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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.

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.

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-β) 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.

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.

Degenerative disk disease is an accelerating cascade of tissue degeneration in the intervertebral disk. A harsh catabolic environment perpetuates the degeneration of the intervertebral disk. Tissue engineering-based techniques offer effective treatment to slow the progression of degenerative disk disease and regenerate intervertebral disk tissue. The purpose of this study was to assess the efficacy of a regenerative therapy for degenerative disk disease by treating human chondrocytes with anabolic growth factors and a proteinase inhibitor. The use of both proved effective in upregulating important extracellular matrix markers of human chondrocytes. These successful in vitro results have implications for the regeneration of the intervertebral disk.

Cost-effectiveness analysis of a randomized plus observational cohort trial.Analyze cost-effectiveness of Spine Patient Outcomes Research Trial data over 4 years comparing surgery with nonoperative care for three common diagnoses: spinal stenosis (SPS), degenerative spondylolisthesis (DS), and intervertebral disc herniation (IDH).Spine surgery rates continue to rise in the United States, but the safety and economic value of these procedures remain uncertain.Patients with image-confirmed diagnoses were followed in randomized or observational cohorts with data on resource use, productivity, and EuroQol EQ-5D health state values measured at 6 weeks, 3, 6, 12, 24, 36, and 48 months. For each diagnosis, cost per quality-adjusted life year (QALY) gained in 2004 US dollars was estimated for surgery relative to nonoperative care using a societal perspective, with costs and QALYs discounted at 3% per year.Surgery was performed initially or during the 4-year follow-up among 414 of 634 (65.3%) SPS, 391 of 601 (65.1%) DS, and 789 of 1192 (66.2%) IDH patients. Surgery improved health, with persistent QALY differences observed through 4 years (SPS QALY gain 0.22; 95% confidence interval, CI: 0.15, 0.34; DS QALY gain 0.34, 95% CI: 0.30, 0.47; and IDH QALY gain 0.34, 95% CI: 0.31, 0.38). Costs per QALY gained decreased for SPS from $77,600 at 2 years to $59,400 (95% CI: $37,059, $125,162) at 4 years, for DS from $115,600 to $64,300 per QALY (95% CI: $32,864, $83,117), and for IDH from $34,355 to $20,600 per QALY (95% CI: $4,539, $33,088).Comparative effectiveness evidence for clearly defined diagnostic groups from Spine Patient Outcomes Research Trial shows good value for surgery compared with nonoperative care over 4 years.

The development of synthetic bone graft substitutes is an intense area of research due to the complications associated with the harvest of autogenous bone and concerns about the supply of allogenic bone. Porous resorbable polymers have been used extensively in hard tissue engineering applications, but currently lack load-bearing capacity. Supercritical carbon dioxide (scCO2) processing is used as a novel method to simultaneously impart a porous structure and disperse a nano-clay in a resorbable polymer matrix suitable for load-bearing applications. Porous resorbable polylactic acid (PLA)/cloisite clay nanocomposite constructs prepared using scCO2 processing exhibit a 2.5-fold increase in compressive strength compared with pure polymer constructs. The resulting mechanical properties are comparable with human cancellous and cortico-cancellous bone. In addition to the significant improvements in mechanical properties, the nanocomposite constructs display a biocompatibility greater than that of polystyrene culture plate controls. Furthermore, calcium phosphate-rich deposits could clearly be seen on the surface of the constructs, as well as at the center of the cultured constructs, indicating that osteoblasts are able to penetrate the porous network of the nanocomposite constructs. Cellular infiltration of these constructs is important for their in vivo use as bone graft substitutes. The diameter of the pores suggests that these constructs would also support neovascularization, which is integral for nutrient transport.

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.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.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.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.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.

Study Design. An in vivo biomechanical anterior cervical discectomy and instrumented fusion (ACDFI) model employing a calibrated distractor and a subminiature load cell used to intraoperatively measure distractive force across the discectomy site and subsequent compressive force across the interbody load cell following distractor removal. Objective. To determine the relationship between the distractive force and resultant initial graft compression in an in vivo ACDFI model. Summary of Background Data. The relationship between the distractive force and subsequent graft compression following distractor removal has not been studied in an in vivo ACDFI model. The consequences of over or under distraction and its subsequent effect on graft compression with regards to axial neck pain, endplate failure with graft subsidence, and fusion rates is an area of clinical significance for ACDFI. Methods. lntraoperative measurements were obtainted from 17 discectomy sites in 12 patients undergoing one and two level ACDFI. Informed consent was obtained from all subjects before surgery. A calibrated Caspar distractor was used to measure the distraction across the discectomy site and a subminiature interbody load cell was placed into the discectomy site and used to measure the resultant initial compressive force following distractor removal. The statistical significance and correlation between the distractive force across the discectomy site and the subsequent compressive force across the load cell were investigated with the Pearson correlation coefficient. Results. The average distractive force across the discectomy site was 33.5 ± 11.6 Ibs and the subsequent compressive force across the interbody load cell was 16.9 ± 5.9 Ibs following distractor removal. The Pearson correlation coefficient was r = 0.912 (P < 0.0005). The data showed a statistically significant linear correlation between the distractive force and the subsequent compressive force across the range of distraction investigated. Conclusion. This study demonstrated a statistically significant linear correlation between the distractive force applied across the discectomy site and the subsequent compressive force across a load cell placed in the interbody space following distractor removal in an in vivo ACDFI model.

Study design Biomechanical study of the ProDisc-L in a cadaveric model under pure moment loading. OBJECTIVE.: To determine the kinematic properties of a lumbar spine motion segment and the adjacent level following ProDisc-L disc replacement in the cadaveric spine. Summary of background data Total disc replacement is intended to preserve native motion, in an attempt to prevent accelerated adjacent segment degeneration. The quality and quantity of the motion following TDR may have important consequences on the facet joints of the same motion segment, as well as the motion at the prosthetic component interface. Methods Ten cadaveric lumbar spines were radiographed (L3-L5) and tested under pure moments (+10 Nm to -10 Nm) with an applied follower load (200 N). Load-deformation was tested in flexion/extension, lateral bending (LB), and axial rotation (AR). Range of Motion (ROM) data were recorded. Superior adjacent disc pressure (L3-L4) was measured using subminiature pressure transducers. The L4-L5 disc was subsequently instrumented with a ProDisc-L. Radiographs and biomechanical tests were repeated. Results Disc replacement significantly reduced extension (ROM 2.2 degrees +/- 0.5 degrees before and 1.2 degrees +/- 0.7 degrees after instrumentation) (P = 0.001), but not flexion (ROM 5.6 degrees +/- 3.1 degrees before and 6.2 degrees +/- 1.2 degrees after) (P = 0.34). Combined flexion/extension motion was marginally reduced (P = 0.517). LB ROM (7.4 degrees +/- 2.0 degrees ) was marginally reduced (P = 0.072) following instrumentation (6.2 degrees +/- 2.5 degrees ), while ROM in AR (3.4 degrees +/- 1.1 degrees ) was significantly increased (4.4 degrees +/- 1.2 degrees ) (P = 0.001). Superior adjacent segment ROM was preserved.No significant differences in disc pressure were observed at the adjacent motion segment before (199 kPa at maximum flexion and 171 kPa at maximum extension) or after disc replacement (252 kPa and 208 kPa, respectively). Conclusion In cadaveric spines, ROM of operated and adjacent motion segments was preserved following ProDisc-L insertion. Excision of the anterior anulus may increase laxity, which is taken up by the restoration of disc height and lordosis, at the cost of a moderate loss of flexion/extension motion. Adjacent segment kinematics were unaffected following TDR.

Degenerative spondylolisthesis is an important disorder of the aging spine, and has a significant effect on health-related quality of life in symptomatic adults. The management of degenerative spondylolisthesis is characterized by significant variability in nonoperative and operative approaches to care. The important questions and controversies in degenerative spondylolisthesis include the role of operative and nonoperative care. Within the realm of operative care, controversies include the role of decompression alone compared with decompression and fusion, the role of instrumentation in arthrodesis surgery, and the role of circumferential surgery compared with a posterolateral approach. The place of surgery for degenerative spondylolisthesis in a value-based healthcare economy is an important controversy that will determine whether allocation of limited healthcare resources to surgical care of this common disorder in the aging population is warranted compared with other demands on the healthcare economy. The objective of this paper is to review the most important literature to address these controversies.

STUDY DESIGN Clinical trial subgroup analysis. OBJECTIVE To compare outcomes of different fusion techniques treating degenerative spondylolisthesis (DS). Summary of Background Data. Surgery has been shown to be more effective than nonoperative treatment out to 4 years. Questions remain regarding the differential effect of fusion technique. METHODS Surgical candidates from 13 centers in 11 states with at least 12 weeks of symptoms and confirmatory imaging showing stenosis and DS were studied. In addition to standard decompressive laminectomy, 1 of 3 fusion techniques was employed at the surgeon's discretion: posterolateral in situ fusion (PLF); posterolateral instrumented fusion with pedicle screws (PPS); or PPS plus interbody fusion (360 degrees). Main outcome measures were the SF-36 bodily pain (BP) and physical function (PF) scales and the modified Oswestry Disability Index (ODI) assessed at 6 weeks, 3 months, 6 months, and yearly to 4 years. The as-treated analysis combined the randomized and observational cohorts using mixed longitudinal models adjusting for potential confounders. RESULTS Of 380 surgical patients, 21% (N = 80) received a PLF; 56% (N = 213) received a PPS; 17% (N = 63) received a 360 degrees; and 6% (N = 23) had decompression only without fusion. Early outcomes varied, favoring PLF compared to PPS at 6 weeks (PF: 12.73 vs. 6.22, P < 0.020) and 3 months (PF: 25.24 vs.18.95, P < 0.025) and PPS compared to 360 degrees at 6 weeks (ODI: -14.46 vs. -9.30, P < 0.03) and 3 months (ODI: -22.30 vs. -16.78, P < 0.02). At 2 years, 360 degrees had better outcomes: BP: 39.08 versus 29.17 PLF, P < 0.011; and versus 29.13 PPS, P < 0.002; PF: 31.93 versus 23.27 PLF, P < 0.021; and versus 25.29 PPS, P < 0.036. However, these differences were not maintained at 3- and 4-year follow-up, when there were no statistically significant differences between the 3 fusion groups. CONCLUSION In patients with DS and associated spinal stenosis, no consistent differences in clinical outcomes were seen among fusion groups over 4 years.

Numerous studies have assessed lumbar interbody fusion, but little data from direct interbody load measurements exists. This manuscript describes an interbody fusion cage with integrated 4-axis load cell that can simulate implant heights of 13, 15, 17, 19 and 21 mm. The calibrated load cell was accurate to within 7.9% for point compressive loads over the central 8 mm x 8 mm region, but up to 26.8% for eccentric loads on the outer 16 mm x 16 mm rim of the device (although typically errors were less than half). Anterior-posterior shear and lateral shear loads did not affect compressive load measurement (

Background: The management of degenerative spondylolisthesis associated with spinal stenosis remains controversial. Surgery is widely used and has recently been shown to be more effective than nonoperative treatment when the results were followed over two years. Questions remain regarding the long-term effects of surgical treatment compared with those of nonoperative treatment. Methods: Surgical candidates from thirteen centers with symptoms of at least twelve weeks' duration as well as confirmatory imaging showing degenerative spondylolisthesis with spinal stenosis were offered enrollment in a randomized cohort or observational cohort. Treatment consisted of standard decompressive laminectomy (with or without fusion) or usual nonoperative care. Primary outcome measures were the Short Form-36 (SF-36) bodily pain and physical function scores and the modified Oswestry Disability Index at six weeks, three months, six months, and yearly up to four years. Results: In the randomized cohort (304 patients enrolled), 66% of those randomized to receive surgery received it by four years whereas 54% of those randomized to receive nonoperative care received surgery by four years. In the observational cohort (303 patients enrolled), 97% of those who chose surgery received it whereas 33% of those who chose nonoperative care eventually received surgery. The intent-to-treat analysis of the randomized cohort, which was limited by nonadherence to the assigned treatment, showed no significant differences in treatment outcomes between the operative and nonoperative groups at three or four years. An as-treated analysis combining the randomized and observational cohorts that adjusted for potential confounders demonstrated that the clinically relevant advantages of surgery that had been previously reported through two years were maintained at four years, with treatment effects of 15.3 (95% confidence interval, 11 to 19.7) for bodily pain, 18.9 (95% confidence interval, 14.8 to 23) for physical function, and −14.3 (95% confidence interval, −17.5 to −11.1) for the Oswestry Disability Index. Early advantages (at two years) of surgical treatment in terms of the secondary measures of bothersomeness of back and leg symptoms, overall satisfaction with current symptoms, and self-rated progress were also maintained at four years. Conclusions: Compared with patients who are treated nonoperatively, patients in whom degenerative spondylolisthesis and associated spinal stenosis are treated surgically maintain substantially greater pain relief and improvement in function for four years. Level of Evidence: Therapeutic Level II. See Instructions to Authors for a complete description of levels of evidence.

Concurrent, prospective, randomized, and observational cohort study.To assess the 4-year outcomes of surgery versus nonoperative care.Although randomized trials have demonstrated small short-term differences in favor of surgery, long-term outcomes comparing surgical to nonoperative treatment remain controversial.Surgical candidates with imaging-confirmed lumbar intervertebral disc herniation meeting SPORT 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 (BP) and Physical Function (PF) scales and the modified Oswestry Disability Index (ODI - AAOS/Modems version) assessed at 6 weeks, 3 months, 6 months, and annually thereafter.Nonadherence to treatment assignment caused the intent-to-treat analyses to underestimate the treatment effects. In the 4-year combined as-treated analysis, those receiving surgery demonstrated significantly greater improvement in all the primary outcome measures (mean change surgery vs. nonoperative; treatment effect; 95% CI): BP (45.6 vs. 30.7; 15.0; 11.8 to 18.1), PF (44.6 vs. 29.7; 14.9;12.0 to 17.8) and ODI (-38.1 vs. -24.9; -13.2; -15.6 to -10.9). The percent working was similar between the surgery and nonoperative groups, 84.4% versus 78.4% respectively.In a combined as-treated analysis at 4 years, patients who underwent surgery for a lumbar disc herniation achieved greater improvement than nonoperatively treated patients in all primary and secondary outcomes except work status.

Surgery for spinal stenosis is widely performed, but its effectiveness as compared with nonsurgical treatment has not been shown in controlled trials.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.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.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].).

The control of postoperative pain is a major concern of the orthopaedic surgeon. Good pain control is not only more pleasant for the patient but can also lead to earlier mobilization, faster rehabilitation, improved patient satisfaction, and possibly earlier discharge1-6. Currently, an array of choices is available to orthopaedic surgeons for postoperative pain management. These include narcotics (both oral and intravenous), nerve blocks, pain pumps, epidural injections, aspirin, nonsteroidal anti-inflammatory drugs, transdermal patches, and muscle relaxants. Similarly, there is an array of orthopaedic procedures, each with different pain management needs. A total joint replacement surgeon, for example, would likely be dealing with different procedures and different patient demographics than would a sports medicine specialist or a spine surgeon. To better understand the current land-scape regarding pain management in orthopaedic surgery, the American Orthopaedic Association (AOA), in collaboration with the Orthopaedic Research and Education Foundation (OREF), surveyed members of the orthopaedic community with respect to pain management. Approximately 20,000 orthopaedic surgeons were invited to complete an online survey posted on the OREF web site (www.oref.org) from February 2006 through June 2006. The survey was drafted through a joint initiative between the AOA, the OREF, a group of surgeon advisors recommended by the AOA, and Knowledge Enterprises. The survey first stratified respondents according to their main area of expertise: total joint replacement, sports medicine, or spine surgery. Respondents were then asked about the following pain management modalities: aspirin, nonsteroidal anti-inflammatory drugs, acetaminophen, narcotics, patient-controlled analgesia with narcotics, pain pumps with continuous infusions of analgesics directly into the wound or by means of a catheter, epidural infusions with local anesthetic or with anesthetic and additives, nerve blocks, transdermal systems, and muscle relaxants. Finally, for each pain management modality, surgeons were asked to choose between three levels of satisfaction: “not …

Congenital stenosis is a diagnostic entity that encompasses a plethora of patient types not adequately classified by currently published schema. This review article introduces a clinical classification based on subtypes of patients with congenital stenosis. Anatomic, clinical, and radiographic presentation as well as treatment options and results are discussed. Potential complications in treating congenital stenosis as well as pearls of management in avoiding those complications are presented.

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.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.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.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].).

The effect of ultraviolet irradiation and glow discharge (GD) processing of the polyethylene (PE) substrates on deposition of calcium phosphate (CaP) films from supersaturated aqueous calcium phosphate solutions was investigated in this study. CaP coatings deposited on the PE substrates were comprised of elongated clusters of spherical particles and 100% of the free surface area of nearly all of the substrates was covered with a porous CaP film after a 3 day immersion. Nano-scratch tests determined that PE–CaP adhesion was most improved when PE substrates were subjected to 50 W GD treatments. As determined by contact angle measurements, the GD-treated PE samples had the highest electron donor parameter of surface energy, suggesting that enhancing the electron donor parameter of PE leads to improved adhesion with the biomimetic CaP coating.

STUDY DESIGN Prospective observational cohorts. OBJECTIVE To describe sociodemographic and clinical features, and nonoperative (medical) resource utilization before enrollment, in patients who are candidates for surgical intervention for intervertebral disc herniation (IDH), spinal stenosis (SpS), and degenerative spondylolisthesis (DS) according to SPORT criteria. SUMMARY OF BACKGROUND DATA Intervertebral disc herniation, spinal stenosis, and degenerative spondylolisthesis with stenosis are the three most common diagnoses of low back and leg symptoms for which surgery is performed. There is a paucity of descriptive literature examining large patient cohorts for the relationships among baseline characteristics and medical resource utilization with these three diagnoses. METHODS The Spine Patient Outcomes Research Trial (SPORT) conducts three randomized and three observational cohort studies of surgical and nonsurgical treatments for patients with IDH, SpS, and DS. Baseline data include demographic information, prior treatments received, and functional status measured by SF-36 and the Oswestry Disability Index (ODI-AAOS/Modems version). The data presented represent all 1,411 patients (743 IDH, 365 SpS, 303 DS) enrolled in the SPORT observational cohorts. Multiple logistic regression was used to generate independent predictors of utilization adjusted for sociodemographic variables, diagnosis, and duration of symptoms. RESULTS The average age was 41 years for the IDH group, 64 years for the SpS group, and 66 years for the DS group. At enrollment, IDH patients presented with the most pain as reported on the SF-36 (BP 26.3 vs. 33.2 SpS and 33.8 DS) and were the most impaired (ODI 51 vs. 42.3 SpS and 41.5 DS). IDH patients used more chiropractic treatment (42% vs. 33% SpS and 26% DS), had more Emergency Department (ED) visits (21% vs. 7% SpS and 4% DS), and used more opiate analgesics (49% vs. 29% SpS and 27% DS). After adjusting for age, gender, diagnosis, education, race, duration of symptoms, and compensation, Medicaid patients used significantly more opiate analgesics (58% Medicaid vs. 41% no insurance, 42% employer, 33% Medicare, and 32% private) and had more ED visits compared with other insurance types (31% Medicaid vs. 22% no insurance, 16% employer, 3% Medicare, and 11% private). CONCLUSION IDH patients appear to have differences in sociodemographics, resource utilization, and functional impairment when compared with the SpS/DS patients. In addition, the differences in resource utilization for Medicaid patients may reflect differences in access to care. The data provided from these observational cohorts will serve as an important comparison to the SPORT randomized cohorts in the future.

Study design A prospective, randomized, controlled, multicenter clinical study. Objective To compare the safety and clinical and radiographic outcomes of OP-1 (BMP-7) Putty to autogenous iliac crest bone graft in a population of patients undergoing laminectomy and posterolateral fusion for symptomatic lumbar stenosis associated with degenerative spondylolisthesis. Summary of background data Although the existing preclinical and clinical data suggest that OP-1 is able to achieve osteoinduction and clinical fusion in a variety of situations, the efficacy of this recombinant protein in a clinical spine fusion population has not been fully elucidated. This study directly compares the efficacy and safety of OP-1 putty to autograft bone for arthrodesis in patients with symptomatic stenosis in association with degenerative spondylolisthesis. Methods Thirty-six patients with degenerative lumbar spondylolisthesis and symptoms of neurogenic claudication underwent laminectomy, bilateral medial facetectomy, and posterolateral fusion using either iliac crest autograft or OP-1 Putty. Oswestry scores and SF-36 questionnaires were used to determine the clinical response to treatment. Independent, blinded neuroradiologists reviewed both static and dynamic radiographs to determine the fusion status. Successful fusion was declared whenthe presence of continuous bridging bone between the transverse processes was observed and less than 5 degrees of angular motion and 2 mm of translational movement was measured using digital calipers. Results Efficacy data were tabulated for 27 patients at the 24-month time point and an additional 4 patients (without evaluable 24-month results) at the 36-month time point. One patient was not evaluable for radiology, so the data reflect clinical information for 31 patients and radiology for 30 patients. Clinical success, defined as a 20% improvement in the preoperative Oswestry score, was achieved by 17 of 20 (85%) OP-1 Putty patients and 7 of 11 (64%) autograft patients. A successful posterolateral fusion was achieved in 11 of 20 (55%) OP-1 Putty patients and 4 of 10 (40%) autograft patients. SF-36 scores showed similar clinical improvement in both groups. No systemic toxicity, ectopic bone formation, recurrent stenosis, or other adverse events specifically related to the use of the OP-1 Putty implant were observed. Conclusion This study represents the first clinical trial to demonstrate the safety and similarity of OP-1 Putty as a replacement for autogenous bone graft in the posterolateral fusion environment with a minimum of 2-year follow-up. OP-1 Putty was able to achieve osteoinduction leading to a radiographically solid fusion in the absence of autogenous iliac crest bone graft in 55% of the patients at 24 and 36 months. These results compare favorably to the historical fusion rates reported for uninstrumented arthrodesis in this challenging clinical scenario.

STUDY DESIGN: A literature-based review. OBJECTIVES: To review management and controversies and to present authors recommendations. SUMMARY OF BACKGROUND DATA: There is considerable controversy regarding indication for surgery, role for decompression alone, and decompression with fusion with or without instrumentation. METHODS: Review of English language medical literature. RESULTS: The condition may stabilize itself with the collapse of the disc spaces and osteophytes but may continue to progress in nearly a third of the cases. It may cause predominantly back pain due to segmental instability, or radicular pain/neurogenic claudication secondary to root entrapment or spinal stenosis. When conservative treatment fails, the mainstay of surgical treatment is decompressive laminectomy and fusion, with or without instrumentation. CONCLUSIONS: Decompression primarily relieves radicular symptoms and neurogenic claudication whereas fusion primarily relieves back pain by elimination of instability. The goals for instrumentation are to promote fusion and to correct deformity. Fusion has a better long-term outcome than decompression alone. There is evidence that instrumentation improves fusion rate but does not improve clinical outcome in a relatively short-term follow-up. However, outcome of pseudarthrosis cases deteriorates over time and solid fusion produces better long-term outcome. The benefit of instrumentation comes with a price of higher postoperative morbidity and complication rate. Bone morphogenetic proteins are being tried to increase the rate of fusion, without increasing the complication rate, but the cost is prohibitive. More recently, dynamic stabilization with instrumentation but without fusion has been introduced as an alternative treatment. The current trends of surgical treatment and controversies are discussed.

Study design A prospective, randomized study on patients who underwent posterior lumbar decompression with bilateral posterolateral arthrodesis. Objective To determine the long-term influence of pseudarthrosis on the clinical outcome of patients with degenerative spondylolisthesis and spinal stenosis. Summary of background data Spinal decompression and posterolateral arthrodesis have been shown to be beneficial in the surgical treatment of symptomatic spinal stenosis with concurrent spondylolisthesis. Methods Forty-seven patients with single-level symptomatic spinal stenosis and spondylolisthesis were prospectively studied. Patients were treated with posterior decompression and bilateral posterolateral arthrodesis with autogenous bone graft. Radiographic evaluation was used to determine if fusion or pseudarthrosis was present. The solid fusion and pseudarthrosis groups were analyzed clinically, roentgenographically, and with a validated self-administered spinal stenosis questionnaire. Results Forty-seven patients were available for review at a range of follow-up from 5 to 14 years. Average follow-up was 7 years 8 months. Clinical outcome was excellent to good in 86% of patients with a solid arthrodesis and in 56% of patients with a pseudarthrosis (P = 0.01). Significant differences in residual back and lower limb pain was discovered between the two groups using a scale ranging from 0 (no pain) to 5 (severe pain). Preoperative back and lower limb pain scores were statistically similar between the two groups. The solid fusion group performed significantly better in the symptom severity and physical function categories on the self-administered questionnaire. The two groups had similar results in the patient satisfaction category of this questionnaire. Conclusions In patients undergoing single-level decompression and posterolateral arthrodesis for spinal stenosis and concurrent spondylolisthesis, a solid fusion improves long-term clinical results. Benefits of a successful arthrodesis over pseudarthrosis were demonstrated with respect to back and lower limb symptomatology compared with prior shorter-term studies, which indicated no significant difference in clinical outcome between the two groups.

An in vitro biomechanical study using a servohydraulic testing machine on cadaveric endplates.To characterize the effects of bone mineral density, endplate geometry, and preparation technique on endplate failure load.The effects of endplate preparation methods on failure loads are only partly characterized in the literature. Endplate burring has been recommended to increase fusion rates. However, graft subsidence may complicate anterior reconstruction procedures.After radiographic screening, 21 cadaveric cervical spines underwent dual-energy x-ray absorptiometry scanning to quantify mineral content. Endplate geometry was calculated in 55 randomly selected endplates from the inferior C2 to the superior T1 levels. These vertebrae were embedded in polyester resin and randomly left intact, perforated, or burred. The cervical endplates were loaded at a rate of 0.2 mm/s on an Instron materials tester with an attached 9 mm diameter polycarbonate rod (an area of 64 mm2). A stepwise, univariate linear regression was used to compare the point of endplate failure with the vertebral level, endplate area, gender, age, bone mineral density, and preparation technique.Mean bone mineral density, as measured by dual-energy x-ray absorptiometry, was 0.713 g/cm2 (+/- 0.173 g/cm2). Mean endplate area was calculated at 323 mm2. A mean compressive force of 754 N (+/- 445 N) was required before endplate failure. Trends toward increasing compressive loads were noted with decreasing endplate area and increasing bone mineral density. Increasing age (P = 0.0203), caudal vertebral level (P0.0001), endplate burring (P = 0.0068), and female gender (P = 0.0452) were associated with significantly lower endplate fracture loads in compression.Bone quality was predictive of endplate compressive failure loads. Intact endplates failed at significantly higher loads than their perforated or burred counterparts.

The ability of bone morphogenetic proteins (BMPs) to induce bone formation has led to an increasing interest in the potential for their use in fusion surgery. The purpose of this multi-center clinical pilot study was to evaluate the safety of one such BMP-osteogenic protein 1, in the form of OP-1 putty-combined with autograft for intertransverse process fusion of the lumbar spine in patients with symptomatic spinal stenosis and degenerative spondylolisthesis following spinal decompression. Twelve patients with spinal stenosis and degenerative lumbar spondylolisthesis underwent laminectomy and partial or complete medial facetectomy as required for decompression of the neural elements followed by intertransverse process fusion by placing iliac crest autograft and OP-1 putty between the decorticated transverse processes. No instrumentation was used. Patients were followed clinically using the Oswestry scale and radiographically using static and dynamic radiographs to assess their fusion status. Independent and blinded radiologists assessed the films for the presence of bridging bone between the transverse processes and measured translation and angulation on dynamic films using digital calipers. In addition to bridging bone, less than or equal to 5 degrees of angular motion and less than or equal to 2 mm of translation were required to classify the patients as successfully fused, as per the definition of successful fusion provided by the FDA for use in clinical trials involving investigational devices to attain spinal fusion. Radiographic outcome was compared to a historical control (autograft alone fusion without instrumentation for the treatment of degenerative spondylolisthesis). All adverse events were recorded prospectively. The results showed 9 of the 12 patients (75%) obtained at least a 20% improvement in their preoperative Oswestry score, while 6 of 11 patients (55%) with radiographic follow-up achieved a solid fusion by the criteria used in this study. Bridging bone on the anteroposterior film was observed in 10 of the 11 patients (91%). No systemic toxicity, ectopic bone formation, recurrent stenosis or other adverse events related to the OP-1 putty implant were observed. A successful fusion was observed in slightly over half the patients in this study, using stringent criteria without adjunctive spinal instrumentation. This study did not demonstrate the superiority of OP-1 combined with autograft over an autograft alone historical control, in which the fusion rate was approximately 45%. The lack of adverse events related to the OP-1 putty implant in this study is in agreement with other studies supporting the safety of bone morphogenetic proteins in spinal 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.

An in vitro biomechanical study using a calibrated distractor and a subminiature load cell in a cadaver anterior cervical discectomy construct was conducted.To study the interrelations of preoperative disc height, graft height, and compressive and distractive forces in an anterior cervical discectomy model.The effects of graft size on compressive and distractive forces in a discectomy model remain unknown. Larger grafts afford neural decompression through anterior column distraction. This distraction may subject the graft and vertebral bodies to excessive loads, increasing graft fracture, and subsidence risk.Disc height was measured radiographically in 18 specimens. A Smith-Robinson discectomy was performed, and the superior and inferior ends of the specimens were embedded in polyester resin. Distraction was applied through a calibrated Caspar distractor to measure the distractive force applied while steel spacers rigidly fixed to a subminiature load cell were introduced. After distraction was removed, immediate compressive force was measured.Distractive forces of 112.4 N and 189.9 N were required to insert the 6-mm and 8-mm grafts, respectively. When this distractive force was removed, immediate compressive loads of 8.8 N and 21.5 N on the graft were noted. When a compressive load of 45 N was applied in a loading frame, measured graft loads of 16.2 N and 29.2 N also increased. No statistically significant relation was observed between preoperative disc height and distractive force or compression of the graft. Significantly lower distractive and compressive forces were associated with insertion of the 6-mm rather than 8-mm graft.Significantly higher distractive and compressive forces were recorded with larger grafts. Preoperative disc height was not an accurate predictor of graft loads.

As degenerative changes progress in the aging population, more patients will present with degenerative spondylolisthesis. The clinical picture is usually of a woman older than 50 years of age with a degenerative lumbar spondylolisthesis at L5 with symptoms of neurogenic claudication or radiculopathy. Imaging studies will reveal a central recess, a lateral recess or both, and/or neuroforaminal stenosis. When patients do not respond to nonoperative treatments, surgical intervention is indicated. Most studies have concluded that the addition of an arthrodesis improves the clinical outcome. A recent longterm study showed that a solid fusion and an adequate decompression is the procedure offering the best outcome. The current authors will review the pathogenesis, clinical picture, and treatment recommendations for degenerative lumbar spondylolisthesis.

Study Design. The intervertebral disc, in a sheep model, was used to assess the effect of directly repairing three different anular incisions on the subsequent healing strength of the intervertebral disc. Objectives. To assess whether directly repairing an anular defect, made at the time of lumbar discectomy, could influence the healing rate and strength of the anulus fibrosus. Methods. Twenty-four sheep underwent a retroperitoneal approach to five lumbar disc levels, An anular incision, followed by partial discectomy was done at each exposed level. Anular incisions used in this study consisted of 1) a straight transverse slit, 2) a cruciate incision, and 3) a window or box excision. Healing strength was measured at three time intervals: 2 weeks, 4 weeks, and 6 weeks. Each anular incision type was performed on 30 lumbar discs, 10 discs in each time interval. Five discs in each time interval underwent direct repair, and five discs were left unrepaired to heal as controls. The sheep were killed at 2, 4, and 6 weeks after surgery. The lumbar spines were removed en bloc, and the intervertebral discs were subjected to pressure-volume testing to assess the anular strength of repaired versus unrepaired disc injuries at each time interval. Results. Statistical analysis was performed to evaluate the effects of healing time, incision technique, and repair on the pressure-volume characteristics of the involved discs. Pressure-volume testing showed trends of stronger healing for repaired discs, but at no time interval was any significant difference found between repaired and nonrepaired anular strength. Of the nonrepaired discs, the box incision was only 40 to 50% as strong as the slit or cruciate incised discs during early healing. Conclusion. Direct repair of anular incisions in the lumbar spine does not significantly alter the healing strength of the intervertebral disc after lumbar discectomy.

STUDY DESIGN A study on the efficacy of recombinant human bone morphogenetic protein 2 (rhBMP-2) in a nonhuman primate anterior interbody fusion model. OBJECTIVES To investigate the efficacy of rhBMP-2 with an absorbable collagen sponge carrier to promote spinal fusion in a nonhuman primate anterior interbody fusion model. SUMMARY OF BACKGROUND DATA RhBMP-2 is an osteoinductive growth factor capable of inducing new bone formation in vivo. Although dosage studies using rhBMP-2 have been performed on species of lower phylogenetic level, they cannot be extrapolated to the primate. Dosage studies on nonhuman primates are essential before proceeding with human primate application. METHODS Six female adult Macaca mulatta (rhesus macaque) monkeys underwent an anterior L7-S1 interbody lumbar fusion. All six sites were assigned randomly to one of two fusion methods: 1) autogenous bone graft within a single freeze-dried smooth cortical dowel allograft cylinder (control) or 2) rhBMP-2-soaked absorbable collagen sponges within a single freeze-dried smooth cortical dowel allograft cylinder also soaked in rhBMP-2. The animals underwent a baseline computed tomography scan followed by 3- and 6-month postoperation scans. Anteroposterior and lateral radiographs of the lumbosacral spine were performed monthly. After the monkeys were killed, the lumbar spine fusion sites were evaluated. Histologic evaluation of all fusion sites was performed. RESULTS The three monkeys receiving rhBMP-2-soaked collagen sponges with a freeze-dried allograft demonstrated radiographic signs of fusion as early as 8 weeks. The control animals were slower to reveal new bone formation. The computed tomography scans revealed extensive fusion of the L7-S1 lumbar vertebrae in the group with rhBMP-2. A pseudarthrosis was present in two of the control animals. CONCLUSIONS This study was able to document the efficacy of rhBMP-2 with an absorbable collagen sponge carrier and a cortical dowel allograft to promote anterior interbody fusion in a nonhuman primate model at a dose of 0.4 mg per implant site (1.5 mg/mL concentration). The late of new bone formation and fusion with the use of rhBMP-2 and cortical dowel allograft appears to be far superior to that of autogenous cancellous iliac crest graft with cortical dowel allograft.

Spinal stenosis is a narrowing or stricture of the spinal canal. Cauda equina and nerve-root compression are noted in many asymptomatic individuals8. Therefore, narrowing alone does not explain all of the symptoms and signs seen in patients who have the clinical syndrome of spinal stenosis, or neurogenic claudication. The spinal degenerative process associated with aging leads to pathoanatomical and pathophysiological changes with occasional clinical consequences. Not only does narrowing occur, but abnormal spinal motion can further increase the degree of compression. With progressive degenerative changes and compression, spinal stenosis may become symptomatic, although the severity of the symptoms is not necessarily associated with the magnitude of the compression seen on imaging studies. Spinal stenosis can be classified as either congenital or acquired3 (Table I). Congenital stenosis is commonly seen in individuals who have achondroplasia or another short-stature syndrome. The congenital classification also includes stenosis in individuals of normal stature who have congenitally short pedicles accompanied by bulging discs at multiple levels. The latter group frequently has symptoms when they are between the ages of thirty and forty years old. View this table: TABLE I CLASSIFICATION OF STENOSIS OF THE SPINAL CANAL Acquired degenerative stenosis tends to lead to symptoms in women at a mean age of seventy-three years and in men at a somewhat younger age86. Degenerative spondylolisthesis, seen more often in women than in men, also may contribute to the symptoms of spinal stenosis67,69,70,147. Although there are many causes of spinal stenosis, this discussion will focus on the degenerative process. Degenerative changes and narrowing can occur (1) centrally; (2) in the lateral recess, leading to nerve-root impingement from an overhanging, hypertrophic facet joint; (3) within the nerve-root canal (foraminal stenosis); or (4) extraforaminally, frequently because of entrapment by osteophytes, …

Study Design. A rabbit model was used to test the efficacy of cefazolin administered in various therapeutic regimens in preventing iatrogenic Staphylococcus aureus infections during spinal instrumentation. Objective. To assess the efficacy of various prophylactic therapeutic regimens of cefazolin in preventing iatrogenic S. aureus infections during spinal instrumentation. Summary of Background Data. Previous studies have not dealt specifically with the occurrence of iatrogenic S. aureus infections during spinal instrumentation in a prospective fashion. Methods. Twenty New Zealand White rabbits underwent a posterior approach to the lumbar spine. Fifteen of the animals then had double-braided 26-gauge surgical wire placed around bilateral L3-L4 and L4-L5 facet joints. A standardized volume of a 103 S. aureus/mL of solution was then inoculated onto the fusion-hardware site in all rabbits. The rabbits were divided into four groups receiving various antibiotic dose regimens. Five days after surgery, the animals were killed, and cultures were obtained. Results. All of the rabbits receiving no antibiotic had fusion sites infected with S. aureus. None of the animals who received prophylactic cefazolin produced cultures that grew S. aureus. A specimen from one fusion site cultured Staphylococcus epidermidis, which is not sensitive to cefazolin. Analysis of these data using Fisher's exact test resulted in a P value of 0.008 when results in antibiotic groups were compared with those in a group receiving no antibiotics and a P value of 0.0003 when all groups were compared. Conclusions. This model was valid and reproducible for the study of spinal instrumentation and infection. In addition, the data support the efficacy and use of prophylactic intravenous antibiotics in preventing infection in spinal instrumentation and fusion surgery.

Candidates who are eligible for the Part-II oral examination of the American Board of Orthopaedic Surgery (ABOS) may select their specific subspecialty area for testing after fellowship training. Subspecialties are hand, spine, pediatrics, sports, adult reconstruction, trauma, oncology, and foot and ankle. Subspecialization means that the candidate commits at least 50% of his or her practice to that subspecialty. This would be declared and reflected in the list of cases managed during the collection period, defined as six consecutive months of operative cases, beginning July 1 of the year prior to the Part-II examination. Sixty-five to seventy orthopaedic surgeons who are part of the oral examination group review the case lists submitted by the applicant and select twelve cases for the oral examination of which two cases can be deleted by the candidate. For each case selected, the candidate must provide the following: (1) notes from the initial history and physical examination (the first visit), (2) notes on the operative procedure, (3) notes from an office visit made at a minimum of three months postoperatively, (4) the discharge summary as well as information on all relevant consultations obtained concerning the care of the patient, and (5) all relevant imaging studies made preoperatively, intraoperatively, and postoperatively. All records must be organized to allow examiners ready access to these materials. In addition to the specialty case list, a candidate who selects a subspecialty designation will be examined by three sets of examiners with two examiners in each group. The ABOS guarantees candidates that at least one examiner in each examination group will be a subspecialist in that designated area. This ensures a fair and knowledgeable exchange of information between the candidate and the examiner and ensures that the interactions will reflect the most up-to-date evidence-based information in that subspecialty. What is expected …

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.

Study design This prospective study analyzed the influence of transpedicular instrumented on the operative treatment of patients with degenerative spondylolisthesis and spinal stenosis. Objectives To determine whether the addition of transpedicular instrumented improves the clinical outcome and fusion rate of patients undergoing posterolateral fusion after decompression for spinal stenosis with concomitant degenerative spondylolisthesis. Summary of background data Decompression is often necessary in the treatment of symptomatic patients who have degenerative spondylolisthesis and spinal stenosis. Results of recent studies demonstrated that outcomes are significantly improved if posterolateral arthrodesis is performed at the listhesed level. A meta-analysis of the literature concluded that adjunctive spinal instrumentation for this procedure can enhance the fusion rate, although the effect on clinical outcome remains uncertain. Methods Seventy-six patients who had symptomatic spinal stenosis associated with degenerative lumbar spondylolisthesis were prospectively studied. All patients underwent posterior decompression with concomitant posterolateral intertransverse process arthrodesis. The patients were randomized to a segmental transpedicular instrumented or noninstrumented group. Results Sixty-seven patients were available for a 2-year follow-up. Clinical outcome was excellent or good in 76% of the patients in whom instrumentation was placed and in 85% of those in whom no instrumentation was placed (P = 0.45). Successful arthrodesis occurred in 82% of the instrumented cases versus 45% of the noninstrumented cases (P = 0.0015). Overall, successful fusion did not influence patient outcome (P = 0.435). Conclusions In patients undergoing single-level posterolateral fusion for degenerative spondylolisthesis with spinal stenosis, the use of pedicle screws may lead to a higher fusion rate, but clinical outcome shows no improvement in pain in the back and lower limbs.

The use of spinal instrumentation as an adjunct to fusion for the treatment of degenerative disorders of the lumbar spine is controversial. Instrumented lumbar fusions, in specific instances, may improve patient outcomes. For patients undergoing single level primary lumbar arthrodesis, the available data do not conclusively support the efficacy of spinal instrumentation. However, in the setting of previous failed lumbar surgery, iatrogenic or degenerative lumbar spondylolisthesis, spinal instrumentation may be useful as an adjunct to fusion. Possible advantages associated with the use of instrumentation include: correction of deformity in frontal and sagittal planes; decreased pseudarthrosis rates; prevention of progression of spondylolisthesis, and provision of spinal stability in the absence of intact posterior elements. Complications associated with the use of instrumentation include: increased cost; increased operative times; increased infection rate; increased reoperation rate; and a steep learning curve. Therefore, when instrumentation is to be used, the benefits must outweigh the risks. These risks can be minimized by the judicious use of instrumentation by experienced surgeons, for specific indications as supported by the literature.

The principles of surgery in spinal stenosis follow a clear understanding of the pathology in the various types ofstenosis. This article describes how the basic technique of one-level decompression in spinal stenosis is modified to deal with the pathology in degenerative spondylolisthesis. We have provided an explanation of the pathology in spinal stenosis with degenerative spondylolisthesis, and how modifications of the basic decompressive technique are necessary to deal with these variations in pathology. The indications and technique for a concomitant lateral spinal fusion are described. Techniques of instrumentation are not covered in this article.

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.

Study Design. A retrospective chart review was performed from 1990-1994. Objectives. To evaluate the outcome of pathologic examination on cervical disc specimens submitted after anterior cervical discectomy. Summary of Background Data. This study is the first to review the outcome of pathologic examination of disc specimens after anterior cervical discectomy and fusion. Methods. Charts were reviewed based on the procedure code of anterior cervical fusion and the main diagnoses of cervical disc and spondylosis. The following data were recorded for each patient: symptoms, examination, diagnostic studies, operative procedure, operative findings, and pathology report. Statistical analysis was performed. Results. Five hundred six disc levels in 394 patients reviewed. All patients had symptoms and examination results consistent with cervical radiculopathy. All patients, had cervical radiographs and some combination of myelography, computed tomography, or magnetic resonance imaging. Findings at the time of surgery included the presence of either a herniated disc or degenerative spondylitic changes. The pathologic examination results of all specimens reported fibrocartilaginous tissue consistent with disc material with the presence of degenerative changes. No infectious, benign, or malignant process was identified at the time of surgery or on gross and histologic examination of any of the disc specimens. Using confidence intervals (95%) for exact proportions and given 500 negatives, the chance the next occurrence would be positive would be 0.0060 or 0.60% or six of 1000. Conclusions. This study shows that if the symptoms, physical examination, radiographic diagnostic studies, and surgical findings are consistent with those of cervical disc herniation or spondylosis, the chance of an unexpected, clinically important pathologic finding within the disc specimen is extremely small. The time and expense involved in routine pathologic examination of cervical disc specimens can be avoided.

Anterior cervical discectomy and fusion is indicated for the operative treatment of either cervical radiculopathy orcervical myelopathy. This article discusses the indications for the procedure, as well as the advantages of this approach, compared with foraminotomy, laminectomy, as well as laminoplasty. The operative technique is described in detail, as well as the results and complications.

The role of arthrodesis in the treatment of degenerative disorders of the lumbar spine is controversial. Most patients with these conditions can be successfully treated nonoperatively. Lumbar fusion, with or without instrumentation, is associated with more complications, especially in the elderly population. Therefore, the potential benefits to be obtained by means of arthrodesis must be measured against the risks. Arthrodesis is indicated as an adjunct to decompression for patients with spinal stenosis associated with degenerative or iatrogenic spondylolisthesis and in the treatment of progressive degenerative lumbar scoliosis and iatrogenic instability resulting from extensive decompression. The occurrence of two or more episodes of disk herniation at the same segment is a relative indication for arthrodesis. In patients with incapacitating nonradicular back pain, arthrodesis should be a consideration only after failure of a trial of nonoperative treatment lasting more than 12 months and after secondary gain issues (e.g., workmen's compensation) have been adequately resolved. Arthrodesis has a poor success rate when used to treat back pain associated with multilevel disk degeneration seen on magnetic resonance images.

Study design Retrospective review. Objectives To determine the efficacy of preoperative antibiotics alone in preventing wound infections following lumbar diskectomy. Summary of background data It is well documented that antibiotics given perioperatively reduce the rate of postoperative wound infections in lumbar disc surgery. At our institution, the current protocol for patients undergoing lumbar diskectomy is a single preoperative antibiotic dose. This study was conducted to compare the rate of postoperative wound infection incurred for single versus multiple perioperative antibiotic doses. It was hypothesized that no significant difference in infection rates would be identified. Methods This retrospective chart review compared the rates of postoperative wound infections incurred when single versus multiple perioperative antibiotic doses were given to patients having lumbar laminotomy for herniated discs. The procedures were performed between 1993 and March 1999. There were 434 patients in the multiple dose group and 201 in the single dose group. The multiple dose group received one preoperative and at least three postoperative doses of antibiotics. The single dose group received one preoperative dose of antibiotics. A postoperative infection was deemed present by either clinical diagnosis or culture results. The medical records were reviewed for 6 weeks after surgery for all patients. Results There were 5 out of 435 (1.15%) infections in the multiple dose group and 3 out of 201 (1.49%) in the single dose group. Statistical analysis showed no significant difference between the two study groups. Conclusion These results support the use of single preoperative dose of antibiotics in lumbar disc surgery. This is relevant as many lumbar diskectomy patients are candidates for early hospital discharge. At our institution, no increased risk of infection occurred for the single dose group.