Reliability of a Novel Classification System for Thoracic Disc Herniations.

STUDY DESIGN: This is a cross-sectional survey. OBJECTIVE: The aim was to assess the reliability of a proposed novel classification system for thoracic disc herniations (TDHs). SUMMARY OF BACKGROUND DATA: TDHs are complex entities varying substantially in many factors, including size, location, and calcification. To date, no comprehensive system exists to categorize these lesions. METHODS: Our proposed system classifies 5 types of TDHs using anatomic and clinical characteristics, with subtypes for calcification. Type 0 herniations are small (≤40% of spinal canal) TDHs without significant spinal cord or nerve root effacement; type 1 are small and paracentral; type 2 are small and central; type 3 are giant (>40% of spinal canal) and paracentral; and type 4 are giant and central. Patients with types 1 to 4 TDHs have correlative clinical and radiographic evidence of spinal cord compression. Twenty-one US spine surgeons with substantial TDH experience rated 10 illustrative cases to determine the system's reliability. Interobserver and intraobserver reliability were determined using the Fleiss kappa coefficient. Surgeons were also surveyed to obtain consensus on surgical approaches for the various TDH types. RESULTS: High agreement was found for the classification system, with 80% (range 62% to 95%) overall agreement and high interrater and intrarater reliability (kappa 0.604 [moderate to substantial agreement] and kappa 0.630 [substantial agreement], respectively). All surgeons reported nonoperative management of type 0 TDHs. For type 1 TDHs, most respondents (71%) preferred posterior approaches. For type 2 TDHs, responses were roughly equivalent for anterolateral and posterior options. For types 3 and 4 TDHs, most respondents (72% and 68%, respectively) preferred anterolateral approaches. CONCLUSIONS: This novel classification system can be used to reliably categorize TDHs, standardize description, and potentially guide the selection of surgical approach. Validation of this system with regard to treatment and clinical outcomes represents a line of future study.

Use of global sagittal flexibility to predict proximal junctional kyphosis after spinal deformity surgery.

OBJECTIVE: Sagittal alignment is an important predictor of functional outcomes after surgery for adult spinal deformity (ASD). A rigid spinal column may create a large lever arm that may impact the rate of proximal junctional kyphosis (PJK) after ASD surgery. In this study, the authors sought to determine whether relatively low preoperative global spinal flexibility (i.e., rigid spine) predicts increased incidence of PJK at 1 year after ASD surgery. METHODS: The authors retrospectively reviewed long-segment thoracolumbar fusions with pelvic fixation performed at a single tertiary care center between October 2015 and September 2020 in patients with a minimum of 1-year radiographic and clinical follow-up. Two cohorts were established on the basis of the optimal value for spinal flexibility, as defined by the absolute difference between the preoperative standing and supine C7 sagittal vertical axes, which the authors termed global sagittal flexibility (GSF). Demographic information, radiographs, various associated complications, and patient-reported outcome measures (PROMs) were analyzed. RESULTS: Eighty-five patients met the inclusion criteria. Receiver operating characteristic (ROC) analysis using GSF to predict an increase in the proximal junctional sagittal Cobb angle (PJCA) greater than or equal to 10° at 1-year follow-up provided an area under the curve of 0.64 and identified an optimal GSF threshold value of 3.7 cm. Patients with GSF > 3.7 cm were considered globally flexible (48 patients), and those with GSF ≤ 3.7 cm were classified as rigid (37 patients). Rigid patients were noted to have a significantly higher risk of ΔPJCA ≥ 10° at 1-year follow-up (51.4% vs 29.3%, p = 0.049). No changes in the reoperation rates or PROMs based on GSF were observed in the 1- or 2-year postoperative window. CONCLUSIONS: Based on these retrospective data, preoperative global spinal rigidity portends an independently elevated risk for the development of PJK after ASD surgery. No differences in other complication rates or PROMs data were observed between groups. Data collection was limited to a 2-year postoperative window; therefore, longer follow-up is required to further elucidate the relationship between rigidity and reoperation rates. Based on these retrospective data, flexibility may influence the outcomes of patients with ASD.

A computer vision approach to identifying the manufacturer of posterior thoracolumbar instrumentation systems.

OBJECTIVE: Knowledge of the manufacturer of the previously implanted pedicle screw systems prior to revision spinal surgery may facilitate faster and safer surgery. Often, this information is unavailable because patients are referred by other centers or because of missing information in the patients' records. Recently, machine learning and computer vision have gained wider use in clinical applications. The authors propose a computer vision approach to classify posterior thoracolumbar instrumentation systems. METHODS: Lateral and anteroposterior (AP) radiographs obtained in patients undergoing posterior thoracolumbar pedicle screw implantation for any indication at the authors' institution (2015-2021) were obtained. DICOM images were cropped to include both the pedicle screws and rods. Images were labeled with the manufacturer according to the operative record. Multiple feature detection methods were tested (SURF, MESR, and Minimum Eigenvalues); however, the bag-of-visual-words technique with KAZE feature detection was ultimately used to construct a computer vision support vector machine (SVM) classifier for lateral, AP, and fused lateral and AP images. Accuracy was tested using an 80%/20% training/testing pseudorandom split over 100 iterations. Using a reader study, the authors compared the model performance with the current practice of surgeons and manufacturer representatives identifying spinal hardware by visual inspection. RESULTS: Among the three image types, 355 lateral, 379 AP, and 338 fused radiographs were obtained. The five pedicle screw implants included in this study were the Globus Medical Creo, Medtronic Solera, NuVasive Reline, Stryker Xia, and DePuy Expedium. When the two most common manufacturers used at the authors' institution were binarily classified (Globus Medical and Medtronic), the accuracy rates for lateral, AP, and fused images were 93.15% ± 4.06%, 88.98% ± 4.08%, and 91.08% ± 5.30%, respectively. Classification accuracy decreased by approximately 10% with each additional manufacturer added. The multilevel five-way classification accuracy rates for lateral, AP, and fused images were 64.27% ± 5.13%, 60.95% ± 5.52%, and 65.90% ± 5.14%, respectively. In the reader study, the model performed five-way classification on 100 test images with 79% accuracy in 14 seconds, compared with an average of 44% accuracy in 20 minutes for two surgeons and three manufacturer representatives. CONCLUSIONS: The authors developed a KAZE feature detector with an SVM classifier that successfully identified posterior thoracolumbar hardware at five-level classification. The model performed more accurately and efficiently than the method currently used in clinical practice. The relative computational simplicity of this model, from input to output, may facilitate future prospective studies in the clinical setting.

Neck Pain: Differential Diagnosis and Management.

Axial neck pain is a common and important problem in the outpatient setting. In isolation, neck pain tends to have a musculoskeletal etiology and responds best to medication and targeted physical therapy. Careful history and physical examination are required to ascertain if there is a neurologic component in addition to the patient's neck pain. For patients needing surgical intervention, there are a variety of approaches and operations that can decompress the appropriate nerve root or the spinal cord itself. These operations are generally well-tolerated and provide significant benefit for appropriately selected patients.

Back Pain: Differential Diagnosis and Management.

Back pain is a common condition affecting millions of individuals each year. A biopsychosocial approach to back pain provides the best clinical framework. A detailed history and physical examination with a thorough workup are required to exclude emergent or nonoperative etiologies of back pain. The treatment of back pain first uses conventional therapies including lifestyle modifications, nonsteroidal anti-inflammatory drugs, physical therapy, and cognitive behavioral therapy. If these options have been exhausted and pain persists for greater than 6 weeks, imaging and a specialist referral may be indicated.

Biomechanical Effects of Proximal Polyetheretherketone Rod Extension on the Upper Instrumented and Adjacent Levels in a Human Long-Segment Construct: A Cadaveric Model.

OBJECTIVE: The high mechanical stress zone at the sudden transition from a rigid to flexible region is involved in proximal junctional kyphosis (PJK) physiopathology. We evaluated the biomechanical performance of polyetheretherketone (PEEK) rods used as a nontraditional long semirigid transition phase from a long-segment metallic rod construct to the nonfused thoracic spine. METHODS: Pure moment range of motion (ROM) tests (7.5 Nm) were performed on 7 cadaveric spine segments followed by compression (200 N). Specimens were tested in the following conditions: (1) intact; (2) T10-pelvis pedicle screws and rods (PSRs); and (3) extending the proximal construct to T6 using PEEK rods (PSR+PEEK). T10-11 rod strain, T9 anterolateral bone strain, and T10 screw bending moments were analyzed. RESULTS: At the upper instrumented vertebra (UIV)+1, PSR+PEEK versus PSR significantly decreased ROM in flexion (115%, p = 0.02), extension (104%, p = 0.003), left lateral bending (46%, p = 0.02), and right lateral bending (63%, p = 0.008). Also, at UIV+1, PSR+PEEK versus intact significantly decreased ROM in flexion (111%, p = 0.01) and extension (105%, p = 0.003). The UIV+1 anterior column bone strain was significantly reduced with PSR+PEEK versus PSR during right lateral bending (p = 0.02). Rod strain polarities reversed with PEEK rods in all loading directions except compression. CONCLUSION: Extending a long-segment construct using PEEK rods caused a decrease in adjacent-level hypermobility as a consequence of long-segment immobilization and also redistributed the strain on the UIV and adjacent levels, which might contribute to PJK physiopathology. Further studies are necessary to observe the clinical outcomes of this technique.

Safe dissection and complication avoidance for L1-2 interbody placement via a lateral access approach.

The lateral access approach for L1-2 interbody placement or other levels at or near the thoracolumbar junction may be difficult without proper knowledge and visualization of anatomy. Specifically, understanding where the fibers of the diaphragm travel and avoiding injury to the diaphragm are paramount. The video can be found here: https://stream.cadmore.media/r10.3171/2022.3.FOCVID2221.

Minimally Invasive Retropleural Thoracic Diskectomy: Step-by-Step Operative Planning, Execution, and Results.

BACKGROUND: Thoracic disk herniation is rare and difficult to treat. The minimally invasive lateral retropleural approach to the thoracic spine enables the surgeon to decompress the neural elements and minimize thecal sac manipulation through direct visualization with less exposure-related morbidity. OBJECTIVE: To provide a detailed step-by-step overview of the minimally invasive retropleural approach for thoracic diskectomies, including preoperative planning through postoperative care as practiced at our institution. METHODS: Lateral retropleural thoracic diskectomies performed at a single institution from July 1, 2017, to June 30, 2020, were reviewed. Clinical and outcome data were collected and analyzed. The retropleural approach was divided into several components: relevant anatomy, indications and contraindications, preoperative setup, exposure and approach, diskectomy, and closure and postoperative care. RESULTS: Twelve patients were treated during the study interval. Their average (SD) age was 44.2 (9.5) years; 10 of 12 were men. Eleven patients presented with thoracic myelopathy. The level treated ranged from T6-7 to T12-L1. Disk herniations were calcified in 10 of 12 patients. These lesions were approached from the left side in 7 of 12 patients. Six patients had complications, none of which were neurological. Chest tubes were placed for pleural violation, pneumothorax, or hemothorax in 3 patients. Two patients experienced postoperative abdominal pseudohernia. Neurological symptoms were stable or improved in all patients. The median (IQR) Nurick scale improved from 3.0 (2.0-3.0) preoperatively to 1.0 (0-3.0) ( P = .026) postoperatively. CONCLUSION: Lateral retropleural diskectomy enables safe, efficient resection of most thoracic disks while minimizing patient morbidity.

Surgical anatomy of minimally invasive lateral approaches to the thoracolumbar junction.

OBJECTIVE: The thoracolumbar (TL) junction spanning T11 to L2 is difficult to access because of the convergence of multiple anatomical structures and tissue planes. Earlier studies have described different approaches and anatomical structures relevant to the TL junction. This anatomical study aims to build a conceptual framework for selecting and executing a minimally invasive lateral approach to the spine for interbody fusion at any level of the TL junction with appropriate adjustments for local anatomical variations. METHODS: The authors reviewed anatomical dissections from 9 fresh-frozen cadaveric specimens as well as clinical case examples to denote key anatomical relationships and considerations for approach selection. RESULTS: The retroperitoneal and retropleural spaces reside within the same extracoelomic cavity and are separated from each other by the lateral attachments of the diaphragm to the rib and the L1 transverse process. If the lateral diaphragmatic attachments are dissected and the diaphragm is retracted anteriorly, the retroperitoneal and retropleural spaces will be in direct continuity, allowing full access to the TL junction. The T12-L2 disc spaces can be reached by a conventional lateral retroperitoneal exposure with the rostral displacement of the 11th and 12th ribs. With caudally displaced ribs, or to expose T12-L1 disc spaces, the diaphragm can be freed from its lateral attachments to perform a retrodiaphragmatic approach. The T11-12 disc space can be accessed purely through a retropleural approach without significant mobilization of the diaphragm. CONCLUSIONS: The entirety of the TL junction can be accessed through a minimally invasive extracoelomic approach, with or without manipulation of the diaphragm. Approach selection is determined by the region of interest, degree of diaphragmatic mobilization required, and rib anatomy.

Surgical Management of Postradiation, Dropped Head Spinal Deformity in Patients with Head and Neck Cancer.

BACKGROUND: Dropped head syndrome is a morbid condition that affects daily functionality, causing pain and dysphagia and respiratory compromise. Reported causes of dropped head syndrome include neuromuscular disorders, iatrogenic from cervical spine surgery, and idiopathic and postradiation for head and neck cancers. Management of this spinal disorder remains challenging, as the complication rates are high. We present our series of 7 patients who underwent surgical correction of dropped head syndrome, all resulting from radiation for head and neck cancers. METHODS: This was a retrospective review of 7 patients who underwent surgery between 2016 and 2019 for dropped head syndrome secondary to postradiation cervical spine deformity. Clinical variables were obtained from medical records. Radiographic parameters pre- and postsurgery including T1 slope, sagittal vertical axis, and C2-C7 cervical lordosis were examined. RESULTS: Seven patients were included in the study, with an average age 69 years. Two patients underwent traction preoperatively. Five patients had posterior fixation and fusion only and 2 patients had a combined anterior and posterior fixation and fusion. Overall, there was improvement in average pre/postoperative sagittal vertical axis (6.96 cm to 3.04 cm), T1 slope (33.61° to 24.34°), and C2-C7 lordosis (-21.65° to -0.03°). CONCLUSIONS: Surgical correction of postradiation dropped head spinal deformity involving anterior and posterior fixation with osteotomies provides improvement in functional and radiographic outcomes as shown in our series. These cases are technically challenging and have a high rate of perioperative complications. Approaches must be tailored to the patient with attention to their specific surgical and radiation history.

Comparison of Surgical Outcomes and Recurrence Rates of Cystic and Solid Vestibular Schwannomas.

Objective Cystic vestibular schwannomas (CVSs) are anecdotally believed to have worse clinical and tumor-control outcomes than solid vestibular schwannomas (SVSs); however, no data have been reported to support this belief. In this study, we characterize the clinical outcomes of patients with CVSs versus those with SVSs. Design This is a retrospective review of prospectively collected data. Setting This study is set at single high-volume neurosurgical institute. Participants We queried a database for details on all patients diagnosed with vestibular schwannomas between January 2009 and January 2014. Main Outcome Measures Records were retrospectively reviewed and analyzed using univariate and multivariate analyses to study the differences in clinical outcomes and tumor progression or recurrence. Results Of a total of 112 tumors, 24% ( n = 27) were CVSs and 76% ( n = 85) were SVSs. Univariate analysis identified the extent of resection, Koos grade, and tumor diameter as significant predictors of recurrence ( p ≤ 0.005). However, tumor diameter was the only significant predictor of recurrence in the multivariate analysis ( p = 0.007). Cystic change was not a predictor of recurrence in the univariate or multivariate analysis ( p ≥ 0.40). Postoperative facial nerve and hearing outcomes were similar for both CVSs and SVSs ( p ≥ 0.47). Conclusion Postoperative facial nerve outcome, hearing, tumor progression, and recurrence are similar for patients with CVSs and SVSs. As CVS growth patterns and responses to radiation are unpredictable, we favor microsurgical resection over radiosurgery as the initial treatment. Our data do not support the commonly held belief that cystic tumors behave more aggressively than solid tumors or are associated with increased postoperative facial nerve deficits.

The Historical Role of the Plastic Surgeon in Spine Reconstruction.

Wound complications occur in up to 19% of patients undergoing complex spine surgery. The role of the plastic surgeon in complex and redo spine surgery is important and evolving. Classically, plastic surgeons have been involved in the management of patients who develop wound complications following surgery. This involves reconstruction of posterior trunk defects with locoregional fasciocutaneous, muscle, and free tissue transfers. There has also been an increasing role for plastic surgeons to become involved in prophylactic closures of complex and/or redo spine surgeries for high-risk populations. Identification of patients with comorbidities and likelihood for multiple reoperations who are prophylactically treated with complex closure with or without local muscle flaps could significantly decrease the postoperative wound complications.

Failure in Cervical Spinal Fusion and Current Management Modalities.

Failed fusion in the cervical spine is a multifactorial problem stemming from a combination of patient and surgical factors. Patient-related risk factors such as steroid use, poor bone quality, and smoking can be optimized preoperatively. Age, prior radiation, prior surgery, and underlying genetics are nonmodifiable patient-centered risk factors. Surgical risks for failed fusion include the number of segments fused, anterior versus posterior approach for fusion, the type of bone graft, and the instrumentation utilized. Many symptomatic cases of failed fusion (pseudarthrosis) result in pain, neurological deficits, or loosened hardware necessitating a revision surgery consisting of extending the prior construct and utilizing additional allografts or autografts to augment the fusion. Given the relatively mobile nature of the cervical spine, pseudoarthrosis (either known or anticipated) must be recognized by the spine surgeon, and steps should be considered to optimize the likelihood of future fusion. This consists of both performing a rigid fixation and using appropriate bone graft to enhance the environment for arthrodesis. Vascularized bone grafts are a useful tool to augment fusion and provide added structural stability in cases at high risk of pseudoarthrosis.

Failures in Thoracic Spinal Fusions and Their Management.

Instrumented fixation and fusion of the thoracic spine present distinct challenges and complications including pseudarthrosis and junctional kyphosis. When complications arise, morbidity to the patient can be significant, involving neurologic injury, failure of instrumentation constructs, as well as iatrogenic spinal deformity. Causes of fusion failure are multifactorial, and incompletely understood. Most likely, a diverse set of biomechanical and biologic factors are at the heart of failures. Revision surgery for thoracic fusion failures is complex and often requires revision or extension of instrumentation, and frequently necessitates complex soft tissue manipulation to manage index level injury or to augment the changes of fusion.

Vascularized Scapular Bone Grafting: Indications, Techniques, Clinical Outcomes, and Alternatives.

Spinal fusion can be challenging to obtain in patients with complex spinal pathology. Medial scapular vascularized bone grafts (S-VBGs) are a novel approach to supplement cervicothoracic arthrodesis in patients at high risk of failed spinal fusion. In this article, we discuss the benefits of using VBGs compared with both nonvascularized bone grafts and free vascularized bone flaps and the surgical technique, feasibility, and limitations specific to the S-VBG.

Vascularized Bone Grafts in Spinal Reconstruction: An Overview of Nomenclature and Indications.

Several vascularized bone grafts (VBGs) have been introduced for reconstruction and augmenting fusion of the spine. The expanding use of VBGs in the field of spinoplastic reconstruction, however, has highlighted the need to clarify the nomenclature for bony reconstruction as well as establish the position of VBGs on the bony reconstructive algorithm. In the current literature, the terms "flap" and "graft" are often applied inconsistently when describing vascularized bone transfer. Such inconsistency creates barriers in communication between physicians, confusion in interpreting the existing studies, and difficulty in comparing surgical techniques. VBGs are defined as bone segments transferred on their corresponding muscular attachments without a named major feeding vessel. The bone is directly vascularized by the muscle attachments and unnamed periosteal feeding vessels. VBGs are best positioned as a separate entity in the bony reconstruction algorithm between nonvascularized bone grafts (N-VBGs) and bone flaps. VBGs offer numerous advantages as they supply fully vascularized bone to the recipient site without the microsurgical techniques or pedicle dissection required for raising bone flaps. Multiple VBGs have been introduced in recent years to optimize these benefits for spinoplastic reconstruction.