Thoracoscopic Anterior Spinal Fusion Research Articles

Video-Assisted Thoracoscopic Lateral Interbody Fusion for Symptomatic Pseudarthrosis in Neurofibromatosis 1-Associated Spinal Deformity

The treatment of symptomatic pseudarthrosis via posterior-only approaches in the setting of neurofibromatosis 1 (NF1) is challenging due to dural ectasias, resulting in erosion of the posterior elements. The purpose of this report is to illustrate a minimally invasive method for performing anterior thoracic fusion for pseudarthrosis in a patient with NF1-associated scoliosis and dysplastic posterior elements. To the best of our knowledge, this is the first documented case of using video-assisted thoracoscopic lateral interbody fusion to treat pseudarthrosis for NF1-associated spinal deformity. The patient underwent video-assisted thoracoscopic anterior spinal fusion via a direct lateral interbody approach with interbody cage placement at T10-T11 and T11-T12, followed by revision of his posterior spinal fusion and instrumentation. The patient had an uneventful postoperative course. At 6 months of follow-up, the patient had complete resolution of his preoperative symptoms and had returned to full-time work with no complaints. At 3 years postoperatively, the patient reported being satisfied with the operation and had continued to work full-time without restrictions. To the best of our knowledge, this is the first report of pseudarthrosis in the setting of NF1-associated scoliosis treated via minimally invasive anterior thoracic fusion facilitated by video-assisted thoracoscopic surgery. This is a powerful technique that allows for safe access for anterior thoracic fusion in the setting of dysplastic posterior anatomy and poor posterior bone stock.

Minimally Invasive Surgery for Adolescent Idiopathic Scoliosis: Anterior and Posterior Techniques

Purpose: Surgical gold standard for adolescent idiopathic scoliosis (AIS) is open posterior spinal instrumentation and fusion. This approach causes significant soft tissue disruption and paravertebral muscle detachment. This review attempts to provide an overview of the current state of knowledge of minimally invasive (MIS) surgery for AIS. Methods: The results of MIS for adult scoliosis are briefly reviewed as the rationale for its application to AIS. A review of the two currently available MIS techniques for AIS is then given, including indications, surgical technique, and results in the literature. Results: Thoracoscopic anterior spinal fusion and instrumentation (TASF) offers similar results and complication rates with decreased blood loss but is technically demanding and has limited indications. The posterior MIS technique seems to offer similar results and complication rates, decreased blood loss and shorter length of hospital stay, at the expense of a longer operative time. Conclusion: Both TASF and posterior MIS are valid alternatives to the gold standard. They have proven similar results and short-term safety to open posterior fusion, with the added theoretical advantage of a less traumatizing exposure and improved cosmesis. While TASF has fallen out of favor due to its technical challenges, specific instrumentation and limited indications, posterior MIS does not suffer from these drawbacks. The limited amount of literature on this technique warrants studies with further follow-up, demonstrating its long-term safety before recommending its routine use.

Is vertebral rotation correction maintained after thoracoscopic anterior scoliosis surgery? A low-dose computed tomography study

BackgroundAxial vertebral rotation is a key characteristic of adolescent idiopathic scoliosis (AIS), and its reduction is one of the goals of corrective surgery. Recurrence of deformity after surgical correction may relate to rotation changes that occur in the anterior vertebral column after surgery, but whether any change occurs within the fused segment or in adjacent unfused levels following thoracoscopic anterior spinal fusion (TASF) is unknown. An analysis of measurements from an existing postoperative CT dataset was performed to investigate the occurrence of inter- and intra-vertebral rotation changes after TASF within and adjacent to the fused spinal segment and look for any relationships with the Cobb angle and rib hump in the two years after surgery.Methods39 Lenke Type 1 main thoracic patients underwent TASF for progressive AIS and low dose computed tomography scanning of the instrumented levels of the spine at 6 and 24 months after surgery. Vertebral rotation was measured at the superior and inferior endplates on true axial images for all vertebral levels in the fused segment plus one adjacent level cranially and caudally. Intra-observer variability for rotation measurements was assessed using 95% limits of agreement to detect significant changes in inter/intra-vertebral rotation.ResultsSignificant local changes in inter- and intra-vertebral rotation were found to have occurred between 6 and 24 months after anterior surgical fusion within the fused spinal segment, albeit with no consistent pattern of location or direction within the instrumented fusion construct. No significant en-bloc movement of the entire fused spinal segment relative to the adjacent un-instrumented cranial and caudal intervertebral levels was found. No clear correlation was found between any vertebral rotation changes and Cobb angle or rib hump measures.ConclusionsLocalised inter- and intra-vertebral rotation occurs between 6 and 24 months after TASF, both within the instrumented spinal segments and in the adjacent un-instrumented levels of the adolescent spine. The lack of measurable en-bloc movement of the fused segment relative to the adjacent un-instrumented levels suggests that overall stability of the instrumented construct is achieved, however the vertebrae within the fusion mass continue to adapt and remodel, resulting in ongoing local anatomical and biomechanical changes in the adolescent spine.

Change in Lung Volume Following Thoracoscopic Anterior Spinal Fusion Surgery: A 3-Dimensional Computed Tomography Investigation.

Lung volumes and thoracic anatomy were measured from low-dose computed tomography (CT) scans preoperatively and 2 years following thoracoscopic anterior spinal fusion (TASF) for adolescent idiopathic scoliosis (AIS). The aim of this study was to assess changes in lung volume after TASF surgical correction. AIS patients are known to have decreased pulmonary function as a consequence of their spinal and ribcage deformity. Several studies have evaluated changes in pulmonary function clinically after scoliosis correction surgery showing varied results. To date, there have been no published studies using CT to evaluate lung volume changes following TASF. Twenty-three female AIS patients with both pre- and 2 years postoperative low-dose CT scans were selected from an ethically approved, historical databank. Three-dimensional lung volumes were reconstructed to determine anatomical lung volumes. Right and left lung volumes, total lung volume, and right-to-left lung volume ratio were obtained as well as hemithoracic symmetry, to indicate the extent of thorax deformity. Cobb angle, rib hump, levels fused in surgery, and patient height were used for correlation analysis with the lung volume results. Left lung volume, total lung volume, and hemithoracic ratio all increased significantly 2 years after surgery. There was no significant change in right-to-left lung volume ratio (P = 0.36). Statistical regression found significant positive correlation between lung volume changes, reduction in Cobb angle, increase in height, and improvement in hemithoracic symmetry ratio. TASF resulted in a statistically significant increase in lung volume following surgery, as well as improvement in the symmetry of the thoracic architecture; however, the postoperative lung volumes remained in the lower 50th percentile relative to females without thoracic deformity. Furthermore, change in lung volume was significantly correlated with changes in Cobb angle, hemithoracic asymmetry, and increased patient height, which are important consequences of thoracic deformity correction surgery. 3.

Evaluating the Change in Axial Vertebral Rotation Following Thoracoscopic Anterior Scoliosis Surgery Using Low-Dose Computed Tomography

Background ContextIn recent years, there has been increasing appreciation of the need to treat scoliosis as a three-dimensional deformity. PurposeAssessment of surgical strategies and outcomes should consider not only the coronal plane correction but also derotation of the transverse plane deformity that can affect trunk appearance. Study DesignThis study included a cohort of 29 female adolescent idiopathic scoliosis patients who received thoracoscopic single rod anterior fusion (TASF) surgery. This study used pre- and postoperative low-dose computed tomographic (CT) scans to accurately measure apical axial vertebral rotation (AVR). MethodsThe pre- and postoperative values for clinically measured coronal Cobb correction and rib hump correction as well as AVR were compared to determine whether these values improved postoperatively. There are no conflicts of interest to report for authors of this investigation. ResultsAs expected, statistically significant reductions in coronal Cobb angle (mean preoperative Cobb 51°, reducing to 24° at the two-year follow-up) and rib hump (mean preoperative rib hump 15°, reducing to 7° at two-year follow-up) were achieved. The mean reduction in apical AVR measured using CT was only 3° (mean preoperative AVR 16°, reducing to 13° at two-year follow-up), which was statistically but not clinically significant. Significant correlations were found between Cobb angle and rib hump, between Cobb angle and AVR, and between AVR and rib hump, suggesting that patients with greater coronal Cobb correction also achieve better derotation with this surgical procedure. ConclusionsThe historical low-dose CT data set permitted detailed three-dimensional assessment of the deformity correction that is achieved using thoracoscopic anterior spinal fusion for progressive adolescent idiopathic scoliosis.

Partial Intervertebral Fusion Secures Successful Outcomes After Thoracoscopic Anterior Scoliosis Correction: A Low-Dose Computed Tomography Study

Study DesignRetrospective review of prospectively collected data. ObjectivesTo analyze intervertebral (IV) fusion after thoracoscopic anterior spinal fusion (TASF) and explore the relationship between fusion scores and key clinical variables. Summary of Background InformationTASF provides comparable correction with some advantages over posterior approaches but reported mechanical complications, and their relationship to non-union and graft material is unclear. Similarly, the optimal combination of graft type and implant stiffness for effecting successful radiologic union remains undetermined. MethodsA subset of patients from a large single-center series who had TASF for progressive scoliosis underwent low-dose computed tomographic scans 2 years after surgery. The IV fusion mass in the disc space was assessed using the 4-point Sucato scale, where 1 indicates <50% and 4 indicates 100% bony fusion of the disc space. The effects of rod diameter, rod material, graft type, fusion level, and mechanical complications on fusion scores were assessed. ResultsForty-three patients with right thoracic major curves (mean age 14.9 years) participated in the study. Mean fusion scores for patient subgroups ranged from 1.0 (IV levels with rod fractures) to 2.2 (4.5-mm rod with allograft), with scores tending to decrease with increasing rod size and stiffness. Graft type (autograft vs. allograft) did not affect fusion scores. Fusion scores were highest in the middle levels of the rod construct (mean 2.52), dropping off by 20% to 30% toward the upper and lower extremities of the rod. IV levels where a rod fractured had lower overall mean fusion scores compared to levels without a fracture. Mean total Scoliosis Research Society (SRS) questionnaire scores were 98.9 from a possible total of 120, indicating a good level of patient satisfaction. ConclusionsResults suggest that 100% radiologic fusion of the entire disc space is not necessary for successful clinical outcomes following thoracoscopic anterior selective thoracic fusion.

Surgical Treatment of Lenke 1 Main Thoracic Idiopathic Scoliosis

Prospective, consecutive, nonrandomized, multicenter study. The purpose of this study was to compare the outcomes of idiopathic scoliosis treatment for Lenke 1 curves with 3 treatment approaches. Surgical treatment options for Lenke 1 or primary main thoracic curve pattern in adolescent idiopathic scoliosis include thoracoscopic anterior spinal fusion, open anterior spinal fusion, and posterior spinal fusion (PSF) and instrumentation procedures. This was a prospective, consecutive, nonrandomized, multicenter study of surgical correction in adolescent idiopathic scoliosis. Patients with Lenke type 1 curve patterns from 7 sites were enrolled in this minimum 2-year follow-up study. Changes in pre- to postoperative radiographs, pulmonary function tests, Scoliosis Research Society questionnaire scores, and trunk rotation measures were compared. A total of 149 patients (age: 14.5 ± 2 yr) were included (91% follow-up at 2 yr). The 3 groups were similar preoperatively in thoracic and lumbar curve size. There were 55 patients with thoracoscopic anterior spinal fusion, 17 patients with open anterior spinal fusion, and 64 patients with PSF. The fusion included on average 3 to 4 more levels in PSF than the 2 anterior approaches (P ≤ 0.001). Surgical time tended to be greater in the anterior groups by approximately 2 to 3 hours; however, blood loss was greatest with PSF. At 2 years, all 3 approaches showed similar improvements in the thoracic Cobb angle, coronal balance, the lumbar Cobb angle, Scoliosis Research Society questionnaire scores, and trunk rotation measures. The PSF approach resulted in overall reduction in kyphosis compared with the anterior approaches. Postoperative hyperkyphosis was an issue only in the 2 anterior groups. Major complication rates were similar. All 3 approaches resulted in similarly satisfactory outcomes for the majority of patients with specific advantages to each technique. The patients with PSF had more levels fused, yet with the shortest operative time. The thoracoscopic anterior spinal fusion group had the smallest incisions and the lowest requirement for transfusion. The open anterior spinal fusion group had a modest loss of pulmonary function without any clear advantages compared with the other 2 groups. 2.

CT and radiographic analysis of sagittal profile changes following thoracoscopic anterior scoliosis surgery

BackgroundPrevious studies report an increase in thoracic kyphosis after anterior approaches and a flattening of sagittal contours following posterior approaches. Difficulties with measuring sagittal parameters on radiographs are avoided with reformatted sagittal CT reconstructions due to the superior endplate clarity afforded by this imaging modality.MethodsA prospective study of 30 Lenke 1 adolescent idiopathic scoliosis (AIS) patients receiving selective thoracoscopic anterior spinal fusion (TASF) was performed. Participants had ethically approved low dose CT scans at minimum 24 months after surgery in addition to their standard care following surgery. The change in sagittal contours on supine CT was compared to standing radiographic measurements of the same patients and with previous studies. Inter-observer variability was assessed as well as whether hypokyphotic and normokyphotic patient groups responded differently to the thoracoscopic anterior approach.ResultsMean T5-12 kyphosis Cobb angle increased by 11.8 degrees and lumbar lordosis increased by 5.9 degrees on standing radiographs two years after surgery. By comparison, CT measurements of kyphosis and lordosis increased by 12.3 degrees and 7.0 degrees respectively. 95% confidence intervals for inter-observer variability of sagittal contour measurements on supine CT ranged between 5-8 degrees. TASF had a slightly greater corrective effect on patients who were hypokyphotic before surgery compared with those who were normokyphotic.ConclusionsRestoration of sagittal profile is an important goal of scoliosis surgery, but reliable measurement with radiographs suffers from poor endplate clarity. TASF significantly improves thoracic kyphosis and lumbar lordosis while preserving proximal and distal junctional alignment in thoracic AIS patients. Supine CT allows greater endplate clarity for sagittal Cobb measurements and linear relationships were found between supine CT and standing radiographic measurements. In this study, improvements in sagittal kyphosis and lordosis following surgery were in agreement with prior anterior surgery studies, and add to the current evidence suggesting that anterior correction is more capable than posterior approaches of addressing the sagittal component of both the instrumented and adjacent non instrumented segments following surgical correction of progressive Lenke 1 idiopathic scoliosis.

Radiographic Classification of Complications of Instrumentation in Adolescent Idiopathic Scoliosis

In spinal deformity surgery, techniques and implants must be assessed for their safety and efficacy. Regulatory bodies, third-party payors, and patients will increasingly scrutinize treatment methods based on the frequency of adverse events. We therefore developed a classification of adverse hardware-related events using plain radiographic criteria. We analyzed the adverse events in 466 patients surgically treated for adolescent idiopathic scoliosis for a Type 1 (Lenke et al.) curve. We used plain radiographic films to define complications as either serious radiographic adverse events or radiographic adverse events in four technique groups: posterior spinal fusion with hooks and/or hybrid systems, posterior spinal fusion using mostly pedicle screws, open anterior spinal fusion, and thoracoscopic anterior spinal fusion. We defined serious radiographic adverse events as those requiring subsequent surgery. The minimum followup was 2 years. We found a reoperation rate ranging from 4.5% (open anterior spinal fusion) to 8.8% (posterior spinal fusion with hooks); we found no difference in the incidence of serious radiographic adverse events between surgical techniques. Among serious radiographic adverse events, the most common problems were revision for lumbar progression, rod breakage, and proximal screw pullout in the anterior spinal fusions and instrumentation removal for pain and infection in the posterior spinal fusions. We propose a new radiographic system of adverse hardware-related events for patients with Type 1 adolescent idiopathic scoliosis. Level III, therapeutic study. See the Guidelines for Authors for a complete description of levels of evidence.

The Awl-Staple Versus Guidewire Method for Placing Vertebral Screws in Thoracoscopic Anterior Spinal Fusion and Instrumentation for Adolescent Idiopathic Scoliosis

A retrospective chart and radiograph review in a consecutive series of patients at a single institution. To compare 2 methods of placing vertebral body screws in thoracoscopic anterior spinal fusion and instrumentation with respect to radiographic, clinical, and perioperative variables. Placing vertebral body screws in thoracoscopic anterior spinal fusion and instrumentation for adolescent idiopathic scoliosis can be performed using 2 methods: the awl/staple technique and the guidewire method. There are no current studies that have compared both of these techniques. Two groups of patients were analyzed depending on the method of screw placement: The AS group (n=15) used the awl/staple method and the GW group (n=27) used the guidewire method. Surgical times and estimated blood loss were obtained from the medical record. Fluoroscopy times were obtained from the radiology technician. Preoperative posteroanterior standing, bending, and immediate postoperative radiographs were examined to determine the primary curve magnitude, postoperative curve correction, curve flexibility, and the Lenke classification. The AS group had significantly less fluoroscopy times (156.6+/-71.4 vs. 328.4+/-171.6 s) and operative times (416.1+/-65.4 vs. 505.6+/-61.8 min) compared with the GW group (P<0.05). When calculating the duration per fusion level, the AS group was also shorter for fluoroscopy times (27.1+/-13.2 vs. 49.3+/-24.5 s/level) (P<0.05) and surgical times (72.0+/-15.2 vs. 76.9+/-9.8 min/level) (P=0.10). There was a trend toward a lower incidence of screw plow or pullout (0.0% vs. 14.8%) for the AS group (P=0.157). The awl/staple technique is the preferred technique for placing vertebral body screws when performing thoracoscopic anterior spinal fusion/instrumentation because it has shorter fluoroscopy times, surgical times, and a lower incidence of screw plow/pullout than the traditional guidewire method.