Faculty Bibliography

OBJECTIVE Sagittal malalignment requires higher energy expenditure to maintain an erect posture. Because the clinical impact of sagittal alignment is affected by both the severity of the deformity and recruitment of compensatory mechanisms, it is important to investigate new parameters that reflect both disability level and compensatory mechanisms for all patients. This study investigated the clinical relevance of the global sagittal axis (GSA), a novel measure to evaluate the standing axis of the human body. METHODS This is a retrospective review of patients who underwent full-body radiographs and completed health-related quality of life (HRQOL) questionnaires: Oswestry Disability Index (ODI), Scoliosis Research Society-22, EuroQol-5D (EQ-5D), and the visual analog scale for back and leg pain. The GSA was defined as the angle formed by a line from the midpoint of the femoral condyles to the center of C-7, and a line from the midpoint between the femoral condyles to the posterior superior corner of the S-1 sacral endplate. After evaluating the correlation of GSA/HRQOL with sagittal parameters, linear regression models were generated to investigate how ODI and GSA related to radiographic parameters (T-1 pelvic angle, pelvic retroversion, knee flexion, and pelvic posterior translation). RESULTS One hundred forty-three patients (mean age 44 years) were included. The GSA correlated significantly with all HRQOL (up to r = 0.6 with EQ-5D) and radiographic parameters (up to r = 0.962 with sagittal vertical axis). Regression between ODI and sagittal radiographic parameters identified the GSA as an independent predictor (r = 0.517, r2 = 0.267; p < 0.001). Analysis of standardized coefficients revealed that when controlling for deformity, the GSA increased with a concurrent decrease in pelvic retroversion (-0.837) and increases in knee flexion (+0.287) and pelvic posterior translation (+0.193). CONCLUSIONS The GSA is a simple, novel measure to assess the standing axis of the human body in the sagittal plane. The GSA correlated highly with spinopelvic and lower-extremities sagittal parameters and exhibited remarkable correlations with HRQOL, which exceeded other commonly used parameters.

Introduction/objectives: Spinal deformity has a known deleterious effect upon the outcomes of THA and acetabular component positioning. This study sought to evaluate the relationship between severity of spinal deformity parameters and acetabular cup position, rate of dislocation, and rate of revision among patients with THAs and concomitant spinal deformity. Methods: A prospectively database of patients with spinal deformity was reviewed and patients with THA were identified. The full standing stereoradiographic images (EOS) were reviewed. Spinal deformity parameters and acetabular cup anteversion and inclination were measured. A chart review was performed to determine dislocation and revision arthroplasty events. Statistical analysis was performed to determine correlation of deformity with acetabular cup position. Subgroup analysis was performed for spinal fusion, dislocation events, and revision THA. Results: 142 patients were identified with THA and spinal deformity, with 152 hips. The rate of dislocation was 5.7%, with a revision rate of 3.6% for instability. Only 42.1% met the radiographic "safe zone" criteria. 7 (77.8%) of the 9 dislocations occurred in patients with acetabular cups outside the safe zone (p = 0.304). Patients with dislocations had significantly higher inclination than those patients who did not dislocate (p = 0.016), but had no difference in anteversion (p = 0.646). Conclusions: In this cohort, patients with THA and concomitant spinal deformity have a high dislocation rate and a high percentage of acetabular cups which lie outside the safe zone in the standing position. Known spinal deformity parameters and the presence of spinal fusion do not correlate strongly with cup position or dislocation rates

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 multicenter, prospective, consecutive database of surgical patients with adult spinal deformity (ASD). OBJECTIVE: This study investigated the use of antifibrinolytic (AF) therapy in ASD surgery. SUMMARY OF BACKGROUND DATA: AF therapy has been shown to be effective in preventing blood loss in some settings. Its effect on major and minor perioperative complications, blood product utilization, vascular events, and postoperative fusion in patients undergoing ASD surgery remains unclear. METHODS: All patients with data on AF use were included. Parameters of blood utilization included transfusion rates and units of packed red blood cells and fresh frozen plasma transfused. Thromboembolic events included stroke, deep vein thrombosis, and pulmonary embolus. Multivariate regression was used, accounting for confounders. RESULTS: Four hundred three patients were included. One hundred thirty-seven patients received aminocaproic acid (EACA), 81 received tranexamic acid (TXA), and 185 received no AFs. The use of AF was associated with a decrease in transfusion (EACA: odds ratio [OR] = 0.38, P = 0.043; TXA: OR = 0.31, P = 0.047), a decrease in the number of units of packed red blood cells transfused (EACA: incidence risk ratio [IRR] = 0.45, P = 0.0005; TXA: IRR = 0.7, P = 0.0005), and a decrease in the number of fresh frozen plasma transfused (EACA: IRR = 0.65, P = 0.003; TXA: IRR = 0.67, P = 0.006). AF use was associated with an increase in minor intraoperative complications (EACA: IRR = 2.15, P = 0.008; TXA: IRR = 2.12, P = 0.011). TXA use (but not EACA) was associated with a decrease in the incidence of major perioperative complications compared with no AF (IRR = 0.37, P = 0.019). There was no difference in the incidence of thromboembolic events. CONCLUSION: TXA or EACA use was associated with increased minor intraoperative complications. TXA was associated with decreased major perioperative complications. AF was associated with decreased utilization of blood products without an increased rate of thromboembolic events. Given the nature of this study, transfusion threshold was not standardized. Future studies with rigid criteria for transfusion should be prospectively performed to better evaluate the impact of AF during ASD surgery. LEVEL OF EVIDENCE: 3.

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.

INTRODUCTION: Bone morphogenetic protein (BMP) can 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. We sought to examine adolescent idiopathic (AIS) and non-idiopathic scoliosis (NIS) for reoperation events with and without the use of BMP using a large statewide database. METHODS: The 2008-2011 New York State Inpatient Database was queried using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. Patients age 10 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 two cohorts for relative risk assessment. RESULTS: A total of 2,658 and 2,431 cases were identified of AIS and NIS, respectively. The use of BMP at the initial visit was performed at a rate of 4.5% for AIS and 21.0% for NIS fusion surgery. For posterior fusion cases longer than eight levels, the reoperation rate for pseudarthrosis was 1.0% in AIS and 18.4% in NIS (p < .001). For NIS fusions greater than eight levels, the rate of reoperation for pseudarthrosis after using BMP at the index surgery was 5% and 22% when BMP was not used, a relative risk of 4.0 (p < .001). For AIS, there was no substantial increase in risk when not using BMP for fusion greater than eight levels (p < .001). CONCLUSION: We found a significant decrease in the risk of reoperation for pseudarthrosis after long fusions when using BMP in the case of NIS. In contrast, use of BMP does not benefit the AIS population.