Instrumentation For Adolescent Idiopathic Scoliosis Research Articles

Efficacy and safety of posteromedial translation for correction of thoracic curves in adolescent idiopathic scoliosis using a new connection to the spine: the Universal Clamp

Correction of adolescent idiopathic scoliosis (AIS) has been reported with various systems. All-screw constructs are currently the most popular, but they have been associated with a significant decrease in thoracic kyphosis, with a potential risk of junctional kyphosis, not observed with hybrid constructs in the literature. In addition, it is important to weigh potential advantages of pedicle screw fixation against risks specific to its use. Because hybrid constructs are associated with a lower risk of complications and better sagittal correction than all-screw constructs, at present we use lumbar pedicle screws combined with a new sublaminar connection to the spine (Universal Clamps) at thoracic levels. The purpose of this study was to determine the efficacy and safety of the Universal Clamp (UC) posteromedial translation technique for correction of AIS. Seventy-five consecutive patients underwent posterior spinal fusion and hybrid instrumentation for progressive AIS. Correction was performed at the thoracic level using posteromedial translation. At the lumbar level, correction was performed using in situ contouring and compression/distractions maneuvers. A minimum 2-year follow-up was required. Medical data and radiographs were prospectively analyzed and compared using a paired t test. The average age at surgery was 15 years and 4 months (+/-19 months). The average number of levels fused was 12+/-1.6. The mean follow-up was 30+/-5 months. The average preoperative Cobb angle of the major curve was 60 degrees+/-20 degrees. The immediate postoperative major curve correction averaged 66+/-13%. The average loss of correction of the major curve between the early postoperative assessment and latest follow-up was 3.5 degrees+/-1.4 degrees . The mean Cincinnati correction index was 1.7+/-0.8 postoperatively, and 1.57+/-1 at last follow up. The mean rotation of the apical vertebra was corrected from 23.3 degrees+/-9 degrees preoperatively to 7.3 degrees+/-5 degrees at last follow up (69% improvement, P<0.0001). In the sagittal plane, the mean thoracic kyphosis improved from 23.8 degrees+/-14.2 degrees preoperatively to 32.3 degrees+/-7.3 degrees at last follow up. For the 68 patients who had a normokyphotic or a hypokyphotic sagittal modifier, thoracic kyphosis increased from 20.5 degrees+/-9.9 degrees to 31.8 degrees+/-7.4 degrees, corresponding to a mean kyphosis correction of 55% at last follow up. No intraoperative complication occurred and none of the patients developed proximal junctional kyphosis during the follow up. The principal limitation of the UC technique was the rate of proximal posterior prominence (14.6%), leading us to recommend the use of conventional claws at the upper extremity of the construct. The technique was safe, and reduced operative time, radiation exposure, and blood loss. While achieving correction of deformity in the coronal and axial planes equivalent to the best reported results of all-screw or previous hybrid constructs, the UC hybrid technique appears to provide superior correction in the sagittal plane. The excellent outcome in all three planes was maintained at 2 year follow up.

P140. Traditional Hybrid vs. Thoracic Pedicle Screw Instrumentation in Adolescent Idiopathic Scoliosis: A Matched Pair Analysis of Clinical Radiographic and Pulmonary Outcomes

P140. Traditional Hybrid vs. Thoracic Pedicle Screw Instrumentation in Adolescent Idiopathic Scoliosis: A Matched Pair Analysis of Clinical Radiographic and Pulmonary Outcomes

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.

Restoration of Thoracic Kyphosis by Posterior Instrumentation in Adolescent Idiopathic Scoliosis

A retrospective comparison of radiographic results for 2 consecutive series of patients treated for adolescent idiopathic scoliosis (AIS) by posterior instrumentations with thoracic screws using 2 methods of reduction: sequential approximation by cantilever reduction (CR) and simultaneous translation technique on 2 rods (ST2R). To compare correction of thoracic hypokyphosis and coronal radiographic results between the 2 methods of reduction. Publications concerning AIS confirm the moderate correction of thoracic hypokyphosis by posterior instrumentation with hooks and also with pedicle screws. Forty-four patients with AIS (Lenke type 1, 2, 3) underwent a posterior spinal fusion and instrumentation (CR series: 21 patients--ST2R series: 23 patients). Three groups of preoperative kyphosis were generated: 12 patients with severe hypokyphosis (<or=10 degrees ) (5 in CR series and 7 in ST2R series); 12 patients with mild hypokyphosis (10-20 degrees ) (5 and 7 patients, respectively) and 20 with normal kyphosis (>20 degrees ) (11 and 9 patients, respectively). Thoracic kyphosis (T4-T12) and Cobb angle measurements of major and minor curves were evaluated by an independent observer. The minimum follow-up was 2 years. At final follow-up, regarding patients with a severe preoperative hypokyphosis, the mean gain was 14 degrees in the CR series (8 degrees preoperative-22 degrees postoperative) and 27 degrees in the ST2R series (3-30 degrees ) (P = 0.018). Concerning patients with mild hypokyphosis, the mean gains were, respectively, 8 degrees (17-25 degrees ) and 18 degrees (16-34 degrees ) (P = 0.052). After surgery, 3 patients of CR series had hypokyphosis whereas the patients of the ST2R series all had normal kyphosis. In coronal plane, the mean correction of scoliosis was similar for both groups (75% vs. 69%; P = 0.177). Simultaneous translation on 2 rods provides a better correction of thoracic kyphosis than the sequential approximation by CR on patients with preoperative hypokyphosis. This surgical technique restores normal thoracic kyphosis in all cases.

Postoperative Ketorolac Does Not Predispose to Pseudoarthrosis Following Posterior Spinal Fusion and Instrumentation for Adolescent Idiopathic Scoliosis

A retrospective review comparing patients who had postoperative ketorolac and those who did not following posterior spinal fusion and instrumentation (PSFI) for adolescent idiopathic scoliosis (AIS). To analyze the effect of postoperative ketorolac on the incidence of pseudoarthrosis in postoperative AIS patients. Ketorolac (Toradol, Roche Laboratories, Nutley, NJ) is a nonsteroidal antiinflammatory drug that is an effective adjunct to manage postoperative pain. It has been previously demonstrated to inhibit spinal fusion in adult patients undergoing a L4 to sacral fusion. To our knowledge, there are no large studies analyzing this effect following PSFI for AIS. An IRB-approved retrospective medical record review was performed from 1994 to 2000 of patients undergoing a PSFI for AIS at a single institution. Segmental spinal instrumentation (Texas Scottish Rite Hospital) and iliac crest bone graft were used in both groups. Demographic and operative data were recorded. Patients were divided into those who had postoperative ketorolac (K group) and those who did not (NK group). Patients who had a surgically confirmed pseudoarthrosis were identified and the K group and NK group were statistically compared. There were 161 patients in the NK group and 158 in the K group. There were no differences with respect to age (14.4 vs. 14.2 years), gender (83.9% vs. 84.8% females), levels fused (9.8 vs. 9.7), or preoperative curve magnitude (57.9 degrees vs. 58.9 degrees ). In the K group, the number of doses of ketorolac administered was 6.7 for an average of 26.7 mg for a duration of 46 hours after surgery. Patients in the K group were more likely to have Motrin (average 5.8 doses) compared with the NK group (average 0.7 doses) (P < 0.01). No patient in the K group had a history of cigarette smoking compared with 2 patients in the NK group, both of whom went on to solid arthrodesis. The overall incidence of pseudoarthrosis was 2.5% for all patients. There was no difference in the incidence of pseudoarthrosis comparing the K (1.9%) and the NK group (3.1%)(P = 0.7). When the single rod posterior implants were excluded, there was no difference between the K (0.7%) and NK groups (1.8%) (P = 0.58). Ketorolac does not increase the incidence of developing a pseudoarthrosis when used as an adjunct for postoperative analgesia following a PSFI for AIS using segmental spinal instrumentation and iliac crest bone graft. The differences seen here compared with adults may be due to the greater healing potential in these young patients. We recommend utilization of ketorolac after surgery to supplement pain management when necessary.

Difficult Thoracic Pedicle Screw Placement in Adolescent Idiopathic Scoliosis

Retrospective radiographic and clinical consecutive case series. The objective of this study was to identify patients treated with posterior spinal fusion and pedicle screw instrumentation for adolescent idiopathic scoliosis (AIS) in whom it was not possible to place a planned pedicle screw, and describe the possible difficulties in screw placement. Despite the knowledge of anatomic characteristics of upper thoracic spine pedicles and considerable experience in thoracic pedicle screw placement, inserting pedicle screws in some patients with AIS may be difficult. We reviewed 96 patients with AIS in whom the intent was to use an all-screw construct in 2004. Placement of the pedicle screws was usually by the freehand method, with intraoperative fluoroscopy used as needed. If a screw could not be safely placed after multiple attempts, a down-going supralaminar or transverse process hook was placed. Medical records were reviewed and radiographs were measured by one of the authors. We identified 17 cases (18%) in which a hook had been placed. All cases had a major thoracic curve (Lenke 1, 2, and 3) and the single hook had always been placed at the most cephalad level of the construct on the patient's right side. The most common levels for hook placement were T3 and T4; these pedicles were noted to be sclerotic, narrow, and have a moderate amount of rotation on the preoperative posterior-anterior and side bending radiographs. Care should be exercised during pedicle screw instrumentation in the apical region of the proximal thoracic curve, whether structural or nonstructural, especially in the concavity. The preoperative radiographs may give helpful clues to intraoperative challenges of pedicle screw insertion at the uppermost level of instrumentation. Hook fixation was satisfactory in this scenario.

Neural Complications in the Surgical Treatment of Adolescent Idiopathic Scoliosis

Multicenter, prospective, consecutive clinical series. To report on neural complications in a prospective cohort study of 1301 children undergoing spinal fusion and instrumentation for adolescent idiopathic scoliosis (AIS). The incidence of neural complications for spinal deformity surgery has been reported to be 0.26% to 17%. However, most studies have relied on retrospective voluntary reporting of nonconsecutive cases. A review of 1301 consecutive surgical cases was conducted using the Prospective Pediatric Scoliosis Study database, which is maintained by the Spinal Deformity Study Group. There were 9 neural complications. There were 3 thecal penetrations, none of which required repair, and none of which demonstrated intraoperative neural monitoring changes or postoperative clinical sequelae. There were 2 nerve root injuries. In 1 nerve root injury, a positional compression femoral neurapraxia resolved over 6 months. The other was an L4 neurapraxia despite lowest instrumented vertebra L1, and resolved spontaneously by 3 months' follow-up. There were 4 spinal cord injuries. One required removal of implants and fusion in situ, 1 required relaxation of correction and in situ fusion with instrumentation, while the other 2 were observed after fusion and instrumentation with reduction. All resolved spontaneously within 3 months after operation. The neural complication rate was 0.69%. Two thecal penetrations were due to medial placement of pedicle screws, and 1 was due to dissection during spine exposure. If these are eliminated, as they imply intraspinal entry but not direct neural injury, together with 1 positional neurapraxia, which is remote from the surgical field, our complication rate is 0.38%. This is consistent with other studies in the North American Literature, including multiple reports from the Scoliosis Research Society. Common themes are significant curve correction producing neural stretch and the use of sublaminar wires. None of the neural injuries was permanent. These results reaffirm that surgical treatment of adolescent idiopathic scoliosis has a low but real neural complication rate.

Late Spontaneous Hemothorax Complicating Anterior Spinal Instrumentation in Adolescent Idiopathic Scoliosis

Case report. Describes a case report of a 16-year-old woman treated for adolescent idiopathic scoliosis (AIS) by anterior spinal fusion and instrumentation, who developed a spontaneous massive intrathoracic bleeding 10 months after surgery. Hemothorax (HT) is a known rare postoperative complication of anterior spinal scoliosis surgery. However, spontaneous HT has never been described as a late complication, in relationship to diaphragm movement over the anterior instrumentation material. Retrospective case report. A 16-year-old woman with Lenke type I AIS underwent a successful anterior spinal fusion with instrumentation. After surgery, there were no complications, however, she experienced a distressing grating sensation while breathing. Ten months after surgery, the patient developed a spontaneous HT that needed emergency surgery. Erosion of a small artery in the scar tissue around the most caudal screw of the instrumentation proved to be the cause of the late HT. Subsequent dynamic magnetic resonance imaging showed the relationship between the moving diaphragmatic muscles and the most caudal screws of instrumentation material during breathing. Sixteen months after the initial surgery, the anterior instrumentation was removed. Late spontaneous HT in patients with anterior fusion and instrumentation for AIS is a rare but life-threatening complication.

Evaluation of the effect of vertebral and disc mechanical torsion on the correction achieved by posterior instrumentation in adolescent idiopathic scoliosis

Conclusion Mechanical torsion within the vertebral bodies and discs of patients with idiopathic scoliosis presents a fundamental obstacle to effective derotational surgery, and is closely related to subsequent changes in the overall three-dimensional deformity following instrumentation.

Idiopathic Scoliosis Treated With Cotrel-Dubousset Instrumentation

Prospective cohort study with 10-year follow-up. To evaluate long-term results after operative treatment with Cotrel-Dubousset (CD) instrumentation for adolescent idiopathic scoliosis (AIS). Limited knowledge exists in the evaluation of long-term function with quality of life measures after CD instrumentation in patients with AIS. A total of 100 (76 females and 24 males) consecutive AIS patients all with single primary curves were included. Radiologic measures and pain were registered at baseline and at 1- to 5-year follow-up. Quality of life and back specific measures, including EuroQol (EQ) and Oswestry Disability Index (ODI), were obtained by a questionnaire mailed to the patients at 10 years after surgery. Mean age at operation was 16.8 (SD, 5.3) years, mean Risser sign was Grade 3.2 (SD, 1.5). All patients were observed for 2 years. The average primary curve was reduced from 56 degrees to 19 degrees, and this correction was maintained during follow-up. Fourteen patients had minor complications, and 5 patients had implants removed because of late clinically suspected infections. A total of 86 patients answered the 10-year questionnaire; 97% of the patients considered back function as excellent, good, or fair, and 96% would have done the operation again. Scores for EQ-5D and ODI were slightly worse than in the normal population. Despite this observation, 45% of the patients reported to have consulted a physician or received physiotherapy for back pain during the last year before the 10-year follow-up. Radiologic results, patient satisfaction, and mean scores for quality of life and back function were excellent after CD instrumentation for AIS, but a considerable number of patients had treatment for back problems.

Intra and interobserver variability of preoperative planning for surgical instrumentation in adolescent idiopathic scoliosis

Surgical instrumentation planning for the correction of scoliosis involves many difficult decisions, especially with the introduction of multi-segmental and other instrumentation technologies. A preliminary study has shown a high variability in planning among a small group of surgeons. The purpose of this paper was to evaluate and analyze the selection of fusion levels and instrumentation choices among a more extended group of scoliosis surgeons. Thirty-two experienced spinal deformity surgeons were asked to provide their preferred posterior instrumentation planning for five patients with adolescent idiopathic scoliosis (AIS) using a graphical worksheet and the usual preoperative X-rays. Overall, the number of implants used ranged from 8 to 30 per patient (mean 16; SD 6): 71% of these were mono-axial screws, 20% multi-axial screws, and 9% hooks. The selected superior and inferior instrumented vertebrae varied up to six levels. The following significant groups of strategies were identified: A- "All Pedicle Screws Constructs" [N(A) = 103; 66%]; B- "All Hooks constructs" [N(B) = 5; 3%]; C- "Hybrid Constructs" [N(C) = 48; 31%]. A top-to-bottom attachment sequence was selected in 49% of all cases, a bottom-up in 46%, and an alternate order in 4%. A large variability in preoperative instrumentation strategy exists in AIS within an experienced group of orthopedic spine surgeons. The impact of such choices on the resulting correction is questioned and will need to be determined with adequate clinical, biomechanical, and computer simulation prospective studies.

The clinical outcome and complication prevention of thoracoscopic instrumentation for adolescent idiopathic scoliosis

后路矫形一直是青少年特发性胸椎侧凸矫形的标准术式,但逐步为大家熟悉的前路矫形技术拥有其独特的优势,首先前路手术通过矫形力直接作用于侧方移位和旋转的椎体,可更好地矫正冠状面畸形、重建平衡以及减少椎体水平面旋转,另外通过压缩椎体螺钉矫正侧凸畸形,可以有效恢复胸椎正常后凸,并通过缩短而不是延长脊柱而矫正侧凸,因此,减少了因牵拉脊髓而致神经损伤的可能性,这些特点使得前路矫形也成为胸椎侧凸的标准入路之一.近年来,胸腔镜矫形技术的应用又使得脊柱矫形步入微创时代,使青少年特发性胸椎侧凸矫形又有了开放与微创的选择[1-4]。

Thoracoscopic Scoliosis Surgery Affects Pulmonary Function Less Than Thoracotomy at 2 Years Postsurgery

Prospective evaluation of pulmonary function before and 2 years after surgery following anterior scoliosis instrumentation. To determine if thoracoscopic anterior scoliosis correction with instrumentation affected pulmonary function less than open thoracotomy approaches at 2 years follow-up. The thoracoscopic approach has been shown to have a smaller reduction in pulmonary function tests (PFTs) compared with an open thoracotomy approach following anterior thoracic instrumentation for adolescent idiopathic scoliosis in the immediate postoperative period; however, it is unclear if a difference remains 2 years following the procedure. A total of 107 patients in a multicenter adolescent idiopathic scoliosis database underwent an anterior instrumented fusion for thoracic scoliosis. PFTs assessing forced vital capacity (FVC), forced expiratory volume (FEV1), and total lung capacity (TLC) were obtained prospectively before and 2 years after surgery. The patients were grouped as follows: Group I, thoracoscopic instrumented fusion (n = 36); Group II, open (thoracotomy) instrumented fusion without thoracoplasty (n = 28); and Group III, open instrumented fusion with thoracoplasty (n = 43). Thoracoscopic instrumentation affected pulmonary function 2 years after surgery minimally, and on an average showed improvements in all parameters except the percent-predicted FVC, which decreased by 1% +/- 11%, and percent predicted FEV, which decreased by 2% +/- 9%. Improvements were noted in absolute FVC, FEV1, TLC, and percent-predicted TLC. This is in contrast to the patients treated with a thoracotomy, who had a greater persistent reduction in PFTs at follow-up. An added thoracoplasty to the thoracotomy approach, however, resulted in even greater residual reduction in PFTs at follow-up, with declines in percent-predicted FVC of 15%, percent-predicted FEV1 of 14%, and percent-predicted TLC of 8%. This study shows a clear advantage to the minimally invasive thoracoscopic approach with regards to pulmonary function when compared with the open thoracotomy approaches.

Sagittal Plane Analysis of Adolescent Idiopathic Scoliosis after VATS (Video-Assisted Thoracoscopic Surgery) Anterior Instrumentations

Radiographic sagittal plane analysis of VATS (video-assisted thoracoscopic surgery) anterior instrumentation for adolescent idiopathic scoliosis. This is retrospective study. To report, in details about effects of VATS anterior instrumentation on the sagittal plane. Evaluations of the surgical outcome of scoliosis have primarily studied in coronal plane correction, functional, and cosmetic aspects. Sagittal balance, as well as coronal balance, is important in functional spine. Recently, scoliosis surgery applying VATS has been increasingly performed. Its outcome has been reported several times; however, according to our search of the literature, the only one study partially mentioned. The study population was a total of 42 cases of idiopathic scoliosis patients (8 male, 34 female). Their mean age was 15.6 years (13 to 18 years). The 18 cases were Lenke IA type, 16 cases were Lenke IB type, and 8 cases were Lenke IC type. The preoperative Cobb's angle was 54.5 ± 13.9°. All patients were followed up for a minimum of 2 years and implanted, on average, at the 5.9 level (5 to 8 levels). The most proximal implant was the 4th thoracic spine, and the most distal implant was the 1st lumbar spine. Whole spine standing PA and lateral radiographs were taken before surgery, 2 months after surgery, and at the last follow up (range 24-48 months, mean 35 months). The C7 plumbline proximal junctional measurement (PJM), distal junctional measurement (DJM), thoracic kyphosis, and lumbar lordosis angles were measured and compared. In all cases, follow-ups were possible and survived till the last follow up. The Cobb's angle in coronal plane at the last follow up was 19.7 ± 9.3° and was corrected to 63.8% on average. The preoperative C7 sagittal plumbline before surgery was -13.9 ± 29.1 mm, the final follow up was -9.9 ± 23.8 mm, and the average positive displacement was 4 mm. Thoracic kyphosis was increased from preoperative 18.2 ± 7.7° to 22.4 ± 7.2° on average at the last follow up, and the increase was, on average, 4.2°. The PJM angel was increased from 6.2 ± 4.3° preoperative to 8.8 ± 3.7° at the last follow up, and the increment was, on the average, 2.6°. The DJM angle before surgery was 6.8 ± 5.1° and 6.7 ± 4° at the last follow up, and did not change noticeably. Preoperative lumbar lordosis was 42 ± 10.7° and 43.5 ± 11.1° after surgery. Similarly, it did not change greatly. The scoliosis surgery applying VATS displaced the C7 sagittal plumb line by 4 mm to the anteriorly, increased thoracic kyphosis by 4.2°, and increased PJM by 2.6°. DJM and lumbar lordosis, before and after operation, were not significantly different. Although the surgical technique of VATS thoracic instrumentation is difficult to make the normal thoracic kyphosis, an acceptable sagittal balance can be obtained in Lenke type I adolescent idiopathic scoliosis using VATS.

Is anterior release effective to increase flexibility in idiopathic thoracic scoliosis? Assessment by traction films

With the advent of thoracoscopy, anterior release procedures in adolescent idiopathic scoliosis (AIS) have come into more frequent use, however, the indication criteria for an anterior release in thoracic AIS are still controversial in the literature. To date, few studies have assessed the influence on spinal flexibility and no study has so far been able to show a beneficial effect on the correction rate as compared to a single posterior procedure. The objective of this study was to evaluate the influence of thoracic disc excision on coronal spinal flexibility. Six patients (5 females, 1 male) with AIS and a mean age of 15.6 years (range 13-20 years) underwent an open anterior thoracic release prior to posterior instrumentation. Cotrel dynamic traction along with radiographs of the whole spine including traction films were conducted pre- and postoperatively and were evaluated retrospectively. The mean preoperative thoracic curve was 89.7 degrees +/- 15.4 degrees (range 65 degrees-110 degrees). The flexibility rate in Cotrel traction was 22.8 +/- 8.1%. After performance of the anterior release the thoracic curve showed a mean increase of coronal correction by 5.5 degrees +/- 5.0 degrees as assessed by traction radiographs. The flexibility index changed by 6.2 +/- 5.6%. After posterior instrumentation the thoracic curve was corrected to a mean of 36.5 degrees +/- 10.1 degrees (correction rate 59.6%). Disc excision in idiopathic thoracic scoliosis only slightly increased spinal flexibility as assessed by traction films. In our view a posterior release with osteotomy of the concave ribs (concave thoracoplasty, CTP) is more effective in increasing spinal flexibility. According to our clinical experience, an anterior release prior to posterior instrumentation in AIS should only be considered in hyperkyphosis, coronal imbalance or massive curves.

Prospective Evaluation of 50 Consecutive Scoliosis Patients Surgically Treated With Thoracoscopic Anterior Instrumentation

Prospective, consecutive, single-surgeon case series of patients treated for scoliosis with thoracoscopic anterior spinal instrumentation. A thoracoscopic approach for insertion of anterior instrumentation has been developed in the past 10 years, which obviates many of the disadvantages of the open anterior thoracic approach. The morbidity associated with a thoracoscopy is limited because of the minimal skin and chest wall dissection required with this method. The purpose of this evaluation is to report a single surgeon's experience with an initial series of 50 patients. The goal is to report the outcomes with regards to the radiographic findings, pulmonary function, and the SRS Outcomes Instrument, as well as a review of the perioperative data and complications. The primary author's initial 50 thoracoscopic anterior spinal instrumentation patients were consecutively collected. Data collection included demographics, such as age, gender, and diagnosis. Data regarding the surgical procedure included the operative time, intraoperative estimated blood loss, as well as the number of levels instrumented anteriorly. In the perioperative hospital period, data were collected with regard to the length of the hospital stay, the number of days in the ICU, the number of days of ventilator support, and the number of days after surgery when conversion from IV to PO pain medication occurred. Radiographic data were obtained systematically on each patient and measured by authors other than the surgeon. The SRS 22 and/or 24 Outcomes Questionnaire and pulmonary function tests were administered to patients at similar intervals. The series consisted of 44 females and 6 males with a mean age of 14 years (range, 9-48 years). Forty-five of the 50 patients were available for clinical and radiographic evaluation at greater than or equal to 2 years after surgery. The average length of follow-up for these 45 patients was 33 months (range, 2-5 years). The mean operative time for the procedure was 350 +/- 50 minutes and ranged from 265 to 528 minutes. The estimated intraoperative blood loss averaged 431 +/- 273 mL (range, 75-1,400 mL). Normalizing the operative time and estimated blood loss based on the number of levels treated resulted in an average operative time per level of 48 +/- 6 minutes per level and an estimated intraoperative blood loss per level of 60 +/- 37 mL per level. The preoperative thoracic Cobb averaged 53 degrees +/- 9 degrees (range, 40 degrees-80 degrees). At most recent follow-up (> or = 2 years), the thoracic Cobb averaged 24 degrees +/- 7 degrees. Implant failure occurred in 3 cases. Thoracoscopic anterior instrumentation for adolescent idiopathic scoliosis is a viable surgical option. The outcomes of this consecutive series of patients is comparable to prior open and endoscopic series presented in the literature. The technical challenges of this operation are evident in the learning curve effect, which has been demonstrated.

Delayed anterior spinal artery syndrome following posterior scoliosis correction

The authors report two cases of delayed post-operative anterior spinal artery syndrome (ASAS) following posterior correction with Cotrel Dubousset (CD) instrumentation for adolescent idiopathic scoliosis. Sensory pathways were continuously monitored from skin incision to awakening. In both cases intraoperative SEPs were normal and the wake-up test revealed no neurological deficit. Both patients were presented with incomplete paraplegia (no sensory impairment) three and ten hours after surgery. Without delay, both patients underwent revision surgery, and the CD instrumentation was removed. Immediately after surgery, both patients' motor power in their lower extremities improved rapidly. In cases with delayed ASAS after posterior scoliosis correction, the removal of the instrumentation system was shown to be sufficient to regain full motor recovery caudal to the level of impairment.

61. Comparative analysis of pedicle screw versus hook instrumentation in posterior spinal fusion of adolescent idiopathic scoliosis: a matched cohort analysis

HYPOTHESIS: 1. Posterior pedicle screw instrumentation of Adolescent idiopathic scoliosis (AIS) offers better curve correction than hook instrumentation. 2. Posterior pedicle screw instrumentation of AIS offers better postoperative pulmonary function than hook instrumentation. 3. Posterior pedicle screw instrumentation of AIS offers better SRS 24 score postoperatively than hook instrumentation.

Preoperative and early postoperative three-dimensional changes of the rib cage after posterior instrumentation in adolescent idiopathic scoliosis.

Rib cage deformity is an important component of scoliosis, but few authors have reported the three-dimensional (3-D) effect of surgical procedures with posterior instrumentation systems on the shape of the rib cage. The objective of this prospective clinical study was to measure the short-term 3-D changes in the shape of the rib cage at the apex of the curve after corrective surgery of adolescent idiopathic scoliosis by a posterior approach using a multi rod, hook and screw system. The 3-D shape of the spine and rib cage was modelled pre- and postoperatively using a 3-D reconstruction technique based on multi-planar radiography in a group of 29 adolescents with idiopathic scoliosis. Geometrical indices describing the scoliotic deformity of the rib cage were computed from these models and were compared pre- and postoperatively using Student's t-tests. The frontal spinal curve correction averaged 53% in the frontal plane, while no significant change was noted in the sagittal plane. Significant changes were noted in the shape of the rib cage: rib hump at the apex and at the adjacent lower level were improved (36% and 38%), and small but significant differences were detected in rib frontal orientation in the concavity of the curves at the apex and adjacent lower rib levels. Multi rod, hook and screw instrumentation systems, such as Cotrel-Dubousset instrumentation, are effective in producing significant improvements in the 3-D shape of the rib cage, but these changes are less important than those observed at the spine level.

Effects of three-dimensional assessment on surgical correction and on hook strategies in multi-hook instrumentation for adolescent idiopathic scoliosis.

A prospective study using intraoperative stereophotogrammetry to analyze change during the correction of scoliosis. To examine the relation between the number of hooks used during segmental instrumentation and the amount of correction achieved. An intraoperative stereophotogrammetric technique was developed at our center. Vertebral translations and rotations can be measured at several stages during scoliosis surgery. Thirty-two patients with right thoracic adolescent idiopathic scoliosis were studied using our stereophotogrammetry technique during surgical correction. Correlations were determined between apical vertebral movements and the hook ratio (number of vertebrae/number of hooks used). Mean curve Cobb angle correction was 66%. Correction occurred in all three planes but primarily along the x and y axes. Scoliotic deformity was corrected by translation of the vertebra along the y axis and rotation about the x; physiologic kyphosis was restored by translation along the x axis and rotation about the y. The plane of maximum deformity as compared with the sagittal plane of the patient corrected from 57 degrees to 25 degrees as an indication of detorsion of the scoliotic deformity. Increasing the number of hooks per vertebral segment significantly enhances the correction of the coronal scoliotic deformity and enhances the z axis derotation, but does not significantly change the reestablishment of the kyphosis, nor does it result in significant elongation of the spine.