Alpesh A. Patel

The subaxial cervical spine injury classification system: a novel approach to recognize the importance of morphology, neurology, and integrity of the disco-ligamentous complex.

Study Design. The classification system was derived through a literature review and expert opinion of experienced spine surgeons. In addition, a multicenter reliability and validity study of the system was conducted on a collection of trauma cases. Objectives. To define a novel classification system for subaxial cervical spine trauma that conveys information about injury pattern, severity, treatment considerations, and prognosis. To evaluate reliability and validity of this system. Summary of Background Data. Classification of subaxial cervical spine injuries remains largely descriptive, lacking standardization and prognostic information. Methods. Clinical and radiographic variables encountered in subaxial cervical trauma were identified by a working section of the Spine Trauma Study Group. Significant limitations of existing systems were defined and addressed within the new system. This system, as well as the Harris and Ferguson & Allen systems, was applied by 20 spine surgeons to 11 cervical trauma cases. Six weekslater, the cases were randomly reordered and again scored. Interrater reliability, intrarater reliability, and validity were assessed. Results. Each of 3 main categories (injury morphology, disco-ligamentous complex, and neurologic status) identified as integrally important to injury classification was assigned a weighted score; the injury severity score was obtained by summing the scores from each category. Treatment options were assigned based on threshold values of the severity score. Interrater agreement as assessed by intraclass correlation coefficient of the DLC, morphology, and neurologic status scores was 0.49, 0.57, and 0.87, respectively. Intrarater agreement as assessed by intraclass correlation coefficient of the DLC, morphology, and neurologic status scores was 0.66, 0.75, and 0.90, respectively. Raters agreed with treatment recommendations of the algorithm in 93.3% of cases, suggesting high construct validity. The reliability compared favorably to the Harris and Ferguson & Allen systems. Conclusion. The Sub-axial Injury Classification and Severity Scale provides a comprehensive classification system for subaxial cervical trauma. Early validity and reliability data are encouraging.

Cervical radiographical alignment: comprehensive assessment techniques and potential importance in cervical myelopathy.

Study Design. Narrative review. Objective. To provide a comprehensive narrative review of cervical alignment parameters, the methods for quantifying cervical alignment, normal cervical alignment values, and how alignment is associated with cervical deformity and myelopathy with discussions of health-related quality of life. Summary of Background Data. Indications for surgery to correct cervical alignment are not well-defined and there is no set standard to address the amount of correction to be achieved. In addition, classifications of cervical deformity have yet to be fully established and treatment options defined and clarified. Methods. A survey of the cervical spine literature was conducted. Results. New normative cervical alignment values from an asymptomatic volunteer population are introduced, updated methods for quantifying cervical alignment are discussed, and describing the relationship between cervical alignment, disability, and myelopathy are outlined. Specifically, methods used to quantify cervical alignment include cervical lordosis, cervical sagittal vertical axis, and horizontal gaze with the chin-brow vertical angle. Updated methods include T1 slope. Evidence from a few recent studies suggests correlations between radiographical parameters in the cervical spine and health-related quality of life. Analysis of the cervical regional alignment with respect to overall spinal pelvic alignment is emerging and critical. Cervical myelopthay and sagittal alignment of the cervical spine are closely related as cervical deformity can lead to spinal cord compression and tension. Conclusion. Cervical deformity correction should take on a comprehensive approach in assessing global cervical-pelvic relationships and the radiographical parameters that effect health-related quality of life scores are not well-defined. Cervical alignment may be important in assessment and treatment of cervical myelopathy. Future work should concentrate on correlation of cervical alignment parameters to disability scores and myelopathy outcomes. Summary Statements. Statement 1: Cervical sagittal alignment (cervical SVA and kyphosis) is related to thoracolumbar spinal pelvic alignment and to T1 slope. Statement 2: When significant deformity is clinically or radiographically suspected, regional cervical and relative global spinal alignment should be evaluated preoperatively via standing 3-foot scoliosis X-rays for appropriate operative planning. Statement 3: Cervical sagittal alignment (C2-C7 SVA) is correlated to regional disability, general health scores and to myelopathy severity. Statement 4: When performing decompressive surgery for CSM, consideration should be given to correction of cervical kyphosis and cervical sagittal imbalance (C2-C7 SVA) when present.

The 36-item short form.

Abstract The use of patient‐derived, objective outcome measures has expanded substantially within the orthopaedic literature. Qualityof‐life instruments are categorized as general health or as condition‐specific questionnaires. The Medical Outcomes Study 36‐Item Short Form (SF‐36) is a general health‐based survey of quality of life. It has been validated, is used widely across medical disciplines, and can be self‐administered by the patient with reliability. The SF‐36 has been implemented to define disease conditions, to determine the effect of treatment, to differentiate the effect of different treatments, and to compare orthopaedic conditions with other medical conditions. However, a bias of lower over upper extremity function has been demonstrated with the SF‐ 36, as have limitations in assessment of certain physical activities of daily living as well as upper and lower limits on the detection of certain changes in quality‐of‐life status. Nevertheless, with an adequate knowledge of its effectiveness and limitations, the SF‐36 can be a useful tool in many branches of orthopaedic surgery.

Perils of intravascular methylprednisolone injection into the vertebral artery. An animal study.

BACKGROUND Intravascular injection of particulate steroids during cervical nerve root blocks has been postulated to be a source of catastrophic neurologic complications that might be avoided with the use of non-particulate steroids. The objective of this study was to compare the effects of direct intravascular injection of particulate and non-particulate steroids on the spinal cord and central nervous system. METHODS Eleven adult pigs underwent direct injection, under fluoroscopic guidance, into the vertebral artery while under general anesthesia. A particulate steroid (methylprednisolone) was injected into four animals (Group 1), whereas seven animals received a non-particulate steroid (dexamethasone in four animals [Group 2] and prednisolone in three [Group 3]). Following injection, the animals were assessed by direct observation of physical activity and with magnetic resonance imaging. After the animals were killed, brain and spinal cord material was retrieved, fixed in paraformaldehyde for one week, and then subjected to histopathologic analysis. RESULTS All four animals in Group 1 failed to regain consciousness after the injection and required ventilatory support. The animals in Groups 2 and 3 recovered fully and demonstrated no evidence of neurologic injury. Magnetic resonance imaging revealed upper cervical cord and brain stem edema in Group 1, but not in Groups 2 and 3. Histologic analysis showed early evidence of hypoxic and ischemic damage-specifically, early eosinophilic neuronal necrosis, nuclear condensation, white-matter pallor, and extracellular edema-in Group 1 but not in Groups 2 and 3. CONCLUSIONS These data suggest that one etiology of neurologic complications following cervical nerve blocks may be inadvertent intravascular injection of particulate steroids, as all animals injected with methylprednisolone had neurologic deficits while none of the controls injected with non-particulate steroids were affected. To our knowledge, this study is the first to demonstrate that particulate steroids cause neurologic deficits and to suggest that use of non-particulate steroids might prevent such complications.

Degenerative magnetic resonance imaging changes in patients with chronic low back pain: A systematic review

Study Design. Systematic review. Objective. To systematically search for critically appraise and summarize studies that (1) evaluated the association between degenerative magnetic resonance imaging (MRI) changes and chronic low back pain (CLBP) and (2) compared surgical and nonsurgical treatment of these degenerative MRI changes. Summary of Background Data. The role of routine MRI in patients with CLBP is unclear. It is also uncertain whether or not surgical treatment of degenerative MRI changes results in alleviation of back pain. Methods. Systematic literature searches were conducted in PubMed for studies published through March 1, 2011. To evaluate whether MRI degenerative changes are associated with CLBP, studies that were designed to compare the prevalence of MRI changes among subjects with and without CLBP were sought. The prevalence odds ratio was used to compare the odds of degenerative MRI findings in subjects with CLBP to the odds of such findings among those without CLBP. To evaluate whether surgical treatment of degenerative MRI changes is associated with different outcomes compared with nonsurgical treatment, comparative studies were sought. The GRADE system as applied to describe the strength of the overall body of evidence. Results. Regarding the association of degenerative changes on MRI and CLBP, five studies were included, all of which were cross-sectional in design. On the basis of these studies, a statistically significant association was found in all but one study regarding the presence of disc degeneration and CLBP (odds ratio range: 1.8–2.8). The overall strength of evidence across studies was considered to be insufficient, however. No comparative studies of surgical versus nonsurgical treatment of degenerative MRI changes were identified. Conclusion. Although there may be an association between degenerative MRI changes and CLBP, it is unknown if these estimates accurately represent the association given the quality of included studies, lack of a direct link between degenerative MRI changes and CLBP, and heterogeneity across studies. Thus, a strong recommendation against the routine use of MRI for CLBP evaluation is made. Since there are no data evaluating the efficacy of the surgical treatment of degenerative MRI changes, a strong recommendation is made against the surgical treatment of CLBP based solely upon degenerative MRI changes. Clinical Recommendations.Recommendation 1: There is insufficient evidence to support the routine use of MRI in patients with CLBP. Recommendation: StrongRecommendation 2: Surgical treatment of CLBP based exclusively on MRI findings of degenerative changes is not recommended. Recommendation: Strong

Anti-infective and osteointegration properties of silicon nitride, poly(ether ether ketone), and titanium implants

Silicon nitride (Si(3)N(4)) is an industrial ceramic used in spinal fusion and maxillofacial reconstruction. Maximizing bone formation and minimizing bacterial infection are desirable attributes in orthopedic implants designed to adhere to living bone. This study has compared these attributes of Si(3)N(4) implants with implants made from two other orthopedic biomaterials, i.e. poly(ether ether ketone) (PEEK) and titanium (Ti). Dense implants made of Si(3)N(4), PEEK, or Ti were surgically implanted into matching rat calvarial defects. Bacterial infection was induced with an injection of 1×10(4)Staphylococcus epidermidis. Control animals received saline only. On 3, 7, and 14days, and 3months post-surgery four rats per time period and material were killed, and calvariae were examined to quantify new bone formation and the presence or absence of bacteria. Quantitative evaluation of osteointegration to adjacent bone was done by measuring the resistance to implant push-out (n=8 rats each for Ti and PEEK, and n=16 rats for Si(3)N(4)). Three months after surgery in the absence of bacterial injection new bone formation around Si(3)N(4) was ∼69%, compared with 24% and 36% for PEEK and Ti, respectively. In the presence of bacteria new bone formation for Si(3)N(4), Ti, and PEEK was 41%, 26%, and 21%, respectively. Live bacteria were identified around PEEK (88%) and Ti (21%) implants, whereas none were present adjacent to Si(3)N(4). Push-out strength testing demonstrated statistically superior bone growth onto Si(3)N(4) compared with Ti and PEEK. Si(3)N(4) bioceramic implants demonstrated superior new bone formation and resistance to bacterial infection compared with Ti and PEEK.

Epidemiological trends in cervical spine surgery for degenerative diseases between 2002 and 2009.

Study Design. Retrospective analysis of a population-based database. Objective. To investigate national epidemiological trends of cervical spine surgical procedures from 2002–2009. Summary of Background Data. Anterior cervical fusion (ACF), posterior cervical fusion (PCF), and posterior cervical decompression (PCD) are procedures routinely performed for cervical degenerative pathology. Studies regarding epidemiological trends of these procedures is currently lacking in the literature. Methods. Data from the Nationwide Inpatient Sample of the Healthcare Cost and Utilization Project was obtained for each year between 2002 and 2009. Patients undergoing ACF, PCF, and PCD for the diagnosis of cervical radiculopathy and myelopathy were identified. Demographics, costs, and mortality were assessed in the surgical subgroups. A P value of 0.001 was used to denote significance. Results. An estimated 1,323,979 cervical spine surgical procedures were performed between 2002 and 2009. There was a significant upward trend in the mean age of patients undergoing cervical spine surgery during this time period. ACF and PCF cohorts demonstrated statistically significant increases in comorbidities and costs from 2002–2009. The PCF group had the greatest mortality, comorbidities, costs, and longest hospitalizations compared with ACF and PCF cohorts across all time periods. Conclusion. Our study demonstrates that cervical spine surgical procedures have increased between 2002 and 2009 (P = 0.001). The primary increase in volume is due to the increasing number of ACFs. Despite older patients with more comorbidities undergoing ACF and PCF procedures, mortality has not changed. However, this patient population trended significant increases in costs during this time period. We hypothesize that these increased costs are due to an increased comorbidity burden in patients undergoing ACF or PCF. Results of this study can be used to set benchmarks for future epidemiological investigations in cervical spine surgery. Level of Evidence: 4

The adoption of a new classification system: time-dependent variation in interobserver reliability of the thoracolumbar injury severity score classification system.

Study Design. Prospective clinical assessment of the interobserver reliability of the Thoracolumbar Injury Classification and Severity Score (TLISS) in a series of consecutive patients. Objective. To evaluate the time-dependent changes in interobserver reliability of the TLISS system. Summary of Background Data. Reliability of an injury classification system is fundamental to its usefulness. A system that can be taught and implemented effectively will be highly reliable. Vaccaro et al recently introduced a novel thoracolumbar injury classification and treatment recommendation system called the “Thoracolumbar Injury Classification and Severity Score.” An improvement over previous traumatic thoracolumbar systems, it has been designed to be both descriptive as well as prognostic. To define better the benefits of this system, the purpose of our study was to assess the time-dependent changes associated with implementation of the TLISS system at 1 institution. Methods. Seventy-one consecutive patients presenting with acute thoracolumbar injury were prospectively assessed at a single training institution. Plain radiographs, computed tomography, and magnetic resonance imaging were independently reviewed, and each case was classified according to the TLISS system. Seven months later, 25 consecutive patients presenting with acute thoracolumbar injuries were prospectively assessed at the same institution. TLISS classification criteria were again applied after reviewing plain radiographs, computed tomography, and magnetic resonance imaging. The unweighted Cohen kappa coefficient and Spearman correlation values were calculated to assess interobserver reliability at each assessment time. Interobserved reliability at the time of the first assessment was then compared with interobserver reliability from the second assessment. Results. Statistically significant (P < 0.05) improvements in interobserver reliability were observed. Both the unweighted Cohen kappa coefficient and Spearman correlation values increased across all comparable fields: TLISS subscores (mechanism of injury, posterior ligamentous complex), total TLISS, and TLISS management scores. Conclusions. The significant improvements observed in interobserver reliability of the TLISS system suggest that the classification system can be taught effectively and be readily incorporated into daily practice. The strong correlation values obtained at the second assessment time suggest that the TLISS system may be reproducibly used to describe thoracolumbar injuries.

Neurologic deficit following percutaneous vertebral stabilization

Study Design. A retrospective review. Objective. The purpose of this study is to document a series of cases of neurologic deficit following percutaneous vertebral stabilization, to identify patterns of neurologic injury, and to describe potential methods for avoiding these injuries. Summary of Background Data. Percutaneous vertebral stabilization procedures, including vertebroplasty and kyphoplasty, have become a widely used for the treatment of osteoporotic vertebral compression fractures, primary and metastatic vertebral tumors, and traumatic burst fractures. Despite an increasing array of indications, there have been few reports of adverse events. Neurologic complications associated with vertebroplasty and kyphoplasty have been described previously as case reports and have generally been considered as infrequent and minor in severity. Methods. The clinical course of 14 patients with documented loss of neurologic function following percutaneous vertebral cement augmentation was retrospectively reviewed. Results. The average patient age was 74.9 years (range, 46–88 years) with 3 male and 11 female patients. Four patients underwent a vertebroplasty procedure while 10 were treated with kyphoplasty. Six patients developed neurologic deficits acutely (<24 hours of procedure). The remaining 8 patients developed neurologic symptoms at an average of 37.1 days (range, 3–112 days) postprocedure. Neurologic deficits were recorded as ASIA A in 4 patients, ASIA B in 2 patients, ASIA C in 1 patient, and ASIA D in 7 patients. Twelve of 14 patients (85.7%) required revision open surgical intervention for treatment of their neurologic injury. Conclusion. Percutaneous vertebroplasty and kyphoplasty have been reported to be safe options for the treatment of painful osteoporotic vertebral fractures. Although complications are infrequent, there remains the potential for catastrophic neurologic injury. Physicians performing these procedures need to be aware of these potential complications and be prepared to respond in an emergent manner (surgically) if a need arises.

The influence of fracture mechanism and morphology on the reliability and validity of two novel thoracolumbar injury classification systems.

Study Design. The Thoracolumbar Injury Severity Score (TLISS) and the Thoracolumbar Injury Classification and Severity Score (TLICS) were prospectively evaluated. Objectives. To compare the reliability and validity of the TLISS and TLICS schemes to determine the importance of injury mechanism and morphology to the identification and treatment of thoracolumbar fractures. Summary of Background Data. Two novel algorithms have been developed for the categorization and management of thoracolumbar injuries: the TLISS system emphasizing injury mechanism and the TLICS scheme involving injury morphology. Methods. The clinical and radiographic findings of 25 patients with thoracolumbar fractures were prospectively presented to 5 groups of surgeons with disparate levels of training and experience with spinal trauma. These injuries were consecutively scored, first using the TLISS and then 3 months later with the TLICS. The recommended treatments proposed by the 2 schemes were compared with the actual management of each patient. Results. For both algorithms, the interrater kappa statistics of all subgroups (mechanism/morphology, status of the posterior ligaments, total score, predicted management) were within the range of moderate to substantial reproducibility (0.45–0.74), and there were no statistically significant differences noted between the respective kappa values. Interrater correlation was higher for the TLISS paradigm on mechanism/morphology, integrity of the posterior ligaments, and proposed management (P ≤ 0.01). The TLISS and TLICS schemes both exhibited excellent overall validity. Conclusions. Although both schemes were noted to have substantial reproducibility and validity, our results indicate the TLISS is more reliable than the TLICS, suggesting that the mechanism of trauma may be a more valuable parameter than fracture morphology for the classification and treatment thoracolumbar injuries. Since these injury characteristics are interrelated and are critical to the maintenance of spinal stability, we think that both concepts should be considered during the assessment and management of these patients.