Segmental Motion of Cervical Arthroplasty Leads to Decreased Adjacent-Level Degeneration: Analysis of the 7-Year Postoperative Results of a Multicenter Randomized Controlled Trial.

BACKGROUND: Cervical artificial disc replacement (C-ADR) has become a common and accepted surgical treatment for many patients with cervical disc degeneration/herniation and radiculopathy who have failed nonoperative treatment. Midterm follow-up studies of the original investigational device exemption trials comparing C-ADR to traditional anterior cervical discectomy and fusion (ACDF) have revealed C-ADR patients have less adjacent-level disease and fewer reoperations at 5 to 7 years. The purpose of this study was to examine the relationship of radiographic adjacent-level disease (R-ALD) with the amount of index-level segmental range of motion (ROM) in C-ADR patients using the long-term follow-up data from the ProDisc-C investigational device exemption trial. METHODS: This was a post hoc analysis of a 1:1 randomized controlled trial. The initial previously described Food and Drug Administration-approved 2-year study was extended, and consenting patients in the original study were followed at annual intervals up to 7 years. Logistic regression was used to assess any progression in adjacent-level disease (ALD). Ordinal logistic regression was also used to assess the relationship between any progressive R-ALD and final flexion extension (F/E) ROM in C-ADR patients. Spearman's rank-order correlation was used when R-ALD was kept as an ordinal variable to assess the same relationship. RESULTS: At the last follow-up visit, the rate of progressive R-ALD was significantly higher in ACDF patients than in C-ADR patients. When C-ADR patients were divided into 3 groups based on final F/E ROM, those with 0° to 3° (n = 19), 4° to 6° (n = 15), and 7° (n = 42) of segmental motion at the index procedure level, the rate of progressive R-ALD trended significantly with final ROM (P = 0.01). CONCLUSIONS: C-ADR leads to a significant decrease in R-ALD compared to ACDF. The difference in R-ALD is related to the preservation of motion at the index level and resultant preservation of kinematics and forces across the adjacent disc space.

Cervical fusion for treatment of degenerative conditions: development of appropriate use criteria.

BACKGROUND CONTEXT: High quality evidence is difficult to generate, leaving substantial knowledge gaps in the treatment of spinal conditions. Appropriate use criteria (AUC) are a means of determining appropriate recommendations when high quality evidence is lacking. PURPOSE: Define appropriate use criteria (AUC) of cervical fusion for treatment of degenerative conditions of the cervical spine. STUDY DESIGN/SETTING: Appropriate use criteria for cervical fusion were developed using the RAND/UCLA appropriateness methodology. Following development of clinical guidelines and scenario writing, a one-day workshop was held with a multidisciplinary group of 14 raters, all considered thought leaders in their respective fields, to determine final ratings for cervical fusion appropriateness for various clinical situations. OUTCOME MEASURES: Final rating for cervical fusion recommendation as either "Appropriate," "Uncertain" or "Rarely Appropriate" based on the median final rating among the raters. METHODS: Inclusion criteria for scenarios included patients aged 18 to 80 with degenerative conditions of the cervical spine. Key modifiers were defined and combined to develop a matrix of clinical scenarios. The median score among the raters was used to determine the final rating for each scenario. The final rating was compared between modifier levels. Spearman's rank correlation between each modifier and the final rating was determined. A multivariable ordinal regression model was fit to determine the adjusted odds of an "Appropriate" final rating while adjusting for radiographic diagnosis, number of levels and symptom type. Three decision trees were developed using decision tree classification models and variable importance for each tree was computed. RESULTS: Of the 263 scenarios, 47 (17.9 %) were rated as rarely appropriate, 66 (25%) as uncertain and 150 (57%) were rated as appropriate. Symptom type was the modifier most strongly correlated with the final rating (adjusted ρ2 = 0.58, p<.01). A multivariable ordinal regression adjusting for symptom type, diagnosis, and number of levels and showed high discriminative ability (C statistic = 0.90) and the adjusted odds ratio (aOR) of receiving a final rating of "Appropriate" was highest for myelopathy (aOR, 7.1) and radiculopathy (aOR, 4.8). Three decision tree models showed that symptom type and radiographic diagnosis had the highest variable importance. CONCLUSIONS: Appropriate use criteria for cervical fusion in the setting of cervical degenerative disorders were developed. Symptom type was most strongly correlated with final rating. Myelopathy or radiculopathy were most strongly associated with an "Appropriate" rating, while axial pain without stenosis was most associated with "Rarely Appropriate."

Enhanced Recovery After Surgery Trends in Adult Spine Surgery: A Systematic Review.

BACKGROUND: Enhanced Recovery After Surgery (ERAS) is a multimodal, multidisciplinary approach to optimizing the postsurgical recovery process through preoperative, perioperative, and postoperative interventions. ERAS protocols are emerging quickly within orthopedic spine surgery, yet there is a lack of consensus on optimal ERAS practices. OBJECTIVE: The aim of this systematic review is to identify and discuss the trends in spine ERAS protocols and the associated outcomes. METHODS: A literature search on PubMed was conducted to identify clinical studies that implemented ERAS protocols for various spine procedures in the adult population. The search included English-language literature published through December 2019. Additional sources were retrieved from the reference lists of key studies. Studies that met inclusion criteria were identified manually. Data regarding the study population, study design, spine procedures, ERAS interventions, and associated outcome metrics were extracted from each study that met inclusion criteria. RESULTS: Of the 106 studies identified from the literature search, 22 studies met inclusion criteria. From the ERAS protocols in these studies, common preoperative elements include patient education and modified preoperative nutrition regimens. Perioperative elements include multimodal analgesia and minimally invasive surgery. Postoperative elements include multimodal pain management and early mobilization/rehabilitation/nutrition regimens. Outcomes from ERAS implementation include significant reductions in length of stay, cost, and opioid consumption. Although these trends were observed, there remained great variability among the ERAS protocols, as well as in the reported outcomes. CONCLUSIONS: ERAS may improve cost-effectiveness to varying degrees for spinal procedures. Specifically, the use of multimodal analgesia may reduce overall opioid consumption. However, the benefits of ERAS likely will vary based on the specific procedure. CLINICAL RELEVANCE: This review contributes to the assessment of ERAS protocol implementation in the field of adult spine surgery.

Three-dimensional printing in spine surgery: a review of current applications.

In recent years, the use of three-dimensional printing (3DP) technology has gained traction in orthopedic spine surgery. Although research on this topic is still primarily limited to case reports and small cohort studies, it is evident that there are many avenues for 3DP innovation in the field. This review article aims to discuss the current and emerging 3DP applications in spine surgery, as well as the challenges of 3DP production and limitations in its use. 3DP models have been presented as helpful tools for patient education, medical training, and presurgical planning. Intraoperatively, 3DP devices may serve as patient-specific surgical guides and implants that improve surgical outcomes. However, the time, cost, and learning curve associated with constructing a 3DP model are major barriers to widespread use in spine surgery. Considering the costs and benefits of 3DP along with the varying risks associated with different spine procedures, 3DP technology is likely most valuable for complex or atypical spine disorder cases. Further research is warranted to gain a better understanding of how 3DP can and will impact spine surgery.

Analysis of Postoperative Thoracolumbar Spine Infections in a Prospective Randomized Controlled Trial Using the Centers for Disease Control Surgical Site Infection Criteria.

INTRODUCTION: Wound infections following spinal surgery place a high toll on both the patient and the healthcare system. Although several large series studies have examined the incidence and distribution of spinal wound infection, the applicability of these studies varies greatly since nearly every study is either retrospective and/or lacks standard inclusion criteria for defining surgical site infection. To address this void, we present results from prospectively gathered thoracolumbar spine surgery data for which the Centers for Disease Control (CDC) criteria were stringently applied to define a surgical site infection (SSI). METHODS: A prospective randomized trial of 314 patients who underwent multilevel thoracolumbar spinal surgery with instrumentation followed by postoperative drain placement was completed (Takemoto et al., 2015). The trial consisted of two antibiotic arms: one for 24-hours, and the other for the duration of the drain; no differences were found between the arms. All infections meeting CDC criteria for SSI were included. RESULTS: A total of 40 infections met CDC criteria for SSI, for an overall incidence of 12.7%. Of these, 20 (50%) were culture-positive. The most common organism was Staphylococcus aureus (4 total: methicillin-sensitive=2; methicillin-resistant=2), followed by coagulase-negative Staphylococcus (3 cases), Propionibacterium acnes and Escherichia coli (2 cases each). Six infections grew multiple organisms, most commonly involving coagulase-negative staphylococcus and enterococcus. CONCLUSIONS: Our findings indicate that thoracolumbar SSI occurs at the higher end of the range cited in the literature (2-13%), which is largely based on retrospective data not subjected to the inclusivity of SSI as defined by the CDC. The three most common organisms in our analysis (S. aureus, P. acnes, E. coli) are consistent with previous reports. Staphylococcus aureus continues to be the most common causative organism and continued vigilance and searching for preventive measures need to be a high priority. This study provides Level I evidence.

Cervical disc replacement - emerging equivalency to anterior cervical discectomy and fusion.

PURPOSE: Cervical disc replacement has become an acceptable alternative to anterior cervical fusion for the surgical treatment of cervical spine spondylosis resulting in radiculopathy or myelopathy following anterior discectomy and decompression. This concise overview considers the current state of knowledge regarding the continued debate of the role of cervical disc replacement with an update in light of the latest clinical trial results. METHODS: A literature review was performed identifying clinical trials pertaining to the use of cervical disc replacement compared to cervical discectomy and fusion. Single level disease and two level disease were considered. Outcome data from the major clinical trials was reviewed and salient points identified. RESULTS: With lengthier follow-up data becoming available, the equivalence of CDR in appropriately selected cases is becoming clear. This is chiefly manifested by reduced re-operation rates and reduced incidence of adjacent level disease in those treated with arthroplasty. CONCLUSION: Cervical disc replacement shows emerging equivalence in outcomes compared to the gold standard anterior cervical discectomy and fusion. Further longer term results are anticipated to confirm this trend.

ProDisc-C Total Disc Replacement Versus Anterior Cervical Discectomy and Fusion for Single-Level Symptomatic Cervical Disc Disease: Seven-Year Follow-up of the Prospective Randomized U.S. Food and Drug Administration Investigational Device Exemption Study.

BACKGROUND: In patients with single-level cervical degenerative disc disease, total disc arthroplasty can relieve radicular pain and preserve functional motion between two vertebrae. We compared the efficacy and safety of cervical total disc arthroplasty with that of anterior cervical discectomy and fusion (ACDF) for the treatment of single-level cervical degenerative disc disease between C3-C4 and C6-C7. METHODS: Two hundred and nine patients at thirteen sites were randomly treated with either total disc arthroplasty with ProDisc-C (n = 103) or with ACDF (n = 106). Patients were assessed preoperatively; at six weeks and three, six, twelve, eighteen, and twenty-four months postoperatively; and then annually until seven years postoperatively. Outcome measures included the Neck Disability Index (NDI), the Short Form-36 (SF-36), postoperative neurologic parameters, secondary surgical procedures, adverse events, neck and arm pain, and satisfaction scores. RESULTS: At seven years, the overall follow-up rate was 92% (152 of 165). There were no significant differences in demographic factors, follow-up rate, or patient-reported outcomes between groups. Both procedures were effective in reducing neck and arm pain and improving and maintaining function and health-related quality of life. Neurologic status was improved or maintained in 88% and 89% of the patients in the ProDisc-C and ACDF groups, respectively. After seven years of follow-up, thirty secondary surgical procedures had been performed in nineteen (18%) of 106 patients in the ACDF group compared with seven secondary surgical procedures in seven (7%) of 103 patients in the ProDisc-C group (p = 0.0099). There were no significant differences in the rates of any device-related adverse events between the groups. CONCLUSIONS: Total disc arthroplasty with ProDisc-C is a safe and effective surgical treatment of single-level symptomatic cervical degenerative disc disease. Clinical outcomes after total disc arthroplasty with ProDisc-C were similar to those after ACDF. Patients treated with ProDisc-C had a lower probability of subsequent surgery, suggesting that total disc arthroplasty provides durable results and has the potential to slow the rate of adjacent-level disease. LEVEL OF EVIDENCE: Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

Association between compensation status and outcomes in spine surgery: a meta-analysis of 31 studies.

BACKGROUND CONTEXT: Numerous studies have demonstrated poorer outcomes in patients with Workers' compensation (WC) when compared with those without WC following treatment of various of health conditions, including spine disorders. It is thus important to consider compensation status when assessing treatment outcomes in spine surgery. However, reported strengths of association have varied significantly (1.31-7.22). PURPOSE: The objective of this study was to evaluate the association of unsatisfactory outcomes on compensation status in spine surgery patients. STUDY DESIGN/SETTING: A meta-analysis was performed. PATIENT SAMPLE: Patient sample is not applicable in this study. OUTCOME MEASURE: Demographics, type of surgery, country, follow-up time, patient satisfaction, return to work and non-union events were the outcome measures. METHODS: Both prospective and retrospective studies that compared outcomes between compensated and non-compensated patients in spine surgery were included. Two independent investigators extracted outcome data. The meta-analysis was performed using Revman software. Random effects model was used to calculate risk ratio (RR, 95% confidence interval [CI]) for dichotomous variables. RESULTS: Thirty-one studies (13 prospective; 18 retrospective) with a total of 3,567 patients were included in the analysis. Follow-up time varied from 4 months to 10 years. Twelve studies involved only decompression; the rest were fusion. Overall RR of an unsatisfactory outcome was 2.12 [1.74, 2.58; p<.001] in patients with WC when compared with those without WC after surgery. The RR of an unsatisfactory outcome in patients with WC, compared with those without, was 2.09 [1.38, 3.17]; p<.01 among studies from Europe and Australia, and 2.14 [1.48, 2.60]; p<.01 among US studies. The RR of decompression-only procedures was 2.53 [1.85, 3.47]; p<.01,and 1.79 [1.45, 2.21]; p<.01 for fusion. Forty-three percent (209 of 491) of patients with WC did not return to work versus 17% (214 of 1250) of those without WC (RR 2.07 [1.43, 2.98]; p<.001). Twenty-five percent (74 of 292) and 13.5% (39 of 287) of patients had non-union in the compensated and non-compensated groups, respectively. This was not statistically significant (RR 1.33 [0.92, 1.91]; p=.07). CONCLUSIONS: Workers' compensation patients have a two-fold increased risk of an unsatisfactory outcome compared with non-compensated patients after surgery. This association was consistent when studies were grouped by country or procedure. Compensation status must be considered in all surgical intervention studies.

A Review of Symptomatic Lumbosacral Transitional Vertebrae: Bertolotti's Syndrome.

BACKGROUND: Lumbosacral transitional vertebrae (LSTV) are increasingly recognized as a common anatomical variant associated with altered patterns of degenerative spine changes. This review will focus on the clinical significance of LSTV, disruptions in normal spine biomechanics, imaging techniques, diagnosis, and treatment. METHODS: A Pubmed search using the specific key words "LSTV," "lumbosacral transitional vertebrae," and "Bertolotti's Syndrome" was performed. The resulting group of manuscripts from our search was evaluated. RESULTS: LSTV are associated with alterations in biomechanics and anatomy of spinal and paraspinal structures, which have important implications on surgical approaches and techniques. LSTV are often inaccurately detected and classified on standard AP radiographs and MRI. The use of whole-spine images as well as geometric relationships between the sacrum and lumbar vertebra increase accuracy. Uncertainty regarding the cause, clinical significance, and treatment of LSTV persists. Some authors suggest an association between LSTV types II and IV and low back pain. Pseudoarticulation between the transverse process and the sacrum creates a "false joint" susceptible to arthritic changes and osteophyte formation potentially leading to nerve root entrapment. The diagnosis of symptomatic LSTV is considered with appropriate patient history, imaging studies, and diagnostic injections. A positive radionuclide study along with a positive effect from a local injection helps distinguish the transitional vertebra as a significant pain source. Surgical resection is reserved for a subgroup of LSTV patients who fail conservative treatment and whose pain is definitively attributed to the anomalous pseudoarticulation. CONCLUSIONS: Due to the common finding of low back pain and the wide prevalence of LSTV in the general population, it is essential to differentiate between symptoms originating from an anomalous psuedoarticulation from other potential sources of low back pain. Further studies with larger sample sizes and longer follow-up time would better demonstrate the effectiveness of surgical resection and help guide treatment.

Systematic Review of Thigh Symptoms after Lateral Transpsoas Interbody Fusion for Adult Patients with Degenerative Lumbar Spine Disease.

BACKGROUND: Lateral transpsoas interbody fusion (LTIF) is a minimally invasive technique for achieving lumbar spinal fusion. While it has many advantages over open techniques it carries with it a distinct set of risks, most commonly post-operative ipsilateral thigh pain, weakness and sensory disturbances. It is vital for both the surgeon and patient to understand the risks for and outcomes of injury associated with this procedure. We conducted a systematic review of the literature to evaluate the incidence, risks, and long-term clinical outcomes of post-operative thigh symptoms in patients treated with LTIF. METHODS: We conducted a search of MEDLINE, EMBASE, CINAHL, Scopus, Web of Science and the Cochrane Collaboration Library, using keywords and MeSH terms, for English-language literature published through September 2014, as well as reference lists from key articles. Studies were then manually filtered to retrieve articles that met inclusion criteria. We were interested in studies that reported postoperative lower extremity symptoms after LTIF, such as pain, weakness and changes in sensation. The strength of evidence was determined based on precepts outlined by the Grades of Recommendation Assessment, Development and Evaluation Working Group (GRADE). RESULTS: A total of 392 articles were initially retrieved, with 24 ultimately meeting criteria for inclusion. The incidence of any post-operative thigh symptom varied, ranging as high as 60.7%, with 9.3% of patients experiencing a motor deficit related to direct nerve injury. Several studies reported cases of persistent symptoms at 6 months follow up. Additionally, inclusion of the L4-5 disc space and a longer duration of surgery were both identified as risks for developing postoperative thigh symptoms. CONCLUSION: The risk of postoperative thigh symptoms after LTIF is high. Thigh pain, paresthesias and weakness were the most commonly reported symptoms. While most patients' symptoms resolved by 6 months follow up, several studies reported patients with symptoms persistent as far as 12 months removed from surgery. Surgery at the L4-5 disc space and longer surgical duration place the patient at greater risk for developing postoperative and long-term thigh symptoms.

Outcomes and complications of the midline anterior approach 3 years after lumbar spine surgery.

Objective. The purpose of this study was to evaluate a new questionnaire to assess outcomes related to the midline anterior lumbar approach and to identify risk factors for negative patient responses. Methods. A retrospective review of 58 patients who underwent anterior lumbar surgery at a single institution for either degenerative disc disease or spondylolisthesis in 2009 was performed. The outcome measures included our newly developed Anterior Lumbar Surgery Questionnaire (ALSQ), ODI, and EQ-5D. Results. There were 58 patients available for followup, 27 women and 31 men. The average age at surgery was 50.8 years, with an average followup of 2.92 years. The average change in ODI was 34.94 (22.7) and EQ-5D was 0.28 (0.29). The rate of complications with the anterior approach was 10.3% and there was one male patient (3.2%) with retrograde ejaculation. Determination of the effectiveness of the new ALSQ revealed that it significantly correlated to the EQ-5D and ODI (P < 0.05). Smoking was associated with a negative response on thirteen questions. BMP use was not associated with a negative response on any sexual function questions. Conclusions. Our new Anterior Lumbar Surgery Questionnaire determines patient perceived complications related to the midline anterior lumbar surgical approach.

Hospital for joint diseases participates in international spine registry Spine Tango after successful pilot study.

Spine Tango is currently the only international spine registry in existence. It was developed under the auspices of Eurospine, the Spine Society of Europe, and is hosted at the University of Bern, Switzerland. The HJD Spine Center successfully tested Spine Tango during a 3-month pilot study and has since expanded documentation activities to more surgeons. Workflow integration and dedicated research staff are key factors for such an endeavor. Participation enables benchmarking against national and international peers and outcome research and quality assurance of surgical and non-surgical treatments.

Conjoined nerve roots of the lumbar spine.

BACKGROUND CONTEXT: Conjoined nerve roots are a relatively uncommon finding but are frequently undiagnosed on preoperative imaging studies. The presence of a conjoined root anomaly represents a significant potential for neurologic injury when nerve root mobilization is necessary during spinal procedures. PURPOSE: This comprehensive review of conjoined lumbar nerve roots encompasses preoperative diagnosis by physical examination and radiographic imaging studies, as well as the intraoperative management of conjoined nerve roots. STUDY DESIGN: Systematic review of existing literature. RESULTS: Findings have been described on standard magnetic resonance imaging (MRI) and computed tomography imaging to increase preoperative diagnosis rates. The literature lacks concrete recommendations regarding intraoperative techniques for conjoined root identification and management. CONCLUSIONS: Preoperative recognition and diagnosis of this anomaly has proven to be the best way to improve the chances of a successful procedure and avoid inadvertently damaging the nerve roots intraoperatively. Several radiographic signs of conjoined lumbar nerve roots have been described using standard MRI techniques including coronal T1- and T2-weighted sequences. Intraoperative management of conjoined nerve roots has not changed significantly since they were first identified, although diagnostic accuracy has improved with advanced MRI techniques.

Biomechanical comparison of translaminar screw versus pedicle screw supplementation of anterior femoral ring allografts in one-level lumbar spine fusion.

Pedicle screws (PS) can provide initial stabilization of anterior interbody femoral ring allograft (FRA) lumbar constructs. Translaminar screws (TLS) have also been advocated for this procedure. The objective of this study was to use an in vitro human cadaveric model to compare the stability of one-level anterior interbody lumbar constructs stabilized with PS and those stabilized with TLS. Five human cadaveric spinal motion segments (L4-S2) were biomechanically evaluated in the intact condition and using the follow- ing methods of stabilization: anterior interbody fusion with FRA, anterior FRA supplemented with PS, and anterior FRA supplemented with TLS. Stability was determined for each construct by measuring construct displacement as a function of applied load under the following conditions: compression, flexion, extension, lateral bending to each side, and axial torsion. There were no statistically significant differences in construct stability between FRA supplemented with PS and FRA supplemented with TLS under any of the loading conditions. In selected cases, supplementation of anterior femoral ring allograft with translaminar screws is a viable alternative to supplementation with pedicle screws.

Outcomes analysis of anterior-posterior fusion for low grade isthmic spondylolisthesis.

BACKGROUND: Traditional surgical treatment of isthmic spondylolisthesis is posterior-lateral fusion, but the addition of anterior surgery has been explored. The purpose of this study was to evaluate the surgical and clinical outcomes of anterior-posterior surgical treatment for low-grade isthmic spondylolisthesis. METHODS: Retrospectively, we enrolled 23 consecutive patients (mean age of 50) who underwent surgical treatment for low grade isthmic spondylolisthesis. The mean follow-up was 10 months. Basic demographic and radiographic data was collected. Pre- and post-surgical clinical surveys (VAS, ODI, and SF-36) were collected. RESULTS: All 23 patients underwent anterior interbody fusion with a femoral ring allograft or ICBG in combination with posterior lumbar decompression and fusion with instrumentation. The average slip percentage decreased from 23.2% to 19.0% (p = 0.24) while slip angle increased from 9.8° to 17.9° (p < 0.001) and average disc height decreased from 1.9 cm to 0.80 cm (p < 0.001). VAS scores decreased from 7.1 to 2.4 (p < 0.001), ODI scores decreased from 52.5 to 28.1 (p < 0.001), and SF-36 scores increased in the Physical Component Scale (PCS) from 29.5 to 42.6 (p < 0.001). CONCLUSION: In our study, patients demonstrated an improvement in the ODI as well the physical component scores of the SF-36, thus having a good clinical outcome.

The Incidence of Potential Candidates for Total Disc Replacement among Lumbar and Cervical Fusion Patient Populations.

STUDY DESIGN: Retrospective chart review. PURPOSE: To evaluate the incidence of potential total disc replacement (TDR) candidates among cervical and lumbar fusion patient populations using strict Food and Drug Administration (FDA) criteria and with relative exclusion criteria removed. OVERVIEW OF LITERATURE: Recent studies suggest that the potential percentage of patients that are candidates for TDR ranges from 0-5% in lumbar fusions and 43% in cervical fusions. METHODS: We performed a retrospective chart review of 280 consecutive patients who had lumbar (n = 174) and cervical (n = 106) fusion or TDR performed by one of four independent adult orthopaedic spine surgeons. Charts were screened for investigational device exemption (IDE) inclusion/exclusion criteria and later reanalyzed excluding relative exclusion criteria, such as history of chronic medical illness, twolevel disease (cervical cases), and history of prior fusion surgery in the anatomic region. RESULTS: Of the 174 lumbar surgeries, 10 were TDR with Prodisc-L and 164 were lumbar fusions. The most common TDR exclusion criteria were lytic spondylolisthesis or spinal stenosis (47.7% of patients) and more than 2 level degenerative disc disease (37.9%). 14.9% had no IDE exclusion criteria and would be considered candidates for TDR. After excluding the relative lumbar exclusion criteria, this percentage increased to 25.8%. Of the 106 cervical cases, 3 had a TDR with Prodisc-C and 103 had a cervical fusion. Twenty eight percent had no IDE exclusion criteria and would be considered candidates for cervical TDR. CONCLUSIONS: A larger percentage of cervical fusion candidates are potential candidates for TDR (28%) than lumbar fusion candidates (14.9%) based on the strict IDE criteria.

The prevalence of transitional vertebrae in the lumbar spine.

BACKGROUND CONTEXT: Lumbosacral transitional vertebrae (LSTVs) are a congenital vertebral anomaly of the L5-S1 junction in the spine. This alteration may contribute to incorrect identification of a vertebral segment, leading to wrong-level spine surgery and poor correlation with clinical symptoms. Although several studies describe the occurrence of this anomaly in back pain populations, investigation of the prevalence in the American general population is lacking. PURPOSE: To establish the prevalence rates for LSTVs in the general population. STUDY DESIGN: Retrospective review. PATIENT SAMPLE: Consecutive kidney-urinary bladder (KUB) radiographs of subjects from the past 2 years (2008-2009). OUTCOME MEASURES: Clinical demographics, number of lumbar vertebrae, L5-S1 transverse process (TP) height, and rib length. METHODS: Consecutive adult KUB studies of adult subjects were queried with clear visibility of the last rib's vertebral body articulation, all lumbar TPs, and complete sacral wings. Exclusion criteria consisted of any radiologic evidence of previous lumbosacral surgery that would obstruct our measurements. A total of 1,100 abdominal films were reviewed, and 211 were identified as being adequate for the measurement of the desired parameters. RESULTS: Two hundred eleven subjects were identified as eligible for the study, and 75 (35.6%) were classified as positive for a transitional lumbosacral vertebra. The most common anatomical variant was the Castellvi Type IA (14.7%). The average age at the time of the KUB study was 59.8 years (18-95 years). One hundred ninety-seven subjects (93.4%) presented five lumbar (nonribbed) vertebrae, and only 14 (6.6%) had six lumbar vertebrae. CONCLUSIONS: The significance of lumbosacral transitional level changes to the establishment of pain, degenerative changes, stenosis, and disc disease have been well documented in symptomatic patients. Although LSTV's role in low back pain remains controversial, our study has shown that, when the same criteria are used for classification, prevalence among the general population and symptomatic patients may be similar.

Prospective, randomized, multicenter Food and Drug Administration investigational device exemption study of the ProDisc-L total disc replacement compared with circumferential arthrodesis for the treatment of two-level lumbar degenerative disc disease: results at twenty-four months.

BACKGROUND: Disc replacement arthroplasty previously has been shown to be an effective alternative to spine fusion for the treatment of single-level lumbar degenerative disc disease. The purpose of the present study was to determine the twenty-four-month results of a clinical trial of the ProDisc-L total disc replacement as compared with spinal fusion for the treatment of degenerative disc disease at two contiguous vertebral levels from L3 to S1. METHODS: A total of 237 patients were treated in a randomized controlled trial designed as a non-inferiority study for regulatory application purposes. Blocked randomization was performed with use of a 2:1 ratio of total disc arthroplasty to circumferential arthrodesis. Evaluations, including patient self-assessments, physical and neurological examinations, and radiographic examinations, were performed preoperatively, six weeks postoperatively, and three, six, twelve, eighteen, and twenty-four months postoperatively. RESULTS: At twenty-four months, 58.8% (eighty-seven) of 148 patients in the total disc replacement group were classified as a statistical success, compared with 47.8% (thirty-two) of sixty-seven patients in the arthrodesis group; non-inferiority was demonstrated. The mean Oswestry Disability Index in both groups significantly improved from baseline (p < 0.0001); the mean percentage improvement for the total disc replacement group was significantly better than that for the arthrodesis group (p = 0.0282). An established clinical criterion for success, a ≥15-point improvement in the Oswestry Disability Index from baseline, occurred in 73.2% (109) of 149 patients in the total disc replacement group and 59.7% (thirty-seven) of sixty-two patients in the arthrodesis group. The Short Form-36 physical component scores were significantly better for the total disc replacement group as compared with the arthrodesis group (p = 0.0141 at twenty-four months). Visual analog scale scores for satisfaction significantly favored total disc replacement from three to twenty-four months. At twenty-four months, 78.2% (111) of 142 patients in the total disc replacement group and 62.1% (thirty-six) of fifty-eight patients in the arthrodesis group responded "yes" when asked if they would have the same surgery again. Lumbar spine range of motion on radiographs averaged 7.8° at the superior disc and 6.2° at the inferior disc in patients with total disc replacement. Reduction in narcotics usage significantly favored the total disc replacement group at twenty-four months after surgery (p = 0.0020). CONCLUSIONS: Despite the relatively short duration of follow-up and design limitations, the present study suggests that two-level lumbar disc arthroplasty is an alternative to and offers clinical advantages in terms of pain relief and functional recovery in comparison with arthrodesis. Longer-term follow-up is needed to determine the risks for implant wear and/or degenerative segment changes.

Intervertebral foramen size and volume changes in low grade, low dysplasia isthmic spondylolisthesis.

STUDY DESIGN: Anatomic study. OBJECTIVE: The purpose of this study is to determine the effect of the slip amount, slip angle, and disc height on the geometry of the L5 foramen in low-grade, low-dysplasia isthmic L5 spondylolisthesis using a human cadaveric model. SUMMARY OF BACKGROUND DATA: Radicular pain and varying degrees of nerve root dysfunction are present in many adult isthmic spondylolisthesis patients and can be the result of compression of the L5 root within its foramen. METHODS: The intervertebral foramens of six L5 vertebra and sacrum cadaver specimens had a standardized pars defect created and were mounted on an adjustable frame. Plasticene molds of the foramens were made by varying sagittal translocation (0%, 12.5%, 25%, and 50%), slip angle (kyphotic 10° and lordotic 0°, 10°, 20°, and 30°), and disc height (0, 5, and 10 mm). The volume of each mold was measured. The surface area was determined by sagittally slicing on a microtome the mold and each section's face was measured by computer image analysis. RESULTS: The area and volume of the foramen at a sagittal slip of 0%, slip angle of 0°, and 0 mm disc height were used as a control. As disc height decreased from 10 to 5 mm, 10 to 0 mm, and 5 to 0 mm, the foramen area and volume significantly decreased (P < 0.05). Incremental slip percentage from 0% to 12.5%, 25%, and 50% produced significantly reduced foramen area and volumes (P < 0.05). As slip angle increased from 10° kyphosis to 0°, 10°, 20°, and 30° lordosis, foramen area and volume decreased (P < 0.05). CONCLUSION: Disc height and slip percentage had the largest effect on intervertebral foramen area and volume in this model of low-grade, low-dysplasia isthmic spondylolisthesis. Slip angle changes affected foramen area to a lesser degree. Surgical treatment strategies should consider restoration of disc height in cases with foraminal stenosis.

Analysis of segmental cervical spine vertebral motion after prodisc-C cervical disc replacement.

STUDY DESIGN: Retrospective study of patients enrolled in a prospective randomized Food and Drug Administration trial with single level cervical disc replacement (CDR) with the ProDisc-C (Synthes, Paoli, PA). OBJECTIVE: Evaluate the segmental range of motion (ROM) in the cervical spine pre- and postoperative after CDR. SUMMARY OF BACKGROUND INFORMATION: Each cervical level is believed to have its own biomechanical characteristics, ultimately leading to different sagittal and lateral ROM. Our understanding of the factors that influence motion after CDR continues to change and expand. METHODS: One hundred sixty-four patients with single level ProDisc-C arthroplasty were evaluated radiographically using Medical Metrics (QMATM, Medical Metrics, Inc., Houston, TX). Pre- and postoperative disc height and ROM were measured from standing lateral and flexion-extension radiographs. Of these 164 patients, 44 had a CDR at C6/C7, 96 at C5/C6, 18 at C4/C5, and 6 at C3/C4. The mean follow-up was of 24 months. Statistical analysis evaluated the difference in mean ROM between the groups. RESULTS: Before surgery, C4/C5 had more sagittal ROM compared with C3/C4, C5/C6, and C6/C7 (P < 0.001.) Before surgery, C4/C5 also had more lateral ROM compared with C3/C4, C5/C6, and C6/C7 (P = 0.015). After surgery, there were no significant differences in sagittal and lateral ROM between C3/C4, C4/C5, C5/C6, and C6/C7. The delta (difference between pre- and postoperative) proved that the C4/C5 CDR actually lost sagittal ROM (-2.5 degrees ) compared with the other levels, which gained sagittal ROM, C3/C4 (0.9 degrees ), C5/C6 (1.8 degrees ), and C6/C7 (1.6 degrees ); P = 0.037. There was no significant difference in the delta lateral ROM between the segments: C3/C4, C4/C5, C5/C6, and C6/C7. CONCLUSION: CDR approximates the different segmental sagittal and lateral ROM. Although C4/C5 had negative delta ROM in the sagittal and lateral planes, it provided a satisfactory final ROM. Long-term clinical outcome studies are needed to properly evaluate if these differences could ultimately affect the patients everyday life.