Which Criterion Is More Reliable for Selecting the Distal Fusion Level in Cases of Adolescent Idiopathic Scoliosis with Structural Thoracolumbar/Lumbar Curves: Static or Dynamic?

STUDY DESIGN: Retrospective comparative study.OBJECTIVES: To compare the reliability of 2 criteria to predict the radiological outcomes of corrective surgery in cases of adolescent idiopathic scoliosis (AIS) with structural thoracolumbar/lumbar (TL/L) curves.SUMMARY OF LITERATURE REVIEW: Distal fusion level selection in AIS with structural TL/L curves is debatable.MATERIALS AND METHODS: This study included 131 AIS patients with structural TL/L curves who underwent corrective surgery in which distal fusion was stopped at L3. Whole-spine standing radiographs and bending radiographs were obtained preoperatively. The patients were divided into 2 groups according to their findings on bending radiographs (dynamic criterion) and by the last touching vertebra and the lower end vertebra (static criterion). Radiological outcomes were assessed by reviewing postoperative radiographs. Reliability tests were conducted to compare the predictability of radiological outcomes using these 2 methods. In addition, radiological parameters were compared between both criteria.RESULTS: Among 131 patients, 25 showed radiologically poor outcomes (19.1%). The sensitivity of the dynamic and static criteria was 0.69 and 0.50, respectively. The specificity of each criterion was 0.49 and 0.64, respectively. Overall, the dynamic criterion showed superior reliability (p=0.03). However, no significant difference in radiological parameters could be found in a comparison of both criteria.CONCLUSIONS: Although the dynamic criterion was more sensitive for predicting poor radiological outcomes when stopping fusion at L3 in patients with structural TL/L curves, its specificity was lower than that of the static criterion. Thus, both dynamic and static criteria should be considered when selecting the distal fusion level in cases of AIS with structural TL/L curves.

Influence of Distal Fusion Level on Sagittal Spinopelvic and Spinal Parameters in the Surgical Management of Adolescent Idiopathic Scoliosis

STUDY DESIGN: Retrospective analysis of adolescent idiopathic scoliosis. PURPOSE: This study aimed to investigate the influence of distinct distal fusion levels on spinopelvic parameters in patients with adolescent idiopathic scoliosis (AIS) who underwent posterior instrumentation and fusion surgery. OVERVIEW OF LITERATURE: The distal fusion level selection in treatment of AIS is the one of milestone to effect on surgical outcome. Most of the paper focused on the coronal deformity correction and balance. The literature have lack of knowledge about spinopelvic changing after surgical treatment and the relation with distal fusion level. We evaluate the spinopelvic and pelvic parameter alteration after fusion surgery in treatment of AIS. METHODS: A total of 100 patients with AIS (88 females and 12 males) were retrospectively reviewed. Patients were assigned into the following three groups according to the distal fusion level: lumbar 2 (L2), lumbar 3 (L3), and lumbar 4 (L4). Using a lateral plane radiograph of the whole spine, spinopelvic angular parameters such as thoracic kyphosis (TK), lumbar lordosis (LL), pelvic incidence (PI), sacral slope (SS), and pelvic tilt (PT) were radiologically assessed. RESULTS: The mean age was 15±2.4 years, and the mean follow-up period was 24.27±11.69 months. Regarding the lowest instrumented vertebra, patients were categorized as follows: 30 patients in L2 (group 1), 40 patients in L3 (group 2), and 30 patients in L4 (group 3). TK decreased from 36.60±13.30 degrees preoperatively to 26.00±7.3 degrees postoperatively in each group (p=0.001). LL decreased from 52.8±9.4 degrees preoperatively to 44.30±7.50 degrees postoperatively (p=0.001). Although PI showed no difference preoperatively among the groups, it was statistically higher postoperatively in group 3 than in the other groups (p 0.05). However, mean SS was significantly higher in group 3 (p=0.042, p < 0.05). PT decreased from 15.50±7.90 degrees preoperatively to 15.2±7.10 degrees postoperatively. The positive relationship (28.5%) between LL and PI measurements was statistically significant (r=0.285; p=0.004, p < 0.01). Furthermore, the positive relationship (36.5%) between LL and SS measurements was statistically significant (r=0.365; p=0.001, p < 0.01). CONCLUSIONS: When the distal instrumentation level in AIS surgery is below L3, a significant change in PT and SS (pelvic parameters) is anticipated.

RESEARCH PROGRESS OF SURGICAL SELECTION OF FUSION LEVELS FOR DEGENERATIVE SCOLIOSIS / 中国修复重建外科杂志

OBJECTIVE: To summarize the progress of the surgical selection of fusion levels for degenerative scoliosis.

Análisis con resonancia magnética de la posición de la amígdala cerebelosa antes de la corrección instrumentada por vía posterior y después de ella en pacientes con escoliosis idiopática del adolescente / Magnetic resonance imaging evaluation of the position of the cerebellar tonsil before and after posterior spinal fusion in adolescent idiopathic scoliosis

Objetivo: Analizar, con resonancia magnética, las variaciones de posición de la amígdala cerebelosa, antes de corregir la deformidad espinal mediante una artrodesis vertebral posterior instrumentada y después, en pacientes con escoliosis idiopática del adolescente sin sintomatología neurológica. Materiales y Métodos: Se evaluaron retrospectivamente 40 pacientes con escoliosis idiopática del adolescente, sin síntomas neurológicos y sometidos a una artrodesis vertebral posterior instrumentada para corregir la deformidad espinal. A todos se les realizó una resonancia magnética de la fosa cerebral posterior y de la columna cervical, antes de la cirugía espinal y después de ella. Resultados: La magnitud preoperatoria promedio de la curva escoliótica fue de 53,15° y la de la cifosis torácica fue de 35,42º. En el posoperatorio inmediato, la magnitud promedio fue de 7,45º y de 27,87º,respectivamente. El valor promedio de la longitud de la columna en el plano coronal fue de 44,5 cm en el preoperatorio y de 48,27 cm en el posoperatorio. El valor promedio de la longitud de la columna vertebral en el plano sagital fue de 50,87 cm en el preoperatorio y de 55,13 cm en el posoperatorio. No se observó unadiferencia significativa respecto de la posición de la amígdala cerebelosa en las mediciones antes de corregir la deformidad espinal y después (p = 0,6042). Conclusión: No se observó una variación significativa en la ubicación de la amígdala cerebelosa respecto del agujerooccipital en pacientes con escoliosis idiopática del adolescente que fueron sometidos artrodesis vertebral posterior instrumentadapara corregir la deformidad espinal.

Objective: To evaluate variations in cerebellar tonsil position after posterior spinal fusion in neurologically intact patients with adolescent idiopathic scoliosis. Methods: We retrospectively evaluated 40 patients with adolescent idiopathic scoliosis and no neurological symptoms that underwent posterior spinal fusion. Anteroposterior and sagittal standing radiographs, and sagittal hindbrain MRI wereperformed in all patients before and after spinal surgery. We evaluated variations in cerebellar tonsil position in relation to spinal correction and spinal elongation after posterior spinal fusion. Results: Mean preoperative magnitude of the curve was 53.15° and thoracic kyphosis was 35.42º. Mean postoperative valueswere 7.45º and 27.87º, respectively. The average length of the spine in the coronal plane was 44.5 cm in preoperative x-rays and 48.27 cm in postoperative x-rays. The average length in the sagittal plane was 50.87 cm in preoperative x-raysand 55.13cm in postoperative x-rays. There was no significant difference in theposition of the cerebellar tonsil before and after spinal correction (p = 0.6042). Conclusion: Position of the cerebellar tonsil did not change with posterior spinal fusion in patients with adolescent idiopathic scoliosis.

Correlation of Adjacent Segmental Disease with Tilt Angles of the Upper and Lower Instrumented Vertebra in the Degenerative Lumbar Scoliosis

STUDY DESIGN: Retrospective study. OBJECTIVES: To evaluate the correlation of adjacent segmental disease with tilt angles of the upper and lower instrumented vertebra after instrumented posterolateral fusion for degenerative lumbar scoliosis. SUMMARY OF LITERATURE REVIEW: There has been no study of radiologic measurement and decision of fusion level using the angle of pedicle screws inserted for treatment of degenerative lumbar scoliosis. MATERIALS AND METHODS: From 2004 to 2008, 74 patients that underwent decompression and posterolateral fusion for degenerative lumbar scoliosis were included in this study. In all cases, instrumentation and posterolateral fusion were both performed. The sex ratio was 31:43, the mean age was 68.7 years and the mean follow up duration was 37.4 months. The angle between each upper end plate of the upper vertebral body and lower end plate of the lower vertebral body of the fusion, and the line parallel to the axis of the sagittal line of vertebrae was each defined as UIV-a and LIV-b. The correlation of development of adjacent segment disease and UIV-a, and LIV-b angle was investigated. RESULTS: Sum of the absolute value of UIV-a and LIV-b had a statistically significant positive correlation with that of adjacent segment disease. Also, UIV-a alone, had a statistically positive correlation with the development of proximal adjacent segment disease. CONCLUSIONS: Since it is proven that adjacent segment disease has positive correlation with the sum of the absolute value of UIV-a and LIV-b, the extent of fusion should be adjusted to make the line parallel to the line perpendicular to the sagittal surface.

Comparison of Surgical Outcomes in Thoracolumbar Fractures Having 6 or Less Scored by Load-Sharing Classification Based on Posterior Fusion Level

PURPOSE: The aim of this study is to decide the optimal level of fusion with comparing the results between the short segment fusion and long segment fusion treated with pedicle screw instrumentation, including fractured vertebra in thoracolumbar junctional fractures. MATERIALS AND METHODS: From February 2000 to November 2009, fifty three patients with junctional fracture of thoracolumbar spine were treated with pedicle screws and posterior fusion at our hospital. They were divided into two groups, the short segment group and long segment group. Preoperatively, immediate postoperative and last follow-up lateral radiological evaluation was done by measuring the correction and loss of segmental kyphosis, wedge angle, body compression rate and instrumented vertebra angle. In addition, operation time and amount of intraoperative bleeding were measured. RESULTS: There were no significant differences of statistical analysis regarding the radiological variables between the two groups, especially the loss of corrected segmental kyphosis, wedge angle, body compression rate and instrumented vertebra angle (p>0.05). However, operative time in the short segment group (234 minutes) was shorter than the long segment group (284 minutes), and there was statistical significance (p=0.002). CONCLUSION: We recommend the short segment transpediculr instrumentation one level above and one level below, including the fractured vertebra for thoracolumbar junctional fracture with 6 points or less of the load-sharing score.

Pedicle Screw Instrumentation for Adolescent Idiopathic Scoliosis: The Insertion Technique, the Fusion Levels and Direct Vertebral Rotation

The pedicle is a power nucleus of the vertebra and offers a secure grip of all 3 columns. Pedicle screw instrumentation has advantages of rigid fixation with improved three-dimensional (3D) correction and it is accepted as a reliable method with a high margin of safety. Accurate placement of the pedicle screws is important to reduce possible irreversible complications. Many methods of screw insertion have been reported. The author has been using the K-wire method coupled with the intraoperative single posteroanterior and lateral radiographs, which is the most safe, accurate and fast method. Identification of the curve patterns and determining the fusion levels are very important. The ideal classification of adolescent idiopathic scoliosis should address the all patterns, predict the extent of accurate fusion and have good inter/intraobserver reliability. My classification system matches with the ideal classification system, and it is simple and easy to learn; and my classification system has only 4 structural curve patterns and each curve has 2 types. Scoliosis is a 3D deformity; the coronal and sagittal curves can be corrected with rod rotation, and rotational deformity has to be corrected with direct vertebral rotation (DVR). Rod derotation and DVR are true methods of 3D deformity correction with shorter fusion and improved correction of both the fused and unfused curves, and this is accomplished using pedicle screw fixation. The direction of DVR is very important and it should be opposite to the direction of the rotational deformity of the vertebra. A rigid rod has to be used to prevent rod bend-out during the derotation and DVR.

Comparison of Proximal Fusion to T1 or T2 in Double Thoracic Adolescent Idiopathic Scoliosis / 대한정형외과학회잡지

PURPOSE: To assess the results of double thoracic fusion using pedicle screw instrumentation fused proximally to T1 or T2 in patients with double thoracic adolescent idiopathic scoliosis (AIS). MATERIALS AND METHODS: Forty patients with double thoracic AIS were analyzed retrospectively after a minimum follow-up of 2 years. The patients were divided into two groups according to the proximal fusion level: the T1 group (n=26) was fused to T1 and the T2 group (n=14) was fused to T2. RESULTS: There were no significant differences in the preoperative curve characteristics between the two groups. In the T1 group, the preoperative upper curve magnitude of 38+/-7o and apical vertebral translation (AVT) of 8+/-6 mm were corrected to 17+/-7o (54% correction) and 4+/-3 mm (3 mm correction) at the final follow-up, respectively. In the T2 group, the preoperative upper curve magnitude of 37+/-5o and the AVT of 7+/-4 mm were corrected to 22+/-6o (42% correction) and 6+/-3 mm (1 mm correction) at the final follow-up, respectively. There was no difference in the correction of lower thoracic curve, sagittal alignment and balance between the two groups. There was a significantly better correction in the upper thoracic curve and T1 tilting in the T1 group than the the T2 group. CONCLUSION: In double thoracic AIS, fusions to T1 and T2 produce satisfactory results. However, fusion to T1 is recommended for a better correction of the upper curve and T1 tilting.

Incidence of Proximal Adjacent Failure in Adult Lumbar Deformity Correction Based on Proximal Fusion Level

STUDY DESIGN: Retrospective study. PURPOSE: To review the results and proximal adjacent problems of long fusion (more than 4 levels) according to the level of proximal fusion (L2~T9) in adult lumbar deformity using pedicle screw fixation. OVERVIEW OF LITERATURE: There are few written reports concerning proximal adjacent segmental failure according to the level of proximal fusion in adult lumbar deformity. METHODS: The radiographs and clinical records of thirty-five patients (30 females, 5 males) of adult lumbar deformity with more than 2-year follow-up after surgery were analyzed. The average age was 62 years (range, 38~75). All patients were divided into three groups according to the level of proximal fusion: Group 1 (n=14) fusion up to L1 or L2; Group 2 (n=14) fusion up to T11 or T12; and Group 3 (n=7) fusion up to T9 or T10. RESULTS: The preoperative coronal curve of 28+/-14degrees was corrected to 9+/-7degrees immediately after surgery and 11+/-7degrees at the final follow-up. The preoperative local kyphosis of 24+/-12degrees was corrected to -1+/-10degrees immediately after surgery and 1+/-11degrees at the final follow-up. The lumbar lordosis was 14+/-18degrees before surgery; 27+/-11degrees after surgery; and 16+/-12degrees at the final follow- up. The parameters of coronal and sagittal balance were improved in all patients after surgery, except one patient in group 2 who showed coronal imbalance due to over-correction. Sagittal imbalance at the most recent follow-up was detected in 10 patients with significant difference between the groups; 5 (36%) in Group 1, 5 (36%) in Group 2, and none in Group 3. Proximal adjacent segmental problems that are consisted with proximal disc degeneration with kyphosis, compression fractures above the fusion and screw failure proximal to the end of the fusion were observed in 15 patients with significant difference between the groups; 7 (50%) in Group 1, 7 (50%) in Group 2, and 1 (14%) in Group 3. There was 1 superficial infection and 2 transient neurologies. CONCLUSIONS: Fusion up to throacolumbar junction (L2~T11) in surgical treatment of adult lumbar deformity had more proximal adjacent problems with poorer results. Fusion higher than T10 is recommended for adult lumbar deformity.

Selection of the Optimal Distal Fusion Level in Posterior Instrumentation and Fusion for Thoracic Hyperkyphosis: The Sagittal Stable Vertebra Concept / 대한척추외과학회지

STUDY DESIGN: A retrospective study for clinical, radiographic assessment. OBJECTIVES: To determine the appropriate level of distal fusion for the posterior instrumentation and fusion for thoracic hyperkyphosis by investigating the relationship between the sagittal stable (the most proximal vertebra touched by the vertical line from the posterior-superior corner of the sacrum), first lordotic (just caudal to the first lordotic disc) and lowest instrumented vertebrae. LITERATURE REVIEW SUMMARY: It has been recommended that the distal level of fusion for thoracic hyperkyphosis should include not only the distal end vertebra of kyphosis, but also the first lordotic disc beyond the transitional zone, distally. However, distal junctional breakdown was noted, even when these rules have been followed. MATERIALS AND METHODS: Thirty-one patients, with a mean age of 18, ranging from 13 to 38 years, who underwent long posterior instrumentation and fusion for thoracic hyperkyphosis, with a minimum of 2 years of follow up, were reviewed. The preoperative diagnosis included: Scheuermann`s disease (n=29), posttraumatic kyphosis (n=1) and postlaminectomy kyphosis (n=1). According to the level of distal fusion, the patients were divided into two groups. Group I (n=24): lowest instrumented vertebra (LIV), including the sagittal stable vertebra (SSV), Group II (n=7): lowest instrumented vertebra proximal to the sagittal stable vertebra. Patients were evaluated utilizing both standing radiographs and chart reviews. RESULTS: The mean thoracic kyphosis was 86.6+/-8.5 before surgery, which had been corrected to 53.0+/-10.4 by the final follow-up, with a correction rate of 39%. The average sagittal balance was slightly negative (0.24+/-3.8 cm) before surgery, and became more negative (1.33+/-2.8 cm) by the final follow-up. There were no statistical differences in the thoracic kyphosis between the two groups. However, there was a statistically significant difference, with Group II having a more posterior translation of the center of the LIV from the posterior sacral vertical line, preoperatively, than at the final follow-up in Group I (p=0.003). In Group I, distal junctional problems developed in only 2 of the 24 (8%) patients, whereas in Group II, they occurred in 5 of the 7 (71%) patients (p<0.05). Despite extending the fusion to the first lordotic vertebra, distal junctional problems developed in 3 of the 8 (38%) patients. CONCLUSIONS: The distal end of the fusion for thoracic hyperkyphosis should include the sagittal stable vertebra. The levels of distal fusion that include the first lordotic vertebra, but not the sagittal stable vertebra, are not always appropriate for the prevention of postoperative distal junctional kyphosis.

Selection of the Optimal Distal Fusion Level in Posterior Instrumentation and Fusion for Thoracic Hyperkyphosis: The Sagittal Stable Vertebra Concept / 대한척추외과학회지

STUDY DESIGN: A retrospective study for clinical, radiographic assessment. OBJECTIVES: To determine the appropriate level of distal fusion for the posterior instrumentation and fusion for thoracic hyperkyphosis by investigating the relationship between the sagittal stable (the most proximal vertebra touched by the vertical line from the posterior-superior corner of the sacrum), first lordotic (just caudal to the first lordotic disc) and lowest instrumented vertebrae. LITERATURE REVIEW SUMMARY: It has been recommended that the distal level of fusion for thoracic hyperkyphosis should include not only the distal end vertebra of kyphosis, but also the first lordotic disc beyond the transitional zone, distally. However, distal junctional breakdown was noted, even when these rules have been followed. MATERIALS AND METHODS: Thirty-one patients, with a mean age of 18, ranging from 13 to 38 years, who underwent long posterior instrumentation and fusion for thoracic hyperkyphosis, with a minimum of 2 years of follow up, were reviewed. The preoperative diagnosis included: Scheuermann`s disease (n=29), posttraumatic kyphosis (n=1) and postlaminectomy kyphosis (n=1). According to the level of distal fusion, the patients were divided into two groups. Group I (n=24): lowest instrumented vertebra (LIV), including the sagittal stable vertebra (SSV), Group II (n=7): lowest instrumented vertebra proximal to the sagittal stable vertebra. Patients were evaluated utilizing both standing radiographs and chart reviews. RESULTS: The mean thoracic kyphosis was 86.6+/-8.5 before surgery, which had been corrected to 53.0+/-10.4 by the final follow-up, with a correction rate of 39%. The average sagittal balance was slightly negative (0.24+/-3.8 cm) before surgery, and became more negative (1.33+/-2.8 cm) by the final follow-up. There were no statistical differences in the thoracic kyphosis between the two groups. However, there was a statistically significant difference, with Group II having a more posterior translation of the center of the LIV from the posterior sacral vertical line, preoperatively, than at the final follow-up in Group I (p=0.003). In Group I, distal junctional problems developed in only 2 of the 24 (8%) patients, whereas in Group II, they occurred in 5 of the 7 (71%) patients (p<0.05). Despite extending the fusion to the first lordotic vertebra, distal junctional problems developed in 3 of the 8 (38%) patients. CONCLUSIONS: The distal end of the fusion for thoracic hyperkyphosis should include the sagittal stable vertebra. The levels of distal fusion that include the first lordotic vertebra, but not the sagittal stable vertebra, are not always appropriate for the prevention of postoperative distal junctional kyphosis.

Segmental Pedicle Screw Fixation in Thoracolumbar or Lumbar Idiopathic Scoliosis / 대한정형외과학회잡지

PURPOSE: To analyze surgical outcomes of thoracolumbar and lumbar scoliosis treated with segmental pedicle screw fixation, and to determine the exact distal fusion level. MATERIALS AND METHODS: Seven idiopathic thoracolumbar and lumbar scoliosis patients (6 thoracolumar and 1 lumbar scoliosis, 7 females with mean age of 15.9 years) subjected to segmental pedicle screw fixation with a minimum follow-up of 2 years were retrospectively analyzed for deformity correction, stable vertebra, lower instrumeted vertebral tilt (LIVT) and coronal balance using pre and post-operative standing radiographs. The bending stable vertebra and the rotational correction of L3 were measured in preoperative bending radiographs. The L3 rotation in the bending radiographs was less than Nash-Moe grade II in all patients. The bending stable vertebra was L3 in 4 patients and L4 in 3. An unsatisfactory result was defined as an LIVT of more than 10degrees or a coronal imbalance of more than 10 mm. RESULTS: Distal fusion went down to L3 in 6 patients and L4 in one patient whose bending stable vertebra had been L4 preoperatively. The preoperative average major curve of 52degrees was corrected to 10degrees (81% correction). The preoperative average thoracic curve of 27degrees and the average lumbosacral curve of 26degrees were corrected to 14degrees and 5degrees, respectively. Two patients with distal fusion to L3 showed unsatisfactory results; LIVT was more than 10degrees in both patients and coronal imbalance more than 10 mm in one. Both the patients had bending stable vertebra of L4 preoperatively. CONCLUSION: In the correction of thoracolumbar and lumbar scoliosis with segmental pedicle screw fixation, the curve could be fused to L3 when the L3 rotation in the bending radiograph was less than Nash-Moe grade II and the bending stable vertebra was L3.

Analysis of Compression Behavior on Intervertebral Disc L4-5 in Pedicle Screw System Instrumented Lumbar Spine under Follower Load / 영남의대학술지

BACKGROUND: Confirm the stability of intervertebral disc sustaining each fused lumbar spine cases, comparing vertical compression, A-P shear force and rotational moment on intervertebral disc of instrumented lumbar spine with simple vertical compression load and follower load using finite element analysis. MATERIALS AND METHODS: We analyze the stability of intervertebral disc L4-5 supporting fused lumbar spine segments. After performing finite element modelling about L1-L5 lumbar vertebral column and L1-L4 each fusion level pedicle screw system for fused lumbar spine fine element model. Intervertebral discs with complex structure and mechanical properties was modeled using spring element that compensate stiffness and tube-to-tube contact element was employed to give follower load. Performing geometrical non-linear analysis. RESULTS: The differences of intervertebral disc L4-5 behavior under the follower compression load in comparision with vertical compression load are as follows. CONCLUSION: As a result of finite element interpretation of instrumented lumbar spine, the stability of L4-5 sustaining fused lumbar segment, the long level fused lumbar spine observed hing stability under follower load. This research method can be the basis tool of effects prediction for instrumentation, a invention of a more precious finite element interpretation model which consider the role of muscle around the spine is loaded.

Analysis of Compression Behavior on Intervertebral Disc L4-5 in Pedicle Screw System Instrumented Lumbar Spine under Follower Load / 영남의대학술지

BACKGROUND: Confirm the stability of intervertebral disc sustaining each fused lumbar spine cases, comparing vertical compression, A-P shear force and rotational moment on intervertebral disc of instrumented lumbar spine with simple vertical compression load and follower load using finite element analysis. MATERIALS AND METHODS: We analyze the stability of intervertebral disc L4-5 supporting fused lumbar spine segments. After performing finite element modelling about L1-L5 lumbar vertebral column and L1-L4 each fusion level pedicle screw system for fused lumbar spine fine element model. Intervertebral discs with complex structure and mechanical properties was modeled using spring element that compensate stiffness and tube-to-tube contact element was employed to give follower load. Performing geometrical non-linear analysis. RESULTS: The differences of intervertebral disc L4-5 behavior under the follower compression load in comparision with vertical compression load are as follows. CONCLUSION: As a result of finite element interpretation of instrumented lumbar spine, the stability of L4-5 sustaining fused lumbar segment, the long level fused lumbar spine observed hing stability under follower load. This research method can be the basis tool of effects prediction for instrumentation, a invention of a more precious finite element interpretation model which consider the role of muscle around the spine is loaded.

Treatment of Posterior Facet Fracture-Dislocation in Lumbar Spine / 대한척추외과학회지

STUDY DESIGN: Retrospective study. OBJECTIVES: The purpose of this study is to compare the outcomes of short segment fusion and long segment fusion in posterior facet fracture-dislocation in the lumbar spine. SUMMARY OF LITERATURE REVIEW: There are many controversies exist about the treatment of fracture-dislocation in lumbar spine. MATERIAL AND METHODS: Sixteen patients with lumbar fracture-dislocation were studied retrospectively. The patients divided two groups; group one treated with one level above and below the fracture segment fixation, group two treated with two level above and below the fracture segment fixation. Two groups were compared with neurologic recovery, bladder function recovery and radiologic changes of deformities. RESULTS: The neurologic deficit in two groups was improved more than one Frankel grade at last follow up. Patients who showed intact dura were neurologically improved significantly than the patients whose dura was ruptured. Radiologic changes were not a sinificant difference in two groups. CONCLUSION: In lumbar fracture-dislocation treatment, one level above and below the fracture segment fixed with pedicle screw fixation system was an effective treatment method which preserved the mobile segment lumbar spine.

Determination of Distal Fusion Level with Segmental Pedicle Screw Fixation in Single Thoracic Idiopathic Scoliosis / 대한척추외과학회지

STUDY DESIGN: Retrospective study. OBJECTIVES: To determine the exact distal fusion level in the treatment of single thoracic idiopathic scoliosis (King III and IV) with segmental pedicle screw fixation and rod rotation. SUMMARY OF LITERATURE REVIEW: Pedicle screw fixation effectively shortens the distal fusion extent by improved 3-D deformity correction. However, the selection of distal fusion extent remains controversial in single thoracic idiopathic scoliosis. MATERIAL AND METHODS: Forty-two single thoracic adolescent idiopathic scoliosis patients subject to segmental pedicle screw fixation and rod rotation with minimum follow-up of 2 years (2-6 years) were analyzed. The patients were grouped according to the distal fusion level with reference to the standing neutral vertebra (NV) for comparison of deformity correction, radiological and clinical spinal balance using standing radiographs. Distal fusion down to NV +1 was in 9 patients, NV in 5, NV-1 in 9, NV-2 in 12 and NV-3 in 7 patients respectively. RESULTS: Preoperative 50+/-11 degrees of thoracic deformity was corrected to 13+/-5 degrees showing 74% of curve correction. Preoperative 23+/-7 degrees of lumbar deformity was corrected to 2+/-8 degrees showing 93% of curve correction. Postoperative adding on deformity was obtained in 14 patients. Significant difference was found not by King classification but by distal fusion level: significantly higher chance of unsatisfactory results from not going to the NV-1 (p=0.001). CONCLUSIONS: In correction of single thoracic idiopathic scoliosis with segmental pedicle screw fixation, the curve should be fused to NV-1 saving one or more motion segments when compared to the fusion to the stable vertebra.

Decision of Posterior Fixation Level by Load-Sharing Classification in Thoracolumbar and Lumbar Burst Fracture / 대한척추외과학회지

STUDY DESIGN: Retrospective study on 54 thoracolumbar and lumbar burst fractures treated with pedicle screw instrumentation. OBJECTIVES: To decide the optimal level of fusion in thoracolumbar and lumbar burst fractures treated with pedicle screw instru-mentation by load sharing concept. SUMMARY OF LITERATURE REVIEW: Short segment pedicle screw fixation is condemned with frequent failure in maintenance of reduction. The type of posterior fixation construct that is most desirable is less well defined. MATERIALS AND METHODS: Using the Load-Sharing classification, Group I consisted of 24 cases with fractures totaling 6 points or less underwent surgery which was subdivided into two subgroups(A : 1 level above and below including fractured vertebra, B : long segment fixation). Group II consisted of 30 cases with fractures totaling 7 points or more underwent surgery which was sub-divided into three subgroups(C : 1 level above and below including fractured vertebra, D : 2 levels above, 1 level below including fractured vertebra, E : 2 levels above and below the fractured vertebra). Change of segmental kyphosis, inter-screw angle, upper disc height, lower disc height and anterior body height were measured using post-operative and follow-up lateral radiographs. RESULTS: Comparing two subgroups in group I(A Vs. B), group A showed definitely more loss of upper disc height than group B but the others were not significantly different. Comparing three subgroups in group II(C, D, E), group C showed definitely more loss of reduction than two other groups but loss of anterior body height was not significantly different. There were no significant differences between group D and E. CONCLUSIONS: For fracture totaling 6 points or less, the long segment fixation(2 level above and 1 level below including fractured vertebra) is a successful method at thoracolumbar junction and short segment fixation to preserve motion segment at lumbar spine. For fracture totaling 7 points or more, short segment fixation is inappropriate and long segment pedicle screw fixation (2 level above and 1 level below including fractured vertebra) could effectively treat burst fractures of thoracolumbar and lumbar spine.

The Influence of Lumbar Fractional Curve Rotation on Fusion Level of King Type III Adolescent Idiopathic Scoliosis ( AIS ) / 대한정형외과학회잡지

Study design. This retrospective study analyzes the influence of lumber rotation on fusion extent in King type III AIS treatment by CD instrumentation. Objectives. To establish a guideline for fusion in King type III AIS Summary Study of background data. Rotational characteristics of the lumber curve may significantly affect the postoperativ e behavior of uninstrumented lumbar curve thus calling for a different lumbar rotation. Methods. Sixteen King type III AIS treated with CD were divided into two groups by the direction of lumbar curve rotation. It was opposite direction (OD) to the rotation of the major curve in 9 and same direction (SD) in 7. In OD, 6 were treated by selective thoracic fusion (TF) and 3 were fused to the stable vertebra (SV). In SD, 6 were treated by TF and 1 was fused to the SV. They were evaluated for balance, major and fractional curve correction after a minimum follow up of 2 years. Result. In OD, all curves were balanced regardless of the fusion extent with satisfactory curve correction. In SD-TF, all were clinically balanced with major curve correction of 75%, but all the fractional curve were overcorrected, adding on the major curve. In SD-SV, the curve was balanced with stable lumbar curve. Conclusion. In King type III curve with lumbar curve rotated to the opposite direction, selective thoracic fusion is sufficient. However, when the fractional curve is rotated in the same direction, fusion to the stable vertebra may be a safer choice.