Spinal cord position in adolescent idiopathic scoliosis.

BACKGROUND: The use of thoracic pedicle screws in deformity surgery provides a stable fixation system. The concept of acceptably positioned screws includes a worrisome subset of screws that perforate the medial pedicle cortex and may result in some compromise of the spinal canal. A significant higher incidence of cortical wall penetration on the concave side compared with the convex was previously found. Although several authors assumed that the spinal cord hugs the concave pedicles when the spinal deformity is scoliosis, the position of spinal cord in adolescent idiopathic scoliosis (AIS) has not been studied in depth. METHODS: We reviewed 45 patients who were candidate for operative treatment for AIS between August 2007 and October 2010 at our institution. Posteroanterior and lateral 3-ft standing preoperative radiographs of the spine were reviewed to determine: Cobb angle of the thoracic curves, apex vertebra of the curves, and end vertebras of the curves. Magnetic resonance images were retrospectively reviewed. The lateral cord space (LCS) ratio, which reflects the relative position of the spinal cord in the spinal canal, was calculated for each level with a thoracic curve. RESULTS: The average LCS for thoracic curves of >50 degrees was 2.123. The average LCS for thoracic curves of <50 degrees was 1.551 (P=0.002). The LCS for the apex vertebra was 1.699. The LCS for the upper end vertebra and lower end vertebra were 1.212, 1.225, respectively (P<0.001). There was a statistically significant difference between right thoracic curves and left thoracic curve regarding the LCS. In right thoracic curve the LCS was 1.487 (1.487+0.45) while in left thoracic curve it was 0.761 (0.761+0.17) meaning that in both curves the spinal cord moved to the concave side of the curve. CONCLUSIONS: Our study confirms that spinal cord in AIS tend to follow the appearance of the curve with its being tethered on the concave side. The spinal cord is close to the pedicle around the apex area.

Lateral transpsoas fusion: indications and outcomes.

Spinal fusion historically has been used extensively, and, recently, the lateral transpsoas approach to the thoracic and lumbar spine has become an increasingly common method to achieve fusion. Recent literature on this approach has elucidated its advantage over more traditional anterior and posterior approaches, which include a smaller tissue dissection, potentially lower blood loss, no need for an access surgeon, and a shorter hospital stay. Indications for the procedure have now expanded to include degenerative disc disease, spinal stenosis, degenerative scoliosis, nonunion, trauma, infection, and low-grade spondylolisthesis. Lateral interbody fusion has a similar if not lower rate of complications compared to traditional anterior and posterior approaches to interbody fusion. However, lateral interbody fusion has unique complications that include transient neurologic symptoms, motor deficits, and neural injuries that range from 1 to 60% in the literature. Additional studies are required to further evaluate and monitor the short- and long-term safety, efficacy, outcomes, and complications of lateral transpsoas procedures.

Surgical versus nonsurgical therapy for lumbar spinal stenosis.

BACKGROUND: Surgery for spinal stenosis is widely performed, but its effectiveness as compared with nonsurgical treatment has not been shown in controlled trials. METHODS: Surgical candidates with a history of at least 12 weeks of symptoms and spinal stenosis without spondylolisthesis (as confirmed on imaging) were enrolled in either a randomized cohort or an observational cohort at 13 U.S. spine clinics. Treatment was decompressive surgery or usual nonsurgical care. The primary outcomes were measures of bodily pain and physical function on the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and the modified Oswestry Disability Index at 6 weeks, 3 months, 6 months, and 1 and 2 years. RESULTS: A total of 289 patients were enrolled in the randomized cohort, and 365 patients were enrolled in the observational cohort. At 2 years, 67% of patients who were randomly assigned to surgery had undergone surgery, whereas 43% of those who were randomly assigned to receive nonsurgical care had also undergone surgery. Despite the high level of nonadherence, the intention-to-treat analysis of the randomized cohort showed a significant treatment effect favoring surgery on the SF-36 scale for bodily pain, with a mean difference in change from baseline of 7.8 (95% confidence interval, 1.5 to 14.1); however, there was no significant difference in scores on physical function or on the Oswestry Disability Index. The as-treated analysis, which combined both cohorts and was adjusted for potential confounders, showed a significant advantage for surgery by 3 months for all primary outcomes; these changes remained significant at 2 years. CONCLUSIONS: In the combined as-treated analysis, patients who underwent surgery showed significantly more improvement in all primary outcomes than did patients who were treated nonsurgically. (ClinicalTrials.gov number, NCT00000411 [ClinicalTrials.gov].).

Analysis of in vivo corrosion of 316L stainless steel posterior thoracolumbar plate systems: a retrieval study.

STUDY DESIGN: One hundred eighteen patients retrieved 316L stainless steel thoracolumbar plates, of 3 different designs, used for fusion in 60 patients were examined for evidence of corrosion. A medical record review and statistical analysis were also carried out. OBJECTIVE: This study aims to identify types of corrosion and examine preferential metal ion release and the possibility of statistical correlation to clinical effects. SUMMARY OF BACKGROUND DATA: Earlier studies have found that stainless steel spine devices showed evidence of mild-to-severe corrosion; fretting and crevice corrosion were the most commonly reported types. Studies have also shown the toxicity of metal ions released from stainless steel corrosion and how the ions may adversely affect bone formation and/or induce granulomatous foreign body responses. METHODS: The retrieved plates were visually inspected and graded based on the degree of corrosion. The plates were then analyzed with optical microscopy, scanning electron microscopy, and energy dispersive x-ray spectroscopy. A retrospective medical record review was performed and statistical analysis was carried out to determine any correlations between experimental findings and patient data. RESULTS: More than 70% of the plates exhibited some degree of corrosion. Both fretting and crevice corrosion mechanisms were observed, primarily at the screw plate interface. Energy dispersive x-ray spectroscopy analysis indicated reductions in nickel content in corroded areas, suggestive of nickel ion release to the surrounding biological environment. The incidence and severity of corrosion was significantly correlated with the design of the implant. CONCLUSIONS: Stainless steel thoracolumbar plates show a high incidence of corrosion, with statistical dependence on device design.

Surgical versus nonsurgical treatment for lumbar degenerative spondylolisthesis.

BACKGROUND: Management of degenerative spondylolisthesis with spinal stenosis is controversial. Surgery is widely used, but its effectiveness in comparison with that of nonsurgical treatment has not been demonstrated in controlled trials. METHODS: Surgical candidates from 13 centers in 11 U.S. states who had at least 12 weeks of symptoms and image-confirmed degenerative spondylolisthesis were offered enrollment in a randomized cohort or an observational cohort. Treatment was standard decompressive laminectomy (with or without fusion) or usual nonsurgical care. The primary outcome measures were the Medical Outcomes Study 36-Item Short-Form General Health Survey (SF-36) bodily pain and physical function scores (100-point scales, with higher scores indicating less severe symptoms) and the modified Oswestry Disability Index (100-point scale, with lower scores indicating less severe symptoms) at 6 weeks, 3 months, 6 months, 1 year, and 2 years. RESULTS: We enrolled 304 patients in the randomized cohort and 303 in the observational cohort. The baseline characteristics of the two cohorts were similar. The one-year crossover rates were high in the randomized cohort (approximately 40% in each direction) but moderate in the observational cohort (17% crossover to surgery and 3% crossover to nonsurgical care). The intention-to-treat analysis for the randomized cohort showed no statistically significant effects for the primary outcomes. The as-treated analysis for both cohorts combined showed a significant advantage for surgery at 3 months that increased at 1 year and diminished only slightly at 2 years. The treatment effects at 2 years were 18.1 for bodily pain (95% confidence interval [CI], 14.5 to 21.7), 18.3 for physical function (95% CI, 14.6 to 21.9), and -16.7 for the Oswestry Disability Index (95% CI, -19.5 to -13.9). There was little evidence of harm from either treatment. CONCLUSIONS: In nonrandomized as-treated comparisons with careful control for potentially confounding baseline factors, patients with degenerative spondylolisthesis and spinal stenosis treated surgically showed substantially greater improvement in pain and function during a period of 2 years than patients treated nonsurgically. (ClinicalTrials.gov number, NCT00000409 [ClinicalTrials.gov].).

Spinal orthoses.

External orthoses are used in the management of a variety of spinal disorders. Many types of brace are available to support the cervical, thoracic, and lumbar spine as well as junctional regions, which have special mechanical considerations. Many prefabricated and custom-made devices are available, made by a variety of manufacturers in this unregulated area of medical practice. Despite the widespread use of spinal orthoses, evidence of their efficacy in managing many spinal conditions is lacking. The most compelling indication for their use is in the management of traumatic spine injury. However, studies evaluating the efficacy of spinal orthoses have several shortcomings; many have evaluated orthoses that are no longer used. Recent data provide general guidelines to help the clinician choose the appropriate device.

Do scores of the USMLE Step 1 and OITE correlate with the ABOS Part I certifying examination?: a multicenter study.

BACKGROUND: The US Medical Licensing Examination (USMLE) and Orthopaedic In-Training Examination (OITE) are commonly used to select medical students or residents, respectively. Knowing how well these examinations predict performance on the American Board of Orthopaedic Surgery (ABOS) Part I certifying examination is important to provide evaluations for medical students and residents. Previous studies comparing the OITE scores with the ABOS Part 1 scores have been limited to one program. QUESTIONS/PURPOSES: Therefore, we compared the scores on the USMLE Step 1 and OITE examinations with those on the ABOS Part I certifying examination using data from four ACGME approved residency programs. METHODS: We reviewed 202 resident files from 1996 to 2008 from four programs in the same geographic region. Of those, 181 (90%) had complete records. De-identified data were used to compare USMLE Step 1 scores, OITE percentile rank scores, and ABOS Part I percentile rank scores. Pearson coefficients and receiver operator curves were calculated to assess the relationships between tests. RESULTS: We found a correlation of 0.53 between the USMLE Step 1 and ABOS Part I, and an average correlation of 0.50 for postgraduate years (PGY) 2 through 5 OITE scores and ABOS Part I. There was a stepwise increase in correlation from PGY 2 through PGY 5 between the OITE scores and ABOS scores. Those who averaged in the 27th percentile or lower on the OITE had a 57% chance of failing the ABOS Part I examination. CONCLUSION: USMLE Step 1 scores correlated with ABOS Part I certifying examination scores, and we therefore believe it may be used as one factor in resident selection. Use of the OITE scores in guiding education and feedback appears to be justified.

Surgical treatment of spinal stenosis with and without degenerative spondylolisthesis: cost-effectiveness after 2 years.

BACKGROUND: The SPORT (Spine Patient Outcomes Research Trial) reported favorable surgery outcomes over 2 years among patients with stenosis with and without degenerative spondylolisthesis, but the economic value of these surgeries is uncertain. OBJECTIVE: To assess the short-term cost-effectiveness of spine surgery relative to nonoperative care for stenosis alone and for stenosis with spondylolisthesis. DESIGN: Prospective cohort study. DATA SOURCES: Resource utilization, productivity, and EuroQol EQ-5D score measured at 6 weeks and at 3, 6, 12, and 24 months after treatment among SPORT participants. TARGET POPULATION: Patients with image-confirmed spinal stenosis, with and without degenerative spondylolisthesis. TIME HORIZON: 2 years. PERSPECTIVE: Societal. INTERVENTION: Nonoperative care or surgery (primarily decompressive laminectomy for stenosis and decompressive laminectomy with fusion for stenosis associated with degenerative spondylolisthesis). OUTCOME MEASURES: Cost per quality-adjusted life-year (QALY) gained. RESULTS OF BASE-CASE ANALYSIS: Among 634 patients with stenosis, 394 (62%) had surgery, most often decompressive laminectomy (320 of 394 [81%]). Stenosis surgeries improved health to a greater extent than nonoperative care (QALY gain, 0.17 [95% CI, 0.12 to 0.22]) at a cost of $77,600 (CI, $49,600 to $120,000) per QALY gained. Among 601 patients with degenerative spondylolisthesis, 368 (61%) had surgery, most including fusion (344 of 368 [93%]) and most with instrumentation (269 of 344 [78%]). Degenerative spondylolisthesis surgeries significantly improved health versus nonoperative care (QALY gain, 0.23 [CI, 0.19 to 0.27]), at a cost of $115,600 (CI, $90,800 to $144,900) per QALY gained. RESULT OF SENSITIVITY ANALYSIS: Surgery cost markedly affected the value of surgery. LIMITATION: The study used self-reported utilization data, 2-year time horizon, and as-treated analysis to address treatment nonadherence among randomly assigned participants. CONCLUSION: The economic value of spinal stenosis surgery at 2 years compares favorably with many health interventions. Degenerative spondylolisthesis surgery is not highly cost-effective over 2 years but could show value over a longer time horizon.

Surgical vs nonoperative treatment for lumbar disk herniation: the Spine Patient Outcomes Research Trial (SPORT) observational cohort.

CONTEXT: For patients with lumbar disk herniation, the Spine Patient Outcomes Research Trial (SPORT) randomized trial intent-to-treat analysis showed small but not statistically significant differences in favor of diskectomy compared with usual care. However, the large numbers of patients who crossed over between assigned groups precluded any conclusions about the comparative effectiveness of operative therapy vs usual care. OBJECTIVE: To compare the treatment effects of diskectomy and usual care. DESIGN, SETTING, AND PATIENTS: Prospective observational cohort of surgical candidates with imaging-confirmed lumbar intervertebral disk herniation who were treated at 13 spine clinics in 11 US states and who met the SPORT eligibility criteria but declined randomization between March 2000 and March 2003. INTERVENTIONS: Standard open diskectomy vs usual nonoperative care. MAIN OUTCOME MEASURES: Changes from baseline in the Medical Outcomes Study Short-Form Health Survey (SF-36) bodily pain and physical function scales and the modified Oswestry Disability Index (American Academy of Orthopaedic Surgeons/MODEMS version). RESULTS: Of the 743 patients enrolled in the observational cohort, 528 patients received surgery and 191 received usual nonoperative care. At 3 months, patients who chose surgery had greater improvement in the primary outcome measures of bodily pain (mean change: surgery, 40.9 vs nonoperative care, 26.0; treatment effect, 14.8; 95% confidence interval, 10.8-18.9), physical function (mean change: surgery, 40.7 vs nonoperative care, 25.3; treatment effect, 15.4; 95% CI, 11.6-19.2), and Oswestry Disability Index (mean change: surgery, -36.1 vs nonoperative care, -20.9; treatment effect, -15.2; 95% CI, -18.5. to -11.8). These differences narrowed somewhat at 2 years: bodily pain (mean change: surgery, 42.6 vs nonoperative care, 32.4; treatment effect, 10.2; 95% CI, 5.9-14.5), physical function (mean change: surgery, 43.9 vs nonoperavtive care 31.9; treatment effect, 12.0; 95% CI; 7.9-16.1), and Oswestry Disability Index (mean change: surgery -37.6 vs nonoperative care -24.2; treatment effect, -13.4; 95% CI, -17.0 to -9.7). CONCLUSIONS: Patients with persistent sciatica from lumbar disk herniation improved in both operated and usual care groups. Those who chose operative intervention reported greater improvements than patients who elected nonoperative care. However, nonrandomized comparisons of self-reported outcomes are subject to potential confounding and must be interpreted cautiously. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00000410.

Lumbar spinal stenosis: indications for arthrodesis and spinal instrumentation.

Surgical indications for simple decompression in patients with lumbar spinal stenosis are well established. Following these guidelines, surgeons can expect good and excellent outcomes in 75% to 90% of patients. Despite the publication of many studies pertaining to the addition of arthrodesis and instrumentation, the indications for adding these procedures to a decompression are much less clear. Preoperative and intraoperative factors must be carefully considered when contemplating the addition of arthrodesis in the setting of spinal stenosis. In patients with preoperative degenerative spondylolisthesis, scoliosis, or kyphosis, and those in whom stenosis develops at a previously decompressed segment, serious consideration should be givenfor inclusion of an arthrodesis. Fusion should also be considered for those patients with stenosis adjacent to a previously fused lumbar segment. Excision of a significant portion of the facet joints or radical excision of the intervertebral disk during the course of the decompression predispose the patient to postoperative instability. The addition of an arthrodesis will likely benefit these patients. Relative indications for the use of spinal instrumentation in the setting of spinal stenosis include correction of deformity, recurrent spinal stenosis with instability, degenerative spondylolisthesis, adjacent segment stenosis with instability, and multiple level fusions.

Predisposing factors for dural tear in patients undergoing lumbar spine surgery.

OBJECT The purpose of this prospective cohort study was to identify risk factors for incidental durotomies in lumbar spine surgery. The authors hypothesized that the incidence of durotomy would be higher in cases involving multiple operations. METHODS The authors prospectively evaluated 523 patients who underwent lumbar and thoracolumbar spine surgery. They compared data on patients in whom a dural tear occurred and those in whom a dural tear did not occur. Data from patients in whom a dural tear occurred were compared with data from patients who did not experience durotomy. The data included basic demographic information, intraoperative data, and clinical information from a medical record review. RESULTS One hundred thirty-one patients underwent discectomy and 392 patients underwent laminectomy. Among the 131 patients who underwent discectomy 6 patients had a dural tear. Among the 392 patients who underwent discectomy 49 patients had dural tear. Patients with incidental durotomy were older (mean 65 ± 13 vs 60 ± 14 years of age; p = 0.044, t-test), and had longer surgery (146 ± 59 vs 110 ± 54 minutes; p = 0.025, t-test), compared with the patients without dural tear. The incidence of dural tear was more common in patients with a history of previous spine surgery (p < 0.001). CONCLUSIONS In patients who underwent lumbar and thoracolumbar spine surgery for degenerative problems, previous surgery and older age were found to be predisposing factors for dural tear.

Techniques in cervical laminoplasty.

BACKGROUND CONTEXT: Laminoplasty provides an alternative to anterior procedures or multilevel laminectomy for patients with multilevel spinal stenosis and myeloradiculopathy. PURPOSE: To review the techniques, results and complications of cervical laminoplasty. STUDY DESIGN: The three basic variations of laminoplasty are the single open door, the French door or midline and the Z-plasty technique. These techniques and their outcome are discussed in detail. RESULTS: The recovery rate after laminoplasty ranges from 50% to 70% without statistical superiority of any one technique over another. Closure of opened laminae, temporary nerve root deficit, decreased neck range of motion and axial pain are the main complications of laminoplasty. CONCLUSIONS: Good to excellent long-term clinical results can be expected for the appropriately selected patients regardless of the specific technique used.

Lumbar spinal stenosis. Treatment strategies and indications for surgery.

Initially, all patients with degenerative lumbar spinal stenosis should be treated conservatively. Rapid deterioration is unlikely. The majority of patients may either improve or remain stable over a long-term follow-up with nonoperative treatment. Surgery should be an elective decision by the patients who fail to improve after conservative treatment. Medical evaluation is mandatory in those elderly patients with frequent comorbidities. For central spinal stenosis, without significant grade I spondylolisthesis or deformity, decompression is the surgical treatment of choice. Iatrogenic instability must be avoided during decompression surgery by preserving the facet joint and the pars interarticularis. Limited decompression with laminotomy may be indicated for lateral canal stenosis. A limited decompression may avoid postoperative instability but is associated with more frequent neurologic sequelae. Postlaminectomy instability is uncommon, and too little decompression is a more frequent mistake than too much. Decompression is usually associated with good or excellent outcome in 80% of patients. Deterioration of initial post-operative improvement may occur over long-term follow-up. When spinal stenosis is associated with instability, degenerative spondylolisthesis, deformity, postoperative instability, or recurrent stenosis, fusion is often recommended. Instrumentation often improves the fusion rate but does not influence the clinical outcome. Generous decompression but selective fusion of the unstable segment only are preferable for degenerative spondylolisthesis and type I degenerative scoliosis with minimal rotation of the spine.

Surgical versus nonoperative treatment for lumbar disc herniation: eight-year results for the spine patient outcomes research trial.

STUDY DESIGN: Concurrent prospective randomized and observational cohort studies. OBJECTIVE: To assess the 8-year outcomes of surgery versus nonoperative care. SUMMARY OF BACKGROUND DATA: Although randomized trials have demonstrated small short-term differences in favor of surgery, long-term outcomes comparing surgical with nonoperative treatment remain controversial. METHODS: Surgical candidates with imaging-confirmed lumbar intervertebral disc herniation meeting Spine Patient Outcomes Research Trial eligibility criteria enrolled into prospective randomized (501 participants) and observational cohorts (743 participants) at 13 spine clinics in 11 US states. Interventions were standard open discectomy versus usual nonoperative care. Main outcome measures were changes from baseline in the SF-36 Bodily Pain and Physical Function scales and the modified Oswestry Disability Index-AAOS/Modems version assessed at 6 weeks, 3 months, and 6 months, and annually thereafter. RESULTS: Advantages were seen for surgery in intent-to-treat analyses for the randomized cohort for all primary and secondary outcomes other than work status; however, with extensive nonadherence to treatment assignment (49% patients assigned to nonoperative therapy receiving surgery versus 60% of patients assigned to surgery) these observed effects were relatively small and not statistically significant for primary outcomes (bodily pain, physical function, Oswestry Disability Index). Importantly, the overall comparison of secondary outcomes was significantly greater with surgery in the intent-to-treat analysis (sciatica bothersomeness [P > 0.005], satisfaction with symptoms [P > 0.013], and self-rated improvement [P > 0.013]) in long-term follow-up. An as-treated analysis showed significant surgical treatment effects for primary outcome measures (mean change, surgery vs. nonoperative care; treatment effect; 95% confidence interval): bodily pain (45.3 vs. 34.4; 10.9; 7.7 to 14); PF (42.2 vs. 31.5; 10.6; 7.7 to 13.5); and Oswestry Disability Index (-36.2 vs. -24.8; -11.3; -13.6 to -9.1). CONCLUSION: Carefully selected patients who underwent surgery for a lumbar disc herniation achieved greater improvement than nonoperatively treated patients; there was little to no degradation of outcomes in either group (operative and nonoperative) from 4 to 8 years. LEVEL OF EVIDENCE: 2.

Cervical intervertebral disc replacement.

Symptomatic adjacent-level disease after cervical fusion has led to the development and testing of several disc-replacement prostheses. Randomized controlled trials of cervical disc replacement (CDR) compared with anterior cervical discectomy and fusion (ACDF) have demonstrated at least equivalent clinical results for CDR with similar or lower complication rates. Biomechanical, kinematic, and radiographic studies of CDR reveal that the surgical level and adjacent vertebral level motion and center of rotation more closely mimic the native state. Lower intradiscal pressures adjacent to CDR may help decrease the incidence of adjacent spinal-level disease, but long-term follow-up is necessary to evaluate this theory.

Molecular and genetic advances in the regeneration of the intervertebral disc.

BACKGROUND: Owing to the debilitating nature of degenerative disc disease (DDD) and other spine pathologies, significant research has been performed with the goal of healing or regenerating the intervertebral disc (IVD). Structural complexity, coupled with low vascularity and cellularity, make IVD regeneration an extremely challenging task. METHODS: Tissue engineering-based strategies utilize three components to enhance tissue regeneration; scaffold materials to guide cell growth, biomolecules to enhance cell migration and differentiation, and cells (autologous, or allogeneic) to initiate the process of tissue formation. Significant advances in IVD regeneration have been made utilizing these tissue engineering strategies. RESULTS: The current literature demonstrates that members of the transforming growth factor beta (TGF-ß) superfamily are efficacious in the regeneration of an anabolic response in the IVD and to facilitate chondrogenic differentiation. Gene therapy, though thwarted by safety concerns and the risk of ectopic transfection, has significant potential for a targeted and sustained regenerative response. Stem cells in combination with injectable, biocompatible, and biodegradable scaffolds in the form of hydrogels can differentiate into de novo IVD tissue and facilitate regeneration of the existing matrix. Therapies that address both anabolism and the inherent catabolic state of the IVD using either direct inhibitors or broad-spectrum inhibitors show extensive promise. CONCLUSION: This review article summarizes the genetic and molecular advances that promise to play an integral role in the development of new strategies to combat DDD and promote healing of injured discs.

Hidden blood loss during posterior spine fusion surgery.

BACKGROUND CONTEXT: Posterior spine fusion is associated with significant intra- and postoperative blood losses. When referring to the total blood loss during spine surgery, the standard is to measure the intraoperative bleeding plus the postoperative drainage. This ignores the "hidden" blood loss that was found to be significant in other fields of surgery. PURPOSE: The purpose of this study was to examine whether posterior spine fusion carries a substantial hidden blood loss. STUDY DESIGN/SETTING: A prospective study. PATIENT SAMPLE: We prospectively studied 114 patients undergoing instrumented posterior spinal fusion at one center between January 2011 and April 2011. OUTCOME MEASURES: Total blood loss, visible blood loss, and hidden blood loss. METHODS: For each patient, the hidden blood loss was calculated by deducting the observed perioperative blood loss from the calculated total blood loss based on the hematocrit changes. We compared the percentage of the hidden blood loss out of the total blood loss for primary versus revision posterior spine fusion. RESULTS: Primary decompression and posterior fusion patients had a mean total true loss of 1,439 mL. Their calculated hidden loss was 600 mL, 42% of the total loss. After revision posterior spinal fusion surgery, the mean total blood loss was 1,606 mL. The mean visible loss was 975 mL, and the mean hidden loss was 631 mL, 39% of the total loss. Thus, there was no statistical difference in the hidden blood loss between primary and revision posterior spinal fusion surgeries (p>.05). We did not find a significant difference in the percentage of the hidden blood loss between patients who underwent one, two, or three or more levels of surgery. CONCLUSIONS: After posterior spinal fusion, there may be a large amount of the hidden blood loss.

Single- versus multilevel fusion for single-level degenerative spondylolisthesis and multilevel lumbar stenosis: four-year results of the spine patient outcomes research trial.

STUDY DESIGN: A subanalysis study. OBJECTIVE: To compare surgical outcomes and complications of multilevel decompression and single-level fusion with multilevel decompression and multilevel fusion for patients with multilevel lumbar stenosis and single-level degenerative spondylolisthesis (DS). SUMMARY OF BACKGROUND DATA: In patients with DS who are treated surgically, decompression and fusion provide a better clinical outcome than decompression alone. Surgical treatment for multilevel lumbar stenosis and DS typically includes decompression and fusion of the spondylolisthesis segment and decompression with or without fusion for the other stenotic segments. To date, no study has compared the results of these 2 surgical options for single-level DS with multilevel stenosis. METHODS: The results from a multicenter randomized and observational study, the Spine Patient Outcomes Research Trial comparing multilevel decompression and single-level fusion and multilevel decompression and multilevel fusion for spinal stenosis with spondylolisthesis, were analyzed. The primary outcome measures were the bodily pain and physical function scales of the Medical Outcomes Study 36-item Short-Form General Health Survey (SF-36) and the modified Oswestry Disability Index at 1, 2, 3, and 4 years postoperatively. Secondary analysis consisted of stenosis bothersomeness index, low back pain bothersomeness, leg pain, patient satisfaction, and self-rated progress. RESULTS: Overall, 207 patients were enrolled for the study, 130 had multlilevel decompression with 1 level fusion and 77 patients had multilevel decompression and multilevel fusion. For all primary and secondary outcome measures, there were no statistically significant differences in surgical outcomes between the 2 surgical techniques. However, operative time and intraoperative blood loss were significantly higher in the multilevel fusion group. CONCLUSION: Decompression and single-level fusion and decompression and multilevel fusion provide similar outcomes in patients with multilevel lumbar stenosis and single-level DS.

Pedicle screw-based posterior dynamic stabilization: literature review.

Posterior dynamic stabilization (PDS) indicates motion preservation devices that are aimed for surgical treatment of activity related mechanical low back pain. A large number of such devices have been introduced during the last 2 decades, without biomechanical design rationale, or clinical evidence of efficacy to address back pain. Implant failure is the commonest complication, which has resulted in withdrawal of some of the PDS devices from the market. In this paper the authors presented the current understanding of clinical instability of lumbar motions segment, proposed a classification, and described the clinical experience of the pedicle screw-based posterior dynamic stabilization devices.

Geographic variation in the surgical treatment of degenerative cervical disc disease: American Board of Orthopedic Surgery Quality Improvement Initiative; part II candidates.

STUDY DESIGN: Retrospective case series. OBJECTIVE: To examine and document the change in rates and the geographic variation in procedure type and utilization of plating by orthopedic surgeons for anterior cervical discectomy-fusion. SUMMARY OF BACKGROUND: Age- and sex-adjusted rates of cervical spine surgery have not increased, but the rate of cervical spinal fusion has, accounting for 41% of all fusion procedures in 2004. METHODS: Records were selected from the American Board of Orthopedic Surgeons part II examination from 1999 to 2008. Current Procedural Terminology (CPT) and International Classification of Diseases, 9th Revision, Clinical Modification (ICDM-9-CM) codes were used to determine utilization of structural allograft, autograft/interbody devices, and anterior cervical plating over time and within geographic region. Main outcome measures were physician workforce, and rates and variation of procedure types. RESULTS: From 1999 to 2008, the number of self-declared orthopedic spine surgeon candidates increased 24%. Over this period, the annual number of discectomies with fusions for degenerative cervical disc disease increased by 67%, whereas the number of such operations per surgeon operating on at least 1 such case increased 48% (P = 0.018). Interbody device (0%-31%; P < 0.0001), anterior cervical plating (39%-79%; P < 0.0001), and allograft (14%-59%; P < 0.0001) use increased, whereas autograft use decreased (86%-10%; P < 0.0001). The Southwest and Southeast were more likely than the Midwest to use interbody devices (OR: 2.42 and 1.66, respectively). The Southwest and Northeast were more likely than the Midwest to use autograft (OR: 1.55 and 1.49). The Southwest, Northeast, and Southeast were less likely to use allograft than the Midwest (OR: 0.408, 0.742, and 0.770). The Northeast was less likely and the Southeast more likely than the Midwest to utilize anterior cervical plating (OR: 0.67 and 1.33). Surgical complications were more often associated with autograft compared with allograft (OR: 1.61). CONCLUSION: From 1999 to 2008, the number of orthopedic surgeon candidates performing spine surgery has increased. These surgeons are performing more fusions and utilizing more structural allografts, interbody devices, and/or anterior cervical plates. Regional variations also remain in the types of constructs utilized.