There was a 1.1- to 1.2-fold increase in cost for patients in the greatest quartiles compared with those in the lowest quartiles for these variables. Surgical site infection, return to the operating room, and spine-related hos- pital readmission during the 90-day global health period were postopera- tive variables independently associated with 2-year cost. Patients in the greatest versus lowest quartiles had a 1.7- to 1.9-fold increase in cost for these variables. CONCLUSIONS: Revision lumbar fusion can be associated with consid- erable 2-year health care costs. These costs can also vary widely among patients, as evidenced by the 2.6-fold overall cost range in this series. Although comorbidities and preoperative severity of disease states contrib- ute to cost of care, the primary drivers of increased cost include perioper- ative complications such as surgical site infection, return to the operating room, and readmission during the global health period. Measures focused on health service improvement will be most successful in reducing the cost of care for patients undergoing revision lumbar fusion. PMID: 22284228 [PubMed - indexed for MEDLINE. Available at: http:// www.ncbi.nlm.nih.gov/pubmed/22284228]. Reprinted with permission from: Parker SL, Shau DN, Mendenhall SK, McGirt MJ. Factors influencing 2-year health care costs in patients undergo- ing revision lumbar fusion procedures. J Neurosurg Spine 2012;16(4):323–8. Epub 2012 Jan 27. Available at: http://thejns.org. doi: http://dx.doi.org/10.1016/j.spinee.2012.07.019 Added value of percutaneous vertebroplasty: effects on respiratory function. Tanigawa N, Kariya S, Komemushi A, Nakatani M, Yagi R, Sawada S. AJR Am J Roentgenol 2012 Jan;198(1):W51–4. OBJECTIVE: The objective of our study was to investigate the effects of percutaneous vertebroplasty on respiratory function in patients with com- pression fractures caused by osteoporosis. SUBJECTS AND METHODS: Ninety-eight patients (87 women, 11 men; mean age, 74 years; age range, 60-90 years) with compression frac- tures of 75 thoracic (Th7-Th12) and 89 lumbar (L1-L5) vertebrae were en- rolled in this study. Percentage vital capacity (VC%), percentage forced vital capacity (FVC%), and percentage forced expiratory volume in 1 sec- ond (%FEV1) were measured using a spirometer before, 1 day after, and 1 month after percutaneous vertebroplasty. The Wilcoxon signed rank test was used to evaluate whether any significant differences in VC%, FVC%, or %FEV1 values existed between before, 1 day after, and 1 month after percutaneous vertebroplasty. RESULTS: The VC% and FVC% values had improved significantly by 1 month after percutaneous vertebroplasty compared with before percuta- neous vertebroplasty (p !0.01). No significant difference was noted be- tween values before and 1 day after percutaneous vertebroplasty. Likewise, no significant difference was identified in %FEV1 before percu- taneous vertebroplasty and either 1 day or 1 month after percutaneous ver- tebroplasty. The mean degree of improvement in VC% values after percutaneous vertebroplasty for patients with one vertebra treated, which we refer to as the ‘‘single-vertebroplasty’’ group, and for patients with two or more vertebrae treated, or ‘‘multiple-vertebroplasty’’ group, was 1.1%67% (SD) and 6.3%68%, respectively, representing a significant dif- ference between groups (p50.01). The mean VC% values before and 1 month after percutaneous vertebroplasty differed significantly (p50.02) in the thoracic group and overlapping group. CONCLUSION: Percutaneous vertebroplasty improves restrictive ventila- tory impairment, but this improvement requires approximately 1 month to occur. Greater improvement in restrictive ventilatory dysfunction was ob- served in patients who underwent multiple vertebroplasty procedures than those who underwent a single procedure and in patients who underwent treatment of thoracic vertebrae than those who underwent treatment of other vertebrae. PMID: 22194515 [PubMed - indexed for MEDLINE. Available at: http:// www.ncbi.nlm.nih.gov/pubmed/22194515]. Reprinted from: Tanigawa N, Kariya S, Komemushi A, Nakatani M, Yagi R, Sawada S. Added value of percutaneous vertebroplasty: effects on respiratory function. AJR Am J Roentgenol 2012 Jan;198(1):W51–4. Reprinted with permission from the American Journal of Roentgenology. doi: http://dx.doi.org/10.1016/j.spinee.2012.07.020 A radiographic analysis of degenerative spondylolisthesis at the L4-5 level. Anderson DG, Limthongkul W, Sayadipour A, et al. J Neurosurg Spine 2012;16(2):130–4. Epub 2011 Nov 25. OBJECT: Lumbar degenerative spondylolisthesis (LDS) is common and has generally been characterized as a homogeneous disease entity in the literature and in clinical practice. Because disease variability has not been carefully characterized, stratification of treatment recommendations based on scientific evidence is currently lacking. In this study, the authors ana- lyzed radiographic parameters of patients with LDS at the L4-5 level to better characterize this entity. METHODS: Demographic data were collected from 304 patients (200 women and 104 men) with LDS at the L4-5 level. Plain radiographs in- cluding anteroposterior, lateral, and flexion-extension lateral radiographs were analyzed for disc height, segmental angulation, segmental translation, and osteophyte formation. Correlations were sought between the variables of age, sex, disc height, segmental angulation, segmental translation, and osteophyte formation. RESULTS: The mean patient age was 63.8 years (range 40-86 years). The mean mid-disc height was 7 mm (range 0-14 mm) on the neutral lateral view. The mean angulation between the superior endplate of L-5 and the inferior endplate of L-4 was 6  of lordosis (range 13  of kyphosis to 23  lordosis) on the neutral lateral view. The mean angular change between flexion and extension lateral radiographs was 5  (range 0  -17  ). The mean translation on the neutral lateral view was 6 mm (range 0-15 mm). The mean change in translational between flexion and extension was 2 mm (range 0-11 mm). Twenty patients (7%) exhibited spondylolisthesis only on the flexion view. A significant positive correlation was found between the change in angula- tion and the change in translation on flexion and extension views (r50.18, p50.001). No significant correlation was found between anterior osteophyte size and mobility with flexion-extension radiographs. CONCLUSIONS: The wide range in all radiographic parameters for LDS confirms the heterogeneous nature of this condition and suggests that a grading system to subclassify LDS may be clinically useful. On flexion and extension radiographs, increased translational motion correlated with increased angular motion. Anterior osteophyte size was not found to be predictive of segmental stability. This data set should prove beneficial to those seeking to subcategorize LDS in the future. PMID: 22117143 [PubMed - indexed for MEDLINE. Available at: http:// www.ncbi.nlm.nih.gov/pubmed/22117143]. Reprinted with permission from: Anderson DG, Limthongkul W, Sayadi- pour A, et al. A radiographic analysis of degenerative spondylolisthesis at the L4-5 level. J Neurosurg Spine 2012;16(2):130–4. Epub 2011 Nov 25. Available at: http://thejns.org. doi: http://dx.doi.org/10.1016/j.spinee.2012.07.021 The impact of provider volume on the outcomes after surgery for lumbar spinal stenosis. Dasenbrock HH, Clarke MJ, Witham TF, Sciubba DM, Gokaslan ZL, Bydon A. Neurosurgery 2012;70(6):1346–53; discussion 1353–4. BACKGROUND: Investigation into the provider volume-outcomes asso- ciation for patients undergoing spine surgery has been limited. OBJECTIVE: To examine the impact of surgeon and hospital volume on the outcomes after decompression with or without fusion for lumbar spinal stenosis. 538 Journal Reports / The Spine Journal 12 (2012) 536–539