Thoracoscopic anterior instrumentation and fusion for idiopathic scoliosis

Pros and Cons of Minimally Invasive Spine Surgery

This paper reviews current knowledge on minimally invasive spine surgery (MISS). Although it has significant advantages, such as less postoperative pain, short hospital stay, quick return to work, better cosmetics, and less infection rate, there are also disadvantages. The long learning curve, the need for special instruments and types of equipment, high costs, lack of tactile sensation and biplanar imaging, some complications that are hard to treat, and more radiation to the surgeon and surgical team are the disadvantages.Most studies remark that the outcomes of MISS are similar to traditional surgery. Although patients demand it more than surgeons, we predict the broad applications of MISS will replace most of our classical surgical approaches.

Evolution of Surgery for Adolescent Idiopathic Scoliosis Over 20 Years: Have Outcomes Improved?

STUDY DESIGN

Retrospective review of a prospective adolescent idiopathic scoliosis (AIS) registry.

OBJECTIVE

To study the evolution of the operative approach, outcomes, and complication rates in AIS surgery over the past 20 years.

SUMMARY OF BACKGROUND DATA

Surgical techniques in AIS surgery have evolved considerably over the past 20 years. We study the trends in the operative management of AIS over this period and their impact on perioperative outcomes.

METHODS

A total of 1819 AIS patients (1995-2013) with 2-year F/U were studied. Operative approach, perioperative parameters, major complication rates, and SRS outcomes were assessed. Linear regression was used to assess the trend of changes over 5-year quartiles.

RESULTS

Mean age at surgery was 14.6 ± 2.1 years, 80.2% were females, and this remained consistent throughout. Operative time, EBL/level, and LOS decreased over the 20 years (P < 0.0001). The use of antifibrinolytic (AF) increased from 6.7% to 68.8% in the past 10 years (P < 0.0001). Number of levels fused increased and LIV was more distal (in relation to stable vertebrae) over time in Lenke 1 and 2 curves (levels fused 7.97-9.94, P < 0.0001 and 9.8-11.0, P=0.0134, respectively). Anterior spinal fusion (ASF) in Lenke 1 curves decreased from 81% in the first quartile to 0% in the last (P = 0.0429). ASF for Lenke 5 curves evolved from 78% in the second quartile to 0 in the last. Thoracoplasty performance decreased from 76% to 20.3% (P = 0.1632). All screw constructs in PSF cases increased from 0% to 98.4% (P = 0.0095). Two-year major complication rates decreased over time (18.7%-5.1%; P = 0.0173). Increased improvement in SRS scores were observed in pain, image, function, and total domains.

CONCLUSION

Evolution of surgical technique in AIS over the past 20 years has resulted in a cessation of anterior only surgery, increasing use of all screw constructs, less blood loss, greater use of AF, shorter operative times and LOS, lower major complications rates, and greater improvements in SRS scores.

LEVEL OF EVIDENCE

2.

Posterior convex release and interbody fusion for thoracic scoliosis: technical note

Anterior release and fusion is sometimes required in pediatric patients with thoracic scoliosis. Typically, a formal anterior approach is performed through open thoracotomy or video-assisted thoracoscopic surgery. The authors recently developed a technique for anterior release and fusion in thoracic scoliosis referred to as "posterior convex release and interbody fusion" (PCRIF). This technique is performed via the posterior-only approach typically used for posterior instrumentation and fusion and thus avoids a formal anterior approach. In this article the authors describe the technique and its use in 9 patients-to prevent a crankshaft phenomenon in 3 patients and to optimize the correction in 6 patients with a severe thoracic curve showing poor reducibility. After Ponte osteotomies at the levels requiring anterior release and fusion, intervertebral discs are approached from the convex side of the scoliosis. The annulus on the convex side of the scoliosis is incised from the lateral border of the pedicle to the lateral annulus while visualizing and protecting the pleura and spinal cord. The annulus in contact with the pleura and the anterior longitudinal ligament are removed before completing the discectomies and preparing the endplates. The PCRIF was performed at 3 levels in 4 patients and at 4 levels in 5 patients. Mean correction of the main thoracic curve, blood loss, and length of stay were 74.9%, 1290 ml, and 7.6 days, respectively. No neurological deficit, implant failure, or pseudarthrosis was observed at the last follow-up. Two patients had pleural effusion postoperatively, with 1 of them requiring placement of a chest tube. One patient had pulmonary edema secondary to fluid overload, while another patient underwent reoperation for a deep wound infection 3 weeks after the initial surgery. The technique is primarily indicated in skeletally immature patients with open triradiate cartilage and/or severe scoliosis. It can be particularly useful if there is significant vertebral rotation because access to the disc and anterior longitudinal ligament from the convex side will become safer. The PCRIF is an alternative to the formal anterior approach and does not require repositioning between the anterior and posterior stages, which prolongs the surgery and can be associated with an increased complication rate. The procedure can be done in the presence of preexisting pulmonary morbidity such as pleural adhesions and decreased pulmonary function because it does not require mobilization of the lung or single-lung ventilation. However, PCRIF can still be associated with pulmonary complications such as a pleural effusion, and care should be taken to avoid iatrogenic injury to the pleura. Placement of a deep wound drain at the level of the PCRIF is strongly recommended if postoperative bleeding is anticipated, to decrease the risk of pleural effusion.

Computed tomography morphometric analysis of anterior instrumentation in the pediatric thoracic spine

OBJECT The authors' goal in this paper was to quantify reference data on the dimensions and relationships of the maximum posterior screw angle and the thoracic spinal canal in different pediatric age groups. METHODS One hundred twelve pediatric patients were divided into 4 age groups, and their thoracic vertebrae were studied on CT scans. The width, depth, and maximum posterior screw angles with different screw entrance points were measured on a Philips Brilliance 16 CT. The statistical analysis was performed using the Student t-test and Pearson's correlation analysis. RESULTS The width and depth of the thoracic vertebrae increased from T-5 to T-12. The width ranged from 18.5 to 37.1 mm, while the depth ranged from 16.1 to 28.2 mm. The maximum posterior screw angle decreased from T-5 to T-12 in all groups. The ranges and mean angles at the entrance points were as follows: initial entrance point, 6.9° to 12.3° with a mean angle of 9.1°; second entrance point, 20.6° to 27.0° with a mean angle of 24.2°; and third entrance point, 29.2° to 37.5° with a mean angle of 33.7°. There were no significant age-related differences noted for the maximum posterior screw angles. CONCLUSIONS The angle decreased from T-5 to T-12. No significant age-related differences were noted in the maximum posterior screw angles. Screws should be placed between the initial and second points and parallel to the coronal section or at a slight anterior orientation.

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

STUDY DESIGN

Retrospective review of prospectively collected data.

OBJECTIVES

To analyze intervertebral (IV) fusion after thoracoscopic anterior spinal fusion (TASF) and explore the relationship between fusion scores and key clinical variables.

SUMMARY OF BACKGROUND INFORMATION

TASF provides comparable correction with some advantages over posterior approaches but reported mechanical complications, and their relationship to non-union and graft material is unclear. Similarly, the optimal combination of graft type and implant stiffness for effecting successful radiologic union remains undetermined.

METHODS

A subset of patients from a large single-center series who had TASF for progressive scoliosis underwent low-dose computed tomographic scans 2 years after surgery. The IV fusion mass in the disc space was assessed using the 4-point Sucato scale, where 1 indicates <50% and 4 indicates 100% bony fusion of the disc space. The effects of rod diameter, rod material, graft type, fusion level, and mechanical complications on fusion scores were assessed.

RESULTS

Forty-three patients with right thoracic major curves (mean age 14.9 years) participated in the study. Mean fusion scores for patient subgroups ranged from 1.0 (IV levels with rod fractures) to 2.2 (4.5-mm rod with allograft), with scores tending to decrease with increasing rod size and stiffness. Graft type (autograft vs. allograft) did not affect fusion scores. Fusion scores were highest in the middle levels of the rod construct (mean 2.52), dropping off by 20% to 30% toward the upper and lower extremities of the rod. IV levels where a rod fractured had lower overall mean fusion scores compared to levels without a fracture. Mean total Scoliosis Research Society (SRS) questionnaire scores were 98.9 from a possible total of 120, indicating a good level of patient satisfaction.

CONCLUSIONS

Results suggest that 100% radiologic fusion of the entire disc space is not necessary for successful clinical outcomes following thoracoscopic anterior selective thoracic fusion.

The rib head as a landmark in the anterolateral approach to the thoracic spine: a computed tomography-based morphometric study

OBJECT

The rib head is an important landmark in the anterolateral approach to the thoracic spine. Resection of the rib head is typically the first step in gaining access to the underlying pedicle and ultimately the spinal canal. The goal of this work is to quantify the relationship of the rib head to the spinal canal and adjacent aorta at each thoracic level using CT-based morphometric measurements.

METHODS

One hundred thoracic spine CT scans (obtained in 50 male and 50 female subjects) were evaluated in this study. The width and depth of each vertebra body were measured from T-1 to T-12. In addition, the distance of each rib head to the spinal canal was determined by drawing a line connecting the rib heads bilaterally and measuring the distance to this line from the most ventral aspect of the spinal canal. Finally, the distance of the left rib head to the thoracic aorta was measured at each thoracic level below the aortic arch.

RESULTS

The vertebral body depth progressively increased in a rostral to caudal direction. The vertebral body width was at its minimum at T-4 and progressively increased to T-12. The rib head extended beyond the spinal canal maximally at T-1. This distance incrementally decreased toward the caudal levels, with the tip of the rib head lying approximately even with the ventral canal at T-11 and T-12. The distance between the aorta and the left rib head increased in a rostral to caudal direction as well.

CONCLUSIONS

The rib head is an important landmark in the anterolateral approach to the thoracic spine. At more cephalad levels, a larger portion of rib head requires resection to gain access to the spinal canal. At more caudad levels, there is a safer working distance between the rib head and aorta.

The morbidity of open transthoracic approach for anterior scoliosis correction

STUDY DESIGN

Retrospective study.

OBJECTIVE

To analyze the patient satisfaction and the patients' perceived approach-related morbidity (ArM) after open thoracotomy (OTC) for instrumented anterior scoliosis surgery.

SUMMARY OF BACKGROUND DATA

There is no mid- to long-term data on the patients' perceived ArM concerning chest wall dissection for open anterior scoliosis correction.

METHODS

A specific questionnaire was used to retrospectively evaluate mid- to long-term follow-up data concerning ArM after OTC of patients younger than 30 years (range, 11-28 years) who underwent anterior open transthoracic scoliosis surgery. The questionnaire was comprised of detailed scar-related questions. Applying strict inclusion criteria, we could analyze outcomes in terms of percentage morbidity (morbidity [%]) of 40 patients who underwent OTC for instrumented scoliosis correction.

RESULTS

Mean age of the patients was 16 ± 3.8 years, follow-up was 61.5 ± 72.6 months on average, and mean incision length was 25.7 ± 3.1 cm. Mean number of levels fused was 5.9 ± 1.5. Single thoracotomy was performed in 25 patients and a thoracoabdominal approach in 15 patients. Mean morbidity (0%, not delineating no ArM; 100%, delineating highest ArM) was 5.4% ± 11.3%; 47.5% of patients had no morbidity; 12.5% had morbidity >10% (mean: 28.5%). Signs of intercostal neuralgia (ICN) were present in 10%. Patients judged their clinical outcome as "good" in 20% and "excellent" in 80%. Statistical analysis did not reveal differences in outcomes and percentage morbidity concerning age of patients, extent of approach (thoracotomy vs. thoracoabdominal approach) and incision length, gender, or follow-up length. However, the presence of ICN had a significant effect on the outcome, showing high correlation with increased morbidity (P < 0.0001). In the clinical judgment of outcomes, the severity of the ArM after OTC was mild, except for 2 patients who had moderate approach and scar-related morbidity.

CONCLUSION

ArM after open thoracic spinal surgery or thoracoscopic procedures can be assessed using the questionnaire. The current study showed that ArM in young patients who underwent OTC for anterior instrumented scoliosis correction was low. Patients with increased signs of ICN did worse in terms of the questionnaire survey. The study showed that neither cosmesis nor scar-related problems were a concern for patients undergoing OTC.

Anatomical study of position of the rib head for placing anterior vertebral body screws in a chinese population

In this study, the variability of rib head position in a Chinese population in terms of the spinal canal and vertebral body was analyzed using computed tomography (CT). Images from transverse CT scan of the T4 to T12 vertebral bodies of 30 normal individuals were 3-dimensionally reconstructed, and analyzed for measurement of parameters that define the relative anatomic position of the rib head. We have found that the distance between the anterior border of the rib head and the posterior margin of the vertebral body, posterior safe angle, and the distance between the most inferior border of the rib head and inferior end plate in the sagittal plane gradually decrease. However, the distance between the anterior boarder of the rib head and the anterior margin of the vertebral body, transverse dimension, anterior safe angle, and the distance between the most inferior border of the rib head and superior end plate in the sagittal plane gradually increase from T4 to T12. This indicates that the position of the rib head is oriented from a more anterior position to a more posterior position and from a more superior position to a more inferior position as the number of the vertebra increases, which is different from what has been reported from western populations. Our study has identified useful parameters to define the position of the rib head, and provides a comprehensive reference guide for accurate and safe instrumentation of vertebral body screws in treating related spine diseases.

Approach-related morbidity in transthoracic anterior spine surgery: a clinical study and review of literature

BACKGROUND: Anterior access to the thoracic spine is done by open thoracotomy (OTC) or video-assisted thoracoscopic surgery (VATS). VATS is known as the method which results in lower morbidity rates, but there is little evidence of its less invasiveness. Objective: The current study yielded for outcome data concerning patients' perception of approach-related morbidity (ArM) following OTC for spinal surgery and that of a control group having a chest tube thoracotomy (CTT). METHODS: We performed a questionnaire assessment of ArM after OTC and CTT. Applying strict inclusion criteria, we compared outcomes in terms of percentage morbidity (Morbidity %) of 43 patients that underwent OTC for instrumented scoliosis correction to 30 patients that had CTT for minor thoracic pathologies (e.g., pneumothorax). RESULTS: Mean age in CTT and OTC Group was 50.2 and 16.5 years old, follow-up was of 32.2 and 58.4 months, and mean incision length was 2.5 and 25.5 cm, respectively. Mean number of levels fused in the OTC Group was 5.8. Mean morbidity (0% delineating no cases, 100% delineating highest morbidity) for the CTT Group was 10.8±15.4% (0-59.5%), 42% of patients had no morbidity. Signs of intercostal neuralgia (ICN) were present in 16.7%. A total of 35.5% had a morbidity >10% (mean: 27.5%), and 10% of morbidity cases were defined as having a chronic post-thoracotomy pain (CPP). In the OTC Group, mean morbidity was 7.0±12.7% (0-52.1%), 44% had no morbidity. Out of the sample, 18.6% had morbidity >10% (mean: 28.6%). Signs of ICN were present in 14%. In both groups, the presence of ICN had a significant impact on and showed correlation with morbidity (p<0.0001). In terms of clinical judgement, the severity of the ArM after a CTT or OTC was generally mild except for one patient in each group. Age and follow-up were significantly different between groups (p<0.0001, p=0.02), but the intergroup difference in morbidity was not significant (p=0.08). CONCLUSIONS: ArM after open thoracic spinal surgery or VATS procedures can be assessed using the questionnaire. To put ArM of OTC into perspective, a Control Group with simple CTT was selected, demonstrating that morbidity was not different between the OTC and CTT groups. Patients with increased signs of ICN do worse which was reflected by increased morbidity in both groups. The study demonstrates that not only the cosmesis is not a concern for patients undergoing OTC, but neither is the ArM a concern, equalling that of a simple CTT.

Thoracolumbar spinal deformity: Part II. Developments from 1990 to today: historical vignette

In the first part of this 2-part historical review, the authors outlined the early diagnostic and therapeutic strategies used in the management of spinal deformity. In this second part, they expand upon those early innovations and further detail the advances from 1990 to the modern era.

Thoracoscopic anterior instrumented fusion for adolescent idiopathic scoliosis with emphasis on the sagittal plane

BACKGROUND CONTEXT

Anterior fusion through an open thoracotomy restores kyphosis more reliably than posterior techniques in patients with thoracic adolescent idiopathic scoliosis (AIS). Video-assisted thoracoscopic spinal fusion and instrumentation (VATS) minimizes the morbidity, from soft tissue and muscle dissection that accompanies traditional open thoracotomy. To our knowledge, there has not been a comprehensive analysis of VATS with respect to radiographic and clinical outcomes in the sagittal plane.

PURPOSE

To measure the radiographic and clinical outcomes after VATS with emphasis on the sagittal plane.

STUDY DESIGN/SETTING

A retrospective, radiographic review of 26 consecutive patients with Lenke type-I AIS who underwent VATS.

METHODS

Radiographs of 26 consecutive patients with Lenke type-I AIS curves operated by a single surgeon were retrospectively reviewed after VATS. Sagittal and coronal parameters were compared with reported data for open anterior and posterior procedures.

RESULTS

There was an increase in kyphosis from baseline to final follow-up by 6.6 degrees (25%) from T2 to T12 (p<.0001), 8.7 degrees (50%) from T5 to T12 (p<.0001), and 8 degrees (54%) in the instrumented segment (p<.0001). Junctional kyphosis did not occur. No differences were detected in sagittal measurements between the first postoperative erect and the final radiographs. Patients experienced significant improvements from baseline to 2 years in Scoliosis Research Society-22 Health-Related Quality-of-Life Outcome Questionnaire scores (p<.0001).

CONCLUSIONS

Video-assisted thoracoscopic spinal fusion and instrumentation, in agreement with results reported for open anterior instrumentation, reliably restores or increases thoracic kyphosis while preserving junctional alignment in thoracic AIS.

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.

Accuracy of thoracic vertebral screw insertion in adolescent idiopathic scoliosis: a comparison between thoracoscopic and mini-open thoracotomy approaches

STUDY DESIGN

A cross-sectional study with axial computed tomography (CT) to compare the accuracy of vertebral screw insertion in the thoracic spine for adolescent idiopathic scoliosis (AIS) between the thoracoscopic and the mini-open thoracotomy approach.

OBJECTIVE

To evaluate the safety of vertebral screw placement in anterior instrumentation for thoracic AIS.

SUMMARY OF BACKGROUND DATA

Thoracoscopic anterior instrumentation has been used with good results for AIS. It is technically demanding especially for the insertion of vertebral screws. The important issue of whether the screws inserted thoracoscopically is as accurate and safe as those inserted through thoracotomy approach has not been well studied.

METHODS

Thirty-one patients with thoracic AIS receiving thoracoscopic or mini-open thoracotomy anterior instrumentation were included in this study. They were divided into Group A and B, respectively. Postoperative sequential CT scanning on the thoracic vertebral screws was carried out. The relative position between screws and the spinal canal, the aorta, and the bicortical purchase were analyzed with CT images. The percentage of screws in good position was defined and further analyzed.

RESULTS

Seventy-three and 162 thoracic vertebral screws were inserted in 10 patients in Group A and 21 patients in Group B, respectively. Eighty-nine percent of screw tips in Group A and 80.2% in Group B were distant from the aorta, 89.0% and 87.0% of screws achieved bicortical purchase in Group A and B, respectively. No significant difference was found in all thoracic levels including the upper thoracic, periapical, or lower thoracic vertebrae. Seventy-four percent and 66.7% of screws were in good positions in Group A and B, respectively and there was no statistically significant difference between the 2 groups.

CONCLUSION

The vertebral screws inserted through thoracoscopic approach were as accurate as those inserted through a mini-open thoracotomy approach. The accuracy could be enhanced by using screws with smaller increments, with special attention to the possible migration of aorta with anterior spinal instrumentation.

Surgical treatment of main thoracic scoliosis with thoracoscopic anterior instrumentation. a five-year follow-up study

BACKGROUND

The surgical outcomes in patients with scoliosis at two years following anterior thoracoscopic spinal instrumentation and fusion have been reported. The purpose of this study was to evaluate the results at five years.

METHODS

A consecutive series of forty-one patients with major thoracic scoliosis treated with anterior thoracoscopic spinal instrumentation was evaluated at regular intervals. Prospectively collected data included patient demographics, radiographic measurements, clinical deformity measures, pulmonary function, an assessment of intervertebral fusion, and the scores on the Scoliosis Research Society (SRS-24) outcomes instrument. Perioperative and postoperative complications were recorded. Patient data for the preoperative, two-year, and five-year postoperative time points were compared. In addition, a univariate analysis compared selected two-year radiographic, pulmonary function, and SRS-24 data of the study cohort and those of the patients lost to follow-up.

RESULTS

Twenty-five (61%) of the original forty-one patients had five-year follow-up data and were included in the analysis. Between the two-year and five-year follow-up visits, no significant changes were observed with regard to the average percent correction of the major Cobb angle (56% +/- 11% and 52% +/- 14%, respectively), average total lung capacity as a percent of the predicted value (95% +/- 14% and 91% +/- 10%), and the average total SRS-24 score (4.2 +/- 0.4 and 4.1 +/- 0.7). Radiographic evaluation of intervertebral fusion at five years revealed convincing evidence of a fusion with remodeling and trabeculae present at 151 (97%) of the 155 instrumented motion segments. No postoperative infections or clinically relevant neurovascular complications were observed. Rod failure occurred in three patients, and three patients required a surgical revision with posterior spinal instrumentation and fusion.

CONCLUSIONS

Thoracoscopic anterior instrumentation for main thoracic idiopathic scoliosis results in five-year outcomes comparable with those reported previously for open anterior and posterior techniques. The radiographic findings, pulmonary function, and clinical measures remain stable between the two and five-year follow-up time points. Thoracoscopic instrumentation provides a viable alternative to treat spinal deformity; however, the risks of pseudarthrosis, hardware failure, and surgical revision should be considered along with the advantages of limited muscular dissection and improved scar appearance.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions to Authors for a complete description of levels of evidence.

Anterior exposures of the pediatric spine and posterior pedicle screw instrumentation

Treatment of spinal deformities, tumors, and trauma is greatly facilitated by correctly understanding the associated anatomy. Exposure of the spine, whether with a standard posterior dissection or a technically demanding costotransversectomy, facilitates surgical treatment of all disorders. When indicated, posterior instrumentation with pedicle screws allows for maximum rigidity and stability until arthrodesis ensues. Appropriate stepwise screw placement and confirmation of placement with radiographs and triggered electromyograms allows safe use of pedicle screws at all regions of the spine, with no associated morbidity to the patient. This article focuses on the classic approaches used to access the pediatric spine and discusses modern-day pedicle screw instrumentation for spinal pediatric deformity, trauma, or tumors.

Lenke 1C, King type II curves: surgical recommendations

The objectives of this article are twofold. The first is to discuss the surgical experience in patients who have Lenke 1C (King type II) curves, including the experience with newer instrumentation. These patients present a significant challenge to the deformity surgeon because they have structural thoracic deformities and significant, but nonstructural, lumbar curves. Over the years, selective instrumentation and fusion of the thoracic curve have been the primary approach to preserve motion of the lumbar segments, and thus, improve the long-term outlook. This strategy has been undertaken with the expectation that the uninstrumented lumbar curve will allow for a well-balanced spinal column postoperatively. The second objective of this article is to present basic strategies that may be helpful when planning for surgery in these patients.

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.

Thoracoscopic scoliosis surgery affects pulmonary function less than thoracotomy at 2 years postsurgery

STUDY DESIGN

Prospective evaluation of pulmonary function before and 2 years after surgery following anterior scoliosis instrumentation.

OBJECTIVES

To determine if thoracoscopic anterior scoliosis correction with instrumentation affected pulmonary function less than open thoracotomy approaches at 2 years follow-up.

SUMMARY OF BACKGROUND DATA

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.

METHODS

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).

RESULTS

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%.

CONCLUSIONS

This study shows a clear advantage to the minimally invasive thoracoscopic approach with regards to pulmonary function when compared with the open thoracotomy approaches.

Histomorphometric assessment of thoracoscopically assisted anterior release in a porcine model: safety and completeness of disc discectomy with surgeon learning curve

STUDY DESIGN

A retrospective study using histomorphometric analysis to quantify the percentage of discectomy following thoracoscopic anterior release and fusion in a porcine model.

OBJECTIVE

To investigate the safety and completeness of disc and endplate removal with respect to the learning curve of the surgeon in a porcine thoracoscopic anterior fusion model.

SUMMARY OF BACKGROUND DATA

The thoracoscopic approach has been used to perform an anterior release and fusion before an open posterior instrumentation, however, there is concern that the technique may not provide sufficient visualization or exposure to perform safely and completely.

METHODS

A total of 32 pigs (160 discs) were assigned to 2 groups (early experience, n = 16; late experience, n = 16), and underwent 5 level thoracoscopic anterior release followed by anterior instrumentation and fusion from T5 to T10. At 4 months after surgery, the spines were harvested, and each discectomy disc was histomorphometrically analyzed to determine the percentage of disc excision and amount of endplate removal.

RESULTS

There were no significant differences in the percent disc excision between the early (67% +/- 11%) and late groups (69% +/- 10%). Greater than 50% of the disc was excised in 151 of 160 discectomies (94%). Both superior and inferior endplates were resected in 92 of 160 disc levels (57%). The amount of endplate removal had improved over time in both early and late groups (P < 0.0001). The histologic examination revealed no evidence for posterior longitudinal ligament disruption or spinal canal encroachment in any disc.

CONCLUSIONS

Video-assisted thoracoscopic discectomy is safe and allows for a significant amount of disc material excision. This study did not demonstrate a learning curve with respect to the amount of disc material excised, but a learning curve was seen for endplate excision.

The position of the aorta relative to the spine before and after anterior instrumentation in right thoracic scoliosis

STUDY DESIGN

Preoperative magnetic resonance images (MRI) and postoperative axial computed tomography (CT) scans in 25 consecutive patients with idiopathic right thoracic adolescent scoliosis (AIS) and anterior correction and fusion with a dual rod system were analyzed in a prospective study.

OBJECTIVES

Evaluation of the spatial relations between the vertebral body and the aorta and the relative migration of the aorta due to the anterior correction and instrumentation in right thoracic scoliosis patients.

SUMMARY OF BACKGROUND DATA

In anterior scoliosis surgery, bicortical screw purchase is performed to increase pullout strength. However, impingement of the aorta due to excessive contralateral screw penetration has been reported, especially after endoscopic instrumentation. For a safe screw placement, knowledge of both the preoperative topographic relation of aorta and vertebral body and its changes due to surgical correction is crucial. Recent studies reported on a more lateral and posterior position of the aorta in AIS patients. However, there are hardly any data on the changes of the aortic position after anterior curve correction available in the current literature.

METHODS

All 25 patients underwent an identical anterior surgical technique with standard open approach and dual rod instrumentation of the primary curve. Preoperative MRI and postoperative sequential CT scans of 180 vertebrae were analyzed with respect to following parameters: vertebral body width and depth, diameter of the aorta, closest distance between aorta and the vertebral body, the aorta-vertebral angle, and the position of the aorta in relation to the spinal canal.

RESULTS

Before surgery, the aorta is positioned posterolaterally with an aorta-vertebral angle of between 78 degrees and 92 degrees (between T5 and T10). Between T11 and L2, the aorta is positioned more anteromedially with an aorta-vertebral angle from 62 degrees (T11) to 16 degrees (L2). After surgery, the aorta has migrated from a posterolateral to a more anteromedial position. This migration is maximal at the apex vertebra with an average change of the aorta-vertebral angle of 31.4 degrees . Whereas the distance between the aorta and the vertebral body increases at the upper and lower fusion levels, the aorta moves significantly closer to the vertebral body at the curve apex due to surgical correction. In patients with thoracic hypokyphosis, the aorta is positioned significantly more posterior than in patients with hyperkyphosis.

CONCLUSIONS

This MRI and CT based study of 25 patients with thoracic AIS treated by standard open dual rod and dual screw instrumentation demonstrates a migration of the aorta by 31 degrees from a more posterolateral position before surgery to a more anteromedial position after surgery at the curve apex. Scoliosis surgeons should be aware of these changes; any excessive contralateral screw penetration must be avoided at any level.

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.

Regional differences in anatomical landmarks for placing anterior instrumentation of the thoracic spine in both normal patients and patients with adolescent idiopathic scoliosis

STUDY DESIGN

A retrospective analysis of patients who had magnetic resonance imaging (MRI) of the thoracic spine, comparing those with a normal straight spine and those with a right thoracic adolescent idiopathic scoliosis (AIS).

OBJECTIVE

To analyze the position of the rib head with respect to the spinal canal and vertebral body in normal patients and those with right thoracic AIS using MRI.

SUMMARY OF BACKGROUND DATA

When placing anterior vertebral body screws in thoracic AIS, the most cephalad screws are most at risk for loosening because of smaller vertebral body size and the position of the rib heads, which may obscure more of the vertebral bodies. To our knowledge, there are no studies defining the relationship of the rib head to the vertebral anatomy in thoracic AIS.

METHODS

Transverse MRIs of the vertebral bodies from the 4th thoracic (T4) vertebra to the 12th thoracic (T12) vertebra in normal patients (n = 21) and patients with AIS (n = 21) group were analyzed regarding the following parameters: (1) percent vertebra obscured by rib head (i.e., the percent of the sagittal plane vertebral body length obscured by the overlapping rib head); (2) posterior safe angle, defined as the most posterior angle a screw can be placed, which avoids the spinal canal; and (3) anterior safe angle, defined as the most anteriorly directed screw trajectory that safely obtained good screw purchase.

RESULTS

In both the normal and AIS groups, the percent vertebra obscured by rib head significantly decreased from T4 (30% in normal group and 34.7% in AIS group) to T12 (-0.4% in normal group and 3.5% in AIS group) (P < 0.05). The rib head was positioned more anterior to the vertebral body in the cephalad-thoracic spine when compared to a more posterior position in the caudal thoracic spine. In each group, the posterior safe angle significantly decreased from T4 (23 degrees in normal group and 20.8 degrees in AIS group) to T12 (-0.9 degrees in normal group and 2.1 degrees in AIS group) (P < 0.05), while the anterior safe angle significantly increased from T4 (27.5 degrees in normal group and 26.6 degrees in AIS group) to T12 (38.3 degrees in normal group and 38.5 degrees in AIS group) (P < 0.05).

CONCLUSIONS

It is important to understand the relationship of the rib head to the vertebral body to provide-excellent screw purchase within the vertebral body without risking penetration into the spinal canal. In both normal and AIS groups, the relationship of the rib head to the vertebral body and spinal canal changes so that the rib head is positioned more anteriorly in the cephalad-thoracic spine and more posteriorly in the caudal thoracic spine. When placing anterior thoracic screws, at the cephalad- thoracic spine (T4, T5, T6, and T7), removal of rib heads is recommended to allow for good screw purchase. However, at the caudal thoracic spine (T10-T12), staying anterior to the rib head is important to avoid penetration into the spinal canal.

The learning curve associated with thoracoscopic spinal instrumentation

STUDY DESIGN

Consecutive case prospective radiographic and medical record review.

OBJECTIVE

To define the learning curve associated with thoracoscopic spinal instrumentation by evaluating operative data and early outcomes of 1 surgeon's (B.L.) cases.

SUMMARY OF BACKGROUND DATA

Thoracoscopic spinal instrumentation for the treatment of thoracic adolescent idiopathic scoliosis has emerged as an alternative to open anterior and posterior techniques. The technique is technically demanding and has been perceived as having a prohibitive learning curve.

METHODS

The operative reports, charts, and surgeon's database were used to evaluate operating time, estimated blood loss, levels fused, complication rate, blood transfusions, and curve correction, among other variables. For purposes of analysis, the entire cohort was divided into 2 groups of 28 and 29 patients, respectively, and then 4 groups of 14 patients (the last group with 15) were used for comparison.

RESULTS

The records of 57 patients were evaluated. No significant difference in estimated blood loss or number of levels fused was noted for either comparison (P = 0.46 and P = 0.66, respectively). There was no significant difference in blood transfusion requirements, with 7% in group 1 and 18% in group 2 (P = 0.35). Operating time was significantly less after 28 patients were operated on 6.2 +/- 1.3 hours versus 5.3 +/- 1.2 hours (P = 0.011). Percent curve correction was significantly better after 28 cases were performed, 54.4 +/- 17.9 in the former groups versus 65.7 +/- 10.4 in the latter half of cases (P = 0.005). Complications were evenly distributed throughout the series. No significant differences were observed between the 2 groups in terms of rate of complication (P = 0.50). No major complications, such as neurologic deficit or significant hemorrhage, were observed.

CONCLUSIONS

The learning curve associated with thoracoscopic spinal instrumentation appears to be acceptable. Significant differences were noted in operating time and percent curve correction after 28 cases. The complication rates remained stable throughout the surgeon's experience.

Neuroendoscopy for spinal disorders: a brief review

Neuroendoscopy has grown rapidly in the last 20 years as a therapeutic modality for treating a variety of spinal disorders. Spinal endoscopy has been widely used to treat patients with cervical, thoracic, and lumbosacral disorders safely and effectively. Although it is most commonly used with minimally invasive lumbar spine surgery, endoscopy has gained widespread acceptance for the treatment of thoracic disc herniations and for anterior release and rod implantation in the correction of thoracic spinal deformity. The authors review the use of endoscopy in spine surgery and in the treatment of spinal disorders as well as in the treatment of intrathoracic nonspinal lesions. Endoscopy has some significant advantages over open or other minimally invasive techniques in that it can allow for better visualization of the lesion, smaller incision sizes with reduced morbidity and mortality, reduced hospital stays, and ultimately lower cost. In addition, spinal endoscopy allows observers and operating room staff to be more involved in each case and fosters education. Spinal endoscopy, like any novel modality, carries with it additional risks and the surgeon must always be prepared to convert to an open procedure. The learning curve for spinal endoscopy is steep and the procedure should not be attempted alone by a novice surgeon. Nevertheless, with training and experience, the spine surgeon can achieve better outcomes, reduced morbidity, and better cosmesis with spinal endoscopy, and the operating times are comparable to open procedures. As technology evolves and more experience is obtained, neuroendoscopy will likely achieve further roles as a mainstay in spine surgery.

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.

Anterior dual rod instrumentation in idiopathic thoracic scoliosis: a computed tomography analysis of screw placement relative to the aorta and the spinal canal

STUDY DESIGN

Axial computed tomography scans (CT) in 20 consecutive patients with idiopathic right thoracic scoliosis and anterior correction and fusion with a dual rod dual screw system.

OBJECTIVES

CT evaluation of screw position in anterior dual rod instrumentation relative to the aorta and the spinal canal.

SUMMARY OF BACKGROUND DATA

In anterior scoliosis surgery, bicortical screw purchase is used to increase pullout strength. However, impingement of the aorta due to excessive contralateral screw penetration has been reported, especially after endoscopic instrumentation. Data on the accuracy of dual screw instrumentation in thoracic scoliosis are missing.

METHODS

All 20 patients underwent an identical anterior surgical technique with double thoracotomy approach and dual rod instrumentation of the primary curve. Postoperative sequential CT scans were analyzed with respect to following parameters: vertebral body width and depth, diameter of the aorta, distance from the aorta to the closest point of the vertebral body cortex, distance between the tip of the screws and the aorta, distance between the screw and the spinal canal, and the amount of contralateral screw penetration. A total amount of 226 screws were evaluated.

RESULTS

All screws were placed correctly without any critical proximity to the aorta or spinal canal. A total of 198 of 226 screws (88%) had a bicortical purchase. Thirteen screw tips (5.8%) were within 1 to 3 mm proximity to the aorta. All other screws were more than 3 mm distant from the aorta. The closest proximity of the screw tips to the thoracic aorta was found at the upper end vertebrae (T5, T6, or T7). There were no screws perforating the spinal canal.

CONCLUSION

Anterior instrumentation and correction of thoracic scoliosis with a dual rod dual screw system enable a correct and safe screw placement using a standard open approach. Excessive bicortical screw perforation should be avoided in order not to endanger the thoracic aorta.

Prospective evaluation of 50 consecutive scoliosis patients surgically treated with thoracoscopic anterior instrumentation

STUDY DESIGN

Prospective, consecutive, single-surgeon case series of patients treated for scoliosis with thoracoscopic anterior spinal instrumentation.

BACKGROUND

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.

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSION

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.

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.