Faculty Bibliography

STUDY DESIGN: Retrospective review OBJECTIVE.: To evaluate preoperative variability in radiographic sagittal parameters in adult spinal deformity (ASD). SUMMARY OF BACKGROUND DATA: In ASD surgical planning, deformity magnitude is determined from pre-op radiographs. The are no studies evaluating the clinical relevance and timing to repeat radiographs during interval clinic visits and timing to repeat radiograph for preoperative planning. METHODS: 139 ASD patients with minimum two pre-operative full body spine x-rays were included. Cervical, thoracic, lumbar, pelvic, and hip/knee sagittal alignment parameters were analyzed using dedicated spine measurement software. Patients were grouped by time intervals between x-rays: A: /=21 weeks. Changes in sagittal parameters were correlated to age and deformity magnitude (T1 pelvic angle [TPA] or pelvic tilt [PT] >20 degrees ). RESULTS: The cohort had mean age 59 years, mean BMI 27, 30% males, 95 patients with no prior spine surgery and 44 patients at minimum nine months since prior spine surgery. There were 25 patients in Group A, 38 in B, and 71 in C. All radiographic measures showed good time-based consistency at intervals <21 weeks (Groups A and B). Group C had significant increases in PT (1.5 degrees ) and hip extension (2.1 degrees ) (p < 0.05). These changes were greater in Group C patients with previous surgery (PT 3.7 degrees ; p < .006, hip extension 3.2 degrees ; p < .025). Greater interval changes in parameters were also associated with higher magnitude of deformity and younger patient age. CONCLUSIONS: All sagittal radiographic parameters were statistically consistent at intervals < 21 weeks. In patients with >21 weeks between interval x-rays, change in PT was greater than the standard error of measurement for patients with prior surgery or severe deformity. Consideration should be made to obtain new x-rays for adult spinal deformity patients when the interval between clinical visits exceeds 5 months. LEVEL OF EVIDENCE: 4.

BACKGROUND CONTEXT: Degenerative lumbar stenosis (DLS) patients have been reported to lean forward in an attempt to provide neural decompression. Spinal alignment in patients with DLS may resemble that of adult spinal deformity (ASD). No previous studies have compared and contrasted the compensatory mechanisms of DLS and ASD patients. PURPOSE: To determine the differences in compensatory mechanisms between DLS and ASD patients with increasing severity of sagittal spino-pelvic malalignment. Contrasting these compensatory mechanisms may help determine at what severity sagittal malalignment represents a clinical sagittal deformity rather than a compensation for neural compression. STUDY DESIGN/SETTING: Retrospective clinical and radiological review PATIENT SAMPLE:: Baseline x-rays in patients without spinal instrumentation, with the clinical radiological and diagnoses of DLS or ASD were assessed for patterns of spino-pelvic compensatory mechanisms. Patients were stratified by sagittal vertical axis (SVA) by the Schwab-SRS classification. OUTCOME MEASURES: Radiographic spino-pelvic parameters were measured in the DLS and ASD groups, including SVA, PI-LL, T1SPi, TPA and PT METHODS: The two diagnosis cohorts were propensity matched for pelvic incidence and age. Each group contained 125 patients. Each group was stratified according to the SRS-Schwab classification. Regional spino-pelvic, lower limb and global alignment parameters were assessed in each group to identify differences in compensatory mechanisms between the two groups with differing degrees of deformity. No funding was provided by any third party in relation to carrying out this study or preparation of the manuscript. RESULTS: With mild to moderate malalignment (SRS-Schwab groups '0', or '+' for pelvic tilt, pelvic incidence-lumbar lordosis mismatch or sagittal vertical axis), DLS patients permit anterior truncal inclination and recruit posterior pelvic shift instead of pelvic tilt to maintain balance, while providing relief of neurological symptoms. ASD patients with mild- moderate deformity recruit pelvic tilt earlier than DLS patients. With moderate- severe malalignment, no significant difference was found in compensatory mechanisms between DLS and ASD patients. CONCLUSIONS: Patients with degenerative lumbar stenosis permit mild-moderate deformity without recruiting compensatory mechanisms of pelvic tilt, reducing truncal inclination and thoracic hypokyphosis in order to achieve neural decompression. However with moderate to severe deformity, their desire for upright posture overrides the desire for neural decompression, evident by the adaptation of compensatory mechanisms similar to that of the adult spinal deformity patients.

STUDY DESIGN: A systematic review. OBJECTIVE: To systematically review the previous literature regarding revision surgery for real recurrent lumbar disk herniation. SUMMARY OF BACKGROUND DATA: "Real" recurrent lumbar disk herniation means the presence of herniated disk material at the same level and side as the primary disk herniation. If conservative treatment fails, revision surgery, a major concern, is indicated. It is important for both patients and spine surgeons to understand epidemiology trends and outcomes of revision surgery for real recurrent lumbar disk herniation (real-RLDH). METHODS: The electronic databases PubMed, the Cochrane library, and EMBASE were queried for English articles regarding revision surgery for real-RLDH, published between January 1980 and May 2014. The incidence, interval between primary and revision surgery, risk factors, surgery type, complications, and clinical outcomes of revision surgery for real-RLDH were summarized. RESULTS: The reported incidence of revision surgery, specifically for real-RLDH, lies between 1.4% and 11.4%. The complication rate is reported between 0% and 34.6%, with dural tear being the most common complication. Previous studies revealed that satisfactory or successful clinical outcome was achieved in 60%-100% of patients after revision surgery for real-RLDH. Several studies reported similar clinical outcomes between primary and revision surgery. CONCLUSIONS: The incidence of revision surgery for real-RLDH is relatively low. It is essential to pay careful attention to prevent a dural tear. Patients may expect clinical outcomes similar to those following primary discectomy. LEVEL OF EVIDENCE: Level III.

BACKGROUND: The maintenance of horizontal gaze is an essential function of upright posture and global sagittal spinal alignment. Horizontal gaze is classically measured by the chin-brow vertical angle (CBVA), which is not readily measured on most lateral spine radiographs. OBJECTIVE: To evaluate relations between CBVA and the slope of the line of sight, the slope of McGregor's line (McGS), and Oswestry Disability Index. METHODS: Patients were identified from a single center database of 531 spine patients who underwent full-body EOS x-rays. Correlations between CBVA, the slope of the line of sight, and McGS were assessed. Using a quadratic regression with Oswestry Disability Index and CBVA, windows of low disability were identified. Comparison of sagittal spinopelvic parameters was carried out between patients with "ascending gaze" and "neutral position." RESULTS: Three hundred three patients were included (74% female, mean age 54.8 years, body mass index 26.6 +/- 6.0 kg/m). CBVA strongly correlated with the slope of the line of sight (r = 0.996) and McGS (r = 0.862). Regression studies between Oswestry Disability Index and CBVA yielded a range of values corresponding to low disability (-4.7 degrees to 17.7 degrees). Similarly, a low disability range for the slope of the line of sight (-5.1 degrees to 18.5 degrees) and McGS (-5.7 degrees to 14.3 degrees) was computed. Patients with "ascending gaze" had a worse spinopelvic alignment than "neutral position" patients. CONCLUSION: The slope of the line of sight and McGS correlated strongly with CBVA and can be used as surrogate measures. The range of values for these measures corresponding to low disability was identified. These values can be used as a general guideline to assess alignment for diagnostic purposes. Cervical compensatory mechanism may modify the natural head position in sagittally misaligned patients. ABBREVIATIONS: CBVA, chin-brow vertical angleHRQoL, health-related quality of lifeMcGS, slope of McGregor's lineODI, Oswestry Disability IndexSLs, slope of the line of sight.

STUDY DESIGN: Retrospective review. OBJECTIVE: This study follows the inpatient-stay administrative data that were collected for a cohort of thousands of patients who had spine fusion surgery in the state of New York. We sought to examine adult spinal deformity (ASD) for reoperation events with and without the use of bone morphogenetic protein-2 (BMP). SUMMARY OF BACKGROUND DATA: Randomized controlled trials have suggested that BMP may increase the likelihood of solid arthrodesis in spinal surgery. This would imply fewer reoperations for pseudarthrosis, but small cohort sizes are inadequate to monitor these events. METHODS: The 2008-2011 New York State Inpatient Database was queried using International Classification of Diseases, Ninth Revision, Clinical Modification codes. Patients age 21 years and older with a diagnosis of scoliosis and an index fusion of greater than 2 spinal motion segments were included. Patient identifiers and linkage variables were used to identify revisits. The relative risk of reoperation was calculated. The use of BMP at the initial inpatient stay was used to define the 2 cohorts for relative risk assessment. RESULTS: A total of 3751 patients of ASD were identified in 2008. The use of BMP at the initial visit was performed at a rate of 37.6% for ASD. For posterior fusion cases longer than 8 levels, the rate of reoperation for a pseudarthrosis was 23.4%. For ASD fusions greater than 8 levels, the rate of reoperation for pseudarthrosis after using BMP at the index surgery was 5% and 33.9% when BMP was not used, a relative risk of 7.5 (P < 0.001). CONCLUSION: Using relevant inhospital patient records from the New York State Inpatient Sample, we found a 7.5-fold decrease in the risk of reoperation for pseudarthrosis after long fusions when using BMP. Decreased reoperation rates are caused by the improved fusion with the use of BMP. If subsequent unnecessary hospitals stays can be avoided, the economics of BMP use should be reexamined. LEVEL OF EVIDENCE: 4.

With the advent of new instrumentation and better imaging techniques that allowed less tissue trauma compared with traditional open procedures, while providing adequate or enhanced visualization of the pathologic site and based upon the successful experience of outpatient spine surgery to assist early ambulation, the trend and evolution toward ''minimal access'' or minimally invasive spine surgery began to develop with greater intensity. Many surgical techniques have flourished with the promise of delivering a safe and efficient alternative, including chemonucleolysis, manual percutaneous discectomy (MPD), automated percutaneous lumbar discectomy (APLD), and percutaneous lumbar laser discectomy (PLLD). Unfortunately, most of these techniques have been demonstrated to be inefficient with high complication rates. Only modifications of the original open discectomy in which direct visualization of the disc is obtained through either microscopic or endoscopic techniques have proven to be successful. This review outlines the historical journey that has inspired the development of these techniques and delineates the progressive clinical experience gained from their advent.

OBJECTIVE Although multiple reports have documented significant benefit from surgical treatment of adult spinal deformity (ASD), these procedures can have high complication rates. Previously reported complications rates associated with ASD surgery are limited by retrospective design, single-surgeon or single-center cohorts, lack of rigorous data on complications, and/or limited follow-up. Accurate definition of complications associated with ASD surgery is important and may serve as a resource for patient counseling and efforts to improve the safety of patient care. The authors conducted a study to prospectively assess the rates of complications associated with ASD surgery with a minimum 2-year follow-up based on a multicenter study design that incorporated standardized data-collection forms, on-site study coordinators, and regular auditing of data to help ensure complete and accurate reporting of complications. In addition, they report age stratification of complication rates and provide a general assessment of factors that may be associated with the occurrence of complications. METHODS As part of a prospective, multicenter ASD database, standardized forms were used to collect data on surgery-related complications. On-site coordinators and central auditing helped ensure complete capture of complication data. Inclusion criteria were age older than 18 years, ASD, and plan for operative treatment. Complications were classified as perioperative (within 6 weeks of surgery) or delayed (between 6 weeks after surgery and time of last follow-up), and as minor or major. The primary focus for analyses was on patients who reached a minimum follow-up of 2 years. RESULTS Of 346 patients who met the inclusion criteria, 291 (84%) had a minimum 2-year follow-up (mean 2.1 years); their mean age was 56.2 years. The vast majority (99%) had treatment including a posterior procedure, 25% had an anterior procedure, and 19% had a 3-column osteotomy. At least 1 revision was required in 82 patients (28.2%). A total of 270 perioperative complications (145 minor; 125 major) were reported, with 152 patients (52.2%) affected, and a total of 199 delayed complications (62 minor; 137 major) were reported, with 124 patients (42.6%) affected. Overall, 469 complications (207 minor; 262 major) were documented, with 203 patients (69.8%) affected. The most common complication categories included implant related, radiographic, neurological, operative, cardiopulmonary, and infection. Higher complication rates were associated with older age (p = 0.009), greater body mass index (p