Comparison of implant density in the management of lenke 1b and 1c adolescent idiopathic scoliosis / Comparação da densidade do implante no tratamento da escoliose idiopática do adolescente lenke 1b e 1c

ABSTRACT Objective: To compare radiographic and surgical outcomes of Lenke 1B and 1C patterns. Methods: One hundred twenty patients with Lenke 1B and 1C scoliosis were grouped according to implant density as follows: low density (LD) of ≤1.4 and high density (HD) of >1.4. Matched subgroups (30 patients each) based on age, curve magnitude, and body mass index (BMI) were analyzed. Radiographic parameters were evaluated before operation, immediately after operation (ipo), and at 2 years' follow-up. SRS-30 was administered before operation and at 2 years' follow-up. Results: The major curves of the LD (n = 82) and HD groups (n=38) were respectively 59.1° and 65.6° before operation (p <.001), 26.3° and 22.9° ipo (p =.05), and 29.9° and 19.8° at 2 years' follow-up (p <.001). No significant differences in postoperative trunk shift and coronal balance were found (p =.69 and p =.74, respectively). The HD group had higher blood loss (p =.02), number of implants (p <.001), levels fused (p =.002), and surgical time (p <.001). The HD group had a higher prevalence of hypokyphosis from before operation to follow-up (p <.001). No significant differences were observed in the SRS-30 scores before operation and at 2 years' follow-up. The matched groups had similar preoperative major curves (p =.56), ages (p =.75), and BMIs (p =.61). Significantly longer surgical time (p =.009), higher density (p <.001), and better correction (p =.0001) were found in the HD group at 2 years' follow-up. No significant differences were found in the SRS-30 scores before operation and at 2 years' follow-up. Conclusion: LD constructs included fewer segments fused, lower intraoperative estimated surgical blood loss, and shorter operation time, and potentially decreasing complication risks due to fewer implants. Level of evidence III, Retrospective Cohort Study.

RESUMO Objetivo: Comparar os desfechos radiográficos e cirúrgicos da escoliose Lenke 1B e 1C. Métodos: Cento e vinte pacientes com escoliose Lenke 1B e 1C foram agrupados de acordo com a densidade do implante, como segue: baixa densidade (BD) de ≤ 1,4 e alta densidade (AD) de > 1,4. Foram analisados os grupos pareados (30 pacientes cada) com base na idade, magnitude da curva e índice de massa corporal (IMC). Os parâmetros radiográficos foram avaliados antes da cirurgia, no pós-operatório imediato (POI) e no acompanhamento de dois anos. O questionário SRS-30 foi administrado antes da cirurgia e no acompanhamento de dois anos. Resultados: As principais curvas dos grupos BD (n = 82) e AD (n = 38) foram respectivamente 59,1° e 65,6° antes da operação (p < 0,001), 26,3° e 22,9° no POI (p = 0,05) e 29,9° e 19,8° aos 2 anos de acompanhamento (p < 0,001). Não foram encontradas diferenças significantes no desvio do tronco e no balanço coronal no pós-operatório (p = 0,69 e p = 0,74, respectivamente). O grupo AD teve mais perda sanguínea (p = 0,02), número de implantes (p < 0,001), níveis de fusão (p = 0,002) e tempo de cirurgia (p < 0,001). O grupo AD teve maior prevalência de hipocifose do período anterior à cirurgia até o acompanhamento (p < 0,001). Não houve diferenças significantes nas pontuações do SRS-30 antes da operação e aos 2 anos de acompanhamento. No pré-operatório, os grupos pareados tinham curvas principais (p = 0,56), idade (p = 0,75) e IMC (p = 0,61) semelhantes. Constatou-se tempo cirúrgico expressivamente maior (p = 0,009), maior densidade (p < 0,001) e melhor correção (p = 0,0001) no grupo AD aos 2 anos de acompanhamento. Não foram encontradas diferenças significantes nas pontuações do SRS-30 antes da cirurgia e no acompanhamento de 2 anos. Conclusão: As estruturas de BD incluíram menos segmentos fundidos, menor perda de sangue intraoperatória estimada, menor tempo de cirurgia e menos risco de complicações, com possibilidade de redução, por causa do menor número de implantes. Nível de evidência III, Estudo retrospectivo de coorte.

Limited Unilateral Decompression and Pedicle Screw Fixation with Fusion for Lumbar Spinal Stenosis with Unilateral Radiculopathy: A Retrospective Analysis of 25 Cases

OBJECTIVE: Lumbar spinal stenosis is conventionally treated with surgical decompression. However, bilateral decompression and laminectomy is more invasive and may not be necessary for lumbar stenosis patients with unilateral radiculopathy. We aimed to report the outcomes of unilateral laminectomy and bilateral pedicle screw fixation with fusion for patients with lumbar spinal stenosis and unilateral radiculopathy. METHODS: Patients with lumbar spinal stenosis with unilateral lower extremity radiculopathy who received limited unilateral decompression and bilateral pedicle screw fixation were included and evaluated using visual analog scale (VAS) pain and the Oswestry Disability Index (ODI) scores preoperatively and at follow-up visits. Ligamentum flavum thickness of the involved segments was measured on axial magnetic resonance images. RESULTS: Twenty-five patients were included. The mean preoperative VAS score was 6.6+/-1.6 and 4.6+/-3.1 for leg and back pain, respectively. Ligamentum flavum thickness was comparable between the symptomatic and asymptomatic side (p=0.554). The mean follow-up duration was 29.2 months. The pain in the symptomatic side lower extremity (VAS score, 1.32+/-1.2) and the back (VAS score, 1.75+/-1.73) significantly improved (p=0.000 vs. baseline for both). The ODI improved significantly postoperatively (6.60+/-6.5; p=0.000 vs. baseline). Significant improvement in VAS pain and ODI scores were observed in patients receiving single or multi-segment decompression fusion with fixation (p<0.01). CONCLUSION: Limited laminectomy and unilateral spinal decompression followed by bilateral pedicle screw fixation with fusion achieves satisfactory outcomes in patients with spinal stenosis and unilateral radiculopathy. This procedure is less damaging to structures that are important for maintaining posterior stability of the spine.

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.

Posterior Hemivertebra Excision in Congenital Scoliosis / 대한척추외과학회지

STUDY DESIGN: Retrospective study OBJECTIVES: To evaluate the surgical outcome of congenital scoliosis with a hemivertebra treated by posterior hemivertebra excision and pedicle screw instrumentation. SUMMARY OF LITERATURE REVIEW: Posterior hemivertebra excision can be accomplished through a single posterior approach, and excellent correction and outcome may be achieved. MATERIALS AND METHODS: Forty patients with one fully segmented hemivertebra treated by posterior hemivertebra excision with pedicle screw instrumentation were retrospectively analyzed after a minimum follow-up of 2 years (range 2~7.7 years). The mean age at surgery was 15.9 years (range 2.6~37.9 years). Preoperative and postoperative standing radiographs were used to assess radiographic parameters. RESULTS: The average number of vertebrae in the major curve was 4.2 (range 3~8), and the average flexibility was 29% (range 8~59%). The average length of fusion was 3.5 segments (range 1~6). The number of fused vertebrae had a positive correlation with age at the index surgery (r=0.345, p<0.05). Mean preoperative scoliosis of 48+/-12degrees was corrected to a mean of 17+/-10degrees (65% correction), and mean preoperative kyphosis of 46+/-18degrees was corrected to a mean of 12+/-12degrees at the most recent follow-up. The compensatory curve had a mean of 25+/-10degrees preoperatively and spontaneously corrected to a mean of 8+/-8degrees (70% correction) at the most recent follow-up. The mean operating time was 233+/-81 min, with an average blood loss of 2904 ml. There was neither crankshaft phenomenon nor iatrogenic spinal stenosis in 6 patients under the age of 5 years after an average follow-up of 6 years. CONCLUSIONS: Posterior hemivertebra excision using pedicle screw instrumentation in congenital scoliosis due to a hemivertebra is a safe and effective procedure. Posterior hemivertebra excision at an early age may reduce the fusion length while avoiding the induction of iatrogenic spinal stenosis during follow-up.

Short-segment Pedicle Instrumentation of Thoracolumbar Burst-compression Fractures; Short Term Follow-up Results

OBJECTIVE: The current literature implies that the use of short-segment pedicle screw fixation for spinal fractures is dangerous and inappropriate because of its high failure rate, but favorable results have been reported. The purpose of this study is to report the short term results of thoracolumbar burst and compression fractures treated with short-segment pedicle instrumentation. METHODS: A retrospective review of all surgically managed thoracolumbar fractures during six years were performed. The 19 surgically managed patients were instrumented by the short-segment technique. Patients' charts, operation notes, preoperative and postoperative radiographs (sagittal index, sagittal plane kyphosis, anterior body compression, vertebral kyphosis, regional kyphosis), computed tomography scans, neurological findings (Frankel functional classification), and follow-up records up to 12-month follow-up were reviewed . RESULTS: No patients showed an increase in neurological deficit. A statistically significant difference existed between the patients preoperative, postoperative and follow-up sagittal index, sagittal plane kyphosis, anterior body compression, vertebral kyphosis and regional kyphosis. One screw pullout resulted in kyphotic angulation, one screw was misplaced and one patient suffered angulation of the proximal segment on follow-up, but these findings were not related to the radiographic findings. Significant bending of screws or hardware breakage were not encountered. CONCLUSION: Although long term follow-up evaluation needs to verified, the short term follow-up results suggest a favorable outcome for short-segment instrumentation. When applied to patients with isolated spinal fractures who were cooperative with 3-4 months of spinal bracing, short-segment pedicle screw fixation using the posterior approach seems to provide satisfactory result.

Correction of Double Thoracic Adolescent Idiopathic Scoliosis Using PedicleScrew Instrumentation: Comparison with Translation and Rod Derotation / 대한정형외과학회잡지

PURPOSE: To compare the results of two different surgical methods (translation vs rod derotation) in a correction of double thoracic adolescent idiopathic scoliosis (AIS) using pedicle screw instrumentation. MATERIALS AND METHODS: Forty-seven patients with double thoracic AIS treated by pedicle screw instrumentation were reviewed retrospectively after a minimum follow-up of 2 years. The patients were divided into two groups; TR group (translation method, n=14) and RD group (rod derotation, n=33). There were no significant differences in the preoperative curve characteristics between the two groups. RESULTS: In the TR group, the preoperative upper thoracic curve of 37+/-4 degrees improved to 24+/-4 degrees (35% correction), and the lower thoracic curve of 52+/-9 degrees improved to 18+/-5 degrees (65% correction). In the RD group, the preoperative upper thoracic curve of 40+/-7 degrees improved to 19+/-7 degrees (51% correction), and the lower thoracic curve of 56+/-12 degrees was improved to 16+/-6 degrees (72% correction). The correction of the upper and lower thoracic curves was significantly better in the RD group (p<0.05). Thoracic sagittal kyphosis was corrected from 21 degrees to 24 degrees in the TR group and from 18 degrees to 26 degrees in the RD group. There was no significant difference in the spinal balance, shoulder height difference, T1 tilt and fusion extent. The operating time and the amount of blood loss was 231 minutes and 2050ml in the TR group and 263 minutes and 3217ml in the RD group, respectively (p<0.05). CONCLUSION: In correcting double thoracic AIS using pedicle screw instrumentation, the rod derotation method showed better correction for the upper and lower thoracic curves. The translation method showed the advantages of easier application, a shorter operation time and less blood loss.

Anterior debridement and interbody arthrodesis with posterior pedicle screw instrumentation for the treatment of tuberculosis of the lower lumbar spine / 中国矫形外科杂志

[Objective]To evaluate the clinical efficacy of posterior pedicle screw instrumentation followed by anterior debridement and bone grafting through the lateral edge of the rectus abdominal muscle and retroperitoneal approach for the treatment of tuberculosis of the lower lumbar spine. [Methods]From June 2002 to January 2007,27 patients suffering from lower lumbar tuberculosis were treated with this technique.[Results]The surgical average time and amount of bleeding was 4.3 h and 438 ml respectively.The length of anterior incision was 5~7 cm.The average time and the amount of bleeding were 21 min and 48 ml respectively during the anterior lesion exposure.The follow-up period were 12~37 months,mean 17.3 months.The average preoperative,immediate postoperative,and final follow-up local lordotic angles of the affected segments were-2.1??4.0?,4.9??1.4?,3.7??3.0?.All patients had healed of disease and there was no recurrence at final follow up.Bony fusion was obtained in all patients.[Conclusion]Anterior exposure through the lateral edge of the rectus abdominal muscle and retroperitoneal approach is simple and less invasive.The spinal stability is achieved through short-segment pedicle screw fixation while reducing the sacrifice of additional motion segments.This technique is safe and effective for the treatment of tuberculosis of the lower lumbar spine.

Comparison of spontaneous correction in thoracic curves after selective anterior versus posterior fusion in Lenke5 adolescent idiopathic scoliosis / 中国矫形外科杂志

[Objective]To compare spontaneous correction of the unfused thoracic curves after selective anterior versus posterior fusion in Lenke5 adolescent idiopathic scoliosis(AIS). [Method]A total of 72 Lenke5 AIS patients were rescruited from May 1997 to October 2005.Out of them,40 received selective anterior fusion(group A) and 32 received selective posterior fusion(group B).All had a minimum of 2-year follow-up.[Result] No complication were found in both groups at the latest follow-up.The thoracic curve was corrected from 30? to 16? for group A,33? to 18? for group B.Both groups had a better spontaneous correction of the unfused thoracic curves.The correction rate had no significant difference between groups.However,the thoracic curve was increased in four patients(2 in each group;group C),which resulted in trunk imbalance.The thoracolumbar/lumbar thoracic(TL/L:T) Cobb's ratio averaged 1.09 in the four patients whereas 1.59 in other 68 patients(group D).The flexibility of the thoracic curve had significant difference in group C and D(34.2% vs 57.3%).[Conclusion]Both of the surgical treatments can get a better spontaneous correction of the unfused thoracic curves.It is important to evaluate the.thoracolumbar/lumbar–thoracic(TL/L:T) Cobb's ratio and the flexibility of the thoracic curve before selective fusion.

The Effect of Pedicle Screw Instrumentation on Fractured Vertebrae in Unstable Thoracolumbar Burst Fractures with Canal Encroachment and Clinical Result / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To evaluate the canal encroachment of fractured bony fragments and neurological deficits of pedicle screw instrumentation for the treatment of unstable thoracolumbar burst fractures with pedicle screws inserted into the fractured vertebrae. MATERIALS AND METHODS: The authors evaluated 18 patients treated surgically with posterior fusions using pedicle screws for unstable thoracolumbar burst fractures, from March 2000 to September 2004. The ratios of the areas occupied by the fractured bony fragments in the canals were analyzed, before and after pedicle screw insertion, by computed tomography scans of the fractured vertebrae. The kyphotic angles, anterior vertebral heights, and neurological deficits were evaluated. RESULTS: The areas occupied by the fractured fragments in the canals were improved significantly after surgery and there were no neurological complications resulting from the placement of pedicle screws or fragment displacements. The kyphotic angles and anterior vertebral heights at the last follow-up visits were improved significantly compared with the preoperative radiographs. The neurological deficits were not aggravated after pedicle screw insertion. CONCLUSION: Our results suggest that pedicle screw instrumentation in fractured vertebrae is safe and effective for the treatment of unstable thoracolumbar burst fractures.

Mono-segment Pedicle-screw Instrumentation and Fusion following Vertebroplasty for Lumbar and Thoracolumbar Fractures / 대한척추외과학회지

STUDY DESIGN: Nineteen of 20 cases that underwent a mono-segment pedicle-screw instrumentation and fusion, following vertebroplasty for lumbar and thoracolumbar fractures, were reviewed retrospectively. OBJECTIVES: To assess the effectiveness of a mono-segment pedicle-screw instrumentation and fusion, following an anterior column reconstruction, using bone cement for a fractured lumbar and thoracolumbar spine. SUMMARY OF LITERATURE REVIEW: With lumbar and thoracolumbar fractures, the untreated anterior instability and pre-stressing of the screws, following reduction, resulted in a high failure rate of the hardware, and posterior screw fixation alone may be not adequate. MATERIALS AND METHODS: We reviewed 19 of 20 cases that underwent a mono-segment pedicle-screw instrumentation and fusion, following vertebroplasty for lumbar and thoracolumbar fractures, between Feb. 2000 and Mar. 2002, with an average follow-up of 1.6 years. The mean age of the patients was 39.2 years, and the male female ratio as 10:9. The criteria for inclusion to the study (McAfee classification) were flexion-distraction injury, burst fracture, translational injury and burst conversion after an osteoporotic compression fracture, in 9, 7, 2 and 2 cases, respectively. We assessed the radiographic results of the local kyphotic angle correction of the fused segment and anterior body height restoration, preoperative, postoperative and at the last follow up, from the lateral views of the spine. The clinical results were evaluated according to Kumano's criteria. RESULTS: The mean local kyphotic angles of the instrumented segment, preoperatively, postoperatively and at the last follow-up were 16.5, 1.1 and 2.1 degrees, with a mean correction gain of 15.4 degrees(p0.05). The mean anterior body heights for each period were 60.4, 89.6 and 85.0%, with a mean restoration gain of 29.2% (p0.05). The clinical results were assessed as good in 18 patients (19 cases) and fair in the other one. There were 3 cases of asymptomatic leakage of the bone cement, but no fixation failures during the follow-up. CONCLUSIONS: A mono-segment pedicle-screw instrumentation and fusion, following the treatment of anterior instability, using vertebroplasty for lumbar and thoracolumbar fractures, can be an effective alternative for preserving the maximal motion segment, without fixation loss through the restoration of the immediate postoperative weight-bearing capability.

A Finite Element Analysis on the Effectiveness and Ideal Positions of the Tansfixators in Pedicle Screw Instrumentation / 대한정형외과연구학회지

Recent studies suggest that addition of transfixators to pedicle screw instrumentation enhances rotational stability of the constructs. However, the effectiveness of the transfixators along with their ideal numbers and positions still remains unclear. In this study, finite element analysis was performed to suggest the most effective positions of the transfixators based on their numbers. For this purpose, a finite element model of a spinal segment(L3-5) with total vertebrectomy at L4 and pedicle screw instrumentation was developed. The finite element model was made with 3-D 8 node solid elements so that they are more realistic and closer to the actual human vertebrae than the preciously published models. On this model, the transfixator(s) were placed along the pre-determined position(s) along the rod while its number was varied between 1 and 2. Appropriate boundary conditions were designated and rotational moment of 6.4 Nm was applied both in axial rotation and lateral bending. Improvement in rotational stability due to addition of the transfixator(s) was calculated as the percent decrease in motion relative to the case without. Results suggested that with one transfixator the rotational stability increased by the average of 19.0% and 6.1% against axial rotation and lateral bending, respectively. With two, the corresponding improvements were 32.3% and 10.7%. Against axial rotation, it was most effective when transfixator was placed at the middle of the rod(22.9%) for one transfixator and at the 1/3 and 2/3 sites along the rod(35.8%) for two. Against lateral bending, the ideal position(s) were at the proximal end(10.7%) for one transfixator and at the proximal and distal ends of the construct(17.7%) for two. It was also found that adding of a transfixator was more sensitive against lateral bending than against axial rotation(78% versus 64%). In conclusion, base on our biomechanical results, it can be suggested that the ideal positions for the ators are located at the equidistance from the both ends of the rod against axial rotation and at the both ends against lateral bending.

Reduction and Fixation of Spondylolisthesis by Using Pedicle Screw

There were many methods to treat spondylolisthesis since the past but completely satisfiable method was not developed until now. Recently, many spinal instruments were introduced and used worldwidely to treat spondylolisthesis. The author reports the experience of nine patients of transpedicular screw instrumentation of obtain reduction and fixation of the spondylolisthesis. Follow-up period was between 7 to 33 months after operation with average 19 months. The result was as follows: The age of the patients was 46 years in average ranging from 29 to 61 years. 2) Types of spondylolisthesis were isthmic type in 6 cases and degenerative type in 3 cases. The level of lesion were L4-5 in 5 cases. L5-S1 in 3 cases and L3-4 in 1 case. 3) Preoperative clinical feature include low back pain(100%), sensory disturbance(78%), radiating pain(67%), neurologic claudication(56%). 4) The amount of displacement measured by Boxall was 22.6% preoperatively to 7.3% postoperatively and the amount of angle by Meschan was from 12.7 degree preoperatively to 4 degree postoperatively. 5) Postoperative complications were urinary tract infection(3 cases), screw loosening(1 case), superficial wound infection(1 case), deep wound infection(1 case), and meralgia paresthetica(1 case). 6) The overall result was satisfactory except 1 case due to screw loosening, and satisfiable bony fusion was obtained except 1 case.

Follow-up Result of Transpedicular Screw Fixation in Lumbar Spinal Stenosis and Spondylolisthesis

Transpedicular screw instrumentation allows good fixation to the unstable spine after wide laminectomy procedure. The authors experienced 30 cases of transpedicular screw instrumentation in lumbar spine surgery, which had been operated from November, 1989 and had follow up at least for 6 months. We evaluated and reviewed the advantages and problems of transpedicular screw instrumentation through our experiences and literatures.