Nerve root retraction time during lumbar endoscopic discectomy: association with new onset radiculitis, a post-operative neurologic complication

PURPOSE

To evaluate the relationship between nerve root retraction time, post-operative radiculitis and patient reported outcomes.

METHODS

Patients who underwent single- or multi-level lumbar discectomy between 2020 and 2022 for lumbar disk herniations were prospectively followed with pre-operative, interoperative and post-operative variables including radiculitis and patient reported outcomes including VAS, ODI and CAT domains Pain interference, Pain intensity and Physical function. Intraoperative nerve root retraction time was recorded. Paired sample two-tailed t-test and multivariate regression were utilized with p < 0.05 being significant.

RESULTS

A total of 157 patients who underwent single- or multi-level endoscopic lumbar discectomy. Average patient age was 44 years, and 64% were male patients. Nerve retraction time ranged from 4 to 15 min. Eighteen percent reported new radiculitis at 2-weeks post-operatively. In patients with new-onset radiculitis 79.2% reported significantly worse VAS leg at 2 weeks post-operative (4.2 vs. 8.3, p < 0.001) compared to 12.5% who had improved VAS leg (9.3 vs. 7, p = 0.1181). Patients with radiculitis and worse VAS scores had substantially longer nerve retraction time (13.8 ± 7.5 min) than patients with improved VAS leg (6.7 ± 1.2 min). At 6 months, patients with longer nerve retraction time had no significant improvement in the ODI or CAT compared to the baseline.

CONCLUSIONS

This is the first study in discectomy literature to show that new onset radiculitis and poorer outcomes in VAS leg correlate with longer nerve retraction time at early and later time points.

Predictors of Complication Severity Following Adult Spinal Deformity Surgery: Smoking Rate, Diabetes, and Osteotomy Increase Risk of Severe Adverse Events

BACKGROUND

Given the physical and economic burden of complications in spine surgery, reducing the prevalence of perioperative adverse events is a primary concern of both patients and health care professionals. This study aims to identify specific perioperative factors predictive of developing varying grades of postoperative complications in adult spinal deformity (ASD) patients, as assessed by the Clavien-Dindo complication classification (Cc) system.

METHODS

Surgical ASD patients ≥18 years were identified in the American College of Surgeons' National Surgical Quality Improvement Program from 2005 to 2015. Postoperative complications were stratified by Cc grade severity: minor (I, II, and III) and severe (IV and V). Stepwise regression models generated dataset-specific predictive models for Cc groups. Model internal validation was achieved by bootstrapping and calculating the area under the curve (AUC) of the model. Significance was set at P < 0.05.

RESULTS

Included were 3936 patients (59 ± 16 years, 63% women, 29 ± 7 kg/m²) undergoing surgery for ASD (4.4 ± 4.7 levels, 71% posterior approach, 11% anterior, and 18% combined). Overall, 1% of cases were revisions, 39% of procedures involved decompression, 27% osteotomy, and 15% iliac fixation. Additionally, 66% of patients experienced at least 1 complication, 0% of which were Cc grade I, 51% II, 5% III, 43% IV, and 1% V. The final model predicting severe Cc (IV-V) complications yielded an AUC of 75.6% and included male sex, diabetes, increased operative time, central nervous system tumor, osteotomy, cigarette pack-years, anterior decompression, and anterior lumbar interbody fusion. Final models predicting specific Cc grades were created.

CONCLUSIONS

Specific predictors of adverse events following ASD-corrective surgery varied for complications of different severities. Multivariate modeling showed smoking rate, osteotomy, diabetes, anterior lumbar interbody fusion, and higher operative time, among other factors, as predictive of severe complications, as classified by the Clavien-Dindo Cc system. These factors can help in the identification of high-risk patients and, consequently, improve preoperative patient counseling.

CLINICAL RELEVANCE

The findings of this study provide a foundation for identifying ASD patients at high risk of postoperative complications .

LEVEL OF EVIDENCE: 4

Predicting 30-Day Perioperative Outcomes in Adult Spinal Deformity Patients With Baseline Paralysis or Functional Dependence

BACKGROUND

Patients undergoing surgical treatment of adult spinal deformity (ASD) are often preoperatively risk stratified using standardized instruments to assess for perioperative complications. Many ASD instruments account for medical comorbidity and radiographic parameters, but few consider a patient's ability to independently accomplish necessary activities of daily living (ADLs).

METHODS

Patients ≥18 years undergoing ASD corrective surgery were identified in National Surgical Quality Improvement Program. Patients were grouped by (1) plegic status and (2) dependence in completing ADLs ("totally dependent" = requires total assistance in ADLs, "partially dependent" = uses prosthetics/devices but still requires help, "independent" = requires no help). Quadriplegics and totally dependent patients comprised "severe functional dependence," paraplegics/hemiplegics who are "partially dependent" comprised "moderate functional dependence," and "independent" nonplegics comprised "independent." Analysis of variance with post hoc testing and Kruskal-Wallis tests compared demographics and perioperative outcomes across groups. Logistic regression found predictors of inferior outcomes, controlling for age, sex, body mass index (BMI), and invasiveness. Subanalysis correlated functional dependence with other established metrics such as the modified Frailty Index (mFI) and Charlson Comorbidity Index (CCI).

RESULTS

A total of 40,990 ASD patients (mean age 57.1 years, 53% women, mean BMI 29.8 kg/m²) were included. Mean invasiveness score was 6.9 ± 4.0; 95.2% were independent (Indep), 4.3% moderate (Mod), and 0.5% severe (Sev). Sev had higher baseline invasiveness than Mod or Indep groups (9.0, 8.3, and 6.8, respectively, P < 0.001). Compared with the Indep patients, Sev and Mod had significantly longer inpatient length of stay (LOS; 10.9, 8.4, 3.8 days, P < 0.001), higher rates of surgical site infection (2.2%, 2.9%, 1.5%, P < 0.001), and more never events (17.7%, 9.9%, 4.0%, P < 0.001). Mod had higher readmission rates than either the Sev or Indep groups (30.2%, 2.7%, 10.3%, P < 0.001). No differences in implant failure were observed (P > 0.05). Controlling for age, sex, BMI, CCI, invasiveness, and frailty, regression equations showed increasing functional dependence significantly increased odds of never events (OR, 1.82 [95% CI 1.57-2.10], P < 0.001), specifically urinary tract infection (OR, 2.03 [95% CI 1.66-2.50], P < 0.001) and deep venous thrombosis (OR, 2.04 [95% CI 1.61-2.57], P < 0.001). Increasing functional dependence also predicted longer LOS (OR, 3.16 [95% CI 2.85-3.46], P < 0.001) and readmission (OR, 2.73 [95% CI 2.47-3.02], P < 0.001). Subanalysis showed functional dependence correlated more strongly with mFI (r = 0.270, P < 0.001) than modified CCI (mCCI; r = 0.108, P < 0.001), while mFI and mCCI correlated most with one another (r = 0.346, P < 0.001).

CONCLUSIONS

Severe functional dependence had significantly longer LOS and more never-event complications than moderate or independent groups. Overall, functional dependence may show superiority to traditional metrics in predicting poor perioperative outcomes, such as increased LOS, readmission rate, and risk of surgical site infection and never events.

LEVEL OF EVIDENCE: 3

Same Day Surgical Intervention Dramatically Minimizes Complication Occurrence and Optimizes Perioperative Outcomes for Central Cord Syndrome

STUDY DESIGN

This was a retrospective cohort study.

OBJECTIVE

The aim of this study was to investigate associations between time to surgical intervention and outcomes for central cord syndrome (CCS) patients.

BACKGROUND

As surgery is increasingly recommended for patients with neurological deterioration CCS, it is important to investigate the relationship between time to surgery and outcomes.

MATERIALS AND METHODS

CCS patients were isolated in Nationwide Inpatient Sample database 2005-2013. Patients were grouped by time to surgery: same-day, 1-day delay, 2, 3, 4-7, 8-14, and >14 days. Means comparison tests compared patient factors, perioperative complications, and charges across patient groups. Controlling for age, comorbidities, length of stay, and concurrent traumatic fractures, binary logistic regression assessed surgical timing associated with increased odds of perioperative complication, using same-day as reference group.

RESULTS

Included: 6734 CSS patients (64% underwent surgery). The most common injury mechanisms were falls (30%) and pedestrian accidents (7%). Of patients that underwent surgery, 52% underwent fusion, 30% discectomy, and 14% other decompression of the spinal canal. Breakdown by time to procedure was: 39% same-day, 16% 1-day, 10% 2 days, 8% 3 days, 16% 4-7 days, 8% 8-14 days, and 3% >14 days. Timing groups did not differ in trauma status at admission, although age varied: [minimum: 1 d (58±15 y), maximum: >14 d (63±13 y)]. Relative to other groups, same-day patients had the lowest hospital charges, highest rates of home discharge, and second lowest postoperative length of stay behind 2-day delay patients. Patients delayed >14 days to surgery had increased odds of perioperative cardiac and infection complications. Timing groups beyond 3 days showed increased odds of VTE and nonhome discharge.

CONCLUSIONS

CCS patients undergoing surgery on the same day as admission had lower odds of complication, hospital charges, and higher rates of home discharge than patients that experienced a delay to operation. Patients delayed >14 days to surgery were associated with inferior outcomes, including increased odds of cardiac complication and infection.

Increased cautiousness in adolescent idiopathic scoliosis patients concordant with syringomyelia fails to improve overall patient outcomes

Background:

Adolescent idiopathic scoliosis (AIS) is a common cause of spinal deformity in adolescents. AIS can be associated with certain intraspinal anomalies such as syringomyelia (SM). This study assessed the rate o f SM in AIS patients and compared trends in surgical approach and postoperative outcomes in AIS patients with and without SM.

Methods:

The database was queried using ICD-9 codes for AIS patients from 2003–2012 (737.1–3, 737.39, 737.8, 737.85, and 756.1) and SM (336.0). The patients were separated into two groups: AIS-SM and AIS-N. Groups were compared using t-tests and Chi-squared tests for categorical and discrete variables, respectively.

Results:

Totally 77,183 AIS patients were included in the study (15.2 years, 64% F): 821 (1.2%) – AIS-SM (13.7 years, 58% F) and 76,362 – AIS-N (15.2 years, 64% F). The incidence of SM increased from 2003–2012 (0.9 to 1.2%, P = 0.036). AIS-SM had higher comorbidity rates (79 vs. 56%, P < 0.001). Comorbidities were assessed between AIS-SM and AIS-N, demonstrating significantly more neurological and pulmonary in AIS-SM patients. 41.2% of the patients were operative, 48% of AIS-SM, compared to 41.6% AIS-N. AIS-SM had fewer surgeries with fusion (anterior or posterior) and interbody device placement. AIS-SM patients had lower invasiveness scores (2.72 vs. 3.02, P = 0.049) and less LOS (5.0 vs. 6.1 days, P = 0.001). AIS-SM patients underwent more routine discharges (92.7 vs. 90.9%). AIS-SM had more nervous system complications, including hemiplegia and paraplegia, brain compression, hydrocephalous and cerebrovascular complications, all P < 0.001. After controlling for respiratory, renal, cardiovascular, and musculoskeletal comorbidities, invasiveness score remained lower for AIS-SM patients (P < 0.001).

Conclusions:

These results indicate that patients concordant with AIS and SM may be treated more cautiously (lower invasiveness score and less fusions) than those without SM.

Esophagopharyngeal perforation and prevertebral abscess after anterior cervical discectomy and fusion: a case report

Anterior cervical discectomy and fusion (ACDF) represents one of the most commonly performed spine surgeries. Dysphagia secondary to esophageal injury during retraction is one of the most common complications, and usually leads to self-limiting dysphagia. However, actual perforation and violation of the esophageal tissue is much rarer and can lead to delayed deep infections. Prevertebral abscess' are one of the most feared complications after ACDF, as they can lead to severe tissue swelling, osteomyelitis, hardware failure, and even death. Due to their rarity, a gold standard of workup and treatment is still unknown. A healthy 47-year-old female presents 9 months after a C4-C7 ACDF done at an outside institution with a large prevertebral abscess, osteomyelitis, hardware failure, and pseudoarthrosis secondary to esophagopharyngeal defect and prominent hardware. Overall, the patient underwent eight surgeries, and required an extended course of intravenous (IV) antibiotics, multiple diagnostic procedures, and complex soft tissue coverage using an anterolateral thigh free flap. Currently, the patient is doing well 6 months from her last procedure without any complications or plan for future surgery. This was an extremely rare case of a late occurring prevertebral abscess after ACDF. Dysphagia in the late postoperative setting should be evaluated carefully and thoroughly for any esophageal perforation and deep infection. As exemplified in this case, even partial thickness injuries to the esophageal-pharyngeal anatomy due to hardware irrigation can lead to catastrophic complications over time. Safe removal of all hardware anteriorly to avoid continued irritation of the esophagopharyngeal mucosa should be prioritized. If anterior hardware is necessary for stability, implants with the smallest footprint should be utilized. Early collaboration with ENT colleagues should be a priority and can provide crucial diagnostic and therapeutic interventions. Complex closure with a free flap was shown to be an effective way to provide successful definitive soft tissue coverage.

The Patient-Reported Outcome Measurement Information System (PROMIS) Better Reflects the Impact of Length of Stay and the Occurrence of Complications Within 90 Days Than Legacy Outcome Measures for Lumbar Degenerative Surgery

BACKGROUND

The Patient-Reported Outcome Measurement Information System (PROMIS) and legacy outcome measures like the Oswestry Disability Index (ODI) have not been compared for their sensitivity in reflecting the impact of perioperative complications and length of stay (LOS) in a surgical thoracolumbar population. The purpose of this study is to assess the strength of PROMIS and ODI scores as they correlate with LOS and complication outcomes of surgical thoracolumbar patients.

METHODS

Retrospective cohort study. Included: patients ≥18 years undergoing thoracolumbar surgery with available preoperative and 3-month postoperative ODI and PROMIS scores. Pearson correlation assessed the linear relationships between LOS, complications, and scores for PROMIS (physical function, pain intensity, pain interference) and ODI. Linear regression predicted the relationship between complication incidence and scores for ODI and PROMIS.

RESULTS

Included: 182 patients undergoing thoracolumbar surgery. Common diagnoses were stenosis (62.1%), radiculopathy (48.9%), and herniated disc (47.8%). Overall, 58.3% of patients underwent fusion, and 50.0% underwent laminectomy. Patients showed preoperative to postoperative improvement in ODI (50.2 to 39.0), PROMIS physical function (10.9 to 21.4), pain intensity (92.4 to 78.3), and pain interference (58.4 to 49.8, all P < .001). Mean LOS was 2.7 ± 2.8 days; overall complication rate was 16.5%. Complications were most commonly cardiac, neurologic, or urinary (all 2.2%). Whereas preoperative to postoperative changes in ODI did not correlate with LOS, changes in PROMIS pain intensity (r = 0.167, P = .024) and physical function (r = -0.169, P = .023) did. Complications did not correlate with changes in ODI or PROMIS score; however, postoperative scores for physical function (r = -0.205, P = .005) and pain interference (r = 0.182, P = .014) both showed stronger correlations with complication occurrence than ODI (r = 0.143, P = .055). Regression analysis showed postoperative physical function (R ² = 0.037, P = .005) and pain interference (R ² = 0.028, P = .014) could predict complications; ODI could not.

CONCLUSIONS

PROMIS domains of physical function and pain interference better reflected perioperative complications and LOS than the ODI. These results suggest PROMIS may offer more utility as an outcomes assessment instrument.

LEVEL OF EVIDENCE

3.

A cost benefit analysis of increasing surgical technology in lumbar spine fusion

BACKGROUND CONTEXT

Numerous advances have been made in the field of spine fusion, such as minimally invasive (MIS) or robotic-assisted spine surgery. However, it is unknown how these advances have impacted the cost of care.

PURPOSE

Compare the economic outcomes of lumbar spine fusion between open, MIS, and robot-assisted surgery patients.

STUDY DESIGN/SETTING

Retrospective review of a single center spine surgery database.

PATIENT SAMPLE

Three hundred sixty propensity matched patients.

OUTCOME MEASURES

Costs, EuroQol-5D (EQ5D), cost per quality adjusted life years (QALY).

METHODS

Inclusion criteria: surgical patients >18 years undergoing lumbar fusion surgery. Patients were categorized into 3 groups based on procedure type: open, MIS, or robotic. Open patients undergoing poster spinal fusion were considered as the control group. MIS patients included those undergoing transforaminal or lateral lumbar interbody fusion with percutaneous screws. Robotic patients were those undergoing robot-assisted fusion. Propensity score matching was performed between all groups for the number of levels fused. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims for ICD-9 codes. For robotic cases, costs were reflective of operational fees and initial purchase cost. Complications and comorbidities and major complications and comorbidities were assessed according to CMS.gov manual definitions. QALYs and cost per QALY were calculated using a 3% discount rate to account for residual decline to life expectancy (78.7 years). Costs per QALY were calculated for both 1 year and life expectancy, assuming no loss of benefit. A 10,000 trial Monte Carlo simulation with probabilistic sensitivity analysis (PSA) assessed our model parameters and costs.

RESULTS

Three hundred sixty propensity matched patients (120 open, 120 MIS, 120 robotic) met inclusion criteria. Descriptive statistics for the cohort were: age 58.8±13.5, 50% women, BMI 29.4±6.3, operative time 294.4±119.0, LOS 4.56±3.31 days, estimated blood loss 515.9±670.0 cc, and 2.3±2.2 average levels fused. Rates of post-op complications were significantly higher in robotic cases versus open and MIS (43% vs. 21% and 22% for open and MIS, p<.05). However, revision rates were comparable between all groups (3% open, 3% MIS, 5% robotic, p>.05). After factoring in complications, revisions, and purchasing and operating fees, the costs of robotic cases was significantly higher than both open and MIS surgery ($60,047.01 vs. $42,538.98 open and $41,471.21 MIS). In a subanalysis of 42 patients with baseline (BL) and 1Y EQ5D data, the cost per QALY at 1Y for open, MIS, and robot-assisted cases was $296,624.48, $115,911.69, and $592,734.30. If utility gained was sustained to life expectancy, the cost per QALY was $14,905.75, $5,824.71, $29,785.64 for open, MIS, and robot-assisted cases. Results of the PSA were consistent with MIS surgery having the most incremental cost effectiveness when compared to open and robotic surgery.

CONCLUSIONS

Numerous advances have been made in the field of spine surgery, however, there has been limited discussion of the effect these advances have on economic outcomes. When matched for levels fused, robot-assisted surgery patients had significantly higher rates of complications and 30% higher costs of surgery compared to minimally invasive and open spine surgery patients. While 1 year economic outcomes were not optimal for robotic surgery cases, the projected costs per QALYs at life expectancy were well below established acceptable thresholds. The above findings may be reflective of an educational learning curve and emerging surgical technologies undergoing progressive refinement.

A Simpler, Modified Frailty Index Weighted by Complication Occurrence Correlates to Pain and Disability for Adult Spinal Deformity Patients

BACKGROUND

The Miller et al adult spinal deformity frailty index (ASD-FI) correlates with complication risk; however, its development was not rooted in clinical outcomes, and the 40 factors needed for its calculation limit the index's clinical utility. The present study aimed to develop a simplified, weighted frailty index for ASD patients METHODS: This study is a retrospective review of a single-center database. Component ASD-FI parameters contributing to overall ASD-FI score were assessed via Pearson correlation. Top significant, clinically relevant factors were regressed against ASD-FI score to generate the modified ASD-FI (mASD-FI). Component mASD-FI factors were regressed against incidence of medical complications, and factor weights were calculated from regression of these coefficients. Total mASD-FI score ranged from 0 to 21, and was calculated by summing weights of expressed parameters. Linear regression and published ASD-FI cutoffs generated corresponding mASD-FI frailty cutoffs: not frail (NF, <7), frail (7-12), severely frail (SF, >12). Analysis of variance assessed the relationship between frailty category and validated baseline measures of pain and disability at baseline.

RESULTS

The study included 50 ASD patients. Eight factors were included in the mASD-FI. Overall mean mASD-FI score was 5.7 ± 5.2. Combined, factors comprising the mASD-FI showed a trend of predicting the incidence of medical complications (Nagelkerke R ² = 0.558; Cox & Snell R ² = 0.399; P = .065). Breakdown by frailty category is NF (70%), frail (12%), and SF (18%). Increasing frailty category was associated with significant impairments in measures of pain and disability: Oswestry Disability Index (NF: 23.4; frail: 45.0; SF: 49.3; P < .001), SRS-22r (NF: 3.5; frail: 2.6; SF: 2.4; P = .001), Pain Catastrophizing Scale (NF: 41.9; frail: 32.4; SF: 27.6; P < .001), and NRS Leg Pain (NF: 2.3; frail: 7.2; SF: 5.6; P = .001).

CONCLUSIONS

This study modifies an existing ASD frailty index and proposes a weighted, shorter mASD-FI. The mASD-FI relies less on patient-reported variables, and it weights component factors by their contribution to adverse outcomes. Because increasing mASD-FI score is associated with inferior clinical measures of pain and disability, the mASD-FI may serve as a valuable tool for preoperative risk assessment.

Patients with psychiatric diagnoses have increased odds of morbidity and mortality in elective orthopedic surgery

Psychiatric diagnoses (PD) present a significant burden on elective surgery patients and may have potentially dramatic impacts on outcomes. As ailments of the spine can be particularly debilitating, the effect of PD on outcomes was compared between elective spine surgery patients and other common elective orthopedic surgery procedures. This study included 412,777 elective orthopedic patients who were concurrently diagnosed with PD within the years 2005 to 2016. 30.2% of PD patients experienced a post-operative complication, compared to 25.1% for non-PD patients (p < 0.001). Mood Disorders (bipolar or depressive disorders) were the most commonly diagnosed PD for all elective Orthopedic procedures, followed by anxiety, then dementia (p < 0.001). Logistic regression analysis found PD to be a significant predictor of higher cost to charge ratio (CCR), length of stay (LOS), and death (all p < 0.001). Between, hand, elbow, and shoulder specialties, spine patients had the highest odds of increased CCR and unfavorable discharge, and the second highest odds of death (all p < 0.001).

Epidural Steroid Injections for Management of Degenerative Spondylolisthesis: Little Effect on Clinical Outcomes in Operatively and Nonoperatively Treated Patients

BACKGROUND

Although epidural steroid injection (ESI) may provide pain relief for patients with degenerative spondylolisthesis in treatment regimens of up to 4 months, it remains unclear whether ESI affects crossover from nonoperative to operative management.

METHODS

This retrospective cohort study analyzed 2 groups of surgical candidates with degenerative spondylolisthesis: those who received ESI within 3 months after enrollment (ESI group) and those who did not (no-ESI group). Annual outcomes following enrollment were assessed within operative and nonoperative groups (patients who initially chose or were assigned to surgery or nonoperative treatment) by using longitudinal mixed-effect models with a random subject intercept term accounting for correlations between repeated measurements. Treatment comparisons were performed at follow-up intervals. Area-under-the-curve analysis for all time points assessed the global significance of treatment.

RESULTS

The study included 192 patients in the no-ESI group and 74 in the ESI group. The no-ESI group had greater baseline Short Form-36 (SF-36) Bodily Pain scores (median, 35 versus 32) and self-reported preference for surgery (38% versus 11%). There were no differences in surgical rates within 4 years after enrollment between the no-ESI and ESI groups (61% versus 62%). The surgical ESI and no-ESI groups also showed no differences in changes in patient-reported outcomes at any follow-up interval or in the 4-year average. Compared with the nonoperative ESI group, the nonoperative no-ESI group showed greater improvements in SF-36 scores for Bodily Pain (p = 0.004) and Physical Function (p = 0.005) at 4 years, Bodily Pain at 1 year (p = 0.002) and 3 years (p = 0.005), and Physical Function at 1 year (p = 0.030) and 2 years (p = 0.002). Of the patients who were initially treated nonsurgically, those who received ESI and those who did not receive ESI did not differ with regard to surgical crossover rates. The rates of crossover to nonoperative treatment by patients who initially chose or were assigned to surgery also did not differ between the ESI and no-ESI groups.

CONCLUSIONS

There was no relationship between ESI and improved clinical outcomes over a 4-year study period for patients who chose or were assigned to receive surgery for degenerative spondylolisthesis. In the nonsurgical group, ESI was associated with inferior pain reduction through 3 years, although this was confounded by greater baseline pain. ESI showed little relationship with surgical crossover.

LEVEL OF EVIDENCE

Therapeutic Level III. See Instructions for Authors for a complete description of levels of evidence.

Complication Risk in Primary and Revision Minimally Invasive Lumbar Interbody Fusion: A Comparable Alternative to Conventional Open Techniques?

STUDY DESIGN

Retrospective cohort study of prospective patients undergoing minimally invasive lumbar fusion at a single academic institution.

OBJECTIVE

To assess differences in perioperative outcomes between primary and revision MIS (minimally invasive surgical) lumbar interbody fusion patients and compare with those undergoing corresponding open procedures.

METHODS

Patients ≥18 years old undergoing lumbar interbody fusion were grouped by surgical technique: MIS or open. Patients within each group were propensity score matched for comorbidities and levels fused. Patient demographics, surgical factors, and perioperative complication incidences were compared between primary and revision cases using means comparison tests, as appropriate.

RESULTS

Of the 214 lumbar interbody fusion patients included after propensity score matching, 44 (21%) cases were MIS, and 170 (79%) were open. For MIS patients, there were no significant differences between primary and revision cases in estimated blood loss (EBL; 344 vs 299 cm³, P = .682); however, primary cases had longer operative times (301 vs 246 minutes, P = .029). There were no differences in length of stay (LOS), intensive care unit LOS, readmission, and intraoperative or postoperative complications (all P > .05). For open patients, there were no differences between primary and revision cases in EBL (P > .05), although revisions had longer operative times (331 vs 278 minutes, P = .018) and more postoperative complications (61.7% vs 23.8%, P < .001). MIS revision procedures were shorter than open revisions (182 vs 213 minutes, P = .197) with significantly less EBL (294 vs 965 cm³, P < .001), shorter inpatient and intensive care unit LOS, and fewer postoperative complications (all P < .05).

CONCLUSIONS

Clinical outcomes of revision MIS lumbar interbody fusion were similar to those of primary surgery. Additionally, MIS techniques were associated with less EBL, shorter LOS, and fewer perioperative complications than corresponding open revisions.

ODI Cannot Account for All Variation in PROMIS Scores in Patients With Thoracolumbar Disorders

STUDY DESIGN

Retrospective review of single institution.

OBJECTIVE

To assess the relationship between Patient-Reported Outcomes Measurement Information System (PROMIS) and Oswestry Disability Index (ODI) scores in thoracolumbar patients.

METHODS

Included: Patients ≥18 years with a thoracolumbar spine condition (spinal stenosis, disc herniation, low back pain, disc degeneration, spondylolysis). Bivariate correlations assessed the linear relationships between ODI and PROMIS (Physical Function, Pain Intensity, and Pain Interference). Correlation cutoffs assessed patients with high and low correlation between ODI and PROMIS. Linear regression predicted the relationship of ODI to PROMIS.

RESULTS

A total of 206 patients (age 53.7 ± 16.6 years, 49.5% female) were included. ODI correlated with PROMIS Physical Function (r = -0.763, P < .001), Pain Interference (r = 0.800, P < .001), and Pain Intensity (r = 0.706, P < .001). ODI strongly predicted PROMIS for Physical Function (R ² = 0.58, P < .001), Pain Intensity (R ² = 0.50, P < .001), and Pain Interference (R ² = 0.64, P < .001); however, there is variability in PROMIS that ODI cannot account for. ODI questions about sitting and sleeping were weakly correlated across the 3 PROMIS domains. Linear regression showed overall ODI score as accounting for 58.3% (R ² = 0.583) of the variance in PROMIS Physical Function, 63.9% (R ² = 0.639) of the variance in Pain Interference score, and 49.9% (R ² = 0.499) of the variance in Pain Intensity score.

CONCLUSIONS

There is a large amount of variability with PROMIS that cannot be accounted for with ODI. ODI questions regarding walking, social life, and lifting ability correlate strongly with PROMIS while sitting, standing, and sleeping do not. These results reinforce the utility of PROMIS as a valid assessment for low back disability, while indicating the need for further evaluation of the factors responsible for variation between PROMIS and ODI.

Readmission in elective spine surgery: Will short stays be beneficial to patients

There has been limited discussion as to whether spine surgery patients are benefiting from shorter in-patient hospital stays or if they are incurring higher rates of readmission and complications secondary to shortened length of stays. Included in this study were 237,446 spine patients >18yrs and excluding infection. Patients with Clavien Grade 5 complications in 2015 had the lowest mean time to readmission after initial surgery in all years at 12.44 ± 9.03 days. Pearson bivariate correlations between LOS ≤ 1 day and decreasing days to readmission was the strongest in 2016.). Logistic regression analysis found that LOS ≤ 1 day showed an overall increase in the odds of hospital readmission from 2012 to 2016 (2.29 [2.00-2.63], 2.33 [2.08-2.61], 2.35 [2.11-2.61], 2.27 [2.06-2.49], 2.33 [2.14-2.54], all p < 0.001).

Obesity negatively affects cost efficiency and outcomes following adult spinal deformity surgery

BACKGROUND CONTEXT

Obesity has risen to epidemic proportions within the United States. As the rates of obesity have increased, so has its prevalence among patients undergoing adult spinal deformity (ASD) surgery. The effect of obesity on the cost efficiency of corrective procedures for ASD has not been effectively evaluated.

PURPOSE

To investigate differences in cost efficiency of ASD surgery for patients stratified by body mass index (BMI).

STUDY DESIGN/SETTING

Retrospective review of a single-center ASD database.

PATIENT SAMPLE

Five hundred five ASD patients.

OUTCOME MEASURES

Complications, revisions, costs, EuroQol-5D (EQ5D), quality-adjusted life years (QALYs), cost per QALY.

METHODS

ASD patients (scoliosis≥20°, SVA≥5 cm, PT≥25°, or TK ≥60°) ≥18, undergoing ≥4 level fusions were included. Patients were stratified into NIH-defined obesity groups based on their preoperative BMI: underweight 18.5< (U), normal 18.5 to 24.9 (N), overweight 25.0 to 29.9 (O), obese I 30.0 to 34.9 (OI), obese II 35.0 to 39.9 (OII), and obesity class III 40.0+ (OIII). Total surgery costs for each ASD obesity group were calculated. Costs were calculated using the PearlDiver database, which reflects both private insurance and Medicare reimbursement claims. Overall complications and major complications were assessed according to CMS definitions. QALYs and cost per QALY for obesity groups were calculated using an annual 3% discount up to life expectancy (78.7 years).

RESULTS

In all, 505 patients met inclusion criteria. Baseline demographics and surgical details were: age 60.8±14.8, 67.6% female, BMI 28.8±7.30, 81.0% posterior approach, 18% combined approach, 10.1±4.2 levels fused, op time 441.2±146.1 minutes, EBL 1903.8±1594.7 cc, and LOS 8.7±10.7 days. There were 17 U, 154 N patients, 151 O patients, 100 OI, 51 OII, and 32 OIII patients. Revision rates by obesity group were: 0% U, 3% N patients, 3% O patients, 5% OI, 4% OII, and 6% for OIII patients. The total surgery costs by obesity group were: $48,757.86 U, $49,688.52 N, $47,219.93 O, $50,467.66 OI, $51,189.47 OII, and $53,855.79 OIII. In an analysis of patients with baseline and 1 Y EQ5D follow-up, the cost per QALY by obesity group was: $153,737.78 U, $229,222.37 N, $290,361.68 O, $493,588.47 OI, $327,876.21 OII, and $171,680.00 OIII. If that benefit was sustained to life expectancy, the cost per QALY was $8,588.70 U, $12,805.72 N, $16,221.32 O, $27,574.77 OI, $18,317.11 OII, and $9,591.06 for OIII.

CONCLUSIONS

Among adult spinal deformity patients, those with BMIs in the obesity I, obesity II, or obesity class III range had more expensive total surgery costs. When assessing 1 year cost per QALY, obese patients had costs 32% higher than nonobese patients ($224,440.61 vs. $331,048.23). Further research is warranted on the utility of optimizing modifiable preoperative health factors for patients undergoing corrective adult spinal deformity surgery.

The Impact of Adult Thoracolumbar Spinal Deformities on Standing to Sitting Regional and Segmental Reciprocal Alignment

Background

Regional and segmental changes of the lumbar spine have previously been described as patients transition from standing to sitting; however, alignment changes in the cervical and thoracic spine have yet to be investigated. So, the aim of this study was to assess cervical and thoracic regional and segmental changes in patients with thoracolumbar deformity versus a nondeformed thoracolumbar spine population.

Methods

This study was a retrospective cohort study of a single center's database of full-body stereoradiographic imaging and clinical data. Patients were ≥ 18 years old with nondeformed spines (nondegenerative, nondeformity spinal pathologies) or thoracolumbar deformity (ASD: PI-LL > 10°). Patients were propensity-score matched for age and maximum hip osteoarthritis grade and were stratified by Scoliosis Research Society (SRS)-Schwab classification by PI-LL, SVA, and PT. Patients with lumbar transitional anatomy or fusions were excluded. Outcome measures included changes between standing and sitting in global alignment parameters: sagittal vertical axis (SVA), pelvic incidence minus lumbar lordosis (PI-LL), pelivc tilt (PT), thoracic kyphosis, cervical alignment, cervical SVA, C2-C7 lordosis (CL), T1 slop minus CL (TS-CL), and segmental alignment from C2 to T12. Another analysis was performed using patients with cervical and thoracic segmental measurements.

Results

A total of 338 patients were included (202 nondeformity, 136 ASD). After propensity-score matching, 162 patients were included (81 nondeformity, 81 ASD). When categorized by SRS-Schwab classification, all nondeformity patients were nonpathologically grouped for PI-LL, SVA, and PT, whereas ASD patients had mix of moderately and markedly deformed modifiers. There were significant differences in pelvic and global spinal alignment changes from standing to sitting between nondeformity and ASD patients, particularly for SVA (nondeformed: 49.5 mm versus ASD: 27.4 mm; P&thinsp;< .001) and PI-LL (20.12° versus 13.01°, P < .001). With application of the Schwab classification system upon the cohort, PI-LL (P = .040) and SVA (P = .007) for severely classified deformity patients had significantly less positional alignment change. In an additional analysis of patients with segmental measurements from C2 to T12, nondeformity patients showed significant mobility of T2-T3 (-0.99° to -0.54°, P = .023), T6-T7 (-3.39° to -2.89°, P = .032), T7-T8 (-2.68° to -2.23°, P = .048), and T10-T11 (0.31° to 0.097°, P = .006) segments from standing to sitting. ASD patients showed mobility of the C6-C7 (1.76° to 3.45°, P < .001) and T11-T12 (0.98° to 0.54°, P = 0.014) from standing to sitting. The degree of mobility between nondeformity and ASD patients was significantly different in C6-C7 (-0.18° versus 1.69°, P = .003), T2-T3 (0.45° versus -0.27°, P = .034), and T10-T11 (0.45° versus -0.30°, P = .001) segments. With application of the Schwab modifier system upon the cohort, mobility was significant in the C6-C7 (nondeformed: 0.18° versus moderately deformed: 2.12° versus markedly deformed: 0.92°, P = .039), T2-T3 (0.45° versus -0.08° versus -0.63°, P = .020), T6-T7 (0.48° versus 0.36° versus -1.85°, P = .007), and T10-T11 (0.45° versus -0.21° versus -0.23°, P = .009) segments.

Conclusions

Nondeformity patients and ASD patients have significant differences in mobility of global spinopelvic parameters as well as segmental regions in the cervical and thoracic spine between sitting and standing. This study aids in our understanding of flexibility and compensatory mechanisms in deformity patients, as well as the possible impact on unfused segments when considering deformity corrective surgery.

Impact of presenting patient characteristics on surgical complications and morbidity in early onset scoliosis

This study sought to assess comorbidity profiles unique to early-onset-scoliosis (EOS) patients by employing cluster analytics and to determine the influence of isolated comorbidity clusters on perioperative complications, morbidity and mortality using a high powered administrative database. The KID database was queried for ICD-9 codes pertaining to congenital and idiopathic scoliosis from 2003, 2006, 2009, 2012. Patients <10 y/o (EOS group) were included. Demographics, incidence and comorbidity profiles were assessed. Comorbidity profiles were stratified by body systems (neurological, musculoskeletal, pulmonary, cardiovascular, renal). K-means cluster and descriptive analyses elucidated incidence and comorbidity relationships between frequently co-occurring comorbidities. Binary logistic regression models determined predictors of perioperative complication development, mortality, and extended length-of-stay (≥75th percentile). 25,747 patients were included (Age: 4.34, Female: 52.1%, CCI: 0.64). Incidence was 8.9 per 100,000 annual discharges. 55.2% presented with pulmonary comorbidities, 48.7% musculoskeletal, 43.8% neurological, 18.6% cardiovascular, and 11.9% renal; 38% had concurrent neurological and pulmonary. Top inter-bodysystem clusters: Pulmonary disease (17.2%) with epilepsy (17.8%), pulmonary failure (12.2%), restrictive lung disease (10.5%), or microcephaly and quadriplegia (2.1%). Musculoskeletal comorbidities (48.7%) with renal and cardiovascular comorbidities (8.2%, OR: 7.9 [6.6-9.4], p < 0.001). Top intra-bodysystem clusters: Epilepsy (11.7%) with quadriplegia (25.8%) or microcephaly (20.5%). Regression analysis determined neurological and pulmonary clusters to have a higher odds of perioperative complication development (OR: 1.28 [1.19-1.37], p < 0.001) and mortality (OR: 2.05 [1.65-2.54], p < 0.001). Musculoskeletal with cardiovascular and renal anomalies had higher odds of mortality (OR: 1.72 [1.28-2.29], p < 0.001) and extLOS (OR: 2.83 [2.48-3.22], p < 0.001). EOS patients with musculoskeletal conditions were 7.9x more likely to have concurrent cardiovascular and renal anomalies. Clustered neurologic and pulmonary anomalies increased mortality risk by as much as 105%. These relationships may benefit pre-operative risk assessment for concurrent anomalies and adverse outcomes. Level of Evidence: III - Retrospective Prognostic Study.

Arm Pain Versus Neck Pain: A Novel Ratio as a Predictor of Post-Operative Clinical Outcomes in Cervical Radiculopathy Patients

Background

Informed patient selection and counseling is key in improving surgical outcomes. Understanding the impact that certain baseline variables can have on postoperative outcomes is essential in optimizing treatment for certain symptoms, such as radiculopathy from cervical spine pathologies. The aim was to identify baseline characteristics that were related to improved or worsened postoperative outcomes for patients undergoing surgery for cervical spine radiculopathic pain.

Methods

Retrospective review of prospectively collected data. Patient Sample: Surgical cervical spine patients with a diagnosis classification of "degenerative." Diagnoses included in the "degenerative" category were those that caused radiculopathy: cervical disc herniation, cervical stenosis, and cervical spondylosis without myelopathy. Baseline variables considered as predictors were: (1) age, (2) body mass index (BMI), (3) gender, (4) history of cervical spine surgery, (5) baseline Neck Disability Index (NDI) score, (6) baseline SF-36 Physical Component Summary (PCS) scores, (7) baseline SF-36 Mental Component Summary (MCS) scores, (8) Visual Analog Scale (VAS) Arm score, and (9) VAS Neck. Outcome Measures: Improvement in NDI (≥50%), VAS Arm/Neck (≥50%), SF-36 PCS/MCS (≥10%) scores at 2-years postoperative. An arm-to-neck ratio (ANR) was also generated from baseline VAS scores. Univariate and multivariate analyses evaluated predictors for 2-year postoperative outcome improvements, controlling for surgical complications and technique.

Results

Three hundred ninety-eight patients were included. Patients with ANR ≤ 1 (n = 214) were less likely to reach improvements in 2-year NDI (30.0% vs 39.2%, P = .050) and SF-36 PCS (42.4% vs 53.5%, P = .025). Multivariate analysis for neck disability revealed higher baseline SF-36 PCS (odds ratio [OR] 1.053) and MCS (OR 1.028) were associated with over 50% improvements. Higher baseline NDI were reduced odds of postoperative neck pain improvement (OR 0.958). Arm pain greater than neck pain at baseline was associated with both increased odds of postoperative arm pain improvement (OR 1.707) and SF36 PCS improvement (OR 1.495).

Conclusions

This study identified specific symptom locations and health-related quality of life (HRQL) scores, which were associated with postoperative pain and disability improvement. In particular, baseline arm pain greater than neck pain was determined to have the greatest impact on whether patients met at least 50% improvement in their upper body pain score. These findings are important for clinicians to optimize patient outcomes through effective preoperative counseling.

Trends in Nonoperative Treatment Modalities Prior to Cervical Surgery and Impact on Patient-Derived Outcomes: Two-Year Analysis of 1522 Patients From the Prospective Spine Treatment Outcome Study

Background

Effects of nonoperative treatments on surgical outcomes for patients who failed conservative management for cervical spine pathologies remain unknown. The objective is to describe conservative modality use in patients indicated for surgery for degenerative cervical spine conditions and its impact on perioperative outcomes.

Methods

The current study comprises a retrospective review of a prospective multicenter database. A total of 1522 patients with 1- to 2-level degenerative cervical pathology who were undergoing surgical intervention were included. Outcome measures used were health-related quality-of-life scores, length of hospitalization, estimated blood loss, length of surgery, and return-to-work status at 2 weeks, 6 months, 1 year, and 2 years postoperatively. Patients were grouped by diagnosis (radiculopathy vs. myelopathy), then divided based on epidural injection(s), physical therapy (PT), or opioid use prior to enrollment. Univariate t-tests and χ² tests were performed to determine differences between groups and impact on outcomes.

Results

Among 1319 radiculopathy patients, 25.7% received preoperative epidural injections, 35.3% received PT, and 35.5% received opioids. Radiculopathy patients who received epidurals and PT had higher 1-year postoperative return-to-work rates (P < .05). Radiculopathy patients without preoperative PT had longer hospitalization times, whereas those who received PT had higher 36-Item Short Form Health Survey (SF-36) physical functioning and physical component scores, lower 2-year visual analog scale (VAS) neck/arm pain scores, and higher 2-year return-to-work incidence (P < .05). Of myelopathy patients (n = 203), 14.8% received epidural injections, 25.1% received opioids, and 41.5% received PT. Myelopathy patients with preoperative PT had worse VAS arm pain scores 2 years postoperatively (P < .05). Patients receiving opioids were younger and had greater baseline-2-year Neck Disability Index improvement (P < .05).

Conclusions

Radiculopathy patients receiving epidurals returned to work after 1 year more frequently. PT was associated with shorter hospitalizations, greater SF-36 bodily pain norm and physical component score improvements, and increased return-to-work rates after 1 and 2 years. No statistically significant nonoperative treatment was associated with return-to-work rate in myelopathy patients.

Clinical Relevance

These findings suggest certain preoperative conservative treatment modalities are associated with improved outcomes in radiculopathy patients.

Differences in primary and revision deformity surgeries: following 1,063 primary thoracolumbar adult spinal deformity fusions over time

Background

This study aims to describe properties of adult spinal deformity (ASD) revisions relative to primary surgeries and determine clinical variables that can predict revision. ASD is a common pathology that can lead to decreased quality of life, pain, physical limitations, and dissatisfaction with self-image. Durability of interventions for deformity treatment is of paramount concern to surgeons, as revision rates remain high.

Methods

Patients undergoing thoracolumbar fusion, five or more levels, for scoliosis (primary diagnosis ICD-9 737.x) were identified on a state-wide database. Primary and revision (returning for re-fusion procedure) surgeries were compared based on demographic, hospital stay, and clinical characteristics. Differences between primary and revision surgeries, and predictors of primary surgeries requiring revision, utilized binary logistic regression controlling for age, comorbidity burden, and levels fused.

Results

A total of 1,063 patients (average 7.4 levels fused, mean age: 47.6 years, 69.0% female) undergoing operative treatment for ASD were identified, of which 123 (average 7.1 levels fused, 11.6%, mean age 61.43, 80.5% female) had surgical revision. Primary surgeries were ~0.3 levels longer (P=0.013), used interbody ~11% more frequently (P=0.020), and used BMP ~12% less frequently (P=0.008). Revisions occurred 176.4 days after the primary on average. The most frequent causes of revisions were: 43.09% implant failure, 24.39% acquired kyphosis, and 14.63% enduring scoliosis. After controlling for age, comorbidities, and levels fused older, more comorbid, female, and white-race patients were more likely to be revised. Upon multivariate regression, after controlling for age and levels fused, overall complications remained non-different (OR: 0.8, 95% CI: 0.6-1.2). However, revision remained an independent predictor for infection (OR: 5.5, 95% CI: 2.8-10.5).

Conclusions

In a statewide database with individual patient follow up of up to 4 years 10% of ASD patients undergoing scoliosis correction required revision. Revision surgeries had higher infection incidence.

Risk Factors for Reoperation in Patients Treated Surgically for Intervertebral Disc Herniation: A Subanalysis of Eight-Year SPORT Data

BACKGROUND

Lumbar discectomy and laminectomy in patients with intervertebral disc herniation (IDH) is common, with variable reported reoperation rates. Our study examined which baseline characteristics might be risk factors for reoperation and compared outcomes between patients who underwent reoperation and those who did not.

METHODS

We performed a retrospective subgroup analysis of patients from the IDH arm of the Spine Patient Outcomes Research Trial (SPORT) randomized and observational cohorts. We analyzed baseline characteristics and outcomes of patients who underwent reoperation and those who did not with use of data collected from enrollment through eight-years of follow-up after surgery. Follow-up times were measured from the time of surgery, and baseline covariates were updated to the follow-up immediately preceding the time of surgery for outcomes analyses.

RESULTS

At eight years, the reoperation rate was 15% (691 no reoperation; 119 reoperation). Sixty-two percent of these patients underwent reoperation because of a recurrent disc herniation; 25%, because of a complication or other factor; and 11%, because of a new condition. The proportion of reoperations that were performed for a recurrent disc herniation ranged from 58% to 62% in the individual years. Older patients were less likely to have reoperation (p = 0.015), as were patients presenting with asymmetric motor weakness at baseline (p = 0.0003). Smoking, diabetes, obesity, Workers' Compensation, and clinical depression were not associated with a greater risk of reoperation. Scores on the Short Form (SF)-36 for bodily pain and physical functioning, the Oswestry Disability Index (ODI), and the Sciatica Bothersomeness Index as well as satisfaction with symptoms had improved less at the time of follow-up in the reoperation group (p < 0.001).

CONCLUSIONS

In patients who underwent surgery for IDH, the overall reoperation rate was 15% at the eight-year follow-up. Patients of older age and patients presenting with asymmetric motor weakness were less likely to undergo a reoperation. Less improvement in patient-reported outcomes was noted in the reoperation group.

Effectiveness of postoperative wound drains in one- and two-level cervical spine fusions

Background

Cervical drains have historically been used to avoid postoperative wound and respiratory complications such as excessive edema, hematoma, infection, re-intubation, delayed extubation, or respiratory distress. Recently, some surgeons have ceased using drains because they may prolong hospital stay, operative time, or patient discomfort. The objective of this retrospective case-control series is to investigate the effectiveness of postoperative drains following one- and two-level cervical fusions.

Methods

A chart review was conducted at a single institution from 2010-2013. Outcome measures included operative time, hospital stay, estimated blood loss and incidence of wound complications (infection, hematoma, edema, and complications with wound healing or evacuation), respiratory complications (delayed extubation, re-intubation, and respiratory treatment), and overall complications (wound complications, respiratory complications, dysphagia, and other complications). Statistical analyses including independent samples t-test, chi-square, analysis of covariance, and linear regression were used to compare patients who received a postoperative drain to those who did not.

Results

The study population included 39 patients who received a postoperative drain and 42 patients who did not. There were no differences in demographics between the two groups. Patients with drains showed increased operative time (100.1 vs 69.3 min, p < 0.001), hospital stay (38.9 vs. 31.7 hrs, p = 0.021), and blood loss (62.7 vs 29.1 mL, p < 0.001) compared to patients without drains. The frequency of wound complications, respiratory complications, and overall complications did not vary significantly between groups.

Conclusions/Level of Evidence

Cervical drains may not be necessary for patients undergoing one- and two-level cervical fusion. While there were no differences in incidence of complications between groups, patients treated with drains had significantly longer operative time and length of hospital stay.

Clinical relevance

This could contribute to excessive costs for patients treated with drains, despite the lack of compelling evidence of the advantages of this treatment in the literature and in the current study.

Mitigating adverse event reporting bias in spine surgery

BACKGROUND

Recent articles in the lay press and literature have raised concerns about the ability to report honest adverse event data from industry-sponsored spine surgery studies. To address this, clinical trials may utilize an independent Clinical Events Committee (CEC) to review adverse events and readjudicate the severity and relatedness accordingly. We are aware of no prior study that has quantified either the degree to which investigator bias is present in adverse event reporting or the effect that an independent CEC has on mitigating this potential bias.

METHODS

The coflex Investigational Device Exemption study is a prospective randomized controlled trial comparing coflex (Paradigm Spine) stabilization with lumbar spinal fusion to treat spinal stenosis and spondylolisthesis. Investigators classified the severity of adverse events (mild, moderate, or severe) and their relationship to the surgery and device (unrelated, unlikely, possibly, probably, or definitely). An independent CEC, composed of three spine surgeons without affiliation to the study sponsor, reviewed and reclassified all adverse event reports submitted by the investigators.

RESULTS

The CEC reclassified the level of severity, relation to the surgery, and/or relation to the device in 394 (37.3%) of 1055 reported adverse events. The proportion of adverse events that underwent reclassification was similar in the coflex and fusion groups (37.9% compared with 36.0%, p = 0.56). The CEC was 5.3 (95% confidence interval [CI], 2.6 to 10.7) times more likely to upgrade than downgrade the adverse event. The CEC was 7.3 (95% CI, 5.1 to 10.6) times more likely to upgrade than downgrade the relationship to the surgery and 11.6 (95% CI, 7.5 to 18.8) times more likely to upgrade than downgrade the relationship to the device. The status of the investigator's financial interest in the company had little effect on the reclassification of adverse events.

CONCLUSIONS

Thirty-seven percent of adverse events were reclassified by the CEC; the large majority of the reclassifications were an upgrade in the level of severity or a designation of greater relatedness to the surgery or device.

CLINICAL RELEVANCE

An independent CEC can identify and mitigate potential inherent investigator bias and facilitate an accurate assessment of the safety profile of an investigational device, and a CEC should be considered a requisite component of future clinical trials.

Facet violation with the placement of percutaneous pedicle screws

STUDY DESIGN

Independent review and classification of therapeutic procedures performed on cadavers by surgeons blinded to purpose of study.

OBJECTIVE

The objective of this study is to determine the rate of facet violation with the placement of percutaneous pedicle screws.

SUMMARY OF BACKGROUND DATA

Improvements in percutaneous instrumentation and fluoroscopic imaging have led to a resurgence of percutaneous pedicle screw insertion in lumbar spine surgery in an attempt to minimize many of the complications associated with open techniques of pedicle screw placement. Rates of pedicle breech and neurologic injury resulting from percutaneous insertion are reportedly similar to those of open techniques. Postoperative pain because of impingement and instability is believed to result from violation of the facet capsule or facet joint. To the authors' knowledge, however, the rate of facet injury associated with the placement of percutaneous pedicle screws is unreported in the literature.

METHODS

Percutaneous pedicle screw placement was performed on 4 cadaveric specimens by 4 certified orthopedic surgeons who had clinical experience in the procedure and who were blinded to the study's purpose. The surgeons were instructed to place pedicle screws from L1-S1 using their preferred clinical techniques and a 5.5-mm screw system with which they were all familiar. All surgeons utilized 1 OEC C-arm for fluoroscopic imaging. After insertion, 2 independent spine surgeons each reviewed and classified the placement of all facet screws.

RESULTS

A total of 48 screws were inserted and classified. The placement of 28 screws (58%) resulted in violation of facet articulation, with 8 of these screws being intra-articular. Interobserver reliability of the classification system was 100%.

CONCLUSION

Percutaneous pedicle screw placement may result in a high rate of facet violation. Facet injury can be reliability classified and therefore, perhaps, easily prevented.

Quality of information concerning cervical disc herniation on the Internet

BACKGROUND CONTEXT

Many Americans seek and are influenced in their decision making by medical information on the Internet. Past studies have repeatedly found information on most medical Web sites to be deficient and of low quality. Physicians must remain aware of the quality and reliability of the information available on the Internet for patient education purposes.

PURPOSE

To assess quality and authorship of Internet Web sites regarding a common cervical spine disorder, cervical disc herniation.

STUDY DESIGN

The present study is a systematic quality assessment survey of Web sites concerning cervical disc herniation.

METHODS

Fifty relevant and unique sites were identified. The five most popular search engines were used to identify 100 Web sites using the search term, "cervical disc herniation." Using a validated technique, three orthopedic surgeons independently generated content quality scores and accuracy scores, then integrated into a single final total summary score for each Web site.

RESULTS

Four of the five identified top-scoring Web sites were found to be commercial and one was academic. Most of the Web sites were found to be physician sponsored, followed by academic and commercial.

CONCLUSIONS

There is wide variability in Web site quality, with most of the Web sites failing to be sufficiently comprehensive and accurate. Physicians treating patients with cervical disc herniation must remain vigilant in guiding their patients to proper information on the Internet.

Posterior tibialis tendon tears: comparison of the diagnostic efficacy of magnetic resonance imaging and ultrasonography for the detection of surgically created longitudinal tears in cadavers

RATIONALE AND OBJECTIVES

The optimal advanced imaging method for detection and characterization of posterior tibialis tendon (PTT) tears is unclear. The purpose of this study was to investigate the utility of ultrasonography (US) and MR imaging in the detection of surgically created PTT tears in cadavers.

MATERIALS AND METHODS

This was a prospective blinded study in which 16 fresh cadaveric foot and ankle specimens (3 men, 13 women; average age at death 83.9 years; age range 71-96 years) were scanned with both US and MR imaging before and after the surgical creation of 64 variable length longitudinal tears of the PTT. Ultrasonography was performed with a 12 MHz linear transducer with independent interpretations of static and dynamic studies separately by two blinded and experienced musculoskeletal radiologists. MR imaging was performed at 1.5 T with a standard transmit-receive extremity coil using axial, sagittal, coronal T1-weighted (TR 600, TE 20), and axial fast spin echo proton density and T2-weighted (TR 3000, TE 161/20, ETL 12) images. MR images were reviewed independently by two experienced musculoskeletal radiologists who were blinded to the status of the PTT.

RESULTS

Sensitivity, specificity, and accuracy of MR imaging in the diagnosis of PTT tears were 73%, 69%, and 72%, respectively. Dynamic US interpretation yielded values of 69% sensitivity, 81% specificity, and 72% accuracy. Static US interpretation was less reliable than dynamic interpretation, and the only significance of static imaging was a high specificity (94%) for detection of longitudinal tears. The positive predictive value (PPV) for MR imaging and US was 88% and 92% respectively, and the negative predictive value (NPV) was 46% for both MR imaging and US.

CONCLUSION

Our results suggest that US and MR imaging perform at the same level for the detection of surgically created longitudinal PTT tears in a cadaveric model. US has a higher specificity compared with MR imaging.

Effect of surgical cricothyrotomy on the unstable cervical spine in a cadaver model of intubation

Cricothyrotomy is indicated for patients who require an immediate airway and in whom orotracheal or nasotracheal intubation is unsuccessful or contraindicated. Cricothyrotomy is considered safe with cervical spine (c-spine) injury; however, the amount of c-spine movement that occurs during the procedure has not been determined. In this experimental study, an established cadaver model of c-spine injury was used to quantify movement during cricothyrotomy. A complete C5--6 transection was performed by using an osteotome on 13 fresh-frozen cadavers. Standard open cricothyrotomy was performed on each cadaver, with c-spine images recorded in real time on fluoroscopy, then transferred to video and Kodachrome still images. Outcome measures included movement across the C5--6 site with regard to angulation expressed in degrees of rotation and linear measures of axial distraction and anterior-posterior (AP) displacement expressed as a proportion of C5 body width. Data were analyzed by using descriptive statistics to determine mean change from baseline in each of three planes of movement. Significance was assumed if 95% confidence intervals did not include zero. A significant amount of movement was observed with regard to AP displacement (6.3% of C5 width) and axial distraction (-4.5% of C5 width, indicating narrowing of the intervertebral space). These correspond to 1--2 mm AP displacement and less than 1 mm axial compression. No significant angular displacement was observed. In conclusion, cricothyrotomy results in a small but significant amount of movement across an unstable c-spine injury in a cadaver model. This degree of movement is less than the threshold for clinical significance.

Effects of cervical spine immobilization technique and laryngoscope blade selection on an unstable cervical spine in a cadaver model of intubation

STUDY OBJECTIVE

Orotracheal intubation (OTI) is commonly used to establish a definitive airway in major trauma victims, with several different cervical spine immobilization techniques and laryngoscope blade types used. This experimental, randomized, crossover trial evaluated the effects of manual in-line stabilization and cervical collar immobilization and 3 different laryngoscope blades on cervical spine movement during OTI in a cadaver model of cervical spine injury.

METHODS

A complete C5-C6 transection was performed by using an osteotome on 14 fresh-frozen cadavers. OTI was performed in a randomized crossover fashion by using both immobilization techniques and each of 3 laryngoscope blades: the Miller straight blade, the Macintosh curved blade, and the Corazelli-London-McCoy hinged blade. Intubations were recorded in real time on fluoroscopy and then transferred to video and color still images. Outcome measures included movement across C5-C6 with regard to angulation expressed in degrees of rotation and axial distraction and anteroposterior displacement with values expressed as a proportion of C5 body width. Cormack-Lehane visualization grades were also recorded as a secondary outcome measure. Data were analyzed by using multivariate analysis of variance to test for differences between immobilization techniques and between laryngoscope blades and to detect for interactions. Significance was assumed for P values of less than.05.

RESULTS

Manual in-line stabilization resulted in significantly less movement than cervical collar immobilization during OTI with regard to anteroposterior displacement. Use of the Miller straight blade resulted in significantly less movement than each of the other 2 blades with regard to axial distraction. The Cormack-Lehane grade was significantly better with manual in-line stabilization versus cervical collar immobilization; no differences were observed between blades.

CONCLUSION

Manual in-line stabilization results in less cervical subluxation and allows better vocal cord visualization during OTI in a cadaver model of cervical spine injury. The Miller laryngoscope blade allowed less axial distraction than the Macintosh or Corzelli-London-McCoy blades. The clinical significance of this degree of movement is unclear.

Invasion of human follicular thyroid carcinoma cells in an in vivo invasion model

Models that demonstrate histological invasion of extracellular matrix barriers by tumor cell lines are useful for assessing new methods to treat or prevent tumor metastasis. An in vivo invasion model using acellular human dermal matrix has been described in a murine squamous cell carcinoma line. The present study examined the application of this tumor invasion model to another epithelial cell line derived from a different species. A human follicular thyroid carcinoma cell line, known to be invasive by other assays, was grown on the dermal-epidermal basement membrane surface of human acellular dermal matrix in culture and then grafted in athymic mice. Immunohistochemical staining of type IV collagen was used to identify the basement membrane and invasion was determined as penetration of the basement membrane by tumor cells. Identification of the human tumor cells in the in vivo grafts was done by in situ hybridization with species specific probes. FTC-133 tumor cells did not invade the matrix after 4 weeks of growth in in vitro culture, but there was extensive loss of the basement membrane and infiltration of the tumor cells into the dermis after 2 weeks growth in vivo. This study suggests that the in vivo dermal matrix model of invasion is applicable to a broad range of epithelial carcinoma cell lines to study their capability to penetrate basement membrane. A model such as this may be useful for studying the local effects of genetic manipulations of implanted tumor cell populations, leading to the development of therapeutic agents that block invasion.