Thoracoscopic Anterior Instrumentation and Fusion for Idiopathic Scoliosis Daniel J. Sucato, MD, MS Abstract Surgical treatment for idiopathic scolio- sis has changed rapidly in the last 20 years. Posterior segmental spinal in- strumentation was an advance over Harrington instrumentation because it improved correction in the sagittal and coronal planes. 1,2 The single solid rod used with anterior surgery was an improvement over the Dwyer ca- ble, especially for thoracolumbar and lumbar curves, because it allowed sur- geons to use a rotational maneuver to correct both the sagittal and coro- nal deformities. 1,2 Recently, the single solid rod placed through an open tho- racotomy has been used to correct tho- racic curves. 3,4 Anterior correction of thoracic scoliosis offers the theoretic advantage of better coronal correction because it permits the surgeon to per- form diskectomies, provides improve- ment in the thoracic hypokyphosis seen in idiopathic scoliosis, and saves mo- tion segments. In a prospective study, Betz et al 4 demonstrated that anterior surgery improved sagittal plane align- ment while saving an average of 2.5 distal motion segments compared with posterior surgery. In the last decade, indications have increased for endoscopic approach- es to thoracic spine surgery. Endos- copywasfirstusedforbiopsyanddisk- ectomy as well as for anterior release and fusion, in combination with pos- terior spinal fusion and instrumenta- tion, to treat severe curves or when there was risk for the development of the crankshaft phenomenon. 5-7 The en- doscopic approach also has been used to perform an anterior instrumen- tation, correction, and fusion. Early results are encouraging, but the tech- nique requires further study and im- provement. Patient Selection and Preoperative Planning The indications for anterior instrumen- tation and fusion include single tho- racic curves or thoracic curves with a compensatory lumbar and/or up- per thoracic curve, that is, type IA, IB, or IC curves using the Lenke classi- fication. 8 It is important to determine the curve type for preoperative plan- ning so that the appropriate thoracic curve correction is achieved, especial- ly in the setting of a so-called selec- tive thoracic fusion in the IC curve type. The ideal patient for thoraco- scopic anterior instrumentation and fusion is one who has a relatively small curve size (50° to 65°) of relative flex- ibility (>50% flexibility index); is thin (40 to 60 kg), which makes placement and utilization of the portals easier; and is tall, because the sizable chest provides a greater working space and larger vertebral bodies for easier in- sertion of screws. For surgeons with experience in the technique, the in- dications can include stiffer curves of up to 75°. The primary contraindica- tion for the procedure is poor pulmo- nary function, which limits the pa- tient’s ability to tolerate single-lung ventilation. All patients should have preoperative pulmonary function tests to assess their ability to tolerate the Dr. Sucato is Assistant Professor, Department of Orthopaedic Surgery, University of Texas at Southwestern, and Staff Orthopaedist, Texas Scot- tish Rite Hospital, Dallas, TX. The author or the department or departments with which he is affiliatedhas received something of val- ue from a commercial or other party related di- rectly or indirectly to the subject of this article. Reprint requests: Dr.Sucato,2222 Welborn Street, Dallas, TX 75219. Copyright 2003 by the American Academy of Orthopaedic Surgeons. 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 instrumen- tation. The technique, which is still evolving, is technically demanding, requiring advanced training and special instrumentation and anesthesia techniques. J Am Acad Orthop Surg 2003;11:221-227 Perspectives on Modern Orthopaedics Vol 11, No 4, July/August 2003 221 procedure and to help predict the post- operative course. Pulmonary function test findings below 60% of predicted results are a relative contraindication to anterior thoracic surgery. Preoperative assessment of the pa- tient should include a physical exam- ination to confirm radiographic find- ings that the upper thoracic and lumbar curves are compensatory without any structural characteristics. Imaging should include standing lateral and posteroanterior and supine bending right and left radiographs. The lateral radiograph should be used to ensure that excessive kyphosis (>40°) is not present. This is a contraindication for anterior correction because, when com- pression is used, anterior correction can increase kyphosis. 9 Fusion levels for the thoracic curve are determined on the posteroanterior radiograph, us- ing the superior and inferior end ver- tebrae of the Cobb measurement as the upper and lower end instrumented vertebrae. In a smaller patient or one who has marked tilt of the upper end instrumented vertebrae, a level supe- rior to the end vertebra may be cho- sen to provide greater fixation because of the risk of cutout of the superior screws.Analysis of the lower end ver- tebra may reveal that the disk prox- imal to it is in fact neutral. If so, the more proximal level may be chosen as the lower end instrumented ver- tebra. Supine bending radiographs are important to confirm that the lumbar and upper thoracic curves are truly compensatory (bend to <25°). Bend- ing radiographs are used to determine the flexibility of the thoracic curve so that a coronal bend may be placed in the rod if the curve is stiff. Anesthesia Considerations Maintaining a proper airway during anesthesia is critical to the success of thoracoscopic surgery. To perform an- terior instrumentation and fusion, the lung on the convexity of the curve must be deflated, and single-lung ven- tilation techniques are used. This is typically accomplished with a double- lumen endotracheal tube, which has a bronchial lumen that sits in the de- pendent mainstem bronchus and a tra- cheal lumen that lies just proximal to the carina (Fig. 1). The dependent lung is ventilated through the bronchial lu- men, while the lung on the convex- ity of the curve becomes deflated when the tracheal lumen is occluded. It is important to recheck tube placement after the patient is in the lateral de- cubitus position because, in up to 80% of cases, the tube tends to move dis- tally. 10 Patients undergoing single-lung ventilation are subjected to significant stresses from the right-to-left shunt through the dependent lung and from that lung’s decreased functional ca- pacity, the result of increased intra- abdominal pressure and compression from the weight of the mediastinal structures. The high pressures that re- sult can lead to airway leaks or trau- ma, which can cause pneumothorax. The so-called down lung syndrome, seen most frequently with lengthy surgeries, is characterized by absorp- tion atelectasis, accumulation of se- cretions, and formation of transudate in the dependent lung. The anesthe- siologist needs to be skilled in the technique to minimize the chance of anesthetic complications. 11,12 Patient Positioning and Operating Room Setup The patient is positioned in the lat- eral decubitus position on a radio- lucent operating table with the con- vexity of the curve up (Fig. 2). An absolutely lateral position is critical, especially during screw placement, and should be checked periodically to ensure that it is maintained through- out the procedure. The patient may be secured using an inflatable radio- lucent beanbag or other positioning system. Whatever method is used, the patient’s spine must be palpable pos- teriorly, and the umbilicus visible an- teriorly, to allow orientation and ex- posure in case conversion to an open thoracotomy is necessary. The thora- cotomy tray should be available in the operating suite. The arm on the con- vexity of the curve can usually be po- sitioned out of the sterile field, espe- cially when the upper instrumented level is at T5 or below.However,when the upper instrumented level is above T5, the arm may be incorporated into the sterile field to provide better con- trol of the patient’s arm and scapula, making proximal portal placement easier. One or two surgeons are positioned on the posterior aspect and one on the anterior aspect of the patient. The scrub assistant is usually anterior. The video monitors should be at the head of the table on both sides of the patient to give the surgeons on each side a di- rect view. The fluoroscopy C-arm unit is brought in anteriorly when screws are placed, with the monitor at the foot of the table. Although some surgeons perform the diskectomy on the posterior as- pect, the anterior position allows bet- ter control of posterior penetration be- yond the posterior anulus fibrosus and Figure 1 Correct positioning of the double- lumen endotracheal tube to ventilate the left lung. The bronchial lumen should be just dis- tal to the carina and the tracheal lumen just proximal to the carina. The tracheal lumen is occluded to allow for selective ventilation of the left lung. Thoracoscopic Anterior Instrumentation and Fusion for Idiopathic Scoliosis 222 Journal of the American Academy of Orthopaedic Surgeons posterior longitudinal ligament. Dur- ing screw placement and instrumen- tation, the surgeon may be more com- fortable at the posterior aspect of the patient because leaning over the op- erating room table is then unneces- sary, and it is safer to direct the screws slightly anteriorly. Surgical Procedure Portal Placement Accurate placement of the portals is critical because they determine the approach for the diskectomies and, more important, the screw starting points and directions. Before the pa- tient is prepared and draped, the spi- nal levels to be instrumented are lo- cated fluoroscopically in the coronal and sagittal planes, and the skin is marked. In general, the incision for the portals should be directly over the rib so that two portals (above and be- low the rib) can be used for each in- cision. A single anterolateral portal is placed at the apex of the curve in the anterior-to-midaxillary line, and the thoracoscope is placed through this portal. The thoracoscope consists of a camera and a scope that is angled at 30° or 45°. Seen from the antero- lateral portal, the spine is horizontal on the monitor; seen from the postero- lateral portal, the spine is vertical, giv- ing a good “pipeline” view (Fig. 3). The scope should be oriented to see the disks straight on when the tho- racoscope is in the anterolateral por- tal. This is best achieved by keeping the orientation light from the lens per- pendicular to the spine, with the scope handle at the 3-o’clock position when looking at the most cephalad disk (Fig. 4, A) and at the 9-o’clock position when looking at the most caudad disk (Fig. 4, B). This position allows visu- alization down the axis of the disk space and provides a true anteropos- terior view of the vertebral bodies. The posterolateral portals are made under direct visualization. The place- ment of the most cephalad portal is very important for proper instrumen- tation. The skin mark initially made under fluoroscopic visualization is used to place a guide pin, which is then assessed using the camera in the anterolateral portal. The ribs should be counted to check the level of the Figure 2 Operating room setup. Figure 3 Thoracoscopic video images. A, With the thoracoscope in the anterolateral portal, the spine is horizontal on the monitor and provides a good assessment of the superior and inferior extent of each vertebral body. B, With the thoracoscope in one of the posterolateral portals, the spine is more vertical on the monitor “pipeline” view, providing a good assess- ment of the anterior and posterior aspects of the spine. The diaphragm is visible at the top of the image. Daniel J. Sucato, MD, MS Vol 11, No 4, July/August 2003 223 guide pin. If the pin is not sufficient- ly superior or posterior to allow the surgeon to place the proximal screw, the pin is moved and the portal in- serted. The camera may then be placed through that portal to check the po- sition further. The remaining posterolateral por- tals are then placed, with close atten- tion paid to the distances between portals and their positions in the an- teroposterior and superoinferior di- rections. Positioning is assessed with the thoracoscope in the anterior por- tal to ensure that the portals are made directly over the vertebral bodies. A typical portal configuration for a seven- or eight-level instrumentation is a single anterolateral portal and four posterolateral portals (Fig. 4, C). Various portal configurations have been described, including posterolat- eral portals only or a combination of three anterolateral with three pos- terolateral portals. Disk Excision and Bone Grafting Disk excision is the most important aspect of the procedure. The surgeon incises the pleura in the midvertebral body, then coagulates the segmental vessels. The pleura should be bluntly teased posteriorly past the rib heads and anteriorly around the front of the spine to allow access to the anterior longitudinal ligament and contralat- eral anulus. Sharp incision of the disk can be made with a scalpel blade or harmonicscalpel.Diskshavers,rongeurs, and curettes are used to excise the disk as completely as possible (Fig. 5). An- imal studies comparing open thora- cotomy with thoracoscopic techniques havedemonstratedcomparableamounts of diskectomy. 13,14 Aquantitative anal- ysis of computed tomography (CT) in 12 adolescent patients (mean age, 13.3 years) demonstrated that a mean of 73% of the disk and end plate was removed, allowing correction from a mean of 55° to a mean of 9°. 15 Autologous rib or iliac crest bone grafts can be used and probably are best placed immediately upon com- pletion of the diskectomy at each lev- el. Bone funnels are used to place the grafts and should start in the depths Figure 4 A, Use of the thoracoscope in the anterolateral portal. To view the proximal (cephalad) portion of the spine, the camera is po- sitioned parallel to the floor and the light source handle is at the 3-o’clock position. The spine appears horizontal on the monitor (inset). B, To view the distal (caudad) aspect of the spine, the camera is positioned parallel to the floor and the light source handle is at the 9-o’clock position. This keeps the spine horizontal on the monitor (inset). C, Portal placement for a typical thoracic idiopathic curve. The anterolateral portal is made in the anterior axillary line at the apex of the curve. Figure 5 Axial CT scan of a thoracic disk space after diskectomy and bone grafting done as part of an anterior thoracoscopic in- strumentation and fusion. Note the bone graft material (arrows) packed all the way to the opposite side of the disk space and posteri- orly. The rod is seen on the right side of the vertebral body. Thoracoscopic Anterior Instrumentation and Fusion for Idiopathic Scoliosis 224 Journal of the American Academy of Orthopaedic Surgeons of the disk space to ensure that the grafts are packed completely. Screw Placement Before screws are placed, the pa- tient’s position should be rechecked toensureitisdirectlylateral.Thefluo- roscopic image should be at right an- gles to the vertebral bodies in the an- teroposterior projection and is used to confirm that the screw is oriented parallel to the end plate. The thora- coscope is placed in the anterior por- tal initially to direct the guidewire with respect to the superoinferior starting point and orientation. The thoracoscope is then moved to a pos- terolateral portal to check the antero- posterior starting point and its direc- tion. The anteroposterior fluoroscopic images are then used to fine-tune the starting point in the superoinferior di- rection. Screws are placed beginning at the apex of the curve, with the starting point of the screw just anterior to the rib head. The screws are directed slightly anteriorly to avoid the spinal canal and to be in the midaxial plane of the rotated apical vertebral bodies. This screw orientation allows for ro- tational correction during rod inser- tion and compression. As screws are placed proximal and distal to the apex, the starting holes move slightly more anteriorly. The cephalad screws are the most difficult to place accurately with good purchase because the vertebral bodies are smaller, the rib heads ob- scure more of the vertebral bodies, and the proximal portals are often not ide- ally placed. The proximal screws must be placed with great care and atten- tion to anatomic landmarks to ensure that these screws are not too poste- rior, which could lead to spinal canal penetration, but are posterior enough to allow secure purchase in good bone stock (Fig. 6). It is often necessary to remove the rib heads at T5 and T6 to gain good access to the vertebral bod- ies at these levels. Present instrumentation systems are modifications of open anterior in- strumentation systems, with all in- struments made to fit through a 10.5- mm–diameter portal. Screws in sizes from 5.5 to 7.5 mm and rods in 4.0-, 4.5-, and 4.75-mm diameters areavail- able. The proximity of the aorta to the vertebral bodies in the upper and midthoracic spine limits the amount of bicortical screw purchase that can be achieved 16 (Fig. 6). In the lower thoracic spine in a patient with idio- pathic scoliosis, the aorta is posi- tioned more anterior to the vertebral body. Newer instruments allow the surgeon to place screws without the use of the guide wire, which can lead to complications with inadvertent ad- vance across the vertebral body. Rod Insertion and Correction Maneuvers The stiffness of the curve, the pur- chase of the most proximal screws, and whether maximum correction is desired (Lenke IA curve) will deter- mine whether a small coronal bend should be placed in the rod before in- serting it into the chest. In taller pa- tients with smaller, more flexible curves and larger vertebral bodies, no coronal bend in the rod is necessary. In patients with a very lordotic tho- racic segment, a kyphotic bend can be placed in the rod. The rod is inserted through the dis- tal or proximal posterolateral portal and grasped within the chest with a rod grabber so that it can be seated into the screws in one step. The rod is initially seated distally to help con- trol the length of rod that protrudes distal to the screw and prevent it from pushing against the diaphragm. Two correction maneuvers are per- formed: compression and cantilever. Because the rod is essentially straight in the coronal plane, in contrast with the deformity, the rod can be seated only in the distal three or four screws. Initially, compression is performed across these screws, followed by can- tilevering the rod down into the re- maining proximal screws. After the rod is captured in the proximal screw heads, compression is then complet- ed at these levels with care taken to avoid excessive force on the top screws. The securing plugs are then tightened fully. The surgeon must be sure to place the guide sleeve over the screw or grasp the rod to produce a countertorque to prevent screw mi- gration or “plowing.” Anteroposterior and lateral radiographs or fluoroscop- ic images should be checked to en- sure that all screws are safely posi- tioned and that correction is adequate in the coronal and sagittal planes. Pleural Closure and Chest Tube Insertion The pleura can be closed to help decrease chest tube output, limit de- velopment of lung adhesions, and contain the bone graft in the disk space. Diaphragmatic repair is incor- porated into the pleural closure when the instrumentation extends to T12 or L1. The pleura is closed with an En- dostitch device (US Surgical, Nor- walk, CT), running a suture begin- ning distally and another beginning proximally, which then meet in the center so that they can then be tied easily. A chest tube is placed through the incision of the most distal poste- rior portal skin incision. Because of the single, small-diameter rod, all pa- Figure 6 Axial CT scan of a thoracic ver- tebral body after anterior thoracoscopic in- strumentation and fusion. The starting posi- tion of thescrew is just anteriorto the rib head. The outline of the aorta is seen at approxi- mately 1 o’clock, just posterior to the left mainstem bronchus.The screw has one totwo threads engaging the opposite cortex; how- ever, the screw tip is close to the aorta. Daniel J. Sucato, MD, MS Vol 11, No 4, July/August 2003 225 tients should wear a brace during the day (when not sleeping) for the first 3 months. Early Results In one series of 28 girls (average age, 12.1 years) with a mean preoperative curve of 55° (range, 46° to 78°), the mean postoperative curve at 1 year was 14° (74.5% correction) 15 (Fig. 7). Complications included six proximal screws that partially pulled from the vertebral body at the time of compres- sion in four patients; two screws that cut out at the time of insertion because of small vertebral bodies in two pa- tients; guidewire migration into the spinal canal in one patient, with re- sultant dural leak without neurologic sequelae; and asymptomatic pseudar- throsis in one patient who underwent a posterior spinal fusion. 15 Picetti and Bueff 17 reported follow- ups over 2 years on 50 patients (mean age, 12.7 years) with a mean preop- erative curve of 58°. Improvements in techniques resulted in enhanced cor- rection and fewer complications over the course of this series. Mean curve correction was 50.1% in the first 10 pa- tients and 68.6% in the last 10. Sur- gical time improved from a mean of 6 hours 6 minutes in the initial 30 cas- es to 3 hours 58 minutes in the last 10 cases. Mean blood loss was 266 mL. The chest tube was in place for a mean of 2.25 days (range, 1 day to 5 days), and hospital stay averaged 2.9 days (range, 2 to 7 days). Report- ed complications included one screw pullout, three patients with chest wall numbness, five mucous plugs, one wound revision, and two rod frac- tures. A demineralized bone matrix product was used in the initial pa- tients, resulting in a high incidence of pseudarthrosis; however, only 1 patient of the remaining 35 had a pseudarthrosis when autologous rib graft was used. 17 Complications There are no published series of pa- tients who have had thoracoscopic in- strumentation and fusion for idio- pathic scoliosis, so the prevalence of complications is not known. How- ever, complications that have been presented and discussed at scientific meetings can be categorized as anesthesia-related and surgical. The anesthesia-related complications in- clude the down lung syndrome, with significant atelectasis present on the initial chest radiograph; inability to tolerate single-lung ventilation and conversion to an open technique or posterior spinal fusion; inability to ob- tain single-lung ventilation because of difficulty in tube placement; and pneumothorax secondary to high air- way pressures. 12 Because this proce- dure is new and technically demand- ing, the incidence of complications can be high, especially early in the surgeon’s experience. Complications that can occur during surgery include blood vessel injury, lymphatic injury with resultant chylothorax, guide-pin migration into the opposite side of the chest with resultant pneumothorax, 18 distal migration or plowing of the screw when the rod is seated prox- Figure 7 Preoperative anteroposterior (A) and lateral (B) radiographs of a 13-year-old girl with a 56° right thoracic idiopathic curve with a notable trunk shift to the right and hypokyphosis (panel B). Anteroposterior (C) and lateral (D) radiographs 1 year after anterior tho- racoscopic instrumentation from T5 to T12, with near-complete correction of the coronal plane deformity and restoration of the normal sag- ittal profile. Thoracoscopic Anterior Instrumentation and Fusion for Idiopathic Scoliosis 226 Journal of the American Academy of Orthopaedic Surgeons imally or is compressed, and screw cutout at the time of screw insertion. Summary The endoscopic approach to curve cor- rection, instrumentation, and fusion for spinal deformity is a new technique that promises improved patient care because it limits the surgical incision and chest wall compromise, improves postoperative pain and pulmonary function, and enhances cosmesis. Compared with posterior instrumen- tation, anterior instrumentation by ei- ther open or thoracoscopic approach can save fusion levels while improv- ing three-dimensional correction. However, no studies have directly compared thoracoscopic instrumen- tation and fusion with open anterior and/or posterior procedures, making any conclusive statements impossible. Amulticenter prospective study may be needed to fully elucidate the ad- vantages this technique may have and to help define the exact indications for a thoracoscopic approach to treat scoliosis. Several important issues must be kept in mind. First, the proposed ad- vantages have not been confirmed through scientific study. Second, the technique continues to evolve to de- crease the duration of surgery while maintaining the safety of the proce- dure. Third, screw migration and proximity of screws to important soft- tissue structures need further study. Finally, this is a technically demand- ing procedure with a steep learning curve and may not be appropriate for all surgeons who treat spinal defor- mity. References 1. Lenke LG, Bridwell KH, Blanke K, Bal- dus C, Weston J: Radiographic results of arthrodesis with Cotrel-Dubousset instrumentation for the treatment of adolescent idiopathic scoliosis: Afive to ten-year follow-up study. J Bone Joint Surg Am 1998;80:807-814. 2. Richards BS, Herring JA, Johnston CE, Birch JG, Roach JW: Treatment of ado- lescent idiopathic scoliosis using Texas Scottish Rite Hospital instrumentation. Spine 1994;19:1598-1605. 3. Lenke LG, Betz RR, Bridwell KH, Harms J, Clements DH, Lowe TG: Spontaneous lumbar curve coronal correction after se- lective anterior or posterior thoracic fu- sion in adolescent idiopathic scoliosis. Spine 1999;24:1663-1672. 4. Betz RR, Harms J, Clements DH III, et al: Comparison of anterior and posteri- or instrumentation for correction of ad- olescent thoracic idiopathic scoliosis. Spine 1999;24:225-239. 5. Wall EJ, Bylski-Austrow DI, Shelton FS, Crawford AH, Kolata RJ, Baum DS: En- doscopic discectomy increases thoracic spine flexibility as effectively as open diskectomy: A mechanical study in a porcine model. Spine 1998;23:9-16. 6. Newton PO, Wenger DR, Mubarak SJ, Meyer RS: Anterior release and fusion in pediatric spinal deformity: A com- parison of early outcome and cost of thoracoscopic and open thoracotomy approaches. Spine 1997;22:1398-1406. 7. Regan JJ, Guyer RD: Endoscopic tech- niques in spinal surgery. Clin Orthop 1997;335:122-139. 8. Lenke LG, Betz RR, Harms J, et al: Ad- olescent idiopathic scoliosis: A new classification to determine extent of spi- nal arthrodesis. J Bone Joint Surg Am 2001;83:1169-1181. 9. Clements DH, Betz RR, Lowe TG, Lenke LG, Newton PO: Abstract: Ado- lescent idiopathic scoliosis with exces- sive thoracic kyphosis: Comparison of anterior versus posterior instrumenta- tion for maintaining correction. Scolio- sis Research Society 35th Annual Meeting Book. Rosemont, IL: Scoliosis Research Society, 2000, p 97. 10. Desiderio DP, Burt M, Kolker AC, Fis- cher ME, Reinsel R, Wilson RS: The ef- fects of endobronchial cuff inflation on double-lumen endobronchial tube movement after lateral decubitus posi- tioning. J Cardiothorac Vasc Anesth 1997; 11:595-598. 11. Dieter RA Jr, Kuzycz GB: Complica- tions and contraindications of thoracos- copy. Int Surg 1997;82:232-239. 12. SucatoDJ, Girgis M: Bilateralpneumotho- races, pneumomediastium, pneumoperi- toneum, pneumoretroperitoneum, and subcutaneous emphysema following in- tubation with a double-lumen endotra- cheal tube for thoracoscopic anterior spi- nal release and fusion in a patient with idiopathic scoliosis. J Spinal Disord Tech 2002;15:133-138. 13. Huntington CF, Murrell WD, Betz RR, Cole BA, Clements DH III, Balsara RK: Comparison of thoracoscopic and open thoracic discectomy in a live ovine model for anterior spinal fusion. Spine 1998;23:1699-1702. 14. Newton PO, Cardelia JM, Farnsworth CL, Baker KJ, Bronson DG: A biome- chanical comparison of open and thora- coscopic anterior spinal release in a goat model. Spine 1998;23:530-536. 15. Sucato D, Kassab F, Dempsey M: Ab- stract: Thoracoscopic anterior spinal in- strumentation and fusion for idiopathic scoliosis: A CT analysis of screw place- ment and completeness of discectomy. Scoliosis Research Society 36th Annual Meeting Book. Rosemont, IL: Scoliosis Research Society, 2001, p 90. 16. Sucato DJ, Duchene C: MRI analysis of the position of the aorta relative to the spine: Acomparison between normal pa- tients and those with idiopathic right tho- racic curves. J Bone Joint Surg Am, in press. 17. Picetti GD III, Bueff HU: Abstract: En- doscopic instrumentation, correction and fusion of thoracic curves in idio- pathic adolescent scoliosis. Scoliosis Re- search Society 35th Annual Meeting Book. Rosemont, IL: Scoliosis Research Soci- ety, 2000, p 110. 18. Roush TF, Crawford AH, Berlin RE, Wolf RK: Tension pneumothorax as a complication of video-assisted thora- scopic surgery for anterior correction of idiopathic scoliosis in an adolescent fe- male. Spine 2001;26:448-450. Daniel J. Sucato, MD, MS Vol 11, No 4, July/August 2003 227