A biomechanical comparison of open and thoracoscopic anterior spinal release in a goat model

Comparison of Thoracoscopic Anterior Release Combined With Posterior Spinal Fusion Versus Posterior-only Approach With an All-pedicle Screw Construct in the Treatment of Rigid Thoracic Adolescent Idiopathic Scoliosis

OBJECTIVE

To compare the effect of thoracoscopic anterior release combined with posterior spinal fusion and posterior-only approach with an all-pedicle screw construct in the treatment of rigid thoracic adolescent idiopathic scoliosis.

METHODS

From June 2001 to June 2010, 63 patients who were admitted to our hospital with thoracic Cobb angle ≥80 degrees and the flexibility ≤40% were enrolled in our study. They were treated with either a combined anterior/posterior spinal fusion with hooks and screws (group A, n=25) or a posterior spinal fusion alone with an all-pedicle screw construct (group B, n=38). The thoracic Cobb angle in the standing whole-spine anteroposterior x-ray, thoracic kyphosis (T5-T12) Cobb angle, imaging examination parameters, fixation segments, implant density, and complications between the 2 groups were compared.

RESULTS

There were no significant differences in operation time, bleeding volume, length of hospital stay, preoperative coronal, sagittal Cobb, coronal curve flexibility, or postoperative coronal Cobb correction ratio between the 2 groups. Moreover, no significant difference in the Scoliosis Research Society-22 score at the last follow-up was present in the 2 groups, although it had been improved compared with that presented during the preoperative period. The implant density of group A (44±4%) was significantly lower than that of group B (55±5%) (P<0.001). In group A, the main complication was chylothorax (n=2) and hemopneumothorax (n=2). In group B, acute intestinal obstruction was observed in 2 patients and pleural effusion was observed in 1 patient. In addition, 12 screws were misplaced (12/403, 3.0%) in group B.

CONCLUSIONS

In patients with rigid thoracic adolescent idiopathic scoliosis, posterior-only approach with an all-pedicle screw construct could achieve the same curve correction as a combined anterior/posterior spinal fusion by increasing the implant density. However, for scoliosis patients with a high risk of implant complications, anterior release combined with posterior spinal fusion is still recommended.

Video-assisted thoracoscopic surgery plus lumbar mini-open surgery for adolescent idiopathic scoliosis

PURPOSE

The objectives of this study are to describe the outcome of adolescent idiopathic scoliosis (AIS) patients treated with Video Assisted Thoracoscopic Surgery (VATS) plus supplementary minimal incision in the lumbar region for thoracic and lumbar deformity correction and fusion.

MATERIALS AND METHODS

This is a case series of 13 patients treated with VATS plus lumbar mini-open surgery for AIS. A total of 13 patients requiring fusions of both the thoracic and lumbar regions were included in this study: 5 of these patients were classified as Lenke type 1A and 8 as Lenke type 5C. Fusion was performed using VATS up to T12 or L1 vertebral level. Lower levels were accessed via a small mini-incision in the lumbar area to gain access to the lumbar spine via the retroperitoneal space. All patients had a minimum follow-up of 1 year.

RESULTS

The average number of fused vertebrae was 7.1 levels. A significant correction in the Cobb angle was obtained at the final follow-up (p = 0.001). The instrumented segmental angle in the sagittal plane was relatively well-maintained following surgery, albeit with a slight increase. Scoliosis Research Society-22 (SRS-22) scores were noted have significantly improved at the final follow-up (p < 0.05).

CONCLUSION

Indications for the use of VATS may be extended from patients with localized thoracic scoliosis to those with thoracolumbar scoliosis. By utilizing a supplementary minimal incision in the lumbar region, a satisfactory deformity correction may be accomplished with minimal post-operative scarring.

Novel dual-rod screw for thoracoscopic anterior instrumentation: biomechanical evaluation compared with single-rod and double-screw/double-rod anterior constructs

STUDY DESIGN

A novel dual-rod screw was designed to provide a second-rod augmentation at the critical apical/middle segments of the single-rod thoracoscopic anterior construct. Biomechanical testing was performed on pig thoracic spines instrumented with 7-segment anterior scoliosis constructs.

OBJECTIVES

To analyze the biomechanical performance of the new implant, and compare it to a single-rod and double-rod anterior constructs.

SUMMARY OF BACKGROUND DATA

Using single-rod thoracoscopic anterior instrumentation for thoracic scoliosis, the complications of rod breakage at apex, high rate of nonunion, and resultant loss of coronal and sagittal correction has been reported. Inadequate construct stiffness because of a smaller diameter single rod has been implicated as the cause of these complications.

METHODS

Twelve pig thoracic spines were instrumented over 7 segments with: (1) single-rod construct, (2) short second-rod augmentation at the apex of the single-rod construct, (3) long second-rod augmentation at middle segments of the single-rod construct, and (4) double-screw/double-rod anterior construct. The spines were tested in flexion-extension, left-right lateral bending, and torsion, using pure bending moments. Strain gauges attached to the primary single rod at the cephalad, middle, and caudal portions were used and the maximum tensile stress was recorded.

RESULTS

In the single-rod construct, the middle portion stress was 39% to 51% greater than the stress in the cephalad and caudal portions in flexion-extension (P < 0.05), and the cephalad portion stress was 39% to 65% greater than the stress in the middle and caudal portions in right lateral bending and torsion (P < 0.05). When a second rod was added at the apical/middle portion, the middle portion stress decreased from 50% to 72% in flexion-extension and right lateral bending (P < 0.05). In addition, the second rod decreased the primary single-rod stress at the cephalad portion by 48% (left torsion) and the caudal portion by 50% (flexion). Double-screw/double-rod construct significantly increases the construct stiffness in comparison with the single-rod construct. However, it did not add any construct stiffness at the critical apical segments when compared to the constructs in which the second rod augmented the single-rod constructs.

CONCLUSION

A novel dual-rod screw was designed to combine the standard single-rod construct with the addition of a second rod at the critical apical/middle segments and increase construct stiffness and stability. This implant may therefore prevent pseudarthrosis and rod breakage by enhancing construct stiffness.

DECISION MAKING IN PEDIATRIC SPINAL DEFORMITY

OBJECTIVE

To review the concepts involved in the decision-making process for management of pediatric patients with spinal deformity.

METHODS

The literature was reviewed in reference to pediatric deformity evaluation and management.

RESULTS

Pediatric spinal deformity includes a broad range of disorders with differing causes, natural histories, and treatments. Appropriate categorization of pediatric deformities is an important first step in the clinical decision-making process. An understanding of both nonoperative and operative treatment modalities and their indications is requisite to providing treatment for pediatric patients with spinal deformity. The primary nonoperative treatment modalities include bracing and casting, and the primary operative treatments include nonfusion instrumentation and fusion with or without instrumentation. In this article, we provide a review of pediatric spinal deformity classification and an overview of general treatment principles.

CONCLUSION

The decision-making process in pediatric deformity begins with appropriate diagnosis and classification of the deformity. Treatment decisions, both nonoperative and operative, are often predicated on the basis of the age of the patient and the natural history of the disorder.

Minimally invasive posterior thoracic fusion

Thoracic spine fusion may be indicated in the surgical treatment of a wide range of pathologies, including trauma, deformity, tumor, and infection. Conventional open procedures for surgical treatment of thoracic spine disease can be associated with significant approach-related morbidity, which has motivated the development of minimally invasive approaches. Thoracoscopy and, later, video-assisted thoracoscopic surgery were developed to address diseases of the thoracic cavity and subsequently adapted for thoracic spine surgery. Although video-assisted thoracoscopic surgery has been used to treat a variety of thoracic spine diseases, its relatively steep learning curve and high rate of pulmonary complications have limited its widespread use. These limitations have motivated the development of minimally invasive posterior approaches to address thoracic spine pathology without the added risk of morbidity involved in surgically entering the chest. Many of these advances are ongoing and represent the forefront of minimally invasive spine surgery. As these techniques are developed and applied, it will be important to assess their equivalence or superiority in comparison with standard open techniques using prospective trials. In this paper the authors focus on minimally invasive posterior thoracic procedures that include fusion, and provide a review of the current literature, a discussion of future pathways for development, and case examples. The topic is divided by pathology into sections including trauma, deformity, spinal column tumors, and osteomyelitis.

Fusion rates after thoracoscopic release and bone graft substitutes in idiopathic scoliosis

STUDY DESIGN

A retrospective assessment of fusion rates using either morselized allograft bone or demineralized bone matrix (DBM) following video-assisted thoracoscopic surgery (VATS) in idiopathic scoliosis.

OBJECTIVE

To compare fusion rates between allograft bone and demineralized bone matrix (Grafton DBM Flex) following VATS using on standard standing lateral spine radiographs.

SUMMARY OF BACKGROUND DATA

Both VATS and bone graft substitutes are accepted surgical techniques. However, their concomitant use in spinal deformity surgery has not been previously reported. Bone graft substitute has the advantage of decreasing operative time, blood loss, and donor site morbidity associated with autografts.

METHODS

Anterior thoracic discectomies were performed using VATS. Forty patients with 1 year or more follow-up were evaluated-12 with morselized allograft bone (Allograft group) and 28 with folded Grafton DBM Flex (DBM group). Factors analyzed included age, number of anterior levels fused, operative time, anterior perioperative blood loss, curve correction, and fusion rates. Clinical and radiographic evaluations were performed before surgery and at month, 1 year, and at most recent follow-up. Interbody fusion was assessed on standing lateral radiographs using the Newton et al 4-level grading scale.

RESULTS

There were no significant differences in age at surgery, number of anterior vertebral levels fused, anterior operative time per level, anterior intraoperative blood loss, chest tube drainage and duration, or total perioperative anterior blood loss between the 2 groups. Percent curve correction from before surgery to the most recent follow-up were very similar in both Allograft (68%) and DBM groups (67%). At most recent assessment, 60 of 73 disc spaces (82%) in the Allograft group and 100 of 109 disc spaces (92%) in the DBM group were rated as radiographically fused (Newton et al Grade I and II). There was no significant difference between the 2 groups (P = 0.088). No patients were observed to have crankshaft, pseudoarthrosis or hardware failure. There were no complications related to the bone graft material used.

CONCLUSION

Demineralized bone matrix (Grafton DBM Flex) seem to be an effective bone graft substitute in thoracoscopic surgery for idiopathic scoliosis.

The use of thoracoscopy in the management of adolescent idiopathic scoliosis

STUDY DESIGN

Retrospective case cohort series.

OBJECTIVE

To analyze the outcomes of thoracoscopy in the surgical treatment of adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Traditionally, progressive idiopathic scoliosis has been treated surgically with either an open posterior, anterior, or combined surgical approach. Surgical methods are being explored to minimize the extent of soft tissue disruption such as thoracoscopy followed spinal release, bone grafting, and instrumentation. Several authors have reported good results using thoracoscopy in the treatment of spinal deformity following a requisite learning curve.

METHODS

A consecutive case cohort series of 45 adolescent patients with idiopathic scoliosis evaluated and treated at a single institution. Patients with a progressive deformity underwent a thoracoscopically assisted curve correction, fusion, and instrumentation procedure. After surgery, patients were assessed at 1, 3, 6, and 12 months and then annually.

RESULTS

All patients underwent successful thoracoscopic instrumentation and fusion without the need for an open conversion. The average preoperative thoracolumbar Cobb measurement of the major curve was 51.6 degrees . The thoracolumbar levels instrumented anteriorly ranged from T7 to L3 and had an average postoperative Cobb angle of 6.58 degrees , with an overall improvement of 87.3%. To date, at a mean follow up of 4.6 years, all curves have maintained correction. Sagittal balance was recreated or maintained through the application of interbody femoral ring allografts. Operative times averaged 5 hours and 46 minutes, with a range of 3 hours, 48 minutes to 6 hours, 55 minutes. Hospital stays averaged 2.9 days, with a range of 2 to 7 days. All patients were completely off pain medication before their first postoperative visit at 4 weeks. Children were back to school between 2 and 4 weeks on average. There were a total of 3 complications. One patient experienced transient chest wall numbness, which resolved by 3 months. Two patients developed postoperative mucus plugging in the ventilated lung.

CONCLUSION

Endoscopic thoracoscopic spinal deformity correction, fusion, and instrumentation is a safe and feasible method of surgical management of an adolescent patient with progressive scoliosis. The key to successful fusion is a total discectomy and complete endplate removal. This method appears to be comparable to open procedures in terms of curve correction with significantly shorter hospitalization and rehabilitation due to less surgical discomfort. The thoracoscopic correction of adolescent scoliosis warrants continued development and evaluation as a surgical method of scoliosis correction.

Treatment of stiff thoracic scoliosis by thoracoscopic anterior release combined with posterior instrumentation and fusion

BACKGROUND

Thoracoscopic anterior release has been shown that it can effectively improve spinal flexibility in animal and human cadaveric studies, and has been advocated for use in patients with scoliosis. This prospective case series aims to investigate the improvement of the spinal flexibility and the effectiveness in deformity correction by anterior thoracoscopic release and posterior spinal fusion.

METHODS

Eleven patients with stiff idiopathic thoracic scoliosis underwent anterior thoracoscopic release followed by posterior instrumentation. The average number of discs excised was five. Spinal flexibility was assessed by the fulcrum bending technique. Cobb angle before and after the anterior release was compared.

RESULTS

The patients were followed for an average of 5.6 years (range 2.2 to 8.1 years). Fulcrum bending flexibility was increased from 39% before the thoracoscopic anterior spinal release to 54% after the release. The average Cobb angle before anterior release was 74 degrees on the standing radiograph and 45 degrees with the fulcrum-bending radiograph. This reduced to 34 degrees on the fulcrum-bending radiograph after the release, and highly corresponded to the 31 degrees measured at the post-operative standing radiograph.

CONCLUSION

It was demonstrated in patients with stiff idiopathic thoracic scoliosis that thoracoscopic anterior spinal release can effectively improve the spinal flexibility and increase the correction of the spinal deformity.

Anterior and thoracoscopic scoliosis surgery for idiopathic scoliosis

Surgical management of idiopathic scoliosis is based on the natural history of this spinal disorder and on the likelihood of developing a worsening deformity. Anterior surgical treatments continue to evolve and provide advantages over posterior procedures in specific instances. Open and thoracoscopic anterior approaches allow direct access to the anterior stabilizing structures of the spine, enable mobilization of a rigid deformity, and provide a large surface area for arthrodesis. Thoracoscopic procedures provide a more cosmetically appealing alternative to a large midline posterior or anterolateral thoracotomy scar. Although the indications and contraindications for anterior versus posterior surgical intervention (for thoracic and thoracolumbar curve patterns) have been defined to some degree, there remains appropriate flexibility in the decision-making process, allowing the surgeon to make an optimal recommendation for each patient based on surgeon experience and patient needs.

Video-assisted thoracoscopic surgery in idiopathic scoliosis: evaluation of the learning curve

STUDY DESIGN

Retrospective review of patients with idiopathic scoliosis who underwent same-day or staged anterior and posterior spinal fusion and segmental spinal instrumentation.

OBJECTIVE

Evaluation of our learning curve with video-assisted thoracoscopic surgery (VATS) with respect to operative time, blood loss, and complications in patients with idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

VATS is a minimally invasive alternative to thoracotomy in the management of idiopathic scoliosis. An increased or steep learning curve has been described in the initial application of this technique.

METHODS

We began performing VATS in 1998. We compared our first 25 consecutive VATS patients (Group 2) and subsequent 28 consecutive VATS patients (Group 3) to our previous 16 consecutive patients (Group 1) with a thoracotomy (1991-1998) for idiopathic scoliosis. Training at a sponsored regional course was obtained before performing our first VATS procedure.

RESULTS

VATS allowed more disc to be excised in Group 2 (4.5 +/- 1, 5.7 +/- 1, and 4.4 +/- 1 discs in Group 1, Group 2, and Group 3, respectively) and significantly decreased the anterior operative time (215 +/- 33, 260 +/- 56, and 177 +/- 47 minutes) and time per individual disc excision (50 +/- 13, 47 +/- 12, and 41 +/- 12 minutes), while providing comparable correction of the thoracic deformity (67% +/- 12%, 66% +/- 10%, and 70% +/- 13% correction). There was no increase in estimated intraoperative anterior blood loss (228 +/- 213, 183 +/- 136, and 211 +/- 158 mL), estimated blood loss per disc excised (51 +/- 42, 34 +/- 29 and 48 +/- 37 mL), or complications in the VATS groups. Complications were primarily pulmonary and resolved with medical therapy. Postoperative chest tube drainage (855 +/- 397, 462 +/- 249, and 561 +/- 261 mL) and total perioperative anterior blood loss (1083 +/- 507, 647 +/- 309, and 773 +/- 308 mL) were significantly decreased in the VATS groups, but this was attributed to the use of Amicar.

CONCLUSIONS

VATS is an effective procedure for anterior spinal fusion in idiopathic scoliosis. The learning curve is short, provided appropriate training is obtained.

In-vivo demonstration of the effectiveness of thoracoscopic anterior release using the fulcrum-bending radiograph: a report of five cases

Thoracoscopic anterior release of stiff scoliotic curves is favored because of its minimally invasive nature. Animal and human cadaveric studies have shown that it can effectively improve spinal flexibility in non-scoliotic spines; however it has not been demonstrated to be effective in actual patients with scoliosis. The fulcrum-bending radiograph has been shown to accurately reflect the post-operative correction. To demonstrate that the flexibility was increased after the anterior release; five patients with idiopathic thoracic scoliosis who underwent staged anterior thoracoscopic release and posterior spinal fusion were assessed using the fulcrum-bending radiograph. The average number of discs excised was four. Spinal flexibility as revealed by the fulcrum-bending technique, was compared before and after the anterior release. The patients were followed for an average of 4 years (range 2.2-4.9 years). Fulcrum-bending flexibility was increased from 39% before the thoracoscopic anterior spinal release to 54% after the release (P<0.05). The average Cobb angle before the anterior release was 71 degrees on the standing radiograph and 43 degrees with the fulcrum-bending radiograph. This reduced to 33 degrees on the fulcrum-bending radiograph after the release, and highly corresponded to the 30 degrees measured at the post-operative standing radiograph and at the latest follow-up. Previous animal and cadaveric studies demonstrating the effectiveness of thoracoscopic anterior release did not have scoliosis. We are able to demonstrate in patients with adolescent idiopathic scoliosis, that thoracoscopic anterior spinal release effectively improves the spinal flexibility.

Thoracoscopic spinal fusion compared with posterior spinal fusion for the treatment of thoracic adolescent idiopathic scoliosis

BACKGROUND

Posterior spinal fusion with segmental instrumentation is the gold standard for the surgical treatment of thoracic adolescent idiopathic scoliosis. More recently, anterior surgery and video-assisted thoracoscopic surgery with spinal instrumentation have become available. The purpose of the present study was to compare the radiographic and clinical outcomes as well as pulmonary function in patients managed with either anterior thoracoscopic or posterior surgery.

METHODS

Radiographic data, Scoliosis Research Society patient-based outcome questionnaires, pulmonary function, and operative records were reviewed for fifty-one patients undergoing surgical treatment of scoliosis. Data were collected preoperatively, immediately postoperatively, and at the time of the final follow-up. The radiographic parameters that were analyzed included coronal curve correction, the most caudad instrumented vertebra tilt angle correction, coronal balance, and thoracic kyphosis. The operative parameters that were evaluated included the operative time, the estimated blood loss, the blood transfusion rate, the number of levels fused, the type of bone graft used, and the number of intraoperative and postoperative complications. The pulmonary function parameters that were analyzed included vital capacity and peak flow.

RESULTS

The thoracoscopic group included twenty-eight patients with a mean age of 14.6 years, and the posterior fusion group included twenty-three patients with a mean age of 14.3 years. The percent correction was 54.5% for the thoracoscopic group and 55.3% for the posterior group. With the numbers available, there were no significant differences between the two groups in terms of kyphosis (p = 0.84), coronal balance (p = 0.70), or tilt angle (p = 0.91) at the time of the final follow-up. The mean number of levels fused was 5.8 in the thoracoscopic group, compared with 9.3 levels in the posterior group (p < 0.0001). The estimated blood loss in the thoracoscopic group was significantly less than that in the posterior fusion group (361 mL compared with 545 mL; p = 0.03), and the transfusion rate in the thoracoscopic group was significantly lower than that in the posterior fusion group (14% compared with 43%; p = 0.01). Operative time in the thoracoscopic group was significantly greater than that in the posterior group (6.0 compared with 3.3 hours, p < 0.0001). There were no intraoperative complications in either group. Vital capacity and peak flow had returned to baseline levels in both groups at the time of the final follow-up. Patients in the thoracoscopic group scored higher than those in the posterior group in terms of the total score (p < 0.0001) and all of the domains (p < 0.01) of the Scoliosis Research Society questionnaire at the time of the final follow-up.

CONCLUSIONS

Thoracoscopic spinal instrumentation compares favorably with posterior fusion in terms of coronal plane curve correction and balance, sagittal contour, the rate of complications, pulmonary function, and patient-based outcomes. The advantages of the procedure include the need for fewer levels of spinal fusion, less operative blood loss, lower transfusion requirements, and improved cosmesis as a result of small, well-hidden incisions. However, the operative time for the thoracoscopic procedure was nearly twice that for the posterior approach. Additional study is needed to determine the precise role of thoracoscopic spinal instrumentation in the treatment of thoracic adolescent idiopathic scoliosis.

Mini-open thoracoscopically assisted thoracotomy versus video-assisted thoracoscopic surgery for anterior release in thoracic scoliosis and kyphosis: a comparison of operative and radiographic results

BACKGROUND CONTEXT

Combining anterior release and interbody fusion with posterior instrumented fusion is an accepted treatment for severe rigid spinal deformity. Video-assisted thoracoscopic surgery (VATS) and mini-open thoracoscopically assisted thoracotomy (MOTA) are two minimally invasive approaches to the thoracic spine. Both reduce surgical trauma, improve cosmesis and provide effective exposure for release and fusion. Published data and the authors' surgical experience have demonstrated that both techniques are equivalent in degree of release to traditional open thoracotomy, but no comparison between these two minimally invasive alternatives has been published to our knowledge.

PURPOSE

This study compared MOTA and VATS under the hypothesis that both result in similar corrections and comparable operative parameters when used in conjunction with posterior instrumented fusion.

STUDY DESIGN/SETTING

Retrospective chart review of consecutive case series by two surgeons.

PATIENT SAMPLE

Twenty-one (13 female, 8 male) patients underwent MOTA and 24 patients (17 female, 7 male) underwent VATS for anterior release, discectomy and fusion prior to posterior instrumented fusion.

OUTCOME MEASURES

Outcomes were measured at a minimum of 1-year follow-up and included radiographic Cobb measurements and operative parameters.

METHODS

The indications for surgery included rigid and severe scoliosis or thoracic kyphosis. Data collection included preoperative demographics, number of levels released, primary curve correction, operative time and blood loss. Data were normalized per number of levels released anteriorly. Statistical analysis of results was done using a two-sample t test assuming equal variances with two-tail p values less than .05.

RESULTS

More anterior levels were operated on average in the VATS group (6.33 vs. 4.38 levels). Curve correction per anterior level released was similar in both groups (8.7 and 8.8 degrees/level for MOTA and VATS, respectively). There was a significant difference in operative time with MOTA averaging 131.7 minutes and VATS averaging 162.8 minutes. However, a comparison of the operative time per anterior level operated, approached statistical significance in favor of VATS (33.0 vs. 28.4 minutes, p=.08). There was no significant difference in estimated blood loss during the anterior portion of the surgeries. There was a trend toward decreased blood loss per operated level favoring VATS (68.4 vs. 38.9 cc, p=.09).

CONCLUSIONS

Both approaches resulted in corrections that compare favorably with open thoracotomy. We suggest that a factor in choosing between these two minimally invasive techniques is the number of thoracic levels requiring release. For four levels or less, MOTA provides an excellent alternative to standard thoracotomy. For five or more levels, VATS provides for excellent exposure of additional levels with the advantages of less operative time and blood loss per operated level.

Endoscopic mechanical spinal hemiepiphysiodesis modifies spine growth

STUDY DESIGN

An in vivo porcine model of progressive scoliosis as an inverse analog of a proposed method of early surgical treatment.

OBJECTIVES

To test the hypothesis that scoliotic curvatures may be repeatedly created using anatomically based vertebral staples and thoracoscopic surgical procedures.

SUMMARY OF BACKGROUND DATA

Staple hemiepiphysiodesis is an established method for treating knee deformities. Similar procedures have so far failed to arrest or correct deformities of the spine. While experimental studies continue to suggest that spine growth is modifiable, no prior clinically translatable method has been shown to clearly and consistently alter vertebral growth.

METHODS

Custom spine staples were implanted into midthoracic vertebrae of seven skeletally immature normal pigs. Each staple spanned an intervertebral disc and two growth plates and was fixed to adjacent vertebrae with screws. The animals were anesthetized biweekly for radiography during the 8-week study period. Final radiographs were taken after spine harvest. Initial and final postoperative Cobb angles were compared statistically.

RESULTS

Five animals completed the protocol with a weight increase of 142% in 8 weeks. Coronal plane curvatures increased significantly with time, from 0.8 (+/-1.8) to 22.4 (+/-2.8; P = 0.0001). On average, sagittal plane curvatures did not increase with time.

CONCLUSIONS

Spinal hemiepiphysiodesis using an anatomically based implant and minimally invasive procedures repeatedly induced spine curvature in a normal porcine model. These techniques may slow, and perhaps even correct, early progressive spine deformity without long rod instrumentation or fusion.

Video-assisted thoracoscopic surgery: the Cincinnati experience

Video-assisted thoracoscopic surgery is an alternative to open thoracotomy. We analyzed our experience during a consecutive series of 100 patients who had this procedure and who were available for study at 3-year followup. Video-assisted thoracoscopic surgery was done on patients with the following diagnoses: idiopathic scoliosis (n = 49), neuromuscular spinal deformity (n = 15), Scheuermann kyphosis (n = 15), congenital and infantile scoliosis (n = 5), neurofibromatosis (n = 5), Marfan (n = 1), postradiation scoliosis (n = 1), and repair of pseudoarthrosis (n = 1). Four patients had excision of the first rib to treat thoracic outlet syndrome. One patient had excision of an intrathoracic neurofibroma and one a benign rib tumor. One had anterior arthrodesis after fracture-dislocation of the thoracic spine and another had anterior fusion for vertebral osteomyelitis. The average operative time for the thoracoscopic anterior release with discectomy and arthrodesis was 253 minutes. The average number of discs excised was 8. Final postoperative scoliosis and kyphosis corrections were 68% and 90%, respectively. Complications related to thoracoscopy occurred in eight patients. Video-assisted thoracoscopic surgery provides a safe and effective alternative to open thoracotomy in the treatment of thoracic pediatric spinal deformities.

Perioperative changes in pulmonary function after anterior scoliosis instrumentation: thoracoscopic versus open approaches

STUDY DESIGN

A prospective evaluation of pulmonary function in patients with adolescent idiopathic scoliosis undergoing surgical correction.

OBJECTIVE

To determine if a minimally invasive thoracoscopic approach had less postoperative pulmonary function impairment compared to open anterior instrumentation for idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

Prior studies suggest that open anterior scoliosis surgery causes an initial decrease in pulmonary function that resolves by 2 years after surgery. However, the effect of thoracoscopic instrumented scoliosis correction on pulmonary function is unknown.

METHODS

Fifty-four patients with AIS undergoing anterior spinal instrumentation and fusion at the authors' institutions were evaluated with pulmonary function tests assessing forced vital capacity (FVC) and forced expiratory volume in one second (FEV1). Patients were evaluated before surgery,as well as 3 months and 1 year after surgery. There were 2 groups of patients: in one group, a thoracoscopic technique was used to visualize and instrument the anterior spine (n = 31); and in the other, an open single or double thoracotomy was used (n = 23).

RESULTS

Three months after surgery, the thoracoscopic group had a significantly smaller decline in FVC than the thoracotomy group; at 1 year after surgery, the thoracoscopic group had recovered, while FVC remained reduced in the open group. The decline in FEV1 from before surgery to 3 months after surgery was similar between groups; however, by 1 year after surgery, the thoracoscopic group had more recovery of pulmonary flow than the thoracotomy group.

CONCLUSIONS

The thoracoscopic approach causes a smaller decline in pulmonary function 3 months and 1 year after surgery as compared to the more invasive technique of open thoracotomy for anterior spinal instrumentation for correction of adolescent idiopathic scoliosis.

The changing role for neurosurgeons and the treatment of spinal deformity

✓ Spinal deformity has classically and historically been studied by those in the discipline of orthopedic surgery. This may be attributable to the orthopedic interventionalists' experience with osseous fixation for long-bone and other skeletal fractures. Neurosurgeons have maintained a long-standing interest in complex cervical spinal disorders, and their interest in the larger field of complex spinal deformity has been expanding.

An understanding of spinal deformity disorders, biomechanics, bone biology, and metallurgy is necessary before clinical, teaching, and research activities can be undertaken within neurosurgery.

The authors describe basic and advanced concepts of spinal deformity management with cases to illustrate teaching points.

Accurate Preoperative Rod Length Measurement for Thoracoscopic Anterior Instrumentation and Fusion for Idiopathic Scoliosis

OBJECTIVE

Anterior thoracoscopic instrumentation/fusion for adolescent idiopathic scoliosis has long operative times and does not allow surgeons to adjust rod length within the chest. Intraoperative rod length measurement requires placing measurement devices into the chest, adding operative time, and results in overestimation of rod length. The study purpose was to develop a method to preoperatively determine accurate rod length.

METHODS

Two groups of patients were analyzed depending on when the rod length was determined: group 1: intraoperatively using intraoperative rod-measuring device (n = 12); group 2: preoperatively using the new technique (n = 12). For group 2, the preoperative convex length was measured between planned instrumented levels on the preoperative posteroanterior (PA) film, and ideal rod length was measured on the postoperative PA radiograph. The conversion ratio was determined by dividing the preoperative convex length by the ideal rod length and was 1.29 +/- 0.08.

RESULTS

For group 1, the actual rod length was 3.8 cm longer than the ideal length compared with 0.8 cm for group 2 (P < 0.05). Operative times improved (51.4 vs 46.2 min/disc level) after adopting this technique.

CONCLUSIONS

A simple and accurate preoperative method to determine appropriate rod length for thoracoscopically assisted anterior instrumentation/fusion was developed, which saves operative time and is more accurate when compared with the intraoperative method. This technique can be applied when using an open anterior approach.

Results of thoracoscopic instrumented fusion versus conventional posterior instrumented fusion in adolescent idiopathic scoliosis undergoing selective thoracic fusion

STUDY DESIGN

Retrospective review of 31 consecutive female patients with adolescent idiopathic scoliosis undergoing selective thoracic fusion.

OBJECTIVE

To compare safety and efficacy of two techniques in treating adolescent idiopathic scoliosis undergoing selective thoracic fusion.

SUMMARY OF BACKGROUND DATA

There is paucity in the literature comparing posterior versus thoracoscopic instrumented fusion in scoliosis.

METHODS

Nineteen patients (group 1) underwent posterior instrumented fusion. Twelve patients (group 2) had thoracoscopic anterior instrumented fusion. All patients had a minimum of 25 months of follow-up observation.

RESULTS

Both groups were similar in terms of age at menarche and surgery. Preoperative Cobb angles in the coronal (erect and bending) and sagittal planes did not differ between the two groups. Group 1 patients had higher estimated blood loss (P = 0.006). Operative time (P < 0.001) and intensive care unit stay (P = 0.01) were longer in group 2 patients. There was no difference in parenteral analgesia requirement. There were no complications in group 1. Complications in group 2 included lobar collapse (1) and scapula winging (1). Improvement in scoliosis among group 1 patients averaged 77 (1 week), 72 (6 months), and 67% (most recent follow-up review). In group 2 patients, mean improvement in scoliosis was 66 (1 week), 62 (6 months), and 62% (most recent follow-up review). The differences between the two groups in terms of scoliosis improvement were not significant. Thoracic kyphosis (T2-T12) did not increase significantly with thoracoscopic versus posterior instrumentation. No significant change in lumbar lordosis (T12-S1) was noted with either procedure.

CONCLUSIONS

The efficacy of thoracoscopic surgery was similar to standard posterior procedures. Advantages included lower intraoperative blood loss. The longer operative time and intensive care unit stay were attributed to the steep learning curve of this technique.

Early experiences with video-assisted thoracoscopic surgery: our first 70 cases

STUDY DESIGN

Prospective consecutive series.

OBJECTIVE

Analysis of the results and outcomes of patients treated with video-assisted thoracoscopic surgery for spinal pathology.

SUMMARY OF BACKGROUND DATA

Video-assisted thoracoscopic surgery is an alternative to open thoracotomy. It has been suggested that the learning curve is substantial. The authors present their early experience in treating a variety of spinal pathologies with this technique.

METHODS

Seventy cases were available at the 2-year follow-up. Video-assisted thoracoscopic surgery with the goal of anterior spinal release and fusion was carried out on patients with the following diagnoses: idiopathic scoliosis, neuromuscular spinal deformity, Scheuermann kyphosis, congenital and infantile scoliosis, neurofibromatosis, Marfan syndrome, postradiation scoliosis, and repair of pseudarthrosis. Three patients had excision of the first rib to treat thoracic outlet syndrome. Two patients had excision of intrathoracic neurofibroma and a benign rib tumor. One had anterior fusion following thoracic spine fracture-dislocation.

RESULTS

The average operative time for the thoracoscopic anterior release with discectomy and fusion procedure was 256 minutes (range 150-405 minutes). The average number of discs excised was 8 (range 4-11 discs). The average operative time per disc was 32.5 minutes (range 20-45 minutes). The average blood loss during the thoracoscopic anterior release with diskectomy and fusion was 285 mL (range 150-405 mL). Final postoperative scoliosis and kyphosis corrections were 68% (range 41-91%) and 90% (range 47-100%), respectively. Complications related to thoracoscopy occurred in 3 patients. All deformity patients had evidence of anterior fusion radiographically.

CONCLUSION

Video-assisted thoracoscopic surgery provides a safe and effective alternative to open thoracotomy in the treatment of thoracic pediatric spinal deformities. The procedure remains time consuming.

Recombinant human bone morphogenetic protein-2 enhances anterior spinal fusion in a thoracoscopically instrumented animal model

BACKGROUND

Thoracoscopically assisted anterior spinal arthrodesis and instrumentation is being used more widely to treat idiopathic scoliosis. However, harvesting autologous bone increases operative time and morbidity. The purpose of this study was to compare autologous iliac crest and rib graft with recombinant human bone morphogenetic protein-2 (rhBMP-2) in thoracoscopically assisted anterior spinal arthrodesis and instrumentation in an animal model.

METHODS

Twenty-two pigs underwent thoracoscopically assisted anterior spinal arthrodesis. Each animal had five contiguous thoracic discectomies followed by anterior instrumentation. The animals were randomly assigned to five treatment groups. Group I consisted of control animals that received no graft material; group II, animals treated with autologous rib graft; group III, animals treated with autologous iliac crest graft; group IV, animals treated with an rhBMP-2-composite sponge (collagen-hydroxyapatite-tricalcium phosphate carrier); and group V, animals treated with a composite sponge carrier alone. The animals were killed four months after the procedure, and the spines were harvested. The fusion mass was assessed with use of axial and sagittal computed tomography scans. The spines were tested biomechanically with incremental loads applied in the frontal and axial planes to achieve bending moments of up to 6.0 N-m. Angular motion at each segment was recorded with use of a three-dimensional motion analysis system. Histomorphometric analysis of each undecalcified disc segment was also performed.

RESULTS

The fusion grades, according to computed tomography analysis with use of a 4-point grading system in which scores of 3 and 4 indicated a solid fusion, were 0.6 point for group I, 2.1 points for group II, 2.3 points for group III, 3.8 points for group IV, and 0.4 point for group V. Group IV (the rhBMP-2-treated animals) had a higher grade than all of the other groups. Group II (rib graft) and group III (iliac crest) had similar grades, and both were greater than group I (the untreated controls) and group V (composite sponge alone) (p < 0.05). In axial rotation, lateral bending, and flexion-extension, the spines in group IV were stiffer than those in the four other groups (p < 0.05); the spines in groups II and III were similar, and the spines in both of those groups were stiffer than those in groups I and V (the control groups). Histologic analysis demonstrated that the total new-bone area, expressed as a percentage of the total disc space area, was 23.2% in group I, 37.1% in group II, 37.2% in group III, 48.5% in group IV, and 5.9% in group V. Group IV had significantly greater bone formation than all of the other groups (p < 0.001). The animals treated with rib graft (group II) and iliac crest (group III) had a similar amount of bone formation, and it was greater than that in both control groups (p < 0.001).

CONCLUSIONS

The rhBMP-2 significantly increased the prevalence and quality of the spinal fusion after thoracoscopically assisted anterior arthrodesis and instrumentation in an animal model compared with that in the other treatment groups and in the controls.

Posterior Releasing Techniques for Idiopathic Scoliosis

The authors describe techniques and preliminary results of two releasing procedures for idiopathic scoliosis, which can be performed concomitantly in the same stage of posterior instrumentation surgery. The transpedicular microscopic discectomy and transverse process resection were clinically applied for adolescent idiopathic scoliosis. Twelve patients were divided into three groups at random: Group A patients underwent no release, group B patients underwent transverse process resection, and group C patients underwent microscopic discectomy of three discs and transverse process resection, in combination. All patients were operated on with derotation procedure with Cotrel-Dubousset instrumentation simultaneously after each releasing procedure. The outcomes-curve correction, disc wedge angle, and rotational changes-were evaluated 12 months postoperatively. The mean correction rate of the Cobb angle in group C (78%) was higher than in groups A (54%) and B (64%). Correction of the disc wedge angle was also higher in group C compared with groups A and B. The authors conclude that microscopic discectomy appeared to be an effective releasing method for thoracic curve and that further investigation is necessary for accurate evaluation of the transverse process resection.

Anterior endoscopic discectomy and fusion for adolescent idiopathic scoliosis

STUDY DESIGN

A review of adolescent patients with idiopathic scoliosis undergoing endoscopic release and spinal fusion.

OBJECTIVE

To describe the indications, techniques, results, and complications of thoracic anterior endoscopic scoliosis surgery.

SUMMARY OF BACKGROUND DATA

Anterior endoscopic treatment of thoracic adolescent idiopathic scoliosis has become an alternative method of surgical treatment.

METHODS

Twenty-one patients with adolescent idiopathic scoliosis have undergone a thoracic anterior endoscopic release and fusion followed by posterior instrumentation and fusion. Indications for the endoscopic fusion were large curve magnitude, skeletal immaturity, and/or thoracic hyperkyphosis. Eleven patients have undergone anterior endoscopic instrumentation and fusion for thoracic scoliosis curves between 45 degrees and 70 degrees, using a single screw/single rod construct and autogenous rib bone graft.

RESULTS

Results from the anterior endoscopic release and fusion procedures followed by a posterior instrumentation and fusion had an average preoperative curve of 82 degrees (range, 41 degrees -125 degrees ), with postoperative correction to 28 degrees (range, 5 degrees -60 degrees ) showing 70% correction. For patients undergoing an anterior endoscopic instrumentation and fusion, the average preoperative Cobb measurement of 53 degrees (range, 44 degrees -62 degrees ) was corrected to an average 26 degrees (range, 18 degrees -38 degrees ) for an average correction rate of 51%. One patient undergoing an anterior endoscopic release was converted to an open procedure for end plate bony bleeding without sequelae. One patient with an anterior endoscopic instrumentation and fusion had revision anterior surgery for a distal set screw dislodgment and subsequent posterior instrumentation and fusion for pseudarthrosis.

CONCLUSIONS

The use of both anterior endoscopic release and fusion combined with either anterior instrumentation or separate posterior instrumentation and fusion continues to evolve. Surgeons treating patients with these techniques must understand that there are specific indications for them and many technique options available to optimize surgical results.

Thoracoscopic anterior instrumentation and fusion for idiopathic scoliosis

Thoracoscopically assisted surgery is a new approach to access the anterior spine to perform biopsies, anterior releases, diskectomies, and anterior instrumentation and fusion for idiopathic thoracic scoliosis. This approach compromises the chest wall less than an open thoracotomy does because it uses several small portal incisions. It has been suggested that this approach allows fusion of fewer motion segments and better correction of curvature than does posterior spinal fusion and instrumentation. The technique, which is still evolving, is technically demanding, requiring advanced training and special instrumentation and anesthesia techniques.

Pediatric spinal deformities

Pediatric spinal deformity results from multiple conditions including congenital anomalies, neuromuscular disorders, skeletal dysplasia, and developmental disorders (idiopathic). Pediatric spinal deformities can be progressive and cause pulmonary compromise, neurological deficits, and cardiovascular compromise. The classification and treatment of these disorders have evolved since surgical treatment was popularized when Harrington distraction instrumentation was introduced.

The advent of anterior-spine instrumentation systems has challenged the concepts of length of fusion needed to arrest curvature progression. Segmental fixation revolutionized the surgical treatment of these deformities. More recently, pedicle screw–augmented segmental fixation has been introduced and promises once again to shift the standard of surgical therapy. Recent advances in thoracoscopic surgery have made this technique applicable to scoliosis surgery.

Not only has surgical treatment progressed but also the classification of different forms of pediatric deformity continues to evolve. Recently, Lenke and associates proposed a new classification for adolescent idiopathic scoliosis. This classification attempts to address some of the shortcomings of the King classification system.

In this article the authors review the literature on pediatric spinal deformities and highlight recent insights into classification, treatment, and surgery-related complications.

Thoracoscopic discectomy and fusion in an animal model: safe and effective when segmental blood vessels are spared

STUDY DESIGN

Disc-endplate excision and spine fusion were compared in animals randomly assigned to segmental vessel-spared and segmental vessel-ligated groups in an in vivo goat model of anterior spine discectomy and fusion using thoracoscopic techniques.

OBJECTIVES

To compare safety and completeness of disc and endplate excision, and to perform a histologic and biomechanical comparison between fusion masses when the segmental vessels are spared and when they are ligated using thoracoscopic techniques. SUMMARY OFF BACKGROUND DATA: Because thoracoscopy is relatively new and technically demanding, many surgeons ligate the segmental blood vessels to enhance spine exposure and limit the risk of injury during discectomy and fusion. Although rare, spinal cord compromise secondary to segmental vessel ligation has been reported.

METHODS

This study was divided into two phases. In Phase 1, 10 mature goats were randomly assigned to either the segmental vessel-ligated or the segmental vessel-spared group. Disc and endplate excision was performed at six consecutive thoracic levels in each animal (30 levels per group). The animals were killed, and the depth of disc excision was measured in the transverse and sagittal planes. The vertebral bodies then were separated through the disc space; photographic images of the endplates were digitized, and the area of endplate excision was calculated. In Phase 2, 12 mature goats were randomly assigned to the segmental vessel-ligated or vessel-spared group, and five noncontiguous thoracic segments were fused using autologous iliac crest graft. At 4 months the animals were killed, and the spines were harvested. At each disc level, the three-dimensional rotational and translational motions were analyzed and histomorphometric analysis was performed.

RESULTS

Phase 1: Each animal survived the operative procedure, and no surgical complications occurred. No difference was found between vessel-ligated and vessel-spared groups in operative time (21.8 vs 22.7 minutes per disc), blood loss (97 vs 159 mL), or transverse (81% vs 74%) or sagittal (85% vs 85%) disc excision. The total area of endplate excision was 70% in the vessel-ligated group and 67% in the vessel-spared group (P > 0.1). Phase 2: Biomechanical testing demonstrated no difference in stiffness of the fused segments between the two groups in flexion-extension or axial rotation. However, greater flexibility in lateral bending was found in the specimens whose vessels were ligated (P < 0.05). The percentage of trabecular bone volume was similar between the two groups.

CONCLUSIONS

The segmental vessels in the thoracic spine can be effectively spared without injury during disc excision and fusion. Although slightly more disc area was excised with ligation of the vessels, this was not statistically significant, and the fusion mass was similar between the two groups. Sparing the segmental vessels may provide blood supply that aids fusion mass, and the result may be greater spine stiffness in the coronal plane. Sparing the segmental vessels during thoracoscopic anterior disc excision and fusion can be safe. It should be considered in patients with a high risk for neurologic injury because of decreased spinal cord perfusion in revision surgery, severe kyphosis, congenital anomalies. Because the neurologic risk of vessel ligation has not been clearly established for idiopathic scoliosis, the surgeon will have to consider the risk-benefit ratio of adopting these methods when deciding not to ligate vessels in these patients.

Prone position endoscopic transthoracic release with simultaneous posterior instrumentation for spinal deformity: a description of the technique

STUDY DESIGN

A prospective series of 15 consecutive adult patients with spinal deformity who underwent endoscopic transthoracic release with simultaneous posterior instrumentation while positioned prone.

OBJECTIVES

To describe the technique and clinical results of endoscopic transthoracic release performed with the patient prone (as opposed to lateral) on the concave side for scoliosis or on either side for kyphosis, with simultaneous posterior exposure, instrumentation, and correction of the deformity.

SUMMARY OF BACKGROUND DATA

Use of endoscopic surgical techniques is rapidly advancing across all subspecialties. These techniques can be used to expose and operate on the spine in a less invasive fashion, thus avoiding damage to other tissues and facilitating earlier mobilization and rehabilitation. Current endoscopic techniques with the patient in the lateral decubitus position mimic open thoracotomy. A new technique is described with the patient positioned prone, which allows simultaneous posterior exposure.

METHODS

Preoperative Cobb angle or thoracic kyphosis angle, maximal correction bending films, and postoperative Cobb angle or kyphosis angle were measured and compared. All perioperative morbidity, intraoperative complications, and surgical variables were prospectively documented and analyzed.

RESULTS

There were no intraoperative technical problems with the endoscopic equipment or instruments and no immediate, 6-month, or 2-year postoperative complications related to the endoscopic component of the procedure. In the scoliosis patients, the average correction was 60%. In the kyphosis patients, the average correction was 39%.

CONCLUSIONS

Transthoracic endoscopic techniques, compared with thoracotomy, offer a less invasive method of accessing the anterior spinal column, with the benefits of an excellent view of the area of the spine being instrumented, minimal soft tissue disruption, and an improved cosmetic result. With the simultaneous technique, staged or subsequent procedures can be eliminated, and a circumferential structural release as well as control of the mobilized spine can be achieved. This simultaneous technique can be extended for use in correction of a variety of thoracic spinal pathologies.

Defining the pediatric spinal thoracoscopy learning curve: sixty-five consecutive cases

STUDY DESIGN

Consecutive case prospective chart and radiographic review.

OBJECTIVES

The purpose of this study was to define the learning curve of spinal thoracoscopy.

SUMMARY OF BACKGROUND DATA

Thoracoscopy is an alternative to open thoracotomy in the treatment of pediatric spinal deformity. The learning curve for spinal thoracoscopy has not been described.

METHODS

In this prospective study 65 consecutive cases of thoracoscopic anterior release with discectomy and fusion performed by one surgeon for the treatment of pediatric spinal deformity were reviewed. The patients were, on average, 14 +/- 3 years old and had the following diagnoses: idiopathic scoliosis (n = 13), Scheuermann's kyphosis (n = 9), neuromuscular spinal deformity (n = 35), congenital scoliosis (n = 4), and tumor/syrinx (n = 4).

RESULTS

The average operative time for the thoracoscopic procedure was 161 +/- 41 minutes (range, 50-240 minutes). There was a slight decrease in the average operative time as the series progressed. The average number of discs excised was 6.5 +/- 1.5 (range, 3-10), and the number increased as the series progressed. The average operative time per disc was 29.3 +/- 7.7 minutes in the first 30 patients compared with 22.3 +/- 4.7 minutes in the next 35 patients (P < 0.01). The average blood loss during the thoracoscopic procedure was 301 +/- 322 mL (range, 25-2000 mL) and did not decrease as the series progressed. Initial postoperative scoliosis and kyphosis corrections were 59% +/- 17% and 92% +/- 12%, respectively. Complications occurred in six patients (cases 4, 8, 17, 31, 39, and 46) and were evenly distributed throughout the series.

CONCLUSIONS

The learning curve for thoracoscopy is substantial, but not prohibitive. This technique provides a safe and effective alternative to thoracotomy in the treatment of pediatric spinal deformity.

[Endoscopic surgery for thoracic spine. Critical review]

After the development of video-assisted technology, endoscopic techniques have assumed an important therapeutic role into thoracic cavity. This is a literature review article to show the current state of the endoscopy for thoracic spine. Disc herniations, deformities, infections, tumors, congenital disorders and traumatic events have been treated by endoscopic techniques. On reviewing the literature, the advantages over open approaches are: enhanced visualization, shorter recovery time and decreased blood loss, costs, infection rate and post operative morbidity. Some disadvantages are: one lung anesthesia, significant learning curve, and technical problems in operating on small children, repairing the dura and performing instrumentation. Overall benefits are apparently clear. However, despite the high degree of enthusiasm, authors are cautious to state that endoscopic techniques to the spine already represent a definitive alternative to standard techniques. Comparison between endoscopic and open approaches are still difficult because of the lack of appropriate comparative studies. Authors, although optimistic recommend more prospective, multicentric and randomized studies in order to stand a definitive conclusion.

Comparison of thoracoscopic and open thoracic discectomy in a live ovine model for anterior spinal fusion

STUDY DESIGN

The authors undertook a randomized comparison of 30 thoracoscopic and 30 open thoracic discectomies for anterior spinal fusion in a live sheep model.

OBJECTIVES

To compare in a live sheep model discectomies performed using a thoracoscopic technique with those using an open thoracotomy technique to validate the efficacy of thoracoscopic disc and end plate removal for potential fusion.

SUMMARY OF BACKGROUND DATA

In 1993, Mack and Regan described a technique for video-assisted thoracic surgery that resulted in less morbidity than open techniques. Subsequent reports support the finding that thoracoscopic spinal surgery results in less morbidity.

METHODS

Sixty discectomies were performed in 10 live sheep. In each sheep, three randomly selected discectomies were performed thoracoscopically, and, subsequently, three open discectomies were performed. The animal then was killed, and the spine was sectioned and analyzed by computer imaging.

RESULTS

Statistical analysis found no significant difference in the amount of disc resected (t' = 1.9639, t0.025, 60 = 2.000, alpha = 0.05). The mean percentage of disc resected was 67.8% (range, 0-92.2%) in the thoracoscopic group and 76.1% (range, 44.9-95.4%) in the open group. More than 50% of the disc was excised in 27 of 30 spines (90%) in the thoracoscopic group and in 29 of 30 (96.7%) in the open group. This difference was not statistically significant (theta 2(0.05, 1) = 3.84, theta 2' = 1.07).

CONCLUSION

The findings in this study indicate that the thoracoscopic discectomy technique is equivalent to the open technique in the amount of disc and end plate resected. In addition, these findings suggest that thoracoscopic discectomies provide adequate disc resection to provide for an acceptable fusion rate according to the criteria demonstrated by Bunnell in 1982 and therefore support the efficacy of a thoracoscopic technique for anterior spinal fusion.