Does a dedicated "Scoliosis Team" and surgical standardization improve outcomes in adolescent idiopathic scoliosis surgery and is it reproducible?

PURPOSE: The objective of this study was to determine if standardization improves adolescent idiopathic scoliosis (AIS) surgery outcomes and whether it is transferrable between institutions. METHODS: A retrospective review was conducted of AIS patients operated between 2009 and 2021 at two institutions (IA and IB). Each institution consisted of a non-standardized (NST) and standardized group (ST). In 2015, surgeons changed institutions (IA- > IB). Reproducibility was determined between institutions. Median and interquartile ranges (IQR), Kruskal-Wallis, and χ2 tests were used. RESULTS: 500 consecutive AIS patients were included. Age (p = 0.06), body mass index (p = 0.74), preoperative Cobb angle (p = 0.53), and levels fused (p = 0.94) were similar between institutions. IA-ST and IB-ST had lower blood loss (p < 0.001) and shorter surgical time (p < 0.001). IB-ST had significantly shorter hospital stay (p < 0.001) and transfusion rate (p = 0.007) than IB-NST. Standardized protocols in IB-ST reduced costs by 18.7%, significantly lowering hospital costs from $74,794.05 in IB-NST to $60,778.60 for IB-ST (p < 0.001). Annual analysis of surgical time revealed while implementation of standardized protocols decreased operative time within IA, when surgeons transitioned to IB, and upon standardization, IB operative time values decreased once again, and continued to decrease annually. Additions to standardized protocol in IB temporarily affected the operative time, before stabilizing. CONCLUSION: Surgeon-led standardized AIS approach and streamlined surgical steps improve outcomes and efficiency, is transferrable between institutions, and adjusts to additional protocol changes.

Paraspinal muscle approach for neuromuscular scoliosis: A comparative study evaluating deformity correction and perioperative morbidity in 91 patients with minimum 2-year follow-up.

Purpose: We present the paraspinal approach use for neuromuscular scoliosis with focus on deformity correction, perioperative (≤30 days) morbidity and outcome at a minimal follow-up length of 2 years. Methods: We prospectively collected data of 61 neuromuscular scoliosis patients operated using a paraspinal (Wiltse) approach between 2013 and 2019. We additionally collected data of 104 control cases, operated using a midline approach between 2005 and 2016. Fifteen Wiltse, respectively 37 control patients were excluded due to a short follow-up (<2 years), and 22 controls were excluded secondary to lacking follow-up data. Hence, 46 Wiltse and 45 control patients were compared. Results: Wiltse and control patients had comparable follow-up lengths, demographics, deformity corrections, complication rates, number of levels fused, and intensive care unit and hospital lengths of stay. Wiltse cases had a lower estimated blood loss (535 vs 1187 mL; p-value < 0.001), allogenic transfusion rate (48% vs 96%; p-value < 0.001), and operating time (ORT) (337 vs 428 min; p-value < 0.001) than controls. This was also the case when selecting for patients without pelvic fixation (p-values < 0.001). When selecting the cases with pelvic fixation (20 among 91 cases), only the number of levels fused and the ORT differed significantly according to the approach (p-value <0.015 and <0.041). Conclusion: The paraspinal approach for neuromuscular scoliosis is safe, associated with significant deformity correction, reduced estimated blood loss, and allogenic transfusion rate. These potential benefits still need to be evaluated, especially for cases with pelvic fixation, with further follow-up of larger cohorts. Level of evidence: level III.

A Newer Way of Determining LIV in AIS Patients: Rotation of the Touched Vertebrae.

STUDY DESIGN: A retrospective review. OBJECTIVE: The objective of this study was to determine whether fusing to touched vertebra (TV) on prone x-rays (XRs) with minimal rotation (Gd 0/1) allow for shorter fusion with optimal correction. SUMMARY OF BACKGROUND: Previous studies have shown risk of "adding on" when TV is not selected as lowest instrumented vertebra (LIV). Fusion proximal to TV leads to suboptimal results but fusing to TV on standing XRs can result in longer fusions. On lying down XRs, TV moves proximally, and its rotation decreases by a grade. METHODS: TV patients with minimal rotation were selected on prone (TVP) or standing XRs (TVS). Patients fused to rotated (Gd 2+) TV on standing or prone XRs were considered touched vertebra rotated (TVR). In the non-TV (NTV) group, LIV was fused proximal to TV. Disk wedging ≥5° determined risk of "adding-on." To compare patients fused to minimally rotated TV, to those that were not, patients in group A (TVP + TVS) were compared with group B (TVR + NTV).In part II: TVP, TVS, TVR, and NTV patients were compared. Subanalysis compared levels saved as the difference between predicted and real LIV in TVP and TVS patients. Another subanalysis was carried out for Lenke 1+2 and Lenke 3, 4, 5.In part III: XRs of nonoperative adolescents idiopathic scoliosis patients with Cobb <30 and Risser 4/5 were analyzed to determine "acceptable" end vertebra tilt and disc wedging and served as controls. RESULTS: There were a significantly greater number of patients in group B patients(TVR + NTV) with final disk wedging ≥5°, final LIV translation ≥1 and ≥2 cm ( P <0.001).Utilizing prone XRs in TVP saved average 1 level, and 1.2 levels in TVS patients. TVP patients also had similar LIV tilt, disk wedging and coronal balance( P >0.05) to controls. CONCLUSION: Choosing minimally rotated (Gd 0/1) TV on prone XR saves levels without sacrificing radiographic outcomes.

In Scheuermann's kyphosis, a proximal UIV and postop kyphosis value close to patients' PI decreases the risk of PJK.

PURPOSE: Prevalence of proximal junctional kyphosis (PJK) in Scheuermann's kyphosis (SK) varies between 24 and 40%. Multiple factors have been implicated, including kyphosis overcorrection, failure to include proximal end vertebra, and implant choice. This study aimed to determine the goal correction parameters based upon patients' pelvic incidence, and UIV to decrease PJK in Scheuermann's kyphosis. METHODS: X-ray and chart review of SK patients operated with all pedicle screw (PS), hybrid fixation (HF), and anterior/posterior fusions with hybrid fixation (AP). T1/T2 were grouped together as proximal fusion groups compared to T3 and distal groups. RESULTS: 96 total patients: PS (n = 41), HF (n = 24), and AP (n = 31). Overall, at early postop 12 (12.5%) patients had PJK. At final follow-up, 33 (34.4%) had PJK. There was no significant difference between groups at early postop (p = 0.86) or final follow-up (p = 0.67). When correcting kyphosis-PI to > - 10.0° and UIV was chosen to be T1 or T2, PJK developed in 6.1% of patients at final follow-up; when fusing to T1/T2 but with kyphosis-PI < - 10.0°, 38.9% of patients developed PJK. With kyphosis-PI > - 10.0° and UIV at T3 or below, 37.0% of patients developed PJK at final follow-up. When fusing to T3 or below but failing to correct kyphosis-PI to > - 10.0°, 77.8% of patients developed PJK. CONCLUSION: Selecting proximal UIV and avoiding kyphosis-PI mismatch can significantly decrease the prevalence of PJK rather than surgical technique or implant choice. Surgeons treating SK should, therefore, aim to correct kyphosis closer to the patient's pelvic incidence and choose T2/T1 as UIV.

A dual-team approach benefits standard-volume surgeons, but has minimal impact on outcomes for a high-volume surgeon in AIS patients.

STUDY DESIGN: Retrospective chart review of prospectively collected data. OBJECTIVE: This study seeks to evaluate the effect of number of surgeons, surgeon experience, and surgeon volume on AIS surgery. Recent literature suggests that utilizing two surgeons for spine deformity correction surgery can improve perioperative outcomes. However, the surgeon's experience and surgical volume are likely as important. METHODS: AIS patients undergoing PSF from 2009 to 2019 were included. Patient demographics, X-ray and perioperative outcomes were collected and collated based on primary surgeon. Analysis was performed for single versus dual surgeons, surgeon experience (≤ 10 years in practice), and surgical volume (less/greater than 50 cases/year). Median (IQR) values, Wilcoxon Rank Sums test, Kruskal-Wallis test, and Fisher's exact test were utilized. RESULTS: 519 AIS cases, performed by 4 surgeons were included. Two surgeons were highly experienced, 1 of whom was also high volume. Five cohorts were studied: a single senior high volume (S1) (n = 302), dual-junior surgeons (DJ) (n = 73), dual senior-junior (SJ) (n = 36), dual-senior (DS) (n = 21) and a single senior, standard-volume surgeon alone (S2) (n = 87). Radiographic parameters were similar between the groups (p > 0.05). Preoperative Cobb was significantly higher for DS compared to S1 (p = 0.034) Pre- and post-op kyphosis were similar (p > 0.05). Cobb correction was similar (p > 0.05). Levels fused, fixation points, anesthesia and surgical times were similar (p > 0.05). When the standard-volume surgeon operated with a second surgeon, radiographic parameters were similar (p > 0.05), but anesthesia time, surgical time, and hospital length of stay were significantly shorter (p < 0.05). Additionally, DJ had significantly shorter anesthesia and operative times (p < 0.001) and length of stay (p < 0.001) compared to S2. CONCLUSION: Standard-volume surgeons have better outcomes with a dual surgeon approach. Junior surgeons benefit operating with an experienced surgeon. A high-volume surgeon, however, does not benefit from a dual surgeon approach. LEVEL OF EVIDENCE: Level II.

End Vertebra Versus Apical Vertebra: Where Are We More Likely to Misplace in Spine Deformity?

BACKGROUND DATA: Pedicle screws placement remains technically demanding. The thoracic curve apex is considerably difficult due to its unique morphology and severe rotation. In comparison the upper end vertebrae have smaller pedicles and limited soft tissue exposure. This study seeks to evaluate the likelihood of screw misplacement at the end vertebra and apex. METHODS: A retrospective review of preoperative and postoperative computed tomographic (CT) scans of spinal deformity patients who underwent posterior spinal fusion with pedicle screw constructs between 2004 and 2011 was performed. Pedicles located at the upper instrumented vertebra (UIV) and lower instrumented vertebra (LIV), and the major and minor apices were evaluated. Pedicle morphology was studied on preoperative CT and screw placement on postoperative CT. RESULTS: In total, 188 patients met the inclusion criteria, 172 had preoperative CT scans and 133 had postoperative CT scans. The UIV had a significantly lower percentage of normal pedicles (type A) compared with apex major, apex minor, or LIV (59.1% vs. 76.1% vs. 77.3% vs. 98.7%; P<0.001). UIV had significantly the lowest percentage of normal normally placed screws compared with LIV, apex major, or apex minor (69.4% vs. 97.3% vs. 87.6% vs. 92.1%; P<0.001). In a logistic regression adjusted for preoperative Cobb angles, UIV was more likely to have screws misplaced (odds ratio =7.56; 95% confidence interval, 4.01-14.30; P<0.001) and abnormal pedicles (odds ratio=2.81; 95% confidence interval, 1.52-5.19; P=0.001) compared with any other location studied. In abnormal pedicles, 41 (39.8%) of the 103 UIV screws were misplaced, whereas 10 (16.4%) of the 61 apex major, apex minor, or LIV screws were misplaced (P=0.007). CONCLUSIONS: The UIV presents more of a risk for pedicle screw misplacement and abnormal morphology when compared with LIV and apical vertebra. We believe these findings can aid in the surgeon's preoperative and intraoperative management to ensure increased success in accurate and safe pedicle screw placement. LEVEL OF EVIDENCE: Level III.

Back-to-Back Surgeries in AIS Patients Can be Performed Safely Without Compromising Radiographic or Perioperative Outcomes: A 10-year Review.

STUDY DESIGN: A retrospective chart review of prospectively collected data. OBJECTIVE: The aim of this study was to determine whether back-to-back scoliosis surgeries can be performed safely without compromising outcomes and the reproducibility of the practice between institutions. SUMMARY OF BACKGROUND DATA: During the summer, spinal surgeons will often book multiple cases in one day. The complexity and demands of spinal fusion surgery call into question the safety. Change of operating room staff including anesthesiologists, nurses, and neurologists may introduce new risks. METHODS: From 2009 to 2018, index AIS surgeries were included. In Groups 1, 2, and 3, surgeries were performed by a single surgeon. In Group 4, they were performed by other institutional surgeons. Group 1: first surgery of the day, Group 2: second surgery of the day, Group 3: only surgery of the day, Group 4: only surgery of the day by different institutional surgeon. Additional analysis was done to determine reproducibility after a surgeon was moved from Institution 1 to Institution 2. RESULTS: Five hundred sixty-seven AIS patients were analyzed. Group 1 patients had similar radiographic outcomes compared with Group 2 (P > 0.05). Surgical time was similar (P = 0.51), but significantly more levels fused (P = 0.01). Compared with Group 3, Group 2 had a smaller preoperative Cobb (P = 0.02), shorter surgeries (P < 0.001), and length of stay (P = 0.04) but similar complication rate (P = 1). Compared with Group 4, Group 2 had smaller preoperative Cobb (P < 0.001), shorter surgery, and lower complication rate (P = 0.03). When determining reproducibility, institution 2 patients had significantly less blood loss, shorter surgeries, and shorter lengths of stay (P < 0.05). CONCLUSION: Although long and involved, back-to-back AIS surgeries do not compromise radiographic or perioperative outcomes. Changes in operating team do not appear to impact safety, efficiency, or outcomes. This study also found that the practice is reproducible between institutions. LEVEL OF EVIDENCE: 3.

The Screw-Aorta Dilemma: Changing Patient Position in Computed Tomography Scan Is Critical in Documenting Aortic Mobility.

STUDY DESIGN: Retrospective chart review. OBJECTIVE: To determine if obtaining a prone computed tomography (CT)-scan can better delineate a questionable screw-aorta relationship. SUMMARY OF BACKGROUND DATA: Pedicle screw misplacement rate is reported between 6% and 15%. Studies looking at misplacements on a per patient basis show up to 14% of patients have screws at risk (impinging vital structures). A screw abutting the aorta is a management challenge and often requires vascular surgery intervention. However, CT scans routinely done in supine position may overestimate screw-aorta relationship. Change in patient position may allow the aorta to roll away and, in most cases, reveal an uncompromised aorta. This will allow safe removal of pedicle screws without any vascular intervention. METHODS: One hundred eleven spinal deformity patients who underwent Posterior spinal fusion from 2004 to 2009 were evaluated. Patients with concerning screw-aorta relationship underwent additional prone CT scan. Mobility of the aorta was determined and distance was compared using prone and supine CT scans. RESULTS: Two thousand two hundred ninety five screws were reviewed, 36 screws in 18 patients were in proximity to the aorta. Fourteen screws (nine patients) appeared to be impinging the aorta. On prone CT, 13 out of the 14 instances the aorta moved away from the screw. The average distance at the screw level was 13.6 ±â€Š4.8 mm in supine position and 8.9 ±â€Š5.4 mm in prone position (P = 0.001). In one instance the relationship was unchanged on prone CT. No screw was noted to violate the lumen or distort the aorta. CONCLUSION: Supine CT scan alone is not entirely accurate in determining screw-aorta relationship. Prone-CT scan provides additional information for better delineation. This additional diagnostic step can change the treatment option by limiting the need for vascular intervention. When in doubt, the additional use of an arteriogram can allow for improved visualization. LEVEL OF EVIDENCE: 3.

Academic Metrics Do Not Explain the Underrepresentation of Women in Orthopaedic Training Programs.

BACKGROUND: Among medical specialties, orthopaedic surgery persistently has one of the lowest representations of women in residency programs. This study examined whether differences exist in the academic metrics of the orthopaedic residency applicants and enrolled candidates by sex, which may be contributing to the persistent underrepresentation of women. Differences in enrollment rate in orthopaedic residency programs also were analyzed. We hypothesized that academic metrics were similar for female and male applicants and thus do not explain the underrepresentation of women in training programs. METHODS: Academic data of first-time applicants (n = 9,133) and candidates who enrolled in an orthopaedic residency (n = 6,381) in the U.S. from 2005 to 2014 were reviewed. The United States Medical Licensing Examination (USMLE) Step-1 and Step-2 Clinical Knowledge (CK) scores, Alpha Omega Alpha (AΩA) Honor Medical Society status, number of publications, and volunteer experiences were compared by sex and were analyzed over time. RESULTS: From 2005 to 2014, representation of female applicants increased from 12.6% to 16.0%, corresponding with an increase in the percentage of enrolled female residents (from 12.9% to 16.1%); 70.3% of male and 67.1% of female applicants to orthopaedic residency enrolled as residents (p = 0.082). Mean academic metrics increased significantly over time for applicants and enrolled candidates, irrespective of sex. Comparing by sex, the mean USMLE Step-1 scores of male applicants and enrolled candidates were approximately 2% higher than those of female applicants (p < 0.0001). Volunteer experiences of female applicants and enrolled candidates were 12% higher compared with male applicants (p < 0.0001). There was no significant difference in USMLE Step-2 CK scores, number of publications, or AΩA status by sex. CONCLUSIONS: The enrollment rate of male and female applicants in orthopaedic residencies was similar and did not change during the 10-year study period. The academic metrics of applicants and enrolled candidates have increased significantly. The academic metrics were found to be comparable by sex; the differences in USMLE Step-1 scores and volunteer experiences were small relative to the magnitude of accomplishments that these values represent. The growth rate of the proportion of women in orthopaedic residencies lags other surgical subspecialties but appears to be independent of academic metrics.

Fentanyl versus remifentanil-based TIVA for pediatric scoliosis repair: does it matter?

INTRODUCTION: Opioid-induced hyperalgesia (OIH) and acute opioid tolerance have been demonstrated extensively in patients undergoing adolescent idiopathic scoliosis (AIS) repair. Remifentanil infusion has been strongly linked to both tolerance and OIH in these patients; however, the impact of using an intraoperative fentanyl infusion has not been well studied. This study aims to determine if patients undergoing operative management of AIS have decreased opioid consumption and pain scores when an intraoperative fentanyl infusion is used as compared with a remifentanil infusion. METHODS: This is a retrospective chart review of patients with AIS who underwent posterior spinal fusion. During the period January 2012-June 2013, patients received remifentanil infusion as part of total intravenous anesthesia. From July 2013 to June 2015, remifentanil was replaced by fentanyl as standard protocol. The remifentanil cohort included 37 patients and the fentanyl cohort included 25 patients. The primary outcome was the total opioid consumption (morphine equivalents) in the first 24 hours postsurgery. Secondary outcomes included mean postoperative pain score in the first 24 hours postsurgery, postoperative opioid consumption 24-48 hours after surgery, time to extubation, time to assisted ambulation, length of stay, and incidence of postoperative nausea and vomiting. RESULTS: Compared with the remifentanil group, the fentanyl group had significantly higher postoperative opioid usage during the first 48 hours and significantly higher postoperative mean pain score during the first 24 hours. There was no difference between the two groups in mean pain score for 24-48 hours, extubation time, time to assisted ambulation, length of stay, or postoperative nausea and vomiting. DISCUSSION: Despite concerns for hyperalgesia and acute tolerance, remifentanil is widely used for intraoperative opioid infusions for surgical correction of AIS. This retrospective study examined a practice change from intraoperative remifentanil to intraoperative fentanyl as a potential approach to avoid OIH. Surprisingly, patients receiving fentanyl intraoperatively showed increased postoperative opioid use and pain scores in the first 24 hours postsurgery compared with the prior cohort receiving remifentanil. Substitution of fentanyl for remifentanil during surgical correction of AIS does not appear to solve the problem of OIH or acute tolerance. Prospective studies are needed to confirm this unexpected result.

Current Trends in Sex, Race, and Ethnic Diversity in Orthopaedic Surgery Residency.

BACKGROUND: The representation of minorities among medical students has increased over the past two decades, but diversity among orthopaedic residents lags behind. This phenomenon has occurred despite a recent focus by the American Academy of Orthopaedic Surgeons on the recruitment of minorities and women. OBJECTIVE: To analyze the impact of recent efforts on diversity in orthopaedic residents in comparison with other surgical specialties from 2006 to 2015. METHODS: Data from the American Association of Medical Colleges on residents in surgical specialty programs in the years 2006 to 2015 were analyzed. Linear regression models were used to estimate trends in diversity among orthopaedic residents and residents in other surgical specialties. A mixed model analysis of variance was used to compare rates of diversification among different specialties over time. RESULTS: Female representation in orthopaedic programs increased from 10.9% to 14.4% between 2006 and 2015. However, the rate of increase was significantly lower compared with other specialties (all P < 0.05) studied, except for urology (P = 0.64). Minority representation in orthopaedics averaged 25.6% over the 10-year period. Residents of Hispanic origin in orthopaedic programs increased (P = 0.0003) but decreased for Native Hawaiian/Pacific Islander (P < 0.0001). During the same period, white representation increased (P = 0.004). No significant changes were found in African Americans or Asian American representation. Diversity decreased among orthopaedic residents over the period studied (P = 0.004). CONCLUSIONS: Recruitment efforts have not reversed the sex, racial, and ethnic disparities in orthopaedic residents. Orthopaedics has the lowest representation of women and minorities among residencies studied. The rate of increase in women lags behind all surgical subspecialties, except for urology.

Underrepresented Minority Applicants Are Competitive for Orthopaedic Surgery Residency Programs, but Enter Residency at Lower Rates.

INTRODUCTION: Orthopaedic surgery residency programs have the lowest representation of ethnic/racial minorities compared with other specialties. This study compared orthopaedic residency enrollment rates and academic metrics of applicants and matriculated residents by race/ethnicity. METHODS: Data on applicants from US medical schools for orthopaedic residency and residents were analyzed from 2005 to 2014 and compared between race/ethnic groups (White, Asian, Black, Hispanic, and Other). RESULTS: Minority applicants comprised 29% of applicants and 25% of enrolled candidates. Sixty-one percent of minority applicants were accepted into an orthopaedic residency versus 73% of White applicants (P < 0.0001). White and Asian applicants and residents had higher USMLE Step 1. White applicants and matriculated candidates had higher Step 2 Clinical Knowledge scores and higher odds of Alpha Omega Alpha membership compared with Black, Hispanic, and Other groups. Publication counts were similar in all applicant groups, although Hispanic residents had significantly more publications. Black applicants had more volunteer experiences. CONCLUSIONS: In orthopaedic surgery residency, minority applicants enrolled at a lower rate than White and Asian applicants. The emphasis on USMLE test scores and Alpha Omega Alpha membership may contribute to the lower enrollment rate of minority applicants. Other factors such as conscious or unconscious bias, which may contribute, were not evaluated in this study.

Evaluation of Sex, Ethnic, and Racial Diversity Across US ACGME-Accredited Orthopedic Subspecialty Fellowship Programs.

In recent years, there has been an increasing trend toward subspecialization in orthopedic surgery via fellowships. This study sought to characterize sex, ethnic, and racial representation within each fellowship program and to examine their changes over time to identify trends and/or gaps. Demographic data were obtained from the National Graduate Medical Education Census. Diversity was assessed using proportions of minority and female trainees. The trends in racial, ethnic, and sex diversity from 2006 to 2015 for orthopedics as a whole and within each subspecialty were analyzed. Of 3722 orthopedic fellows, 2551 identified as white (68.5%), 648 as Asian (17.4%), 175 as Hispanic (4.7%), 161 as black (4.3%), 8 as Native Hawaiian/Pacific Islander (0.21%), and 3 as American Indian/Alaskan Native (0.08%). Further, 479 identified as female (12.9%). Racial and ethnic minority representation among orthopedic fellows did not increase over time. Female representation did increase proportionally with female residents. Asian fellows preferred reconstructive adult and spine, whereas white fellows preferred sports medicine, hand surgery, and trauma. Female fellows preferred pediatrics, hand surgery, and musculoskeletal oncology. Although sex diversity among orthopedic fellows has increased in the past 10 years, racial and ethnic minority representation lacked similar growth. Asian and female fellows preferred specific subspecialties over others. These data are presented as an initial step in determining factors that attract minority groups to different orthopedic subspecialties. Further research should define specific factors and identify ways to increase minority distribution among fellowship programs. [Orthopedics. 2018; 41(5):282-288.].

Cadaveric Study of the Safety and Device Functionality of Magnetically Controlled Growing Rods After Exposure to Magnetic Resonance Imaging.

STUDY DESIGN: Cadaveric study. OBJECTIVE: To establish the safety and efficacy of magnetically controlled growing rods (MCGRs) after magnetic resonance imaging (MRI) exposure. SUMMARY OF BACKGROUND DATA: MCGRs are new and promising devices for the treatment of early-onset scoliosis (EOS). A significant percentage of EOS patients have concurrent spinal abnormalities that need to be monitored with MRI. There are major concerns of the MRI compatibility of MCGRs because of the reliance of the lengthening mechanism on strongly ferromagnetic actuators. METHODS: Six fresh-frozen adult cadaveric torsos were used. After thawing, MRI was performed four times each: baseline, after implantation of T2-T3 thoracic rib hooks and L5-S1 pedicle screws, and twice after MCGR implantation. Dual MCGRs were implanted in varying configurations and connected at each end with cross connectors, creating a closed circuit to maximize MRI-induced heating. Temperature measurements and tissue biopsies were obtained to evaluate thermal injury. MCGRs were tested for changes to structural integrity and functionality. MRI images obtained before and after MCGR implantation were evaluated. RESULTS: Average temperatures increased incrementally by 1.1°C, 1.3°C, and 0.5°C after each subsequent scan, consistent with control site temperature increases of 1.1°C, 0.8°C, and 0.4°C. Greatest cumulative temperature change of +3.6°C was observed adjacent to the right-sided actuator, which is below the 6°C threshold cited in literature for clinically detectable thermal injury. Histologic analysis revealed no signs of heat-induced injury. All MCGR actuators continued to function properly according to the manufacturer's specifications and maintained structural integrity. Significant imaging artifacts were observed, with the greatest amount when dual MCGRs were implanted in standard/offset configuration. CONCLUSIONS: We demonstrate minimal MRI-induced temperature change, no observable thermal tissue injury, preservation of MCGR-lengthening functionality, and no structural damage to MCGRs after multiple MRI scans. Expectedly, the ferromagnetic actuators produced substantial MR imaging artifacts. LEVEL OF EVIDENCE: Level V.

When Do Patients Return to Physical Activities and Athletics After Scoliosis Surgery?: A Validated Patient Questionnaire Based Study.

STUDY DESIGN: A retrospective chart review with a survey. OBJECTIVES: This study seeks to determine time of return to normal, physical and athletic activities, and delaying factors after all pedicle screw fixation. SUMMARY OF BACKGROUND DATA: Return to athletic activity after posterior spine fusion (PSF) in adolescent idiopathic scoliosis (AIS) is largely dependent on a surgeon's philosophy. Some allow contact and collision sports by 6 and 12 months, while others avoid contact sports for 1 year and never allow collision sports. We have utilized a patient driven self-directed approach. METHODS: The sports activity questionnaire (SAQ) was developed and activities were categorized into normal (school, gym, and backpack), physical (running, bending, and bicycling) and athletics (AAP criteria: noncontact, contact and collision sports). SAQ was validated through the "test-retest" method on 25 patients and retesting after 3 weeks to minimize recall bias. Questions with kappa >0.7 were included. Patient demographics, x-ray measurements, and perioperative details were recorded. RESULTS: Ninety five patients completed the SAQ. By 3 months; 77% (72/93) returned to school, 60% (54/90) to bending, 52% (48/93) to carrying backpacks, 43% (37/87) to running, and 37% (30/81) to gym. By 6 months, 54% (27/50) returned to noncontact sports, and 63% (21/33) to contact sports. 79% and 53% returned to preoperative level of contact and noncontact sports, respectively. Higher body mass index (BMI) was a risk for delayed return (>3 mo) to school and gym (P < 0.05), while fusion below L2 and younger age for running, bending, and carrying backpacks (P < 0.05). In contrast, there was no patient/curve characteristics associated with a delay to sports. Lowest instrumented vertebra (LIV), Lenke types were not risk factors. There was no correction loss, implant failure, or complications. CONCLUSION: Patients return to athletics much earlier than expected; a quarter returned by 3 months, and over half by 6 months. Age and LIV are determinants for return to "physical activity." LEVEL OF EVIDENCE: 3.

Can Postoperative Radiographs Accurately Identify Screw Misplacements?

STUDY DESIGN: Retrospective case series. OBJECTIVE: The objective of this study was to determine the safety of postoperative radiographs to assess screw placement. SUMMARY OF BACKGROUND DATA: Previously defined criteria are frequently employed to determine pedicle screw placement on intraoperative supine radiographs. Postoperatively, radiographs are typically used as a precursor to identify screws of concern, and a computed tomographic (CT) is typically ordered to confirm screw safety. METHODS: First, available postoperative PA and lateral radiographs were reviewed by 6 independently blinded observers. Screw misplacement was assessed using previously defined criteria. A musculoskeletal radiologist assessed all CT scans for screw placement. Pedicle screw position was classified either as acceptable or misplaced. Misplacements were subclassified as medial, lateral, or anterior. RESULTS: One hundred four patients with scoliosis or kyphosis underwent posterior spinal fusion and had postoperative CT scan available were included. In total, 2,034 thoracic and lumbar screws were evaluated. On CT scan, 1,772 screws were found to be acceptable, 142 were laterally misplaced, 30 medially, and 90 anteriorly. Of the 30 medially placed screws, 80% to 87% screws were believed to be in positions other than medial, with a median of 73% (63% to 92%) of these screws presumed to be in normal position. Similarly, of the 142 screws placed laterally, 49% to 81% screws were identified in positions other than lateral, with a median of 77% (59% to 96%) of these screws felt to be in normal position. Of the 90 anteriorly misplaced screws, 16% to 87% screws were identified in positions other than anterior, with 72% (20% to 98%) identified as normal. The criteria produced a median 52% sensitivity, 70% specificity, and 68% accuracy across the 6 observers. CONCLUSION: Radiograph is a poor diagnostic modality for observing screw position. LEVEL OF EVIDENCE: Level IV.

Pedicle Screw Safety: How Much Anterior Breach Is Safe?: A Cadaveric and CT-Based Study.

MINI: The objective of this study was to determine the safety limits of anterior/anterolateral pedicle screw breaches. Through clinical and cadaveric study, it appears that less than 4 mm of breach has a significantly lower likelihood of impingement on vital structures (P < 0.001). STUDY DESIGN: Clinical retrospective chart review and basic science study. OBJECTIVES: To determine the safety limits of an anterior/anterorolateral misplaced pedicle screw on computed tomography (CT) scan in spinal deformity. SUMMARY OF BACKGROUND DATA: Although the limits of medial breaches (<4 mm) are known, the safe limits for anterior/anterolateral breaches in spine deformity are not yet defined. METHODS: The present study had two parts. In part I, postoperative CT scans of 165 patients operated on for spine deformity were reviewed for screw misplacement (2800 screws). The amount of anterior/anterolateral breach was measured. Protrusions were also evaluated for proximity to vital structures. All scans were reviewed by musculoskeletal radiologist. In part II, eight cadavers were instrumented with 6 × 30 and 6 × 40 mm bilaterally from T1-S1. Screws were randomly inserted under navigation guidance either "IN" or "OUT-anterior/lateral." CT scan was performed, followed by gross dissection to determine screw position. RESULTS: Part I: 116(4.2%) screws were misplaced anterior/anterolaterally. Thirty-one (26.7%) were adjacent to vital structures. Fisher exact test showed 4 mm or less breach has significantly lower likelihood of impingement (P < 0.001). Screws adjacent/impinging the aorta protruded an average 5.7 ±â€Š0.6 mm, whereas screws not involving the aorta breached an average 3.9 ±â€Š0.2 mm, (P < 0.001). Part II: 285 screws were inserted. On CT scan, 125 were misplaced anterior/anterolaterally. On gross dissection, 89 were visibly misplaced; 23 were covered entirely by soft tissue but were palpable; and 13 were contained in bone. All 23 screws did not endanger any structures and protruded less than 4 mm on CT scan. CONCLUSION: Anterior/anterolateral breaches of 4 mm or less on CT poses no significant risk of impingement and therefore can be considered safe. LEVEL OF EVIDENCE: 3.

Low-Dose Radiation 3D Intraoperative Imaging: How Low Can We Go? An O-Arm, CT Scan, Cadaveric Study.

MINI: The objective of this study was to evaluate the accuracy and reliability of pedicle screw placement using O-Arm at dosages below the manufactured recommended dose. O-Arm at reduced dose showed a 90% accuracy when compared with computed tomography; however, about 30% medial breaches were misclassified. STUDY DESIGN: Cadaveric study. OBJECTIVE: The objective was to evaluate O-Arm's ability at low-dose (LD) settings to assess intraoperative screw placement. SUMMARY OF BACKGROUND DATA: Accurate placement of pedicle screws is crucial because of proximity to vital structures. Malposition of screws may result in significant morbidity and potential mortality. O-arm provides real-time, intraoperative imaging of patient's anatomy and provides higher accuracy in scoliosis surgeries, avoiding risk to vital structures. We hypothesize using LD or ultra-low doses (ULDs) to obtain intraoperative images allow for accurate assessment of screw placement, both minimizing radiation exposure and preventing screw misplacement. METHODS: Eight cadavers were instrumented with pedicle screws bilaterally from T1 to S1. Screws were randomly placed using O-arm navigation into three positions: contained within the bone, OUT-anterior/lateral, and OUT-medial. O-arm images were obtained at three dosage settings: LD (kVp120/mAs125-lowest manufacturer recommended), very-low dose (VLD) (kVp120/mAs63), and ULD (kVp120/mAs39). Computed tomography (CT) scan was performed using institution's LD protocol (kVp100/mAs50) and gross dissection to identify screw positions. RESULTS: LD, VLD, ULD, and CT for identifying "IN" screws relative to gross dissection had, a mean (standard deviation) sensitivity of 84.2% (±5.7), specificity of 76.1% (±9.3), and accuracy of 79.9% (±3.1) from all three observers. Across the three observers, the interobserver agreement was 0.67 (0.61-0.72) for LD, 0.74 (0.69-0.79) for VLD, 0.61 (0.56-0.66) for ULD, and 0.79 (0.74-0.84) for CT. Effective doses of radiation (mSV) for LD O-arm scan was 2.16, VLD 1.08, ULD 0.68, and our LD CT protocol was 1.05. CONCLUSION: Accuracy of pedicle screw placement is similar for O-arm at all doses and CT compared to gross dissection. Interobserver reliability was substantial for VLD and CT. Approximately 30% of medial screw breaches are, however, misclassified. ULD and VLDs can be used for intraoperative navigation and evaluation purposes within these limitations. LEVEL OF EVIDENCE: N/A.

A pilot cadaveric study of temperature and adjacent tissue changes after exposure of magnetic-controlled growing rods to MRI.

PURPOSE: To test for possible thermal injury and tissue damage caused by magnetic-controlled growing rods (MCGRs) during MRI scans. METHODS: Three fresh frozen cadavers were utilized. Four MRI scans were performed: baseline, after spinal hardware implantation, and twice after MCGR implantation. Cross connectors were placed at the proximal end and at the distal end of the construct, making a complete circuit hinged at those two points. Three points were identified as potential sites for significant heating: adjacent to the proximal and distal cross connectors and adjacent to the actuators. Data collected included tissue temperatures at baseline (R1), after screw insertion (R2), and twice after rod insertions (R3 and R4). Tissue samples were taken and stained for signs of heat damage. RESULTS: There was a slight change in tissue temperature in the regions next to the implants between baseline and after each scan. Average temperatures (°C) increased by 0.94 (0.16-1.63) between R1 and R2, 1.6 (1.23-1.97) between R2 and R3, and 0.39 (0.03-0.83) between R3 and R4. Subsequent histological analysis revealed no signs of heat induced damage. CONCLUSION: Recurrent MRI scans of patients with MCGRs may be necessary over the course of treatment. When implanted into human cadaveric tissue, these rods appear to not be a risk to the patient with respect to heating or tissue damage. Further in vivo study is warranted. LEVEL OF EVIDENCE: N/A.

MRIs Are Less Accurate Tools for the Most Critically Worrisome Pedicles Compared to CT Scans.

STUDY DESIGN: Retrospective review of magnetic resonance imaging (MRI) and computed tomographic (CT) scan imaging modalities. OBJECTIVE: To determine MRI's capability of identifying pedicle morphology. SUMMARY OF BACKGROUND DATA: Understanding pedicle morphology is important for accurate placement of pedicle screws. The gold standard modality to assess pedicle morphology is CT scan. However, CT scans carry the risk of radiation exposure. We have studied MRI as a potential alternative to CT scan. METHODS: Nine hundred seventy pedicles in 33 spinal deformity patients were reviewed. Pedicle morphology was classified as follows: Type A (normal pedicle): >4-mm cancellous channel; Type B: 2-4-mm channel; Type C: any size cortical channel; and Type D: <2-mm cortical or cancellous channel. Pedicles in the same patients were classified on both low-dose CT scan and MRI. Concordance and discordance rates of MRI relative to CT scan in classification of pedicles into types A, B, C, and D were calculated for the entire length of the thoracolumbar spine and subgrouped into spinal sections. All images were evaluated by a single fellowship-trained musculoskeletal radiologist. RESULTS: CT scan had 809 Type A, 126 Type B, 29 Type C, and 6 Type D pedicles. Group II (MRI) had 735 Type A, 203 Type B, 30 Type C, and 2 Type D pedicles. Analysis of the entire spinal column showed a concordance rate of 86.7% in classification of the pedicles into the 4 types. In the upper thoracic region, the concordance rate was 77.1%, main thoracic 85.5%, thoracolumbar 96%, and lumbar 98.1%. MRI has a poor overall accuracy for detecting Type C pedicles, only a 44.8% concordance with CT scan. MRI overcalls Type B pedicles, often calling Type A pedicles Type B. CONCLUSIONS: MRI is an inferior alternative to CT scan as it has poor accuracy to properly detect pedicle abnormalities. The more severe the pedicle abnormality, the less diagnostic value the MRI has. LEVEL OF EVIDENCE: Level III, diagnostic.