Minimally Invasive Revision of Luque Plate Instrumentation: A Case Report.

Extension of existing spinal fusions may necessitate the removal of or linkage to prior constructs. Knowledge of previously placed instrumentation is critical to success in these revision scenarios. The Luque spinal instrumentation system, developed in the late 1980s, is a legacy pedicle screw and plate system that may be encountered during revision operations today. A 67-year-old male with a remote history of L4-S1 fusion with Luque instrumentation presented with bilateral lower extremity neurogenic claudication due to adjacent segment disease at L3-4. Decompression and extension of fusion to the L3-4 level were performed using minimally invasive techniques. Of note, posterior instrumentation was extended by removing prior L4 pedicle screws with a 7 mm female hexagonal driver through tubular retractors, leaving the Luque plates in place, placing modern pedicle screws at L4 (through the plates) and L3, and linking these with standard rods. The surgery and post-operative course were uncomplicated, and the patient experienced complete resolution of his pre-operative claudication symptoms. Extension of prior Luque plate instrumented fusion can be accomplished minimally invasively without removing the plates themselves, resulting in greater operative efficiency and less surgical morbidity.

Development of an Endoscopic Spine Surgery Program: Overview and Basic Considerations for Implementation.

Endoscopic spine surgery (ESS) is an innovative technique allowing for minimally invasive, direct visualization of spinal abnormalities. The growth of ESS in the United States has been stunted by high start-up costs, low reimbursement rates, and the steep learning curve associated with mastering endoscopic techniques. Hergrae, we describe the current state and future direction of ESS and provide key action items for ESS program implementation.

Comparative analysis of perioperative characteristics and early outcomes in transforaminal endoscopic lumbar diskectomy: general anesthesia versus conscious sedation.

PURPOSE: To better understand how anesthesia type impacts patient selection and recovery in TELD, we conducted a multicenter prospective study which evaluates the differences in perioperative characteristics and outcomes between patients who underwent TELD with either general anesthesia (GA) or conscious sedation (CS). METHODS: We prospectively collected data from all TELD performed by five neurosurgeons at five different medical centers between February and October of 2022. The study population was dichotomized by anesthesia scheme, creating CS and GA cohorts. This study's primary outcomes were the Oswetry Disability Index (ODI) and the Visual Analog Scale (VAS) for back and leg pain, assessed preoperatively and at 2-week follow-up. RESULTS: A total of 52 patients underwent TELD for symptomatic lumbar disk herniation. Twenty-three patients received conscious sedation with local anesthesia, and 29 patients were operated on under general anesthesia. Patients who received CS were significantly older (60.0 vs. 46.7, p < 0.001) and had lower BMI (28.2 vs. 33.4, p = 0.005) than patients under GA. No intraoperative or anesthetic complications occurred in the CS and GA cohorts. Improvement at 2-week follow-up in ODI, VAS-back, and VAS-leg was greater in patients receiving CS relative to patients under GA, but these differences were not statistically significant. CONCLUSION: In our multicenter prospective analysis of 52 patients undergoing TELD, we found that patients receiving CS were significantly older and had significantly lower BMI compared to patients under GA. On subgroup analysis, no statistically significant differences were found in the improvement of PROMs between patients in the CS and GA group.

Collagen Matrix Inlay Graft for Management of Incidental Durotomy During Full-Endoscopic Lumbar Spine Surgery: Technique and Case Series.

BACKGROUND: Endoscopic spine surgery (ESS) has a reduced rate of incidental durotomy (ID) compared with open spine surgery. However, there are unique challenges regarding the management of ID in ESS due to the single, deep, narrow working corridor and aqueous environment. Here, we present a collagen matrix inlay graft technique for the management of ID encountered during ESS. METHODS: Three patients were identified via medical record review of full ESS where an intraoperative ID was encountered. These were all addressed endoscopically. All surgeries were performed by a single surgeon in the years 2019 to 2023. Patient, operative, and postoperative details, including patient-reported outcomes, were recorded. Briefly, the collagen matrix inlay graft technique included introducing a segment of collagen matrix into the surgical field and manipulating the collagen matrix so that it passed through the durotomy and resided within the dura, plugging the hole. RESULTS: Three IDs were identified out of a total of 295 eligible cases (1.02%). The IDs measured 2 to 2.5 mm in length. For these 3 patients, the duration of hospital stay ranged from 172 to 1,068 minutes. No patients exhibited signs or symptoms of cerebrospinal fluid leak at any postoperative timepoint. At the 6-week postoperative visit, all patients had achieved the minimum clinically important difference in Oswestry Disability Index, and all patients with available visual analog scale scores for leg and low back pain had achieved the cutoff for the minimum clinically important difference. CONCLUSIONS: We presented 3 cases of ID during uniportal full ESS who were repaired using a collagen matrix inlay technique. Prolonged bed rest was avoided, and all patients achieved excellent clinical outcomes without further complication. This technique may also be appropriate for other minimally invasive spine surgery techniques. CLINICAL RELEVANCE: ID is a common and undesirable complication of degenerative lumbar spine surgery. Endoscopic ID repair techniques provide an option to avoid conversion to open or tubular surgery for the management of ID.

Device profile of the FlareHawk interbody fusion system, an endplate-conforming multi-planar expandable lumbar interbody fusion cage.

INTRODUCTION: The FlareHawk Interbody Fusion System is a family of lumbar interbody fusion devices (IBFDs) that include FlareHawk7, FlareHawk9, FlareHawk11, TiHawk7, TiHawk9, and TiHawk11. These IBFDs offer a new line of multi-planar expandable interbody devices designed to provide mechanical stability, promote arthrodesis, and allow for restoration of disc height and lordosis through a minimal insertion profile during standard open and minimally invasive posterior lumbar fusion procedures. The two-piece interbody cage design consists of a PEEK outer shell that expands in width, height, and lordosis with the insertion of a titanium shim. Once expanded, the open architecture design allows for ample graft delivery into the disc space. AREAS COVERED: The design and unique features of the FlareHawk family of expandable fusion cages are described. The indications for their use are discussed. Early clinical and radiographic outcome studies using the FlareHawk Interbody Fusion System are reviewed, and properties of competitor products are outlined. EXPERT OPINION: The FlareHawk multi-planar expandable interbody fusion cage is unique amongst the many lumbar fusion cages currently on the market. The multi-planar expansion, open architecture, and adaptive geometry set it apart from its competitors.

Preservation of Motion in Spine Surgery.

The number of spinal procedures and spinal fusions continues to grow. Although fusion procedures have a high success rate, they have inherent risks such as pseudarthrosis and adjacent segment disease. New innovations in spine techniques have sought to eliminate these complications by preserving motion in the spinal column. Several techniques and devices have been developed in the cervical and lumbar spine including cervical laminoplasty, cervical disk ADA, posterior lumbar motion preservation devices, and lumbar disk ADA. In this review, advantages and disadvantages of each technique will be discussed.

Learning curve for endoscopic posterior cervical foraminotomy.

PURPOSE: While anterior cervical discectomy and fusion as well as cervical disk arthroplasty are gold standard treatments for the surgical treatment of cervical radiculopathy, posterior endoscopic cervical foraminotomy (PECF) as a substitute procedure is gaining popularity. To date, studies investigating the number of surgeries needed to achieve proficiency in this procedure are lacking. The purpose of the study is to examine the learning curve for PECF. METHODS: The learning curve in operative time for two fellowship-trained spine surgeons at independent institutions was retrospectively assessed for 90 uniportal PECF procedures (PBD: n = 26, CPH: n = 64) performed from 2015 to 2022. Operative time was assessed across consecutive cases using a nonparametric monotone regression, and a plateau in operative time was used as a proxy to define the learning curve. Secondary outcomes assessing achievement of endoscopic prowess before and after the initial learning curve included number of fluoroscopy images, visual analog scale (VAS) for neck and arm, Neck Disability Index (NDI), and the need for reoperation. RESULTS: There was no significant difference in operative time between surgeons (p = 0.420). The start of a plateau for Surgeon 1 occurred at 9 cases and 111.6 min. The start of a plateau for Surgeon 2 occurred at 29 cases and 114.7 min. A second plateau for Surgeon 2 occurred at 49 cases and 91.8 min. Fluoroscopy use did not significantly change before and after surmounting the learning curve. The majority of patients achieved minimally clinically important differences in VAS and NDI after PECF, but postoperative VAS and NDI did not significantly differ before and after achieving the learning curve. There were no significant differences in revisions or postoperative cervical injections before and after reaching a steady state in the learning curve. CONCLUSION: PECF is an advanced endoscopic technique with an initial improvement in operative time that occurred after as few as 8 cases to as many as 28 cases in this series. A second learning curve may occur with additional cases. Patient-reported outcomes improve following surgery, and these outcomes are independent of the surgeon's position on the learning curve. Fluoroscopy use does not change significantly along the learning curve. PECF is a safe and effective technique that current and future spine surgeons should consider as part of their armamentarium.

Cervical Disk Arthroplasty and Range of Motion at 7 Years: Impact on Adjacent Level Degeneration.

STUDY DESIGN: Secondary analysis of data collected in a prospective, randomized, noninferiority Food and Drug Administration (FDA) Investigational Device Exemption (IDE) clinical trial. OBJECTIVE: The objective of this study was to evaluate the impact of range of motion (ROM) following single-level cervical disk arthroplasty (CDA) on the development of radiographic adjacent level degeneration (ALD). SUMMARY OF BACKGROUND DATA: The rationale for CDA is that maintenance of index-level ROM will decrease adjacent level stresses and ultimately reduce the development of ALD compared with anterior cervical discectomy and fusion. However, little information is available on the impact of hypermobility on the development of ALD after CDA. MATERIALS AND METHODS: Radiographic assessments were evaluated for index-level flexion-extension ROM and ALD. Continuous data was assessed using 1-way analysis of variance. The relationship between ALD progression and ROM was evaluated using χ 2 tests. The α was set at 0.05. RESULTS: More ALD progression was observed after anterior cervical discectomy and fusion than CDA ( P =0.002 at the superior and P =0.049 at the inferior level). Furthermore, there was an association between ALD progression and ROM ( P =0.014 at the superior level and P =0.050 at the inferior level) where patients with mid-ROM after CDA experienced the lowest frequency of ALD progression at the superior and inferior levels. Patients with the lowest and highest ROM after CDA experienced a greater increase in ALD score at the inferior level ( P =0.046). Sex and age were associated with ROM groups ( P =0.001 and 0.023, respectively). CONCLUSIONS: While maintenance of index-level ROM is protective after CDA, patients with the highest ROM after CDA have similar rates of ALD progression to the lowest ROM and greater increases in ALD compared with mid-ROM after CDA. High ROM after CDA may contribute to ALD progression.

Review of Prospective Trials for Degenerative Cervical Myelopathy.

Degenerative cervical myelopathy (DCM) is the leading cause of spinal cord dysfunction in adults. DCM refers to a collection of degenerative conditions that cause the narrowing of the cervical canal resulting in neurological dysfunction. A lack of high-quality studies and a recent increase in public health awareness has led to numerous prospective studies evaluating DCM. Studies evaluating the efficacy of surgical intervention for DCM can be characterized by the presence (comparative) or absence (noncomparative) of a nonoperative control group. Noncomparative studies predominate due to concerns regarding treatment equipoise. Comparative studies have been limited by methodological issues and have not produced consistent findings. More recent noncomparative studies have established the safety and efficacy of surgical intervention for DCM, including mild myelopathy. The optimal surgical intervention for DCM remains controversial. A recent randomized clinical trial comparing dorsal and ventral techniques found similar improvements in patient-reported physical function at early follow-up. Recent prospective studies have enriched our understanding of DCM and helped guide current treatment recommendations.

Prediction of Admission Costs Following Anterior Cervical Discectomy and Fusion Utilizing Machine Learning.

STUDY DESIGN: Retrospective case series. OBJECTIVE: Predict cost following anterior cervical discectomy and fusion (ACDF) within the 90-day global period using machine learning models. BACKGROUND: The incidence of ACDF has been increasing with a disproportionate decrease in reimbursement. As bundled payment models become common, it is imperative to identify factors that impact the cost of care. MATERIALS AND METHODS: The Nationwide Readmissions Database (NRD) was accessed in 2018 for all primary ACDFs by the International Classification of Diseases 10th Revision (ICD-10) procedure codes. Costs were calculated by utilizing the total hospital charge and each hospital's cost-to-charge ratio. Hospital characteristics, such as volume of procedures performed and wage index, were also queried. Readmissions within 90 days were identified, and cost of readmissions was added to the total admission cost to represent the 90-day healthcare cost. Machine learning algorithms were used to predict patients with 90-day admission costs >1 SD from the mean. RESULTS: There were 42,485 procedures included in this investigation with an average age of 57.7±12.3 years with 50.6% males. The average cost of the operative admission was $24,874±25,610, the average cost of readmission was $25,371±11,476, and the average total cost was $26,977±28,947 including readmissions costs. There were 10,624 patients who were categorized as high cost. Wage index, hospital volume, age, and diagnosis-related group severity were most correlated with the total cost of care. Gradient boosting trees algorithm was most predictive of the total cost of care (area under the curve=0.86). CONCLUSIONS: Bundled payment models utilize wage index and diagnosis-related groups to determine reimbursement of ACDF. However, machine learning algorithms identified additional variables, such as hospital volume, readmission, and patient age, that are also important for determining the cost of care. Machine learning can improve cost-effectiveness and reduce the financial burden placed upon physicians and hospitals by implementing patient-specific reimbursement.

Allograft Versus Autograft in Anterior Cervical Discectomy and Fusion: A Propensity-Matched Analysis.

Objective To compare the 30-day complication rate associated with allograft versus autograft in anterior cervical discectomy and fusion (ACDF) and to determine preoperative factors that may influence complication rate. Methods The American College of Surgeons National Surgical Quality Improvement Program database was retrospectively queried from 2014 to 2017 for all procedures with CPT codes for ACDF (22551). Patients undergoing ACDF with either autograft or allograft were matched by propensity scores based on age, sex, body mass index, and comorbidities. The incidence of adverse events in the 30-day postoperative period was compared. Results A total of 21,588 patients met the inclusion and exclusion criteria. Following the 10:1 propensity match, 17,061 remained in the study (1,551 autograft and 15,510 allograft). The overall adverse event rate was 3.18%; 3.48% for autograft and 3.15% for allograft (P=0.494). Autograft had a significantly greater incidence of extended length of stay (>2 d) (LOS) (48.9% vs 34.8%; P<0.001). Multivariate analysis suggested that autograft selection was associated with extended LOS (OR 1.4; 95% CI 1.3-1.5). Conclusion The results of this study provide information regarding how graft selection can relate to extended hospital LOS and influence postoperative complications. Extended LOS may be associated with worse patient outcomes and increase the overall cost of care. Further study should be performed to determine which patients would benefit from autograft versus allograft with regards to long-term outcomes, in consideration of these increased short-term complications.

Appropriate Telemedicine Utilization in Spine Surgery: Results From a Delphi Study.

STUDY DESIGN: Delphi expert panel consensus. OBJECTIVE: To obtain expert consensus on best practices for appropriate telemedicine utilization in spine surgery. SUMMARY OF BACKGROUND DATA: Several studies have shown high patient satisfaction associated with telemedicine during the COVID-19 peak pandemic period as well as after easing of restrictions. As this technology will most likely continue to be employed, there is a need to define appropriate utilization. METHODS: An expert panel consisting of 27 spine surgeons from various countries was assembled in February 2021. A two-round consensus-based Delphi method was used to generate consensus statements on various aspects of telemedicine (separated as video visits or audio visits) including themes, such as patient location and impact of patient diagnosis, on assessment of new patients. Topics with ≥75% agreement were categorized as having achieved a consensus. RESULTS: The expert panel reviewed a total of 59 statements. Of these, 32 achieved consensus. The panel had consensus that video visits could be utilized regardless of patient location and that video visits are appropriate for evaluating as well as indicating for surgery multiple common spine pathologies, such as lumbar stenosis, lumbar radiculopathy, and cervical radiculopathy. Finally, the panel had consensus that video visits could be appropriate for a variety of visit types including early, midterm, longer term postoperative follow-up, follow-up for imaging review, and follow-up after an intervention (i.e., physical therapy, injection). CONCLUSION: Although telemedicine was initially introduced out of necessity, this technology most likely will remain due to evidence of high patient satisfaction and significant cost savings. This study was able to provide a framework for appropriate telemedicine utilization in spine surgery from a panel of experts. However, several questions remain for future research, such as whether or not an in-person consultation is necessary prior to surgery and which physical exam maneuvers are appropriate for telemedicine.Level of Evidence: 4.

Spine Patient Satisfaction With Telemedicine During the COVID-19 Pandemic: A Cross-Sectional Study.

STUDY DESIGN: Original research, cross-sectional study. OBJECTIVES: Evaluate patient satisfaction with spine care delivered via telemedicine. Identify patient- and visit-based factors associated with increased satisfaction and visit preference. METHODS: Telemedicine visits with a spine surgeon at 2 practices in the United States between March and May 2020 were eligible for inclusion in the study. Patients were sent an electronic survey recording overall satisfaction, technical or clinical issues encountered, and preference for a telemedicine versus an in-person visit. Factors associated with poor satisfaction and preference of telemedicine over an in-person visit were identified using multivariate logistic regression. RESULTS: A total of 772 responses were collected. Overall, 87.7% of patients were satisfied with their telemedicine visit and 45% indicated a preference for a telemedicine visit over an in-person visit if given the option. Patients with technical or clinical issues were significantly less likely to achieve 5 out of 5 satisfaction scores and were significantly more likely to prefer an in-person visit. Patients who live less than 5 miles from their surgeon's office and patients older than 60 years were also significantly more likely to prefer in-person visits. CONCLUSIONS: Spine telemedicine visits during the COVID-19 pandemic were associated with high patient satisfaction. Additionally, 45% of respondents indicated a preference for telemedicine versus an in-patient visit in the future. In light of these findings, telemedicine for spine care may be a preferable option for a subset of patients into the future.

Assessing the cone of economy in patients with spinal disease using only a force plate: an observational retrospective cohort study.

STUDY DESIGN: This is a retrospective cohort with multiple regression modeling. OBJECTIVE: The aim is to develop a new method for estimating cone of economy (CoE) using a force plate rather than traditional motion capture. BACKGROUND: Currently, most spinal deformity surgeons rely on static radiographic parameters for alignment, balance, and outcomes data alongside patient-reported outcome measures. The CoE, the stable region of upright posture, can be objectively measured to determine the efficiency and balance of the spine. Motion capture technology is currently used to collect data to calculate CoE, but this requires expensive and complex equipment, which is a barrier to widespread adoption and clinical use of CoE measurements. Force plates, which measure pressure, are less expensive and can be used in a clinical setting. METHODS: Motion capture and a force plate were used to quantify the CoE of 473 subjects (423 spinal surgical candidates; 50 healthy controls; 271 females; age: 58.60 ± 15.27; height: 1.69 ± 0.13; weight: 81.07 ± 20.91), and a linear multiple regression model was used to predict CoE using force plate data in a human motion laboratory setting. Patients were required to stand erect with feet together and eyes open in their self-perceived balanced and natural position for a full minute while measures of sway and center of pressure (CoP) were recorded. RESULTS: The CoP variable regression model successfully predicted CoE measurements. The variables that were used to predict vertical CoE were CoP coronal sway, CoP sagittal sway, and CoP total sway in several combinations. The coefficient of determination for the head total sway model indicated a 87.0% correlation (F(3,469) = 1044.14, p < 0.001). The coefficient of determination for the head sagittal sway model indicated a 69.2% correlation (F(3,469) = 351.70, p < 0.001). The coefficient of determination for the head coronal sway model indicated a 85.2% correlation (F(3,469) = 899.27, p < 0001). CONCLUSION: Cone of economy was estimated from force plate data using center of pressure with high correlation without the use of motion capture in healthy controls and a variety of spine patients. This could lower the entry burden for measurement of the CoE in patients, enabling widespread use. This would provide surgeons objective global balance data, along with Haddas' CoE classification system, that could assist with surgical decision-making and facilitate objective monitoring surgical outcomes.

Risk factors for reoperation after lumbar total disc replacement at short-, mid-, and long-term follow-up.

BACKGROUND CONTEXT: The reoperation rate following TDR (Total Disc replacement) has been established at short- and mid-term time points through the Food and Drug Administration Investigational Device Exemption (FDA IDE) trials. However, these trials include highly selected centers and surgeons with strict governance of indications. The utilization of TDR throughout the community needs further analysis. PURPOSE: To identify the risk factors for lumbar spine reoperation in patients undergoing lumbar total disc replacement (TDR) at short-, mid-, and long-term follow-up. STUDY DESIGN/SETTING: This study is a multi-center retrospective cohort study utilizing the New York Statewide Planning and Research Cooperative System database. PATIENT SAMPLE: We identified 1,368 patients who underwent an elective primary lumbar TDR in New York State between January 1, 2005 and September 30, 2013. OUTCOME MEASURES: The primary functional outcome of interest was lumbar reoperation, specifically the evaluation of independent risk factors for lumbar reoperation at a minimum of 2 years, with sub-analyses performed at 5 and ten years. METHODS: International Classification of Diseases, Ninth revision codes were utilized to identify patients undergoing a primary lumbar TDR. We excluded patients with primary/revision lumbar fusion procedures and revision disc replacement procedures. Hospital academic status was determined by the Accreditation Council for Graduate Medical Education. Unique encrypted patient identifiers allowed for longitudinal follow-up for reoperation. Logistic regression models compared reoperation and no-reoperation cohorts, and were performed on sub-analyses for significant univariate predictors of reoperation. RESULTS: Between January 2005 and September 2013, 1368 patients underwent a primary lumbar TDR. Reoperation occurred in 8.8% by 2 years, 15.8% by 5 years, and 19.5% by ten years. Diabetics were more likely to have reoperations (7.5% vs 3.8%, p=.013). Teaching hospitals experienced a decreased reoperation rate compared to nonteaching hospitals at 2-year (5.0% vs 10.5%, p=.002), 5-year (10.7% vs 17.9%, p=.002) and 10-year (11.7% vs 21.9%, p=.045) follow-up. Lumbar fusion was the most common reoperation (14.2%). CONCLUSION: We identified an 8.8% reoperation rate after inpatient lumbar TDR at 2-years, 15.8% at 5-years, and 19.5% at 10-years. When stratifying by teaching status, reoperation rates at teaching centers align with those reported in FDA IDE studies. Diabetes was the only patient factor influencing reoperation rate. There is a growing consensus that lumbar TDR is a durable and appropriate surgical option for lumbar degenerative disc disease. Proper indications are crucial to obtaining good outcomes with lumbar TDR.

Indirect Decompression for the Treatment of Degenerative Lumbar Stenosis.

BACKGROUND: Surgical treatment of symptomatic lumbar stenosis has traditionally included laminectomy for direct decompression. With increasing options for lumbar interbody fusion, there has been growing interest in indirect decompression to treat degenerative stenosis. The primary purpose of this study was to determine whether indirect decompression via anterior lumbar interbody fusion (ALIF) can provide symptomatic relief in patients with lumbar spinal stenosis. Secondary purposes were to (1) identify risk factors for failure of indirect decompression and (2) to identify risk factors for failure to obtain relief and to compare outcomes between patients undergoing stand-alone ALIF versusand those in whom ALIF was supplemented with posterior instrumentation. METHODS: Chart review was performed on a consecutive series of 568 patients undergoing single-level ALIF without posterior decompression to treat degenerative stenosis during a 5-year period. Failure of indirect decompression was defined as return to the operating room for direct decompression. Subgroup analysis was performed to compare patients who underwent stand-alone ALIF (n = 247) vs those in whom supplemental posterior instrumentation was used (ALIF + PI; n = 321). RESULTS: Reoperation due to failure of indirect decompression occurred in 4.0% (23/568) of patients. The only factor related to failure was age. Patients older than 60 years were more likely to fail indirect decompression than were younger patients (7.0% vs 3.1%, P < 0.05). ALIF and ALIF + PI subgroups both improved significantly when comparing preoperative to postoperative mean scores on Oswestry Disability Index (ODI), back pain, and leg pain (all P < 0.01). There were no significant differences between these groups, including reoperation rate for direct decompression. CONCLUSIONS: Indirect decompression via ALIF was effective in treating appropriately selected patients with degenerative lumbar spinal stenosis. Older patients are at higher risk for failure of indirect decompression-potentially because of greater osseous stenosis as well as subsidence due to age-related diminished bone density with subsequent loss of distraction. LEVEL OF EVIDENCE: 4. CLINICAL RELEVANCE: This study supports that indirect decompression via ALIF is a viable alternative to direct decompression in appropriately selected patients with degenerative stenosis.

Accuracy of various fluoroscopic landmarks for determination of midline implant placement within the cervical disc space.

PURPOSE: The traditional teaching has been that proper function of a cervical disc replacement is dependent upon appropriate placement, which includes centering the device in the coronal plane. The purpose of this study was to identify the most reliable anatomical landmark for determining midline placement of an implant within the cervical disc space under fluoroscopy. METHODS: Digital fluoroscopy images were taken for each cervical level at 0 °, 2.5 °, 5 °, 7.5 °, 10 °, and 15 ° from the mid-axis by rotating the C-arm beam of six cadavers. Thin-slice CT scanning of the same levels was subsequently performed. Three independent reviewers measured the distance between anatomic structures: (a) tip of the right uncinate; (b) medial border of the right pedicle; and (c) center of the spinous processes for different x-ray angles across cervical levels C3-7. RESULTS: Both the uncinate and pedicle demonstrated superior overall accuracy to that of the spinous process (p ≤ 0.02) at all angles except at 0 ° for the pedicle where the difference was not statistically significant. Overall (pooled C3-7), the accuracy of the uncinate did not differ significantly from that of the pedicle at any fluoroscopic angle. The center of the spinous process measurement was particularly sensitive to deviations from the perfect anteroposterior fluoroscopy image. CONCLUSIONS: The results of this investigation suggest that the tip of the uncinate and the medial border of the pedicle are more accurate measures of midline in the cervical spine than the center of the spinous process and are less susceptible to inadvertent off-axis imaging.

Cervical Disc Arthroplasty: Rationale and History.

Biomechanical studies have demonstrated that cervical fusion results in increased motion and intradiscal pressures at adjacent levels. Cervical disc arthroplasty (CDA) is an alternative treatment for cervical radiculopathy and myelopathy resulting from degenerative disc disease. By maintaining segmental motion, surgeons hope to avoid some of the primary drawbacks of anterior cervical discectomy and fusion (ACDF), such as pseudoarthrosis and adjacent segment disease. First introduced in the 1960s, CDA has evolved over the years with changes to implant geometry and materials. Early devices produced suboptimal outcomes, but more recent generations of implants have shown long-term outcomes rivaling or even surpassing those of ACDF. In this article, the rationale for CDA as well as the history of such devices is reviewed.

Surgical Strategies for the Treatment of Lumbar Pseudarthrosis in Degenerative Spine Surgery: A Literature Review and Case Study.

BACKGROUND: Pseudarthrosis after lumbar fusion can generate pain and disability and often requires revision. However, results of revision procedures have historically been relatively poor. QUESTIONS/PURPOSE: The aim of this review was to examine the current evidence related to the management of lumbar pseudarthrosis, with a focus on revision after failure of posterolateral fusion or lumbar interbody fusion. METHODS: A review of orthopedic spine literature published before March 2019 was conducted using PubMed and Google Scholar. Studies addressing revision after failed posterolateral fusions and after failed interbody fusion were selected. We also present a case of successful revision after failed transforaminal lumbar interbody fusion (TLIF). RESULTS: The review revealed that persistent pseudarthrosis after revision posterolateral fusion occurs at rates of 35 to 51%. No significant difference has been demonstrated in rates of successful fusion after anterior lumbar interbody fusion (ALIF) and ALIF with revision posterolateral fusion for pseudarthroses after failed TLIF procedures (81% versus 88%), although ALIF alone may be appealing because it avoids further disruption of the posterior musculature. No significant differences have been observed in quality-of-life scores among patients undergoing revision after posterolateral fusion, TLIF, ALIF, or ALIF with posterior fusion. Failed TLIF cages may be extracted and replaced through an anterior or lateral approach. If the geometry of the failed cage permits insertion of a second cage, a contralateral approach may be used. Revision retroperitoneal approaches are associated with higher complication rates. CONCLUSIONS: The management of lumbar pseudarthrosis requires careful planning, as well as intra-operative attention to detail, for revision surgery to be successful. Circumferential procedures have shown success in revision posterolateral and interbody fusion failures.