Brandon D. Lawrence

Quantifying the Effects of Age, Gender, Degeneration, and Adjacent Level Degeneration on Cervical Spine Range of Motion Using Multivariate Analyses

Study Design. Retrospective review and multivariate analysis. Objective. Assess cervical spine segmental range of motion (ROM) with flexion/extension (F/E) radiographs and determine the relation to clinical variables. Summary of Background Data. Previous studies investigated the roles of age and degeneration on cervical ROM with univariate analyses. Multivariate analyses are required to account for multiple factors that may affect ROM and quantify their relative effects. Methods. Radiographs of 195 patients were analyzed, including 133 females and 62 males with ages ranging from 15 to 93 years. Segmental ROM and Kellgren score (KS) of degeneration were assessed for C2–C7. Patient’s age and gender were documented. Multivariate analyses were performed for each level. Independent variables evaluated were: (1) KS at the level of interest, (2) KS at the level above, (3) KS at the level below, (4) age, and (5) gender. Significance was defined as P < 0.05. Results. Interobserver reliabilities for assessing KS (intraclass correlation coefficient 0.81) and segmental ROM (intraclass correlation coefficient 0.72) were good to excellent. Age had a significant negative association with ROM at C2–C3, C3–C4, C4–C5, and C5–C6. KS at the level of interest had a significant negative association with ROM at C2–C3, C3–C4, C4–C5, C5–C6, and C6–C7. KS at the inferior segment had a significant positive association with ROM at C2–C3, C3–C4, and C4–C5. Gender had a significant association with ROM only at C2–C3. Conclusion. Age was associated with declining ROM independent of degeneration, amounting to a 5° decrease in subaxial cervical ROM every 10 years. Degeneration was also associated with ROM. For every point increase in KS at a given level, there was an associated 1.2° decrease in ROM at that level, and a 0.8° increase in ROM at the level above. These results provide a framework with which to counsel patients about cervical ROM and a benchmark from which procedure specific changes can be compared.

Psychometric properties of the PROMIS physical function item bank in patients with spinal disorders.

Study Design. Patient-reported outcomes provide vital information when assessing effectiveness of clinical care. Yet, most patient-reported outcome instruments are limited by lack of validation and reliability to measure PF adequately. As part of the Patient-Reported Outcomes Measurement Information System (PROMIS), a PF item bank consisting of 124 items has been developed. Objective. There is validation evidence for the PROMIS PF item bank in the general orthopedic patient population in general, but has yet to be validated in the patient with spinal disorders. This study aims to evaluate the psychometric properties of the PROMIS PF item bank specifically for patients presenting with spine-related complaints. Summary of Background Data. Data were collected from adult patients visiting a university spine clinic for back and neck problems. All patients older than 18 years were eligible to participate. A total of 438 patients (49% male) were enrolled in this prospective study. Patients were 18- to 89-year old and presented with back problems (n = 286) and neck problems (n = 152). All patients were administered a 131 item questionnaire. Methods. Conventional descriptive statistics such as means, standard deviations, and proportions were conducted to examine patient characteristics. A Rasch model was used to examine the psychometric properties of the instrument including dimensionality, floor/ceiling effects, reliabilities, and item bias. Results. Results showed that a single PF dimension was supported by the data (i.e., unexplained variance was 2.9%). The instrument had 1.7% ceiling effect and 0.2% floor effect. Item reliability was 1.00 and person reliability was 0.99. We found evidence of item response bias associated with sex, age, and education in some items. Conclusion. The PROMIS PF item bank adequately addressed outcomes of patients with spinal disorders as reliabilities were excellent, minimal ceiling/floor effect existed, and item bias was limited. Future effort should be focused on eliminating, rescaling, or modifying those items that had item bias. Level of Evidence: 2

Predicting the risk of adjacent segment pathology after lumbar fusion: a systematic review.

Study Design. Systematic review. Objective. To perform a systematic review to define the incidence of clinical adjacent segment pathology (CASP) after lumbar fusion surgery and define potential risk factors for the development of CASP. Summary of Background Data. Concerns for the longevity of current arthrodesis constructs and the effects of arthrodesis on adjacent segments have received increasing attention during the past decade. There is a lack of precision regarding the terminology used to describe the pathologies of adjacent segment disease. The term ASP is proposed as an umbrella term to refer to the breadth of clinical and/or radiographical changes at adjacent motion segments that developed subsequent to a previous spinal intervention. Methods. A systematic search was performed in Medline and the Cochrane Collaboration Library for literature published through January 2012. Level of evidence ratings were assigned to each article independently by 2 reviewers. Extracted were the percentage risks of CASP during 5- and 10-year time periods, risk factors, the effect estimates (relative risks and odds ratios), and corresponding confidence intervals reported from each studys multivariate analyses. Forest plots of odds ratios or relative risks with their 95% confidence intervals evaluating patient, disease, and surical risk factors were constructed using the data provided by the individual studies. Results. We identified 162 total citations from our literature search. Of these, 31 full- text articles were evaluated for meeting inclusion criteria. From these 31 studies, 5 studies met inclusion criteria. The mean patient ages ranged from 50 to 64 years. The mean annual incidence of CASP ranged from 0.6% to 3.9%. With respect to patient factors, age more than 60 years was associated with an increased risk of developing CASP. Other factors that may increase the risk of developing CASP are pre-existing facet degeneration, degenerative disc disease, performing a multilevel fusion, stopping a construct at L5, performing a laminectomy adjacent to a fusion, and excessive disc height distraction during posterior interbody fusion. Conclusion. This systematic review was limited to higher-quality studies that evaluated risk factors using multivariate analyses. Identified were key patient, disease, surgical, and radiographical factors that may be considered when counseling and treating patients with degenerative conditions. Further high-quality studies are required before any concrete conclusions can be made about this controversial topic. Consensus StatementsThe risk of developing CASP after lumbar fusion occurs at a mean annual incidence of 0.6% to 3.9%.Strength of Statement: StrongPatients older than 60 years or who have pre-existing facet/disc degeneration may have an increased risk of developing CASP.Strength of Statement: StrongThe risk of developing CASP may be greater after multilevel fusions and fusions adjacent to but not including the L5–S1 level, and may increase when performing a laminectomy adjacent to a fusion.Strength of Statement: Strong

Predicting the risk of adjacent segment pathology in the cervical spine: a systematic review.

Study Design. Systematic review. Objective. We performed a systematic review to determine the risk and to define potential identifiable risk factors for the development of adjacent segment pathology (ASP) after cervical fusion surgery. Summary of Background Data. During the past several decades, the indications for spinal arthrodesis have expanded, with a dramatic increase in the rate of cervical spine fusion in the United States during the past decade. However, as more of these procedures are performed over time, there have been concerns regarding the potential for these patients to develop changes at levels adjacent to the index procedure. Questions remain whether the development of clinical ASP (CASP) are iatrogenic in nature or part of natural history. Methods. A systematic review of the literature was undertaken for articles published in English language between 1990 and March 15, 2012. Electronic databases and reference lists of key articles were searched to identify articles reporting risk factors for CASP after cervical fusion. Two independent reviewers assessed the level of evidence and the overall quality of the literature using the Grades of Recommendation Assessment, Development, and Evaluation criteria. Disagreements were resolved by consensus. Results. We identified 5 studies (4 retrospective cohorts, 1 database study) from our search strategy that met the inclusion criteria from a total of 176 possible studies for review. The prevalence of CASP ranged from 11% to 12% at 5 years, 16% to 38% at 10 years, and 33% at 17 years. Factors that may contribute to the development of CASP include age less than 60 years, fusing adjacent to the C5–C6 and/or C6–C7 levels, a pre-existing disc herniation, and/or dural compression secondary to spinal stenosis with a mean anteroposterior diameter spinal canal of 13 mm or smaller. Conclusion. CASP remains a controversial topic despite multiple attempts of elucidating an iatrogenic effect of spinal fusion versus the natural history of spinal degeneration. The mean rate of the development of symptomatic degeneration in the cervical spine after arthrodesis is estimated between 1.6% and 4.2% per year. The mean rate of reoperation for CASP is estimated at 0.8% per year. In addition, fusing adjacent to but not including the C5–C6 and/or C6–C7 disc spaces seems to consistently increase the risk of developing CASP. Consensus StatementThe risk of developing new symptoms secondary to adjacent segment pathology causing radiculopathy and/or myelopathy after cervical fusion surgery ranges from a cumulative rate of 1.6% to 4.2% per year.Strength of Statement: StrongThe risk of developing adjacent-level symptoms may be increased if disc protrusion, disc degeneration, or cord effacement is present at C5–C6 and/or C6–C7 and if those levels are adjacent to the planned surgical level.Strength of Statement: Strong

Early proximal junctional failure in patients with preoperative sagittal imbalance.

BACKGROUND CONTEXT Proximal junctional failure (PJF) is a recognized complication of spinal deformity surgery. Acute PJF (APJF) has recently been demonstrated to be 5.6% in the adult spinal deformity (ASD) population. The incidence and rate of return to the operating room for APJF have not been specifically investigated in individuals with sagittal imbalance. PURPOSE The purpose of this study was to report the incidence of APJF in patients with preoperative sagittal imbalance and the rate of return to the operating room for APJF. STUDY DESIGN/SETTING This study is based on a retrospective review of prospectively collected database of ASD patients. PATIENT SAMPLE One hundred seventy-three consecutive patients were included with preoperative sagittal imbalance according to one of the following common parameters: sagittal vertical axis (SVA) greater than 50 mm, global sagittal alignment greater than 45°, or pelvic incidence minus lumbar lordosis greater than 10°. OUTCOME MEASURES Outcome measure was presence and/or absence of APJF defined as fracture at the upper instrumented vertebra (UIV) or UIV+1, failure of UIV fixation, 15° or more proximal junctional kyphosis, or need for extension of instrumentation within 6 months of surgery. METHODS We performed radiographic measurements on X-rays at preoperative, immediate postoperative, and 6-month follow-up visits. The APJF rate was reported for the entire patient population with preoperative sagittal imbalance. Acute PJF incidence was calculated postoperatively for each of the accepted sagittal balance parameters and/or formulas. Patients with persistent postoperative sagittal imbalance were compared with the sagittally balanced group. We also assessed for threshold values. RESULTS Acute PJF was observed in 60 of 173 patients (35%) and was least common in fusions with the UIV in the upper thoracic (UT) spine (p=.035). Of those who developed APJF, 21.7% required surgery. Proximal junctional kyphosis 15° or more was the most common form of APJF in fusions to the UT spine but least likely to need revision (p=.014). The most common mode of failure in lower thoracic (LT) or lumbar (L) fusions was UIV fracture. Postoperative SVA less than 50 mm was a significant risk factor for APJF (p=.009). CONCLUSIONS Acute PJF is more common in patients with preoperative sagittal imbalance (35%) than the general adult deformity patient population, and 37% of those with APJF require revision. It is least common when the UIV is in the UT spine, compared with the LT or L spine. Sagittal balance correction to an SVA 50 mm or less was a significant risk factor in patients with preoperative sagittal imbalance.

Anterior versus posterior approach for treatment of cervical spondylotic myelopathy: a systematic review.

Study Design. Systematic review. Objective. We performed a systematic review to determine the comparative effectiveness and safety profiles of anterior versus posterior decompression procedures for multilevel cervical spondylotic myelopathy (CSM). Summary of Background Data. CSM is a common cause of neurological dysfunction. It is well established that surgical decompression of the cervical spinal cord is an effective treatment option for CSM. Because of the lack of well-designed prospective studies, there remains a lack of consensus whether multilevel spondylotic compression is best treated via an anterior or posterior surgical route and whether one of these surgical approaches is superior in terms of patient outcomes and/or complication profiles. Methods. We conducted a systematic search for literature published through September 2012. We sought to identify comparative studies (e.g., randomized controlled trials, cohort studies) comparing anterior with posterior procedures in patients with 2-level or greater cord compression resulting in CSM. Standardized mean differences were calculated to allow comparisons of the change (i.e., improvement or decline) in scores between anterior and posterior surgical procedures by study. Clinical recommendations were made through a modified Delphi approach by applying the GRADE (Grading of Recommendation Assessment, Development and Evaluation)/AHRQ (Agency for Healthcare Research and Quality) criteria. Results. We identified 8 level III retrospective cohort studies that met the inclusion criteria from a total of 135 possible studies for review. With regard to effectiveness between the 2 approaches, improvements in JOA (Japanese Orthopaedic Association) scores were similar, whereas canal diameter change was larger after posterior surgery. With regard to safety, postoperative C5 palsy rates were similar, infection rates were lower with anterior surgery, and dysphagia rates were lower with posterior surgery. Conclusion. This systematic review demonstrates that, for both effectiveness and safety, there is no clear advantage to either an anterior surgical approach or a posterior surgical approach when treating patients with multilevel CSM. With that, a surgical strategy developed on a patient-to-patient basis should be used to achieve optimal patient outcomes. In addition, development of a consensus for standardized reporting of outcome measures and complication profiles would facilitate improved comparisons across differing treatment centers and surgical techniques. Evidence-Based Clinical Recommendations. Recommendation. We recommend an individualized approach when treating patients with CSM accounting for pathoanatomical variations (ventral vs. dorsal, focal vs. diffuse, sagittal, dynamic instability) because there are similar outcomes between the anterior and posterior approaches with regard to effectiveness and safety. Overall Strength of Evidence. Low Strength of Recommendation. Strong

Retrospective evaluation of the validity of the Thoracolumbar Injury Classification System in 458 consecutively treated patients

BACKGROUND CONTEXT The Thoracolumbar Injury Classification System (TLICS) system has been developed to improve injury classification and guide surgical decision-making, yet validation of this new system remains sparse. PURPOSE This study evaluates the use of the TLICS in a large, consecutive series of patients. STUDY DESIGN/SETTING This is a retrospective case series. PATIENT SAMPLE A total of 458 patients treated for thoracic or lumbar spine trauma between 2000 and 2010 at a single, tertiary medical center were included in this study. OUTCOME MEASURES American Spinal Injury Association (ASIA) status and crossover from conservative to surgical treatment were measured. METHODS Clinical and radiological data were evaluated, classifying the injuries by ASIA status, the Magerl/AO classification, and the TLICS system. RESULTS A total of 310 patients (67.6%) was treated conservatively (group 1) and 148 patients (32.3%) were surgically (group 2) treated. All patients in group 1 were ASIA E, except one (ASIA C). In this group, 305 patients (98%) had an AO type A fracture. The TLICS score ranged from 1 to 7 (mean 1.53, median 1). A total of 307/310 (99%) patients matched TLICS treatment recommendation (TLICS≤4), except three with distractive injuries (TLICS 7) initially misdiagnosed. Nine patients (2.9%) were converted to surgical management. In group 2, 105 (70.9%) were ASIA E, whereas 43 (29%) had neurological deficits (ASIA A-D). One hundred and three patients (69.5%) were classified as AO type A, 36 (24.3%) as type B, and 9 (6%) as type C. The TLICS score ranged from 2 to 10 (mean 4.29, median of 2). Sixty-nine patients (46.6%) matched the TLICS recommendation; all discordant patients (53.4%) were treated for stable burst fractures (TLICS=2). No neurological complications occurred in either group. CONCLUSIONS The TLICS recommendation matched treatment in 307/310 patients (99%) in the conservative group. However, in the surgical group, 53.4% of patients did not match TLICS recommendations, all were burst fractures without neurological injury (TLICS=2). The TLICS system can be used to effectively classify thoracolumbar injuries and guide conservative treatment. Inconsistencies, however, remain in the treatment thoracolumbar burst fractures.

Surgical management of degenerative cervical myelopathy: a consensus statement.

Degenerative cervical myelopathy (DCM), including cervical spondylotic myelopathy and ossification of the posterior longitudinal ligament, presents a heterogeneous set of variables reflecting its complex nature. Multiple studies in the past have attempted to elucidate an ideal surgical algorithm that surgeons may use when treating these patients, unfortunately all studies to date, including the rigorous systematic review used in this focus issue, have fallen short in identifying a superior approach when addressing DCM. Likely because of a superior approach being nonexistent because there are multiple pathoanatomical considerations. In addition to the multitude of variables that spine surgeons face when deciding the treatment options for patients with DCM, the previous studies that have been published, unfortunately, lack in consistent outcome and complication reporting. Therefore, synthesizing a treatment algorithm remains difficult, however, the articles in this focus issue use the GRADE system to assess the overall quality (strength) of available evidence and, where appropriate, formulate evidence-based recommendations. Factors that should be included in surgical decision making are the sagittal alignment, anatomical location of the compressive pathology, number of levels of compression, presence of absence or instability or subluxation, the type compressive pathology (e.g., spondylosis vs. ossification of the posterior longitudinal ligament), neck anatomy, bone quality, and surgeon experience or preference. Fortunately, as reviewed in the accompanying articles, a number of excellent surgical options exist that can be selected on the basis of the aforementioned pathoanatomical considerations.

Cortical screws used to rescue failed lumbar pedicle screw construct: a biomechanical analysis.

OBJECT Cortical trajectory screw constructs, developed as an alternative to pedicle screw fixation for the lumbar spine, have similar in vitro biomechanics. The possibility of one screw path having the ability to rescue the other in a revision scenario holds promise but has not been evaluated. The objective in this study was to investigate the biomechanical properties of traditional pedicle screws and cortical trajectory screws when each was used to rescue the other in the setting of revision. METHODS Ten fresh-frozen human lumbar spines were instrumented at L3-4, 5 with cortical trajectory screws and 5 with pedicle screws. Construct stiffness was recorded in flexion/extension, lateral bending, and axial rotation. The L-3 screw pullout strength was tested to failure for each specimen and salvaged with screws of the opposite trajectory. Mechanical stiffness was again recorded. The hybrid rescue trajectory screws at L-3 were then tested to failure. RESULTS Cortical screws, when used in a rescue construct, provided stiffness in flexion/extension and axial rotation similar to that provided by the initial pedicle screw construct prior to failure. The rescue pedicle screws provided stiffness similar to that provided by the primary cortical screw construct in flexion/extension, lateral bending, and axial rotation. In pullout testing, cortical rescue screws retained 60% of the original pedicle screw pullout strength, whereas pedicle rescue screws retained 65% of the original cortical screw pullout strength. CONCLUSIONS Cortical trajectory screws, previously studied as a primary mode of fixation, may also be used as a rescue option in the setting of a failed or compromised pedicle screw construct in the lumbar spine. Likewise, a standard pedicle screw construct may rescue a compromised cortical screw track. Cortical and pedicle screws each retain adequate construct stiffness and pullout strength when used for revision at the same level.

Geographic variations in the cost of spine surgery.

Study Design. Retrospective review. Objective. To define the geographic variation in costs of anterior cervical discectomy and fusion (ACDF) and posterolateral fusion (PLF). Summary of Background Data. ACDF and lumbar PLF are common procedures that are used in the treatment of spinal pathologies. To optimize value, both the benefits and costs of an intervention must be quantified. Data on costs are scarce in comparison with data on total charges. This study aims at defining the costs of ACDF and PLF and describing the geographic variation within the United States. Methods. Medicare Provider Utilization and Payment data were used to investigate the costs associated with ACDF, PLF, and total knee arthroplasty (TKA). Average total costs of the procedures were compared by state and geographic region. Results. Combined professional and facility costs for a single-level ACDF had a national mean of