Jordan A. Gruskay

Methods of evaluating lumbar and cervical fusion

Introduced in 1911, spinal fusion is now widely used to stabilize the cervical, thoracic, and lumbar spine. Despite advancements in surgical techniques, including the use of instrumentation and optimizing bone graft options, pseudarthrosis remains one of the most significant causes of clinical failure following attempted fusion. Diagnosis of this common complication is based on a focused clinical assessment and imaging studies. Pseudarthrosis classically presents with the onset of or return of axial or radicular symptoms during the first postoperative year. However, this diagnosis is complicated because other diagnoses can mimic these symptoms (such as infection or adjacent segment degeneration) and because many cases of pseudarthrosis are asymptomatic. Computed tomography and assessment of motion on flexion/extension radiographs are the two preferred imaging modalities for establishing the diagnosis of pseudarthrosis. The purpose of this article was to review the current status of imaging and clinical practices for assessing fusion following spinal arthrodesis.

Factors Affecting Length of Stay and Complications After Elective Anterior Cervical Discectomy and Fusion: A Study of 2164 Patients From The American College of Surgeons National Surgical Quality Improvement Project Database (ACS NSQIP).

Study Design: Retrospective review of the prospective American College of Surgeons National Surgical Quality Improvement Project (ACS NSQIP) database with 30-day follow-up of 2164 patients undergoing elective anterior cervical discectomy and fusion (ACDF). Objective: To determine factors independently associated with increased length of stay (LOS) and complications after ACDF to facilitate preoperative planning and setting of realistic expectations for patients and providers. Summary of Background Data: The effect of individual preoperative factors on LOS and complications has been evaluated in small-scale studies. Large database analysis with multivariate analysis of these variables has not been reported. Methods: The ACS NSQIP database from 2005 to 2010 was queried for patients undergoing ACDF procedures. Preoperative and perioperative variables were collected. Multivariate regression determined significant predictors (P<0.05) of extended LOS and complications. Results: Average LOS was 2.0±4.0 days (mean±SD) with a range of 0–103 days. By multivariate analysis, age 65 years and above, functional status, transfer from facility, preoperative anemia, and diabetes were the preoperative factors predictive of extended LOS. Major complications, minor complications, and extended surgery time were the perioperative factors associated with increased LOS. The elongating effect of these variables was determined, and ranged from 0.5 to 5.0 days. Seventy-one patients (3.3%) had a total of 92 major complications, including return to operating room (40), venous thrombotic events (13), respiratory (21), cardiac (6), mortality (5), sepsis (4), and organ space infection (3). Multivariate analysis determined ASA score ≥3, preoperative anemia, age 65 years and above, extended surgery time, and male sex to be predictive of major complications (odds ratios ranging between 1.756 and 2.609). No association was found between levels fused and LOS or complications. Conclusion: Extended LOS after ACDF is associated with factors including age, anemia, and diabetes, as well as the development of postoperative complications. One in 33 patients develops a major complication postoperatively, which are associated with an increased LOS of 5 days.

Is surgical case order associated with increased infection rate after spine surgery

Study Design. Retrospective database review. Objective. To determine whether surgical site infections are associated with case order in spinal surgery. Summary of Background Data. Postoperative wound infection is the most common complication after spinal surgery, with incidence varying from 0.5% to 20%. The addition of instrumentation, use of preoperative prophylactic antibiotics, length of procedure, and intraoperative blood loss have all been found to influence infection rate. No previous study has attempted to correlate case order with infection risk after surgery. Methods. A total of 6666 spine surgery cases occurring between January 2005 and December 2009 were studied. Subjects were classified into 2 categories: fusion and decompression. Case order was determined, with each procedure labeled 1 to 5 depending on the number of previous cases in the room. Variables such as the American Society of Anesthesiologists score, number of operative levels, wound class, age, sex, and length of surgery were also tracked. A step-down binary regression was used to analyze each variable as a potential risk factor for infection. Results. Decompression cases had a 2.4% incidence of infection. Longer surgical time and higher case order were found to be significant risk factors for lumbar decompressions. Fusion cases had a 3.5% incidence of infection. Posterior approach and revision cases were significant risk factors for infection in cervical cases. For lumbar fusion cases, longer surgical time, higher American Society of Anesthesiologists score, and older age were all significant risk factors for infection. Conclusion. Decompressive procedures performed later in the day carry a higher risk for postoperative infection. No similar trend was shown for fusion procedures. Our results identify potential modifiable risk factors contributing to infection rates in spinal procedures. Specific risk factors, although not defined in this study, might be related to contamination of the operating room, cross-contamination between health care providers during the course of the day, use of flash sterilization, and mid-day shift changes.

The Effect of Iliac Crest Autograft on the Outcome of Fusion in the Setting of Degenerative Spondylolisthesis A Subgroup Analysis of the Spine Patient Outcomes Research Trial (SPORT)

BACKGROUND There is considerable controversy about the long-term morbidity associated with the use of posterior autologous iliac crest bone graft for lumbar spine fusion procedures compared with the use of bone-graft substitutes. The hypothesis of this study was that there is no long-term difference in outcome for patients who had posterior lumbar fusion with or without iliac crest autograft. METHODS The study population includes patients enrolled in the degenerative spondylolisthesis cohort of the Spine Patient Outcomes Research Trial who underwent lumbar spinal fusion. Patients were divided according to whether they had or had not received posterior autologous iliac crest bone graft. RESULTS There were 108 patients who had fusion with iliac crest autograft and 246 who had fusion without iliac crest autograft. There were no baseline differences between groups in demographic characteristics, comorbidities, or baseline clinical scores. At baseline, the group that received iliac crest bone graft had an increased percentage of patients who had multilevel fusions (32% versus 21%; p=0.033) and L5-S1 surgery (37% versus 26%; p=0.031) compared with the group without iliac crest autograft. Operative time was higher in the iliac crest bone-graft group (233.4 versus 200.9 minutes; p<0.001), and there was a trend toward increased blood loss (686.9 versus 582.3; p=0.057). There were no significant differences in postoperative complications, including infection or reoperation rates, between the groups. On the basis of the numbers available, no significant differences were detected between the groups treated with or without iliac crest bone graft with regard to the scores on Short Form-36, Oswestry Disability Index, Stenosis Bothersomeness Index, and Low Back Pain Bothersomeness Scale or the percent of patient satisfaction with symptoms averaged over the study period. CONCLUSIONS The outcome scores associated with the use of posterior iliac crest bone graft for lumbar spinal fusion were not significantly lower than those after fusion without iliac crest autograft. Conversely, iliac crest bone-grafting was not associated with an increase in the complication rates or rates of reoperation. On the basis of these results, surgeons may choose to use iliac crest bone graft on a case-by-case basis for lumbar spinal fusion.

July effect in elective spine surgery: analysis of the American College of Surgeons National Surgical Quality Improvement Program database.

Study Design. Retrospective cohort. Objective. To evaluate for the presence and magnitude of the “July effect” within elective spine surgery. Summary of Background Data. The July effect is the hypothetical increase in morbidity and mortality thought to be associated with the influx of new (or newly promoted) trainees during the first portion of the academic year. Studies evaluating for the presence and magnitude of the July effect have demonstrated conflicting results. Methods. We accessed the American College of Surgeons National Surgical Quality Improvement Program database from 2005–2010. Statistical analyses were conducted using bivariate and multivariate logistic regression. Results. A total of 14,986 cases met inclusion criteria and constitute the study population. Of these, 26.5% occurred in the first academic quarter and 25.3% had resident involvement. The rate of serious adverse events was 1.9 times higher and the rate of any adverse events was 1.6 times higher among cases with resident involvement than among those without (P < 0.001 for both). Among cases without resident involvement, the rates of serious adverse events and any adverse events did not differ by academic quarter. Similarly, among cases with resident involvement, the rates of serious adverse events and any adverse events did not differ by academic quarter. Conclusion. We could not demonstrate that the training of new (or newly promoted) residents is associated with an increase in the adverse events of spine surgery. Safeguards that have been put in place to ensure patient safety during this training period seem to be effective. Although adverse events were more common among cases with resident involvement than among cases without resident involvement, our data suggest that this association is more likely a product of the riskier population of cases in which residents participate than of the resident involvement itself. Level of Evidence: 3

Complications of Flat Bed Rest After Incidental Durotomy

Study Design:Retrospective case series. Objective:To determine whether bed rest is a risk factor for specific medical complications. Summary of Background Data:Flat bed rest after incidental durotomy is commonly used to reduce the risk of CSF leakage and associated complications. Methods:Retrospective case series of consecutive patients after lumbar laminectomy were identified. Medical records were reviewed for duration of bed rest and complications (pulmonary, wound, neurological, gastrointestinal, and urinary) in the chart notes, repair methods, subfascial drain placement, consultant notes, imaging reports, and discharge summaries. Patients were compared with duration of bed rest >24 hours versus duration of bed rest ⩽24 hours. The incidence of complications was compared between groups using the Fisher exact test. Results:There were a total of 42 patients with incidental durotomy. There were 18 patients in the bed rest ⩽24 hours group and 24 patients in the bed rest >24 hours group. Comparing the bed rest ⩽24 hours to bed rest >24 hours patients, there was no statistically significant difference in the incidence of postdurotomy-related neurological complications, wound complications, and need for revision surgery. There was a statistically significant decrease in the incidence of total medical complications in the ⩽24-hour group (0% vs. 50%, P=0.0003). Conclusion:There was an increased incidence of medical complications in the bed rest group >24 hours. Flat bed rest after modern dural repair method may not be a necessity in all cases and may be associated with a higher incidence of medical complications.

Preoperative factors affecting length of stay after elective anterior cervical discectomy and fusion with and without corpectomy: a multivariate analysis of an academic center cohort.

Study Design. Retrospective cohort study of 183 patients who underwent elective anterior cervical discectomy and fusion (ACDF) at a single institution during a 2-year period. Objective. To determine which preoperative factors were independently associated with a prolonged hospital length of stay (LOS) after ACDF. Summary of Background Data. ACDF has become the most common treatment modality for addressing cervical spine pathology. Extended LOS after ACDF is associated with increased costs and complications. There is a lack of conclusive data for factors affecting LOS after ACDF. This study aims to create a multivariate model to determine the association of various patient and operative characteristics with LOS after ACDF. Methods. Patients who underwent elective ACDF at a single academic institution between January 2011 and February 2013 were identified using billing records. Their charts were reviewed to collect variables available preoperatively such as patient demographics, comorbidities, and surgery planned. Patients were categorized as normal or extended LOS, with extended LOS defined as LOS more than the 75th percentile. A multivariate logistic regression was used to determine which factors were independently associated with extended LOS. Results. A total of 183 patients with ACDF were identified. The average LOS for this cohort was 2.0 ± 2.5 days (mean ± standard deviation). Extended LOS was defined as 3 days or more. Multivariate analysis revealed that preoperative factors independently associated with extended LOS were history of nonspinal malignancy (odds ratio [OR] = 4.9), history of pulmonary disease (OR = 4.0), and procedures that included corpectomy (OR = 4.5). Conclusion. Patients with a history of nonspinal malignancy or pulmonary disease, as well as patients who underwent corpectomy, were more likely to have an extended LOS (ORs, 4.0–4.9). Of significant note, other factors that one might expect to be associated with extended LOS did not independently predict extended LOS in this analysis. Level of Evidence: 3

Short-term adverse events, length of stay, and readmission after iliac crest bone graft for spinal fusion.

Study Design. Retrospective cohort study of 13,927 patients, 820 of whom received iliac crest bone graft (ICBG). Objective. To compare adverse events, length of stay (LOS), and readmission for patients receiving ICBG with those who did not using multivariate analysis to control for potentially confounding factors. Summary of Background Data. The use of ICBG in spinal fusion has been associated with increased surgical time, LOS, and donor site morbidity. Development of expensive bone graft substitutes has been predicated on these issues. Data on the effect of bone graft harvest on LOS and readmission rate are sparse, and multivariate analysis has not been used to control for confounding factors. Methods. Prospectively collected data from the American College of Surgeons National Surgical Quality Improvement Project 2010–2012 database were retrospectively reviewed. This includes demographics, comorbidities, surgical data, and hospital and 30-day follow-up outcomes data including adverse events, LOS, and readmission. Results. Only 5.9% of spinal fusions use ICBG. Bivariate logistic regression (used for categorical variables) found the ICBG cohort was more likely to have a postoperative blood transfusion (11.6% vs. 5.5%, P < 0.001). Bivariate linear regression (used for continuous variables) found the ICBG cohort to have an extended operative time (+36.0 min, P < 0.001) and extended LOS (+0.6 d, P < 0.001). Multivariate analyses controlling for comorbidities, demographics, and approach-determined postoperative blood transfusion (odds ratio, 1.5), extended operative time (+22.0 min, P < 0.001), and LOS (+0.2 d, P = 0.037) to be significantly associated with ICBG use. No other adverse event was significantly associated with ICBG use. Readmission rates were not significantly different. Conclusion. This study used a large national database cohort and identified increased postoperative blood transfusion, extended operative time, and increased LOS as short-term outcomes associated with ICBG on multivariate analysis. Other short-term morbidities were not significantly associated with ICBG. Readmission rates were not affected. Level of Evidence: 4

Comparison of open and minimally invasive techniques for posterior lumbar instrumentation and fusion after open anterior lumbar interbody fusion.

BACKGROUND CONTEXT Minimally invasive techniques for spinal fusion have theoretical advantages for the reduction of iatrogenic injury. Although this topic has been investigated previously for posterior-only interbody surgery, such as transforaminal lumbar interbody fusion, similar studies have not evaluated these techniques after anteroposterior spinal fusion, a study design that can more accurately determine the effect of pedicle screw placement and decompression via a minimally invasive technique without the confounding effect of simultaneous interbody cage placement. PURPOSE To compare process measures that provide insight into the morbidity of surgery, such as surgical time and the length of postoperative hospital stay between open and minimally invasive anteroposterior lumbar fusion; and to compare the complications during the intraoperative and early postoperative period between open and minimally invasive anteroposterior lumbar fusion. STUDY DESIGN Retrospective case-control study. PATIENT SAMPLE One hundred sixty-two patients. OUTCOME MEASURES Estimated blood loss, length of surgery, intraoperative fluoroscopy time, length of postoperative hospital stay, malpositioned instrumentation on postoperative imaging, and postoperative complications, including pulmonary embolus and surgical site infection. METHODS Patients who underwent open anterior lumbar interbody fusion followed by either traditional open posterior fusion (Open group) or minimally invasive posterior fusion (minimally invasive surgery [MIS] group) were matched by the number of surgical levels. A chart review was performed to document the intraoperative and postoperative process measures and associated complications in the two groups. Secondary analyses were performed to compare the subgroups of patients, who did and did not undergo a posterior decompression at the time of posterior instrumentation to determine the effect of decompression. RESULTS Baseline characteristics were similar between the Open and MIS groups. Estimated blood loss and postoperative transfusion rate were significantly higher in the Open group, differences that the subanalyses suggested were largely because of those patients who underwent concomitant decompression. Length of stay was not significantly different between the groups but was significantly shorter for MIS patients treated without decompression than for Open patients treated without decompression. Intraoperative fluoroscopy time was significantly longer in the MIS group. There was no difference in the infection or complication rates between the groups. CONCLUSIONS Our case-control study comparing patients who underwent anterior lumbar interbody fusion followed by open posterior instrumentation with those who underwent anterior lumbar interbody fusion followed by minimally invasive posterior instrumentation demonstrated that patients undergoing MIS fusion without decompression had less blood loss, less need for transfusion in the perioperative period, and a shorter hospital stay. In contrast, most outcome measures were similar between MIS and Open groups for patients who underwent decompression.

Outpatient Anterior Cervical Discectomy and Fusion is Associated With Fewer Short-term Complications in One- and Two-level Cases: A Propensity-adjusted Analysis

Study Design. Retrospective cohort study of prospectively collected data from the National Surgical Quality Improvement Program (NSQIP) database. Objective. To determine the postoperative morbidity of one- and two-level outpatient anterior cervical discectomy and fusion (ACDF) relative to inpatient cases, and risk factors for postdischarge complications. Summary of Background Data. ACDF is increasingly performed as an outpatient procedure, with evidence demonstrating outpatient one-level ACDF to be associated with fewer postoperative complications than inpatients. The postoperative morbidity and safety of outpatient two-level ACDF as a separate cohort is not well understood. Methods. ACDF cases from NSQIP 2011 to 2014 were identified. Differences in baseline characteristics between inpatient and outpatient cases were determined, and propensity score adjustment was used to account for selection bias. One- and two-level ACDF cohorts were analyzed separately. Unadjusted and propensity-adjusted multivariable logistic regressions were performed to determine the risk of postoperative complications in outpatient cases relative to inpatient cases, and predictors of postdischarge complications. Results. A total of 22,006 ACDF cases were included, of which 4759 were outpatient procedures. Propensity-adjusted differences in preoperative characteristics were all P > 0.5, indicating successful adjustment of selection bias. Among 6890 two-level cases, of which 1429 (20.7%) were outpatient, the overall unadjusted rate of complications was 1.47% for outpatients and 3.94% for inpatients, P < 0.001. Propensity-adjusted multivariable regression showed a lower rate of postoperative complications in the outpatient cohort (odds ratio 0.48, 95% confidence interval 0.30–0.75). Greater comorbidity burden as measured by Charlson Comorbidity Index, higher American Society of Anesthesiologists class, chronic steroid use, hypertension, and male sex were independent risk factors for postdischarge complications. Conclusion. After adjusting for selection bias and patient risk factors, outpatient two-level ACDF was not associated with increased postoperative morbidity relative to inpatients, and may be considered in appropriately indicated patients. Level of Evidence: 3