Junyoung Ahn

Timing of Complications After Spinal Fusion Surgery.

Study Design. Retrospective cohort study. Objective. To characterize the timing of complications after spinal fusion procedures. Summary of Background Data. Despite many publications on risk factors for complications after spine surgery, there are few publications on the timing at which such complications occur. Methods. Patients undergoing anterior cervical decompression and fusion (ACDF) or posterior lumbar fusion (PLF; with or without interbody) procedures during 2011–2013 were identified in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. For each of 8 different complications, the median time from surgery until complication was determined, along with the interquartile range and middle 80%. Results. A total of 12,067 patients undergoing ACDF and 11,807 patients undergoing PLF were identified. For ACDF, the median day of diagnosis (and interquartile range; middle 80%) for anemia requiring transfusion was 0 (0–1; 0–2), myocardial infarction 2 (1–5; 0–15), pneumonia 4 (2–9; 1–14), pulmonary embolism 5 (2–9; 1–10), deep vein thrombosis 10.5 (7–16.5; 5–21), sepsis 10.5 (4–18; 1–23), surgical site infection 13 (8–19; 5–25), and urinary tract infection 17 (8–22; 4–26). For PLF, the median day of diagnosis (and interquartile range; middle 80%) for anemia requiring transfusion was 0 (0–1; 0–2), myocardial infarction 2 (1–4; 1–8), pneumonia 4 (2–9; 1–17), pulmonary embolism 5 (3–11; 2–17), urinary tract infection 7 (4–14; 2–23), deep vein thrombosis 8 (5–16; 3–20), sepsis 9 (4–16; 2–22), and surgical site infection 17 (13–22; 9–27). Conclusion. These precisely described postoperative time periods enable heightened clinical awareness among spine surgeons. Spine surgeons should have the lowest threshold for testing for each complication during the time period of greatest risk. Authors, reviewers, and surgeons utilizing research on postoperative complications should carefully consider the impact that the duration of follow-up has on study results. Level of Evidence: 3

Minimally invasive lumbar decompression—the surgical learning curve

BACKGROUND CONTEXT Minimally invasive spine surgery (MIS) procedures carry an inherently difficult learning curve based upon anecdotal evidence. Few studies have investigated the surgeons learning curve for MIS lumbar laminectomy or laminotomy with or without discectomy. PURPOSE To characterize the learning curve of a 1- or 2-level MIS lumbar decompression (LD) based on perioperative and postoperative parameters . STUDY DESIGN/SETTING Retrospective analysis of a prospectively maintained registry was used for this study. PATIENT SAMPLE There were 228 consecutive patients who underwent a primary 1- or 2-level MIS LD by a single surgeon for degenerative spinal pathology from 2009 to 2014. From 2005 to 2006, 50 patients underwent 1- or 2-level open LD consecutively. OUTCOME MEASURES Perioperative and postoperative outcomes (complications, visual analogue scale [VAS] scores, reoperations) were the outcome measures for this study. METHODS Patients were stratified into first and second groups as determined by the case number at which the procedural time reached a plateau. Demographics, comorbidity, pain scores, and surgical outcomes were compared between the first 50 patients and the subsequent 178 patients. The secondary analysis compared the surgical outcomes between the initial 50 MIS and 50 open LD patients. No funds were received in support of this work. RESULTS The initial cohort was older with a higher comorbidity burden (p<.05). However, body mass index, gender, smoking status, and ethnicity did not differ between cohorts. The initial cohort incurred a greater procedural time (p<.001) and longer length of hospitalization (p<.05) than the second cohort. Estimated blood loss (EBL), pain scores, complication rates, recurrent herniation rates, and reoperation rates were similar between groups. In the secondary analysis, the open LD patients demonstrated greater procedural time, higher EBL, and longer length of hospital stay than the MIS patients. However, the reoperation rate and 30-day readmission rate were not different between the MIS and open patients. CONCLUSIONS Continued surgical experience was associated with a reduced operative time, shorter length of hospitalization, and similar blood loss following an MIS LD. Independent of surgical experience, all patients demonstrated similar improvements in clinical outcomes. These findings appear to suggest that although surgical experience may improve perioperative parameters (operative time, length of hospitalization), an MIS LD may initially be performed safely without prior experience.

Minimally Invasive Transforaminal Lumbar Interbody Fusion

Minimally invasive transforaminal lumbar interbody fusion (MIS TLIF) is performed via tubular dilators thereby preserving the integrity of the paraspinal musculature. The decreased soft tissue disruption in the MIS technique has been associated with significantly decreased blood loss, shorter length of hospitalization, and an expedited return to work while maintaining comparable arthrodesis rates when compared with the open technique particularly in the setting of spondylolisthesis (isthmic and degenerative), recurrent symptomatic disk herniation, spinal stenosis, pseudoarthrosis, iatrogenic instability, and spinal trauma. The purpose of this article and the accompanying video wass to demonstrate the techniques for a primary, single-level MIS TLIF.

Incidence and Risk Factors for Pneumonia After Posterior Lumbar Fusion Procedures: An ACS-NSQIP Study.

Study Design. Retrospective study of data collected prospectively by the American College of Surgeons National Surgical Quality Improvement Program. Objective. To determine the incidence and risk factors for development of pneumonia after posterior lumbar fusion (PLF). Summary of Background Data. Postoperative pneumonia has important clinical consequences for patients and the health care system. Few studies have examined pneumonia after spinal fusion procedures. Methods. Patients in the American College of Surgeons National Surgical Quality Improvement Program database who underwent PLF during 2005 to 2013 were included. The primary outcome was a diagnosis of pneumonia within the first 30 postoperative days. Independent risk factors for the development of postoperative pneumonia were identified using multivariate regression. Rates of sepsis and mortality were compared between patients who did and did not develop pneumonia using multivariate regression that adjusted for all demographic, comorbidity, and procedural characteristics. Results. A total of 12,428 patients undergoing PLF were identified. The incidence of pneumonia was 0.59%. Independent risk factors for the development of pneumonia were chronic obstructive pulmonary disease (relative risk [RR] = 2.7, P = 0.006), steroid use (RR = 2.6, P = 0.017), non-insulin–dependent diabetes mellitus (DM) (RR = 2.4, P = 0.003), insulin-dependent DM (RR = 2.9, P = 0.005), and greater number of operative levels (two level: RR = 1.7, P = 0.033; three level: RR = 2.7, P = 0.007). Patients who developed pneumonia had a higher rate of sepsis (15.1% vs. 0.8%, adjusted RR = 14.5, P < 0.001) and mortality (2.7% versus 0.1%, adjusted RR = 27.0, P < 0.001) than other patients. Of all sepsis cases and postoperative mortalities, 10.5% and 18.2% occurred in patients who had developed pneumonia, respectively. Conclusion. Pneumonia occurs in approximately 1 in 200 patients after PLF. Pneumonia plays a significant role in the development of sepsis and mortality, with 10% of sepsis and 20% of mortality cases occurring in patients who had developed pneumonia. Patients with chronic obstructive pulmonary disease, steroid use, DM, and a greater number of operative levels are at greater risk. These patients should be counseled, monitored, and targeted with preventative interventions accordingly. Level of Evidence: 3

Urinary Tract Infection Following Posterior Lumbar Fusion Procedures: An American College of Surgeons National Surgical Quality Improvement Program Study.

Study Design. Retrospective review of prospectively collected data. Objective. To determine the incidence and risk factors for the development of a urinary tract infection (UTI) after a posterior lumbar fusion procedure. Summary of Background Data. UTI after surgery is common and has important clinical consequences for both patients and the health care system. Few studies have examined UTI after spinal fusion procedures. Methods. Patients undergoing posterior lumbar fusion procedures during 2011 to 2013 were identified in the American College of Surgeons National Surgical Quality Improvement Program database. Statistical comparisons were made using multivariate regression with adjustment for demographic, comorbidity, and operative characteristics. Results. A total of 10,825 patients met inclusion criteria. The incidence of a UTI was 1.77% (95% confidence interval = 1.52%–2.02%). Independent risk factors for a UTI were greater age (for 50–59 yr, relative risk [RR] = 1.0; 60–69 yr, RR = 2.1; ≥70 yr, RR = 3.5; P < 0.001), female sex (RR = 2.2, P < 0.001), dependent functional status (RR = 2.1, P = 0.010), malnutrition (RR = 2.3, P = 0.004), diabetic status (for non–insulin‐dependent diabetes, RR = 1.5; for insulin‐dependent diabetes, RR = 1.9; P = 0.011), and increased operative duration (for 120–179 min, RR = 1.4; 180–239 min, RR = 2.3; and for ≥240 min, RR = 2.7; P < 0.001). Patients who developed a UTI had a greater risk for systemic sepsis than other patients (11.5% vs. 0.63%; adjusted RR = 14.4, P < 0.001). Patients who developed a UTI had a greater risk for readmission than other patients (36.7% vs. 5.0%; adjusted RR = 6.1, P < 0.001). Conclusion. UTIs occur in nearly 1 in 50 patients undergoing posterior lumbar fusion procedures. Patients who are older, female, dependent, malnourished, or diabetic are at greater risk and should be counseled and monitored accordingly. In addition, morbidity associated with a UTI in this population is substantial, as demonstrated by a 14‐fold increase in the risk for systemic sepsis and a 6‐fold increase in the risk for readmission. As such, increased preventative measures should be targeted to the patients identified here to be at greatest risk. Level of Evidence: 3

Incidence and risk factors for pneumonia following anterior cervical decompression and fusion procedures: an ACS-NSQIP study

BACKGROUND CONTEXT Postoperative pneumonia has important clinical consequences for both patients and the health-care system. Few studies have examined pneumonia following anterior cervical decompression and fusion (ACDF) procedures. PURPOSE This study aimed to determine the incidence and risk factors for development of pneumonia following ACDF procedures. STUDY DESIGN/SETTING A retrospective cohort study of data collected prospectively by the American College of Surgeons National Surgical Quality Improvement Program was carried out. PATIENT SAMPLE This study comprised 11,353 patients undergoing ACDF procedures during 2011-2013. OUTCOME MEASURES The primary outcome was diagnosis of pneumonia in the first 30 postoperative days. METHODS Independent risk factors for the development of pneumonia were identified using multivariate regression. Readmission rates were compared between patients who did and did not develop pneumonia using multivariate regression that adjusted for all demographic, comorbidity, and procedural characteristics. RESULTS The incidence of pneumonia was 0.45% (95% confidence interval=0.33%-0.57%). In the multivariate analysis, independent risk factors for the development of pneumonia were greater age (p<.001), dependent functional status (relative risk [RR]=5.3, p<.001), chronic obstructive pulmonary disease (RR=4.4, p<.001), and greater operative duration (p=.020). Patients who developed pneumonia following discharge had a higher readmission rate than other patients (72.7% vs. 2.4%, adjusted RR=24.5, p<.001). In total, 10.2% of all readmissions were caused by pneumonia. CONCLUSIONS Pneumonia occurs in approximately 1 in 200 patients following ACDF procedures. Patients who are older, are functionally dependent, or have chronic obstructive pulmonary disease are at greater risk. These patients should be counseled, monitored, and targeted with preventative interventions accordingly. Greater operative duration is also an independent risk factor. Approximately three in four patients who develop pneumonia following hospitalization for ACDF procedures are readmitted. This elevated readmission rate has implications for bundled payments and hospital performance reports.

Mesenchymal stem cell allograft as a fusion adjunct in one- and two-level anterior cervical discectomy and fusion: a matched cohort analysis

BACKGROUND CONTEXT Live mesenchymal stem cell (MSC) allograft-containing allogeneic bone grafts have recently gained popularity and currently account for greater than 17% of all bone grafts and bone graft substitutes used in spinal surgery. Although the claim of cellular bone matrices containing osteogenic cells with osteoinductive properties is attractive, little is known about their clinical success when used in anterior cervical discectomy and fusion (ACDF). PURPOSE The objective of this study was to report on the radiographic fusion rates in one- and two-level instrumented ACDF using an MSC. STUDY DESIGN/SETTING This was a retrospective review of prospectively matched cohort of patients with radiologic assessment of fusion as the primary end point. PATIENT SAMPLE Two matched cohorts of adult patients who underwent ACDF with MSC or standard allograft were included. OUTCOMES MEASURES The outcome measures included radiographic and clinical evidence of healing at 1 year. METHODS A consecutive series of 57 patients who underwent a one- or two-level instrumented ACDF procedure between 2010 and 2012 were retrospectively analyzed. All fusion constructs comprised an interbody allograft, an anterior plate, and Osteocel (NuVasive, San Diego, CA, USA). These patients were matched to a control group of 57 patients. RESULTS Of the 57 cases in both cohorts, 29 (50.9%) were single-level, and 28 (49.1%) were two-level instrumented ACDFs. There were no significant differences in patient age (p=.71), gender, comorbidity burden (Charlson Comorbidity Index [CCI]: 1.95; 2.42, p=.71) or body mass index (p=.79). At the 1-year follow-up, 50 of 57 (87.7%) patients in the Osteocel cohort demonstrated a solid fusion compared with 54 of 57 (94.7%) in the control group (p=.19). Seven (12.3%) patients in the Osteocel cohort were reported as having a failed fusion at 1 year. CONCLUSIONS This is the first non-industry sponsored study to analyze a matched cohort assessing the 1-year arthrodesis rates associated with a nonstructural MSC allograft in one- and two-level ACDF procedures. Although not statistically significant, patients treated with MSC allografts demonstrated lower fusion rates compared with a matched non-MSC cohort.

Quantification of Multifidus Atrophy and Fatty Infiltration Following a Minimally Invasive Microdiscectomy.

Background Multifidus muscle degeneration and atrophy have been demonstrated following traditional open spine surgery. The purpose of this study was to quantify multifidus muscle atrophy and fatty infiltration following a 1-level minimally invasive (MIS) lumbar discectomy. Methods Magnetic resonance imaging (MRI) of 24 patients who underwent a primary 1-level MIS microdiscectomy were reviewed. Demographics, operative levels, and time from surgery to imaging were assessed. Total and lean cross-sectional areas (CSA), T1-signal intensity ratio between the multifidus and psoas muscles, and lean-to-total CSA ratio were measured. Pre- and postoperative values were compared within each patient utilizing paired sample T-tests. Results The mean age was 47.8±14.2 years. MRI was obtained 182.5±194.4 days following index surgery. On the ipsilateral side, total CSA decreased at the index level (-4.9%) and the lean CSA decreased at the index (-6.2%), inferior pedicle (-13.0%), and inferior disc levels (-18.6%). On the contralateral side, no significant decreases in total or lean CSA were demonstrated. T1-signal intensity ratios increased at all levels, but the differences were not statistically significant. The lean-to-total CSA ratio was decreased at the superior disc (-5.2%), inferior pedicle (-8.4%), and inferior disc levels (-17.2%) on the ipsilateral side and at the contralateral inferior disc level (-5.3%). Conclusions Primary 1-level MIS discectomy results in minimal short-term atrophy and fatty infiltration of the multifidus at the index level. Total CSA atrophy was mainly confined to the ipsilateral side at the index level. Lean CSA atrophy was observed mainly at and below the index level on the ipsilateral side. Fatty infiltration, as measured by the lean-to-total CSA ratio, ranged 1.2-17.2% on the ipsilateral and 0-5.3% on the contralateral side with greater fat content demonstrated caudally to the surgical level. Clinical Relevance Overall, the majority of the multifidus muscle appears to be radiographically preserved following an MIS lumbar discectomy.

Primary Versus Revision Single-level Minimally Invasive Lumbar Discectomy: Analysis of Clinical Outcomes and Narcotic Utilization.

Study Design. Retrospective cohort analysis of a prospectively maintained registry. Objective. To compare the intraoperative variables, surgical outcomes, and narcotic utilization between primary and revision 1-level minimally invasive (MIS) lumbar discectomies. Summary of Background Data. Revision spine surgery may be associated with longer procedural time and greater soft tissue disruption. Few studies have analyzed the surgical outcomes and narcotic utilization associated with MIS revision lumbar discectomies. Methods. A retrospective analysis of 227 consecutive cases of MIS 1-level lumbar discectomy for degenerative spinal pathology between 2009 and 2014 by a single surgeon was performed. Patients were stratified into primary and revision cohorts. Demographics, comorbidity, intraoperative parameters, peri- and postoperative outcomes, and reoperations were assessed. Postoperative narcotic utilization was compared between cohorts. Statistical analyses were performed using Student t-test and Pearson &khgr;2 test. A P < 0.05 denoted statistical significance. Results. Of the 227 cases included, 186 patients (81.9%) and 41 patients (18.1%) were included in the primary and revision cohorts, respectively. Demographics, comorbidity, smoking status, preoperative visual analogue scale (VAS) scores, and estimated blood loss did not differ between cohorts. However, the revision cohort demonstrated a longer procedural time, increased length of hospitalization, and higher postoperative narcotic utilization. Although not statistically significant, revision patients trended toward higher 6-week postoperative VAS scores and reherniation rates. In addition, revision patients were more likely to undergo subsequent lumbar fusion than primary patients. Conclusion. The findings suggest that revision MIS lumbar discectomy may be associated with increased procedural time, increased length of hospitalization, and increased postoperative narcotic utilization. Whereas revision patients trended toward higher postoperative VAS scores at 6 weeks, both cohorts demonstrated similar pain levels at final follow-up. Finally, revision patients may be at a greater risk of reherniation and subsequent reoperation. Further studies are warranted to characterize the independent risk factors for a revision lumbar discectomy. Level of Evidence: 3

Spine Surgeon Selection Criteria: Factors Influencing Patient Choice.

Study Design. A prospective questionnaire. Objective. The aim of this study was to evaluate factors that patients consider when selecting a spine surgeon. Summary of Background Data. The rise in consumer-driven health insurance plans has increased the role of patients in provider selection. The purpose of this study is to identify factors that may influence a patients criteria for selecting a spine surgeon. Methods. Two hundred thirty-one patients who sought treatment by one spine surgeon completed an anonymous questionnaire consisting of 26 questions. Four questions regarded demographic information; 16 questions asked respondents to rate the importance of specific criteria regarding spine surgeon selection (scale 1–10, with 10 being the most important); and six questions were multiple-choice regarding patient preferences toward aspects of their surgeon (age, training background, etc.). Results. Patients rated board certification (9.26 ± 1.67), in-network provider status (8.10 ± 3.04), and friendliness/bedside manner (8.01 ± 2.35) highest among factors considered when selecting a spine surgeon. Most patients (92%) reported that 30 minutes or less should pass between check-in and seeing their surgeon during a clinic appointment. Regarding whether their spine surgeon underwent training as a neurosurgeon versus an orthopedic surgeon, 25% reported no preference, 52% preferred neurosurgical training, and 23% preferred orthopedic training. Conclusion. Our findings suggest that board certification and in-network health insurance plans may be most important in patients’ criteria for choosing a spine surgeon. Advertisements were rated least important by patients. Patients expressed varying preferences regarding ideal surgeon age, training background, proximity, medical student/resident involvement, and clinic appointment availability. The surgeon from whom patients sought treatment completed an orthopedic surgery residency; hence, it is notable that 52% of patients preferred a spine surgeon with a neurosurgical background. In the context of patients’ increasing role in health care decision-making and provider selection, understanding the factors that influence patients’ selection of a spine surgeon is important. Level of Evidence: 3