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PubMed2003

Preclinical testing of a wedge-rod system for fusionless correction of scoliosis.

STUDY DESIGN: Biomechanical study. OBJECTIVES: This paper describes the biomechanical comparison of calf spines instrumented with a wedge alone versus a wedge-rod construct for the fusionless correction of scoliosis. SUMMARY OF BACKGROUND DATA: Current techniques for the correction of scoliosis require either anterior or posterior spinal fusion for correction. We propose a technique allowing correction via vertebral body osteotomies along with fixation using a wedge-rod construct without the requirement of intervertebral segment fusion. METHODS: Calf spines were used to test the biomechanical difference between the intact spine, transverse osteotomized spine with wedge-rod reconstruction, and transverse osteotomized spine with wedge alone reconstruction. Unconstrained segments (L1-L5) were first tested under five nondestructive static loading conditions to evaluate the intact stability of the operative motion segments in axial compression (-600 N), axial rotation (+/-5.0 Nm, 150 axial preload), flexion and extension (+/-5.0 Nm), and lateral bending (+/-5.0 Nm). Following the intact analysis, vertebral wedge osteotomies in the transverse plane were performed at the L2, L3, and L4 levels. The defects were reconstructed using the Sofamor Danek Wedge Spacer, and stainless steel TSRH one-quarter inch single rod with modified CD HORIZON 6.5-mm diameter vertebral body screws at each level (L2-L4). Standard CD HORIZON 6.5-mm bone screws and staples were used at the superior and inferior ends of the five-level construct. The wedge was on the left side and the rod and screw heads on the right side. After testing the reconstructed specimen, the TSRH rod was removed and the construct retested to evaluate the stability of the wedge alone reconstruction. RESULTS: Construct stiffness was calculated as the peak applied load (N or Nm) divided by the corresponding segmental displacement (mm or degrees) normalized to the intact specimen. Reconstruction static data are expressed as a percentage change from the intact condition. Statistical analysis included descriptives, a one-way analysis of variance, and the Student-Newman-Keuls test for multiple comparisons among the reconstruction groups. Axial compression: under axial compressive loads, the stiffness of the wedge-rod construct was approximately equal to that of the intact group. The stiffness of the wedge alone construct was 56% less than that of the intact group except for extension and left lateral bending. For the other modes of loading (right rotation, left rotation, flexion, extension, right lateral bending, and left lateral bending), the wedge-rod construct was stiffer than that of the intact group. The stiffness of the wedge alone construct was consistently less than that of the intact group. CONCLUSIONS: Based on the results of this biomechanical comparison, the calf spines instrumented with the wedge-rod system for fusionless correction were significantly stiffer as compared to the intact calf spine. The wedges alone were not as stiff as the intact spine. This suggests that the theory of performing transverse osteotomies of vertebral bodies with fixation with wedge-rod construct for 8 to 12 weeks, followed by removal of the rod, could provide adequate fixation and correction of a scoliotic deformity without requiring fusion of motion segments.

Animals↗
PubMed2003

Adolescent idiopathic scoliosis: case report with 63-year follow-up postsurgery.

STUDY DESIGN: Retrospective case report. PURPOSE: To provide true outcome analysis by a 63-year follow-up. MATERIAL AND METHODS: A 16-year-old girl had a posterior spine fusion for adolescent idiopathic scoliosis in 1939 and has been followed ever since. Both original photographs and radiographs as well as current material are available. BACKGROUND INFORMATION: A follow-up of this duration has not previously been reported. RESULTS: She had a solid T9-L3 arthrodesis and had no problems until age 50 when degenerative changes at L3-L4 required extension of the fusion to L4. When seen in 2002 at age 79, she had problems with degenerative disc disease at L4-S1 with spinal stenosis symptoms. CONCLUSIONS: The original fusion area remained solid and without symptoms for 63 years. Distal degenerative changes began 34 years after her original surgery and are still present at the 63-year follow-up. These degenerative changes at L4-L5 and L5-S1 are often thought to be secondary to the arthrodesis to L4, but because they are extremely common in persons of this age who do not have scoliosis or a fusion mass to L4, it is not possible to imply a cause and effect relationship. True outcome results cannot be ascertained at a 2-year or even 10-year follow-up.

Adolescent↗
PubMed2004

Biomechanical evaluation of the Boston brace system for the treatment of adolescent idiopathic scoliosis: relationship between strap tension and brace interface forces.

STUDY DESIGN: Prospective study to evaluate the association between strap tension and brace interface forces in the treatment of adolescent idiopathic scoliosis using the Boston brace system. OBJECTIVES: To determine the strap tension associated with optimal brace interface forces. SUMMARY OF BACKGROUND DATA: Trim lines, pad placement, and areas of relief for the brace are guided by radiographic studies. However, optimal adjustment of strap tension is unclear and remains mostly empirical. METHODS: Brace interface forces in all regions of the trunk were measured for 41 patients with adolescent idiopathic scoliosis at three standardized strap tensions (20 N, 40 N, and 60 N). The brace interface forces were assessed using a mat made of force-sensing transducers. Equivalent interface pressure for each trunk region was also calculated to estimate the distribution of the interface forces. RESULTS: The brace interface forces and the corresponding effective areas increased along with the strap tension for all patients. For patients with a single right thoracic curve, the interface pressure tended to increase with increasing strap tension. This increase was significant in the left axillary, right thoracic, right pelvic, and sternal regions. For double right thoracic-left lumbar curves, the increase in interface pressure was significant in the left axillary, right pelvic, and sternal regions. However, most of this increase occurred between 20 N and 40 N of strap tension, with only slight increase or even a decrease in interface pressures between 40 N and 60 N. CONCLUSIONS: The strap tension should be set as high as possible (up to 60 N) for right thoracic curves. For right thoracic-left lumbar curves, the optimal strap tension was approximately 40 N. However, clinicians should ensure that the prescribed strap tension does not cause excessive skin pressure or affect the compliance with the brace. A side opening in the right lumbar area may improve the effectiveness of the brace for double right thoracic-left lumbar curves, but care must be taken to avoid skin problems at the opening.

Adolescent↗
PubMed2004

Analysis of screw placement relative to the aorta and spinal canal following anterior instrumentation for thoracic idiopathic scoliosis.

STUDY DESIGN: Axial computed tomographic (CT) evaluation of the position of anterior vertebral body screws placed thoracoscopically in patients with adolescent idiopathic scoliosis (AIS). OBJECTIVE: To evaluate the position of the anterior vertebral body screws relative to the spinal canal and the thoracic aorta following anterior spinal fusion and instrumentation for AIS. SUMMARY OF BACKGROUND DATA: Thoracoscopic anterior instrumentation and fusion is gaining more widespread use in the treatment of idiopathic scoliosis. However, the accuracy in the positioning of instrumentation has not been previously studied for this technically difficult surgery. METHODS: CT examinations were performed following thoracoscopic anterior spinal fusion and instrumentation in 14 patients with right thoracic AIS. The vertebral body width (transverse dimension) and depth (anterior-posterior dimension) was measured for each thoracic vertebra. At each instrumented level, the position of the screw was analyzed to determine its proximity to the spinal canal and the aorta. The distance from the anterior cortex of the spinal canal to the posterior edge of the screw was measured. The position of each screw relative to the aorta was determined: D, the screw tip was distant to the aorta; A, the screw tip was adjacent to the aorta; C, the screw tip was felt to be against the aorta and creating some contour deformity on the outer wall of the aorta. RESULTS: All 14 patients were female and had a single right thoracic curve. The average age of the patients was 13.3 years (range 12.4-15.1 years). The average preoperative coronal Cobb measurement was 55.9 degrees (bending 26.4 degrees) with correction to 8.9 degrees at 2 years after surgery. The average number of levels fused was 6.6 (range 5-8) and a total of 106 screws were used (average 7.6/patient). The width of the vertebral bodies increased from T4 (24.0 mm) to T12 (33.6 mm), increasing an average of 1.2 mm per level, while the depth increased from 17.7 mm at T4 to 25.5 mm at T12. The average distance from the posterior aspect of the screw to the spinal canal was 5.3 mm (range-1.2 to 11.4 mm). There were no neurologic deficits in any patient. When analyzing the position of the screw tip relative to the aorta, 78 (73.6%) screws were distant from the aorta, 15 (14.2%) were adjacent to the aorta, and there were 13 (12.3%) screws that were thought to create a contour deformity of the aorta. There were no vascular complications at 2 years after surgery. CONCLUSIONS: Thoracoscopic instrumentation and fusion is technically demanding and relies on adequate visualization for accurate screw placement. The vertebral body width and depth are consistent between patients, with the vertebral body width increasing approximately 1.2 mm when progressing down the thoracic spine. Safe screw placement was achieved with adequate distance from the spinal canal; however, close screw proximity to the aorta was seen. The aorta was positioned on the left lateral aspect of the vertebral body in these patients, making anterior screw placement challenging in right thoracic AIS.

Adolescent↗
PubMed2004

The Spanish version of the SRS-22 patient questionnaire for idiopathic scoliosis: transcultural adaptation and reliability analysis.

STUDY DESIGN: Validation of the transcultural adaptation of a questionnaire for measuring health-related quality of life. OBJECTIVES: To translate and culturally adapt the SRS-22 questionnaire to Spanish. To determine the metric qualities (internal consistency and test-retest reproducibility) of this questionnaire. SUMMARY OF BACKGROUND DATA: The SRS-22 Patient Questionnaire has proven to be a valid instrument for clinical assessment of patients with idiopathic scoliosis. The widespread use of the SRS-22 in non-English-speaking countries requires its transcultural adaptation. METHODS: Transcultural adaptation of the SRS-22 was carried out according to the International Quality of Life Assessment Project guidelines and included two translations and two back-translations of the material. A committee of experts decided on the final version. The questionnaire was administered to 175 individuals (152 women and 23 men) with idiopathic scoliosis. The mean age of the participants at the time they received the questionnaire was 18.9 years, thoracic curve magnitude was 28.8 degrees, and lumbar curve magnitude was 28.1 degrees. At this time, 85 patients had been treated surgically, 45 had been treated with orthesis, and 45 were under observation. A subgroup of 30 patients completed the questionnaire a second time 1 week later. Internal consistency was determined with Cronbach's alpha coefficient and test-retest reliability with the intraclass correlation coefficient. RESULTS: The overall alpha coefficient of the questionnaire was 0.89. Coefficients for individual domains were as follows: function/activity, 0.67; pain, 0.81; mental health, 0.83; self-image, 0.73; and satisfaction, 0.78. The questionnaire as a whole had an intraclass correlation coefficient of 0.96. Intraclass correlation coefficients for individual domains were as follows: pain, 0.93; function, 0.82; self-image, 0.94; mental health, 0.94; and satisfaction, 0.98. CONCLUSIONS: The Spanish version of the SRS-22 Patient Questionnaire demonstrated adequate internal consistency for the majority of domains and excellent reproducibility. These results suggest that the process of adaptation has produced an instrument that is apparently equivalent to the original and suitable for clinical research.

Adolescent↗
PubMed2004

Safety and efficacy of Isola instrumentation and arthrodesis for adolescent idiopathic scoliosis: two- to 12-year follow-up.

STUDY DESIGN: Retrospective case series including patient outcome assessment. OBJECTIVE: To study the safety and efficacy of Isola instrumentation in comparison with similar series. SUMMARY OF BACKGROUND DATA: Both the technique and technology used in the surgical treatment of adolescent idiopathic scoliosis continue to evolve, the common theme since the 1980s being provision of instrumentation stable and strong enough to eliminate the need for postoperative immobilization. The purpose of this study is to determine the safety and efficacy of a system deliberately integrating hook, wire, and screw anchors to deliver torsional and countertorsional corrective loads. METHODS: A total of 185 consecutive patients, index patient included, were treated by posterior instrumentation and arthrodesis from January 1989 through December 2000. Safety was studied by complications, and reoperation type and occurrence. Effectiveness was studied by deformity correction and health-related quality of life questionnaire response. Variables affecting effectiveness were sought. A total of 179 patients (97%) had outcome assessment at an average of 6 years postoperative, and 176 had radiographic evaluation at an average of 5 years postoperative. RESULTS: There were no deaths, spinal cord or nerve root problems, or acute posterior wound infections. Proven pseudarthrosis occurred in 4 patients (2.2%) and delayed deep wound infection in 2 patients (1.1%). The implant-related reoperation rate was 8% and was necessary more often in the first quarter of the series (17% vs. 4.6%, P = 0.0062). The largest Cobb angle averaged 62 degrees preoperative and 23 degrees at latest follow-up, 63% correction. The largest angle of trunk inclination averaged 16.7 degrees before surgery and 9.9 degrees at latest follow-up, a 39% correction (P < 0.0001). Eighty-eight percent of patients were satisfied or very satisfied with the outcome. The principal problems identified were the need for a stronger transverse connector, stable end-instrumented vertebrae foundations, and convex thoracic anchorage. CONCLUSIONS: Isola instrumentation seems to be at least as safe and effective as other instrumentations being used for the surgical treatment of adolescent idiopathic scoliosis.

Adolescent↗
PubMed2004

Cotrel-Dubousset (CD) or Universal Spine System (USS) instrumentation in adolescent idiopathic scoliosis (AIS): comparison of midterm clinical, functional, and radiologic outcomes.

STUDY DESIGN: A retrospective comparison of the clinical, radiologic, and functional results of Cotrell-Dubousset (CD) and Universal Spine System (USS) instrumentation for adolescent idiopathic scoliosis (AIS). OBJECTIVES: To establish whether there are any differences in outcome between the 2 instrumentation systems. SUMMARY OF BACKGROUND DATA: CD is the first complex posterior double rod instrumentation system to provide multiple hook fixation. USS instrumentation permits the use of rod translation instead of rod rotation, the option to secure pedicle hooks with fixation screws, and the option to use transpedicular screws in the lower thoracic and lumbar spine. Midterm and long-term results of USS instrumentation are lacking. METHODS: Fifty-seven (mean age, 28 years at follow up) patients treated with CD instrumentation and 55 (mean age, 23 years at follow up) patients treated with USS instrumentation for AIS participated in the study. The average follow-up rate was 80% and time 13.0 years for the CD group, and 95% and 7.8 years for the USS group. Radiographs were obtained before surgery, at 2-year follow up, and at final follow up. Additionally, a physical examination was performed by 2 independent observers, and the Scoliosis Research Society (SRS) questionnaire was completed; spinal mobility and nondynamometric trunk strength were measured at the final follow-up visit. RESULTS.: The mean Cobb angle of the instrumented thoracic curve was before surgery 55 degrees (range, 36-83 degrees for the CD and 52 degrees (range, 35-85 degrees) for the USS group. The mean number of instrumented vertebrae was 9.9 (range, 7-12) in the CD and 9.8 (range, 6-12) in the USS group. At final follow up, the mean angles were 32 degrees (range, 13-63 degrees) for the CD group and 29 degrees (range, 9-63 degrees) for the USS group (not significant). No significant difference was observed in thoracic kyphosis or lumbar lordosis between the study groups at final follow up. In the SRS questionnaire, the total score averaged 97 for the CD and 101 for the USS groups, respectively. In the questionnaire, 6 (11%) patients in the CD group, but none in the USS group, reported having low back pain often or very often at rest. No correlation was found between the Cobb angle of the thoracic or lumbar curves at follow up and the total score or back pain indexes of this questionnaire. Nondynamometric trunk strength measurements corresponded with age- and sex-adjusted reference values, on average, but patients in the CD group performed significantly better in the squatting test (P = 0.021) and patients in the USS group performed better in trunk side bending (P = 0.004). Complications were recorded in 15 (26%) patients in the CD and in 13 (24%) patients in the USS group (not significant). CONCLUSIONS: The midterm radiologic and functional outcomes were quite similar in both groups as were the SRS scores. The patients performed, on average, as well as did the reference population in nondynamometric trunk strength measurements. Intraoperative and late complications were similar in both groups.

Adult↗
PubMed2004

Evaluation of a functional position for lateral radiograph acquisition in adolescent idiopathic scoliosis.

STUDY DESIGN: A retrospective examination of lateral spine radiographs of 50 patients with adolescent idiopathic scoliosis (AIS) was performed to evaluate the sagittal profile of patients in two different standing positions. OBJECTIVES: To evaluate segmental and global changes in the sagittal profile of the spine associated with two standing radiographic positions and determine if one position represents a more functional stance for accurate sagittal balance evaluation. SUMMARY OF BACKGROUND DATA: Studies of spinal sagittal balance during relaxed standing have indicated that the sagittal vertical axis (SVA), as determine by the horizontal displacement of a C7 plumb line from the posterior superior corner of the sacrum, is neutral or slightly positive. However, standing with the arms forward flexed to allow radiographic visualization of the spine results in a negative shift in SVA. METHODS.: Measurements were obtained from standing lateral radiographs in patients with AIS in two different standing positions: arms forward flexed to 45 degrees with elbows fully extended versus elbows fully flexed with fists resting on clavicles. Sagittal plane parameters were analyzed using correlation analyses and repeated-measures analyses of variance with significance set at 0.005. RESULTS: The study cohort included 25 patients who had undergone solely nonoperative treatment (without progression) and 25 patients who had undergone operative intervention for their scoliosis. In all patients, SVA was more negative (C7 shifted more posterior with respect to the sacrum) when the arms were in the forward flexed position compared to the fists on clavicles position (-4.2 +/- 2.5 cm vs. -1.3 +/- 2.4 cm, P < 0.001). In operative patients, the shoulder forward flexed position was associated with relative posterior rotation of the pelvis represented by an average increase of 2.7 +/- 3.8 degrees in pelvic tilt (P = 0.002) and an average decrease of 3.2 +/- 4.5 degrees in sacral slope (P = 0.002). There was no correlation between the degree of arm forward flexion and changes in sagittal measures between the two positions. CONCLUSIONS: The fists on clavicles position for lateral radiograph acquisition has less negative shift in SVA, and in patients with spinal instrumentation, less compensatory posterior rotation of the pelvis. This position is more representative of a patient's functional balance while still allowing adequate lateral radiographic visualization of the spine.

Adolescent↗
PubMed2005

The role of preoperative pulmonary function tests in the surgical treatment of scoliosis.

STUDY DESIGN: A retrospective study on the correlation between preoperative pulmonary function tests, preoperative pulmonary symptoms, and postoperative pulmonary complications. OBJECTIVE: To evaluate the incidence of immediate postoperative pulmonary complications and their correlation to pulmonary function tests, preoperative pulmonary symptoms, and surgical approaches. SUMMARY OF BACKGROUND DATA: The pulmonary function of patients with scoliosis is likely to be abnormal, whereas surgical procedures may lead to further deterioration and postoperative pulmonary complications. Evaluation of the pulmonary symptoms and pulmonary function before surgery is helpful to predict and avoid postoperative pulmonary complications by selecting the appropriate surgical approach. METHODS: This study reviewed 298 scoliosis patients (107 male, 191 female) who underwent anterior and/or posterior operation. The mean age of the patients was 16.4 years (range 6-62 years). The average coronal Cobb angle was 73.26 degrees (range 45-141 degrees). Preoperative pulmonary function tests of 115 cases were normal, whereas the other 183 cases were abnormal. Seventeen cases had preoperative pulmonary symptoms and 3 of them had normal preoperative pulmonary function tests. Seventy-nine cases received transthoracic surgery, and 19 cases had postoperative pulmonary complications, including postoperative ventilation support in 6 cases, atelectasis in 4 cases, hydrothorax in 2 cases, pneumothorax in 3 cases, pneumonia in 3 cases, and hypoxemia in 1 case. Of these 19 patients, 12 patients received anterior transthoracic procedure. When the patients with abnormal pulmonary function tests were divided into 3 groups: 1) 60% < or = forced vital capacity ratio < 80%; 2) 40% < or = forced vital capacity ratio < 60%; and 3) forced vital capacity ratio < 40%, the incidence of postoperative pulmonary complications were 2.72% (3 out of 110), 7.40% (4 out of 54) and 31.60% (6 out of 19), respectively. RESULTS: There was significant correlation between abnormal preoperative pulmonary function tests and preoperative pulmonary symptoms (P = 0.0086). No significant correlation was found between preoperative pulmonary symptoms and postoperative pulmonary complications (P = 0.5164). There was a trend that the postoperative complications increased with the deterioration of pulmonary function. The correlation between postoperative pulmonary complications and the surgical approach was statistically significant (P = 0.0000); the incidence of postoperative pulmonary complication of transthoracic procedure was 18 times as that of posterior approach. No significant difference was noted regarding ages, preoperative coronal Cobb angles, and preoperative pulmonary function between these 2 groups. There was no significant correlation between preoperative pulmonary symptoms and postoperative complications. CONCLUSIONS: The incidence of postoperative pulmonary complications increased with the deterioration of pulmonary function tests. The posterior procedure had a very low incidence of postoperative pulmonary complications, but a transthoracic procedure increased the complications significantly. Preoperative pulmonary symptoms usually predicted abnormal results of pulmonary function tests but had no correlation with postoperative pulmonary complication.

Adolescent↗
PubMed2005

The memory properties of cold-worked titanium rods in scoliosis constructs.

STUDY DESIGN: Time series monitoring changes in titanium and stainless steel rod curvature kept at a constant temperature of 37 C as a function of time. OBJECTIVES: To assess the possibility of loss of curvature in titanium rods after scoliosis surgery. SUMMARY OF BACKGROUND DATA: Titanium rods have gained use in scoliosis surgery due to their excellent biocompatibility, while allowing medical personnel to obtain undistorted magnetic resonance imaging scans following surgery. However, the impression of several clinicians has been that when screw pullout and/or loss of sagittal balance occurs, it may be due to the rods losing some of their curvature. METHODS: Five 6-mm rods of differing compositions and lengths (titanium 300 and 100 mm, stainless steel 300 and 100 mm, prebent titanium 85 mm) were bent at room temperature with a 3-point rod bender, then placed in an incubator at 37 C. Digital photographs were taken every 2 weeks and analyzed to extract the radius of curvature of each rod. RESULTS: The Ti rods had a significantly decreasing curvature with time. The prebent Ti and stainless steel rods did not exhibit significant change in curvature. CONCLUSIONS: Titanium rods bent at room temperature and then exposed to body temperature over time tend to exhibit "metal memory"; they gradually revert to their original shape. This may result in loss of sagittal balance and/or proximal screw pullout.

Bone Nails↗
PubMed2005

Orthoses for mild scoliosis: a prospective study comparing traditional plaster mold manufacturing with fast, noncontact, 3-dimensional acquisition.

STUDY DESIGN: A prospective comparison of 2 different methods to make orthoses in mild scoliosis. OBJECTIVE: To evaluate the therapeutic efficiency of orthoses made by a computer-aided design procedure. SUMMARY OF BACKGROUND DATA: It is now possible to make orthoses by a computer-aided design procedure. In order to evaluate this new method, we carried out a comparative study between the traditional and computer-aided design-manufactured orthoses. METHODS: In this prospective study, we compared the 2 methods by studying the cases of 30 adolescents with mild scoliosis. For each patient requiring orthopaedic treatment, we made 2 ortheses: 1 using the traditional method and 1 using the computer-aided design method. There were 26 girls and 4 boys whose average age was 13 years and 3 months. Each body jacket was successively used in random order following the same protocol. Neither the prescriber nor the patient knew the origin of the orthosis used. The final choice of the orthosis was made using 3 criteria: first, improvement of the scoliotic curves on the frontal and lateral radiologic planes, and second, the patient's impression of comfort. RESULTS: For the 30 cases, 13 traditional and 16 computer-aided design body jackets were chosen. In 1 case, no significant difference allowed us to chose one body jacket rather than the other. For the frontal radiologic correction, the better results were obtained 3 times with the computer-aided design body jacket, 5 times with the traditional one, and in 22 cases, the results were equivalent. For the lateral radiologic correction, the better results were obtained 11 times with the computer-aided design body jacket, 3 times with the traditional one, and in 16 cases, the results were equivalent. For the comfort of the 2 body jackets for each patient, the better results were obtained 12 times with the computer-aided design body jacket, 8 times with the traditional one, and in 10 cases, the results were equivalent. CONCLUSION: Based on our results, we believe that the computer-aided design procedure is equally efficient to traditional method for mild scoliotic curves.

Adolescent↗
PubMed2005

Does gender affect outcome of surgery in adolescent idiopathic scoliosis?

STUDY DESIGN: A retrospective follow-up study comparing 2 matched groups. OBJECTIVE: To compare long-term results of operative treatment of adolescent idiopathic scoliosis (AIS) between males and females matched for age, curve magnitude and type, and the instrumentation used. SUMMARY OF BACKGROUND DATA: It has been suggested that in AIS, the spine is more rigid in males than in females, because brace treatment fails to halt progression of the curves in males. However, there are no studies comparing the results of surgical treatment of AIS between males and females. METHODS: Thirty male and female pairs were matched for age (+/-1 year), major curve magnitude (+/-5 degrees), curve type according to the King classification, and the instrumentation used (Harrington in 11 pairs, Cotrel-Dubousset in 9 pairs, and Universal Spine System in 10 pairs). The mean age at the time of operation was 16.2 +/- 2.6 years for the males and 15.5 +/- 2.3 years for the females. The mean follow-up times were 14.3 years (range 6.7-23.0 years) and 14.1 year (range 6.4-23.7 years), respectively. Radiographs were obtained presurgery and after surgery, at the 2-year follow-up assessment, and at the final follow-up visit. In addition, a physical examination was performed, and the Scoliosis Research Society (SRS) questionnaire was completed. Spine mobility and nondynamometric trunk strength were measured at the final follow-up visit. RESULTS: Before surgery, the mean Cobb angle of the thoracic curve was 55 degrees (range 42-83 degrees) in the males and 56 degrees (range 43-80 degrees) in the females. In bending radiographs, the major curve reduced significantly more in females than in males (P = 0.027). The mean angles of the thoracic and lumbar curves were similar at all follow-up visits. The final correction of the thoracic curves was 30% (range -19-65%) in the males and 33% (range -7-71%) in the females (not significant). No significant difference was observed in thoracic kyphosis or lumbar lordosis between the study groups at the final follow-up. The total SRS questionnaire score averaged 96 (range 66-113) in the males and 95 (range 75-108) in the females. None of the males and 2 of the females reported back pain often or very often in the questionnaire. Nondynamometric trunk strength measurements corresponded with reference values, on average, and were similar in both groups. Abnormal trunk side bending tended to be more common in the males than in the females (43% vs. 23%, P = 0.10, not significant). CONCLUSIONS: Curves in males appear to be more rigid than in females with AIS. However, posterior surgery for AIS provides similar short and long-term results in males and females.

Adolescent↗
PubMed2005

Assessment of trunk balance in thoracic scoliosis.

STUDY DESIGN: A retrospective radiographic review was undertaken in patients with idiopathic thoracic scoliosis. OBJECTIVES: To determine if a mathematical relationship exists between the 2 methods used to assess trunk balance (lateral trunk shift [LTS] and thoracic apical vertebral translation [AVT]), and to determine if one of these measurements can satisfactorily predict the value of the other. SUMMARY OF BACKGROUND DATA: No previous reports exist, to our knowledge, comparing these 2 methods used to asess trunk balance. METHODS: Coronal balance (CB), LTS, thoracic AVT, and curve magnitude were measured from standing preoperative posteroanterior radiographs of 91 patients with Lenke 1A/1B curves. The data were analyzed to determine if predictive relationships existed between LTS and thoracic AVT alone or between LTS and the sum of CB and thoracic AVT. RESULTS: A statistically significant relationship was shown between LTS and the sum of thoracic AVT and CB. In general, the LTS can be estimated by taking two thirds of the sum of thoracic AVT and CB (in centimeters) and subtracting 0.8. This relationship weakened as CB improved. The relationship between LTS and AVT was not statistically significant when CB was excluded. CONCLUSIONS: In patients with thoracic idiopathic scoliosis, if the CB and thoracic AVT values are known, then the LTS can be reliably estimated. The use of correct terminology for describing trunk balance and CB is important if valid comparisons of spinal deformity literature are desired.

Adolescent↗
PubMed2005

Assessment of curve flexibility in adolescent idiopathic scoliosis.

STUDY DESIGN: A prospective comparative evaluation of the commonly accepted or described radiologic techniques to determine curve flexibility in adolescent idiopathic scoliosis (AIS), comparison of the results to those obtained by supine traction radiographs taken with the patient under general anesthesia (UGA) just before surgery and correlation of all findings to surgical correction. OBJECTIVE: To determine if supine traction radiographs taken with the patient UGA help provide better assessment of curve flexibility and better predicting surgical correction. SUMMARY OF BACKGROUND DATA: Supine lateral bending radiographs are the standard methods of evaluating curve flexibility before surgery in idiopathic scoliosis. Supine traction radiographs have also been used at the authors' institution in addition to the supine lateral bending radiographs before surgery, believing that it is usually more helpful to analyze the response of the main and compensatory curves to corrective forces. METHODS: A total of 34 consecutive patients with AIS who had surgical treatment were studied. Preoperative radiologic evaluation consisted of standing anteroposterior and lateral, supine lateral bending and traction, fulcrum bending radiographs, and also supine traction radiographs taken with the patient UGA just before surgery. All structural curves were measured, and the flexibility ratio was determined on each radiograph. The amount of correction obtained by all radiographic methods was compared with the amount of surgical correction by evaluating the differences from surgery as absolute values. Mean absolute differences from surgery were used to determine the confidence intervals. Statistical differences were calculated with the comparison of the exact 95% confidence intervals for the mean. RESULTS: Curves were accepted to be moderate if between 40 degrees and 65 degrees (29 patients) and severe if >65 degrees (5 patients). In these 29 patients, average frontal Cobb angle of the thoracic and lumbar curves were 49.7 degrees (range 40 degrees-60 degrees) and 39.4 degrees (range 22 degrees-58 degrees), respectively. For the moderate thoracic curves, fulcrum radiographs provided the best amount of flexibility, with no significant difference from traction with the patient UGA but with significant difference from bending radiographs. For the moderate lumbar curves, flexibility obtained by fulcrum and bending radiographs were significantly better than traction radiographs with the patient UGA. For the lumbar and thoracic curves more than 65 degrees, traction radiographs with the patient UGA provided clearly better flexibility compared to bending and fulcrum radiographs, however, the number of patients is not enough to determine whether the differences are statistically significant. Better flexibility in traction radiographs with the patient UGA helped us eliminate the need for anterior release in all 5 patients who had severe and rigid curves more than 65 degrees, which did not bend to less than 40 degrees and were planned to have anterior release. CONCLUSION: Fulcrum higher than bending higher than traction with the patient UGA is the order of radiographs for better predicting flexibility and correction in curves between 40 degrees and 65 degrees. Flexibility obtained at traction radiographs with the patient UGA is clearly better in numerical values, and closer to the amount of surgical correction than the amount of flexibility at fulcrum and side-bending radiographs for curves larger than 65 degrees, although not statistically significant as a result of the small number of patients in this group. However, pedicle screw instrumentation provides even more correction than the traction radiographs with the patient UGA. Thus, traction radiographs with the patient UGA may show much better flexibility, especially in more than 65 degrees and rigid curves.

Adolescent↗
PubMed2005

The role of amicar in decreasing perioperative blood loss in idiopathic scoliosis.

STUDY DESIGN: Four separate studies on the role of Amicar in decreasing perioperative blood loss in idiopathic scoliosis. OBJECTIVES: To assess the efficacy and possible mechanisms of action for Amicar. SUMMARY OF BACKGROUND DATA: Preliminary prospective, randomized double-blind and analysis of same-day anterior spinal fusion (ASF), fibrinogen, and posterior spinal fusion (PSF) studies have demonstrated Amicar to be effective in idiopathic scoliosis surgery. Increased fibrinogen secretion is a possible explanation. METHODS: Amicar is administered at 100 mg/kg over 15 minutes not to exceed 5 g at anesthesia induction. Maintenance is 10 mg/kg per hour until wound closure. RESULTS: Preliminary study: Amicar (N = 28) was effective compared with a control group (N = 31). Perioperative blood loss and transfusion following PSF were 1,604 +/- 517 mL and 1.1 +/- 1.0 U in the Amicar group compared with 2,312 +/- 994 mL and 2.1 +/- 1.1 U in the control group (P < 0.003). Prospective, randomized double-blind study confirmed this efficacy, although primarily in postoperative suction drainage: 1,391 +/- 212 mL and 1.1 +/- 1.0 U compared with 1,716 +/- 513 mL and 2.1 +/- 1.3 U (P < 0.002). A fibrinogen study (N = 21) demonstrated steady and excessive increase following PSF: before surgery it was 266 +/- 63 mg/dL and on the fifth postoperative day 699 +/- 94 mg/dL. In same-day anterior and posterior spinal surgery, Amicar was again effective, but primarily in decreasing chest tube drainage and during PSF. Group 1 (N = 15, no Amicar) 3,807 +/- 105 mL and 3.1 +/- 1.5 U; Group 2 (N = 27, Amicar for PSF only) 2,080 +/- 659 mL and 1.9 +/- 0.9 U; and Group 3 (N = 16, both ASF and PSF) 2,183 +/- 851 mL and 1.0 +/- 0.8 U. CONCLUSIONS: Amicar appears highly effective in decreasing perioperative blood loss. This results in less autologous blood donation, blood transfusion, costs, and complications. Its mechanism of action is uncertain but may be related to increased fibrinogen secretion.

Adolescent↗
PubMed2005

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.

Adolescent↗
PubMed2005

Proximal junctional kyphosis in adolescent idiopathic scoliosis following segmental posterior spinal instrumentation and fusion: minimum 5-year follow-up.

STUDY DESIGN: A retrospective study. OBJECTIVE: To analyze the long-term proximal junctional change in adolescent idiopathic scoliosis (AIS) following segmental posterior spinal instrumentation and fusion 5 years or more after surgery. SUMMARY OF BACKGROUND DATA: No study has concentrated on time-dependent long-term proximal junctional change in AIS following segmental posterior spinal instrumentation and fusion after 5 years postoperation. Risk factors for developing proximal junctional kyphosis (PJK) are unknown. METHODS: A total of 193 consecutive AIS patients with a minimum 5-year follow-up (average, 7.3 years; range, 5-16.7 years) treated with segmental posterior spinal instrumentation and fusion were evaluated. Radiographic measurements analyzed included sagittal Cobb angle at the proximal junction on preoperative, early postoperation, 2-year postoperation, and final follow-up (> or = 5 years) by standing long cassette radiographs. Postoperative Scoliosis Research Society (SRS)-24 outcome scores were also evaluated. Abnormal PJK was defined as the final proximal junctional sagittal Cobb angle between the lower endplate of the uppermost instrumented vertebra and the upper endplate of two vertebrae supra-adjacent, which was > 10 degrees and at least 10 degrees greater than the preoperative measurement. RESULTS: The incidence of PJK at 7.3 years postoperation was 26% (50 of 193 patients). The average proximal junctional angle increased 15.2 degrees until 2 years postoperation and then increased 1.7 degrees until final follow-up in the PJK group (n = 50). Factors that were statistically significant for PJK development were as follows: a thoracoplasty procedure (P = 0.001), preoperative hyperkyphotic thoracic alignment (T5-T12 > 40 degrees) (P = 0.015), and hybrid instrumentation (proximal hooks and distal pedicle screws) compared with the hooks only group (P = 0.029). The number of fused vertebrae more than 11 was also related with PJK (P = 0.08). The level of the uppermost instrumented vertebra did not affect the PJK incidence. SRS-24 outcome scores did not demonstrate any significant differences (P = 0.54 for total score and P = 0.49 for self-image subscale) between the PJK and non-PJK groups. CONCLUSION: The incidence of proximal junctional kyphosis at 7.3 years postoperation was 26% and did not progress significantly after 2 years postoperation. Risk factors for developing PJK were an associated thoracoplasty, hybrid instrumentation (proximal hooks and distal pedicle screws), and a preoperative larger sagittal thoracic Cobb angle (T5-T12 > 40 degrees). The SRS-24 outcome instrument was not affected by PJK.

Adolescent↗
PubMed2005

Apical sublaminar wires versus pedicle screws--which provides better results for surgical correction of adolescent idiopathic scoliosis?

STUDY DESIGN: The results of correction for adolescent idiopathic scoliosis (AIS) were compared using apical sublaminar wires versus pedicle screws. OBJECTIVE: To compare comprehensively the 2-year minimum postoperative results of posterior correction and spinal fusion using translational correction through either hybrid hook/sublaminar wire/pedicle screw constructs versus in situ rod-contouring correction with pedicle screw constructs in the treatment of AIS at 2 institutions. SUMMARY OF BACKGROUND DATA: Despite the reports of satisfactory correction of scoliotic curves by both apical (sublaminar wire) instrumentation and apical pedicle screw instrumentation, to our knowledge, no reports on the comprehensive comparison of hybrid (hook/sublaminar wire/pedicle screw) instrumentation versus segmental pedicle screw instrumentation exist. METHODS: A total of 50 patients with AIS at 2 institutions who underwent posterior spinal fusion with sublaminar wire (25 patients) or pedicle screw (25) constructs were sorted and matched according to 4 criteria: (1) similar age at surgery (14.2 years in the sublaminar wire and 14.4 in the pedicle screw group, P = 0.72); (2) similar number of fused vertebrae (11.4 in the sublaminar wire and 11.8 in the pedicle screw group, P = 0.36); (3) similar operative methods; and (4) identical Lenke curve types and similar preoperative major curve measurements (63.5 degrees in the sublaminar wire and 59.5 degrees in the pedicle screw group, P = 0.42). Patients were evaluated preoperatively, immediately postoperatively, and at 2-year follow-up according to radiographic changes in curve correction, operating time, intraoperative blood loss, implant costs, and the Scoliosis Research Society patient questionnaire (SRS-24) scores. RESULTS: After surgery, average major curve correction was 67.4% in the sublaminar wire and 68.1% in the pedicle screw group (P = 0.56). At 2-year follow-up, loss of the major curve correction was 4.6% in the sublaminar wire compared to 5.1% in the pedicle screw group (P = 0.79). Postoperative global coronal and sagittal balance were similar in both groups. No significant difference was found in the average number of levels fused from the distal end vertebra (1.48 in the sublaminar wire and 0.64 in the pedicle screw group, P = 0.21). Operating time averaged 350 minutes in the sublaminar wire and 357 in the pedicle screw group (P = 0.86). Intraoperative blood loss was significantly different in both groups (1791 +/- 816 mL in the sublaminar wire and 824 +/- 440 mL in the pedicle screw group) (P = 0.0003). Average implant cost in the sublaminar wire group (16.0 fixation points; 8,341 US dollars) was significantly lower than that of the pedicle screw group (17.1 fixation points; 13,462 US dollars) (P < 0.0001). Postoperative 2-year SRS-24 scores were similar in both groups (sublaminar wire = 107.3, pedicle screw = 103.5, P = 0.19). There were no neurologic or visceral complications related to sublaminar wire or pedicle screw instrumentation and no reoperations at a minimum 2-year follow-up. CONCLUSIONS: Apical sublaminar wire and pedicle screw instrumentation both offer similar major curve correction with similar fusion lengths without neurologic problems in the operative treatment of AIS. Although more expensive, pedicle screw constructs had significantly less blood loss and slightly shorter fusion lengths than the sublaminar wire constructs.

Adolescent↗