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Andrew T. Healy, Prasath Mageswaran, Daniel Lubelski, Benjamin P. Rosenbaum, Virgilio Matheus, Edward C. Benzel and Thomas E. Mroz

OBJECT

The degenerative process of the spinal column results in instability followed by a progressive loss of segmental motion. Segmental degeneration is associated with intervertebral disc and facet changes, which can be quantified. Correlating this degeneration with clinical segmental motion has not been investigated in the thoracic spine. The authors sought to determine if imaging-determined degeneration would correlate with native range of motion (ROM) or the change in ROM after decompressive procedures, potentially guiding clinical decision making in the setting of spine trauma or following decompressive procedures in the thoracic spine.

METHODS

Multidirectional flexibility tests with image analysis were performed on thoracic cadaveric spines with intact ib cage. Specimens consisted of 19 fresh frozen human cadaveric spines, spanning C-7 to L-1. ROM was obtained for each specimen in axial rotation (AR), flexion-extension (FE), and lateral bending (LB) in the intact state and following laminectomy, unilateral facetectomy, and unilateral costotransversectomy performed at either T4–5 (in 9 specimens) or T8–9 (in 10 specimens). Image grading of segmental degeneration was performed utilizing 3D CT reconstructions. Imaging scores were obtained for disc space degeneration, which quantified osteophytes, narrowing, and endplate sclerosis, all contributing to the Lane disc summary score. Facet degeneration was quantified using the Weishaupt facet summary score, which included the scoring of facet osteophytes, narrowing, hypertrophy, subchondral erosions, and cysts.

RESULTS

The native ROM of specimens from T-1 to T-12 (n = 19) negatively correlated with age in AR (Pearson’s r coefficient = -0.42, p = 0.070) and FE (r = -0.42, p = 0.076). When regional ROM (across 4 adjacent segments) was considered, the presence of disc osteophytes negatively correlated with FE (r = −0.69, p = 0.012), LB (r = −0.82, p = 0.001), and disc narrowing trended toward significance in AR (r = −0.49, p = 0.107). Facet characteristics, scored using multiple variables, showed minimal correlation to native ROM (r range from −0.45 to +0.19); however, facet degeneration scores at the surgical level revealed strong negative correlations with regional thoracic stability following decompressive procedures in AR and LB (Weishaupt facet summary score: r = −0.52 and r = −0.71; p = 0.084 and p = 0.010, respectively). Disc degeneration was not correlated (Lane disc summary score: r = −0.06, p = 0.861).

CONCLUSIONS

Advanced age was the most important determinant of decreasing native thoracic ROM, whereas imaging characteristics (T1–12) did not correlate with the native ROM of thoracic specimens with intact rib cages. Advanced facet degeneration at the surgical level did correlate to specimen stability following decompressive procedures, and is likely indicative of the terminal stages of segmental degeneration.

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Benjamin D. Kuhns, Daniel Lubelski, Matthew D. Alvin, Jason S. Taub, Matthew J. McGirt, Edward C. Benzel and Thomas E. Mroz

OBJECT

Infections following spine surgery negatively affect patient quality of life (QOL) and impose a significant financial burden on the health care system. Postoperative wound infections occur at higher rates following dorsal cervical procedures than ventral procedures. Quantifying the health outcomes and costs associated with infections following dorsal cervical procedures may help to guide treatment strategies to minimize the deleterious consequences of these infections. Therefore, the goals of this study were to determine the cost and QOL outcomes affecting patients who developed deep wound infections following subaxial dorsal cervical spine fusions.

METHODS

The authors identified 22 (4.0%) of 551 patients undergoing dorsal cervical fusions who developed deep wound infections requiring surgical debridement. These patients were individually matched with control patients who did not develop infections. Health outcomes were assessed using the EQ-5D, Pain Disability Questionnaire (PDQ), Patient Health Questionnaire (PHQ-9), and visual analog scale (VAS). QOL outcome measures were collected preoperatively and after 6 and 12 months. Health resource utilization was recorded from patient electronic medical records over an average follow-up of 18 months. Direct costs were estimated using Medicare national payment amounts, and indirect costs were based on patients' missed workdays and income.

RESULTS

No significant differences in preoperative QOL scores were found between the 2 cohorts. At 6 months postsurgery, the noninfection cohort had significant pre- to postoperative improvement in EQ-5D (p = 0.02), whereas the infection cohort did not (p = 0.2). The noninfection cohort also had a significantly higher 6-month postoperative EQ-5D scores than the infection cohort (p = 0.04). At 1 year postsurgery, there was no significant difference in EQ-5D scores between the groups. Health care–associated costs for the infection cohort were significantly higher ($16,970 vs $7658; p < 0.0001). Indirect costs for the infection cohort and the noninfection cohort were $6495 and $2756, respectively (p = 0.03). Adjusted for inflation, the total costs for the infection cohort were $21,778 compared with $9159 for the noninfection cohort, reflecting an average cost of $12,619 associated with developing a postoperative deep wound infection (p < 0.0001).

CONCLUSIONS

Dorsal cervical infections temporarily decrease patient QOL postoperatively, but with no long-term impact; they do, however, dramatically increase the cost of care. Knowledge of the financial burden of wound infections following dorsal cervical fusion may stimulate the development and use of improved prophylactic and therapeutic techniques to manage this serious complication.

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Daniel Lubelski, Nicolas R. Thompson, Sachin Bansal, Thomas E. Mroz, Daniel J. Mazanec, Edward C. Benzel and Tagreed Khalaf

OBJECT

The goal of this study was to determine whether pretreatment depression is predictive of quality of life (QOL) improvement for patients with lumbar spinal stenosis (LSS) who are treated conservatively.

METHODS

This retrospective cohort study included patients with LSS and concordant neurogenic claudication who were treated nonoperatively at a single institution between September 2010 and March 2013. Patient QOL measures were recorded pretreatment and then 4 months after treatment. Pretreatment depression was assessed using the Patient Health Questionnaire–9 (PHQ-9). Successful outcome was defined as posttreatment improvement in EuroQol-5D (EQ-5D) index or in Pain and Disability Questionnaire (PDQ) scores. Regression analysis was performed to identify independent predictors of outcome while controlling for confounding variables.

RESULTS

A total of 502 patients were included in the study. The average age for these patients was 66.1 years, with 51% female and 90.6% white. After adjusting for baseline demographic and clinical variables, there was a statistically significant association between baseline PHQ-9 score and posttreatment change in EQ-5D index (β = −0.007, p = 0.0002). All other things being equal, a patient with a baseline PHQ-9 score of 0 (no depression) would be expected to improve in the EQ-5D index by 0.14 points (greater than the minimum clinically important difference) more than would a patient with a baseline PHQ-9 score of 20 (major depression). There was no significant association between baseline PHQ-9 score and change in Pain and Disability Questionnaire scores.

CONCLUSIONS

When controlling for other baseline characteristics, severely depressed patients with LSS who are treated nonoperatively have significantly less improvement in their QOL compared with those with little or no depression. These data are similar to the negative predictive effects of depression on posttreatment QOL following lumbar fusion surgery.

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Daniel Lubelski, Nilgun Senol, Michael P. Silverstein, Matthew D. Alvin, Edward C. Benzel, Thomas E. Mroz and Richard Schlenk

OBJECT

The authors investigated quality of life (QOL) outcomes after primary versus revision discectomy.

METHODS

A retrospective review was performed for all patients who had undergone a primary or revision discectomy at the Cleveland Clinic Center for Spine Health from January 2008 through December 2011. Among patients in the revision cohort, they identified those who needed a second revision discectomy. Patient QOL measures were recorded before and after surgery. These measures included responses to the EQ-5D health questionnaire, Patient Health Questionnaire–9, Pain and Disability Questionnaire, and quality-adjusted life years (QALYs). Cohorts were compared by using independent-sample t-tests and Fisher exact tests for continuous and categorical variables, respectively. Multivariable logistic regression was performed to adjust for confounding.

RESULTS

A total of 196 patients were identified (116 who underwent primary discectomy and 80 who underwent revision discectomy); average follow-up time was 150 days. There were no preoperative QOL differences between groups. Postoperatively, both groups improved significantly in all QOL measures. For QALYs, the primary cohort improved by 0.25 points (p < 0.001) and the revision cohort improved by 0.18 points (p < 0.001). QALYs improved for significantly more patients in the primary than in the revision cohort (76% vs 59%, respectively; p = 0.02), and improvement exceeded the minimum clinically important difference for more patients in the primary cohort (62% vs 45%, respectively; p = 0.03). Of the 80 patients who underwent revision discectomy, yet another recurrent herniation (third herniation) occurred in 14 (17.5%). Of these, 4 patients (28.6%) chose to undergo a second revision discectomy and the other 10 (71.4%) underwent conservative management. For those who underwent a second revision discectomy, QOL worsened according to all questionnaire scores.

CONCLUSIONS

QOL, pain and disability, and psychosocial outcomes improved after primary and revision discectomy, but the improvement diminished after revision discectomy.

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Daniel Lubelski, William E. McCormick, Lisa Ferrara, Edward C. Benzel and Mark Kayanja

Object

The authors conducted a study to compare biomechanical effects on the cervical spine of bridging fixation and intermediate fixation techniques, in both fixed and dynamic modes.

Methods

A biaxial, servohydraulic machine biomechanically tested 23 human cervical spines for stiffness and strain in compression, extension, flexion, and lateral bending through 3 specimen states: 1) intact, 2) defect (corpectomy and discectomy), and 3) grafting with plate application in 1 of 4 constructs: C3–7 dynamized long strut (DLS), C3–7 fixed long strut (FLS), C3–5–7 dynamized multisegment (DMS), and C3–5–7 fixed multisegment (FMS).

Results

Compared with FMS, FLS had significantly greater strain in extension (at C-3 and at the rostral and caudal parts of the graft) and in lateral bending (at C-3 and at the caudal part of the graft). Fixed (FLS and FMS) constructs had greater flexion stiffness than did dynamized (DLS and DMS) constructs and showed a trend toward greater lateral bending stiffness. Instrumentation revealed greater extension strain with the long fixed (FLS and DLS) constructs than with the multifixed (FMS and FMS) constructs at the rostral and caudal parts of the graft but no significant differences between the dynamized (DLS and DMS) and fixed (FLS and FMS) constructs.

Conclusions

Multisegmental fixation provided greater stabilizing forces than did bridging constructs for both dynamized and fixed plates. Use of multisegmental fixation can potentially decrease strain at the screw-plate interface and reduce the rate of hardware failure.

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Matthew D. Alvin, Jacob A. Miller, Daniel Lubelski, Benjamin P. Rosenbaum, Kalil G. Abdullah, Robert G. Whitmore, Edward C. Benzel and Thomas E. Mroz

Object

Cost-effectiveness research in spine surgery has been a prominent focus over the last decade. However, there has yet to be a standardized method developed for calculation of costs in such studies. This lack of a standardized costing methodology may lead to conflicting conclusions on the cost-effectiveness of an intervention for a specific diagnosis. The primary objective of this study was to systematically review all cost-effectiveness studies published on spine surgery and compare and contrast various costing methodologies used.

Methods

The authors performed a systematic review of the cost-effectiveness literature related to spine surgery. All cost-effectiveness analyses pertaining to spine surgery were identified using the cost-effectiveness analysis registry database of the Tufts Medical Center Institute for Clinical Research and Health Policy, and the MEDLINE database. Each article was reviewed to determine the study subject, methodology, and results. Data were collected from each study, including costs, interventions, cost calculation method, perspective of cost calculation, and definitions of direct and indirect costs if available.

Results

Thirty-seven cost-effectiveness studies on spine surgery were included in the present study. Twenty-seven (73%) of the studies involved the lumbar spine and the remaining 10 (27%) involved the cervical spine. Of the 37 studies, 13 (35%) used Medicare reimbursements, 12 (32%) used a case-costing database, 3 (8%) used cost-to-charge ratios (CCRs), 2 (5%) used a combination of Medicare reimbursements and CCRs, 3 (8%) used the United Kingdom National Health Service reimbursement system, 2 (5%) used a Dutch reimbursement system, 1 (3%) used the United Kingdom Department of Health data, and 1 (3%) used the Tricare Military Reimbursement system. Nineteen (51%) studies completed their cost analysis from the societal perspective, 11 (30%) from the hospital perspective, and 7 (19%) from the payer perspective. Of those studies with a societal perspective, 14 (38%) reported actual indirect costs.

Conclusions

Changes in cost have a direct impact on the value equation for concluding whether an intervention is cost-effective. It is essential to develop a standardized, accurate means of calculating costs. Comparability and transparency are essential, such that studies can be compared properly and policy makers can be appropriately informed when making decisions for our health care system based on the results of these studies.