.05). There were no significant differences between the occipital anchor and plate treatments in terms of angular rotation (degrees; p = 0.150) or x-axis displacement (mm; p = 0.572), but there was a statistically significant difference in y-axis displacement (p = 0.031) based on quantitative analysis of the pre- and postfatigue fluoroscopic images (p > 0.05). Under destructive anterior flexural loading, the occipital anchor group failed at 90 ± 31 Nm, and the occipital plate group failed at 79 ± 25 Nm (p > 0.05). CONCLUSIONS: Both reconstructions reduced flexion-extension, lateral bending, and axial rotation at the occipitocervical and atlantoaxial junctions, as expected. Flexural load to failure did not differ significantly between the 2 treatment groups despite occipital anchors using a compression-fit mechanism to provide fixation in less dense bone. These data suggest that an occipital anchor technique serves as a biomechanically viable clinical alternative to occipital plate fixation.

Intracranial hemorrhage type and same-admission mortality in patients with left ventricular assist devices.

OBJECTIVES: Left ventricular assist devices (LVAD) provide mechanical circulatory support for patients with advanced heart failure. Intracranial hemorrhage in this population represent a significant management challenge. The objective of this study is to report our initial experience on same-admission outcomes with LVAD patients that presented with various types of intracranial hemorrhage (ICH). PATIENTS AND METHODS: A retrospective review of a large volume center over a two-year period was performed. LVAD patients with ICH requiring a neurosurgical consultation were identified. Hemorrhage type, interventions, discharge disposition and cause of death were recorded. RESULTS: 27 LVAD patients with ICH received a neurosurgical consultation. The average INR at the time of ICH was 2.7 (1.0-8.8). Hemorrhage types seen were lobar (10/27, 37 %), SAH (5/27, 19 %), SDH (4/27, 15 %), cerebellar ICH (3/27, 11 %), multiple ICH (3/27, 11 %), and hemorrhagic conversion (2/27, 7 %). The overall mortality rate was 48.2 % (13/27), with the highest mortality being in those patients who had multiple ICH at the time of presentation (3/3, 100 %). The majority of patients with ICH (85.2 %) were non-operative. Lobar IPH was <3 cm in 80 % (8/10) of these, and 6/8 (75 %) ultimately died. 11 %(3/27) received surgical intervention. Of these, 67 % ultimately withdrew care. 77 % (10/13) of patients died as a result of the ICH. 80 % of patients with SAH were ultimately discharged home. CONCLUSIONS: Patients with a LVAD and ICH have a high rate of same-admission mortality (48 %). Hemorrhage location, intra-axial or extra-axial, resulted in patients being a risk for death secondary to either the hemorrhage itself or pump thrombosis, respectively.

How I do it: en-bloc subaxial cervical laminectomy using a high-speed drill with a footplate attachment.

BACKGROUND: Cervical laminectomy is a common strategy to decompress the spinal canal. METHODS: The anatomy of the cervical spine and surrounding critical structures as viewed from the posterior approach is described. The use of a high-speed drill with a footplate attachment to make laminar troughs with an en-bloc subaxial cervical laminectomy is described with a discussion on surgical technique and complication avoidance. CONCLUSION: This technique allows for a safe, comfortable, and rapid decompression of the cervical spine with minimal risk. For routine cases, this may potentially be more safe and cost-effective than using a cutting bur or bone scalpel attachment.

S2-AI screw placement with the aide of electronic conductivity device monitoring: a retrospective analysis.

STUDY DESIGN: A retrospective analysis of two consecutive patients who underwent a novel surgical technique. OBJECTIVE: A report of a novel surgical technique utilizing an electronic conductivity device guidance to aide placement of S2-Alar-Iliac (S2-AI) instrumentation. Electronic conductivity guidance for instrumentation of the thoracolumbar spine is an accepted means of improving intraoperative accuracy. Although commercially available for percutaneous techniques, there is a paucity of literature regarding its use. Percutaneous implantation of S2-AI screws has been previously described as another technique surgeons can avail, primarily employing fluoroscopy as a means of intraoperative feedback. We describe a novel technique that utilizes electronic conductivity as an added feedback measure to increase accuracy of percutaneous S2-AI fixation. METHODS: Two patients were treated by the senior author (FAS) who underwent surgery employing S2-AI fixation utilizing an electronic conductivity device (Pediguard cannulated probe, Spineguard, Paris, France). The surgical technique, case illustrations, and radiographic outcomes are discussed. RESULTS: Stable and accurate fixation was attained in both patients. There were no peri-operative complications related to hardware placement. CONCLUSION: To the authors' knowledge, this is the first reported literature combining S2-AI screws with electronic conductivity for immediate intraoperative feedback. This technique has the opportunity to provide surgeons with increased accuracy for placement of S2-AI screws while improving overall radiation safety. This feedback can be particularly helpful when surgeons are learning new techniques such as placement of S2AI screws.