Thoracic Fusion Research Articles

Clavicle Chest Cage Angle Difference (CCAD)

Retrospective case series of surgically treated patients with adolescent scoliosis. To establish a new radiographical measurement method to determine the best preoperative predictor of postoperative shoulder balance. Shoulder balance is an important aspect of the overall cosmetic balance in patients with adolescent idiopathic scoliosis. Despite recent reports, it is still difficult to estimate the postoperative shoulder balance accurately. A retrospective review of 89 consecutive patients who had thoracic fusion with a minimum 2-year follow-up (mean, 3.1 yr) was conducted to investigate the radiographical measurements and patient demographics. The shoulder height difference (SHD) was measured as the graded height difference of the soft tissue shadows. SHD more than 2 cm indicated an unbalanced shoulder. The clavicle chest cage angle difference (CCAD) was established and evaluated. The CCAD was graded as grade A: no imbalance (<0°), grade B: mild imbalance (0°-10°), and grade C: significant imbalance (>10°). Of the 89 patients, 22 patients had a moderate or significant SHD at 2 years postoperatively and were categorized as the unbalanced shoulder group (unbalanced SD). A significant difference was observed in preoperative CCAD between the balanced and unbalanced SD groups (P = 0.01). The intraclass correlation coefficient for CCAD was 0.94 among the observers. CCAD was consistent from the preoperative to the final postoperative follow-ups in both groups. The classification of the CCAD preoperatively indicated that 12 of 22 (54.4%) patients who were classified into the postoperative unbalanced SD group showed grade 3 CCAD preoperatively, whereas only 9 of 67 (13.4%) patients who were classified in the postoperative balanced SD group had grade 3 CCAD preoperatively. The developed method to predict postoperative shoulder balance was demonstrated to be easy to perform, reliable, and practical. Additionally, we classified the estimation of postoperative shoulder imbalance by preoperation CCAD. The results of this comprehensive review will guide spinal surgeons in their preoperative planning and in the surgical management of adolescent idiopathic scoliosis to reduce postoperative shoulder imbalance. 4.

Is Decompensation Preoperatively a Risk in Lenke 1C Curves?

A review of a multicenter, prospective registry of patients surgically treated for adolescent idiopathic scoliosis. To investigate preoperative and postoperative distribution of coronal decompensation in Lenke 1C curves and to determine whether a selective thoracic fusion (STF) affects the results of coronal decompensation. Numerous causes of postoperative coronal decompensation in Lenke 1C curves have been reported; however, there are few reports focusing on preoperative decompensation and its relation to postoperative decompensation in Lenke 1C curves. Patients with Lenke 1C prospectively collected from a multicenter study were analyzed. Preoperatively, patients were grouped as decompensated (C7-CSVL > 2 cm) or balanced (C7-CSVL within 2 cm, where CSVL is central sacral vertical line). Preoperative distribution and factors for postoperative coronal decompensation were investigated. Seventy-one patients (53 STF, 18 nonselective fusions) were included. Preoperatively, coronal balance was skewed to the left (-17 ± 13 mm). Of the 21 STF decompensated to the left preoperatively, 12 (57%) remained to the left at 2 years. Postoperative thoracic correction was significantly better in those balanced postoperatively (57%) compared with those who remained decompensated (46%; P < 0.05). There were 32 STF patients who were balanced preoperatively, with 10 of these (31%) decompensated to the left at 2-year follow-up. This rate (31%) was significantly less than the group that was decompensated preoperatively (57%, P = 0.04). In the nonselective fusion group, 16 out of 18 patients (89%) were balanced at 2-year follow-up, independent of preoperative balance. Patients with Lenke 1C tended to be decompensated to the left preoperatively. In those decompensated preoperatively who underwent a STF, the majority remained greater than 2 cm to the left at 2-year follow-up. Patients with both thoracic and lumbar curves fused had better coronal balance at 2 years than selectively treated patients. Although not a contraindication to performing a selective fusion, treating surgeons should be prepared for modest coronal decompensation in 40% of patients with Lenke 1C treated with selective fusion of the thoracic curve alone. 3.

Postoperative Distal Adding-on and Related Factors in Lenke Type 1A Curve

A retrospective, multicenter study. To investigate the occurrence of and factors related to postoperative adding-on in Lenke type 1A curve. Although several studies have investigated factors associated with adding-on in Lenke type 1A curve, these factors have not been elucidated in a large study population. This study included 112 patients who were followed more than 2 years after undergoing selective posterior thoracic fusion surgery for Lenke Type 1A curve (8 males, 104 females; mean age at surgery, 16.1 yr; mean follow-up, 3.6 yr). The lower instrumented vertebra (LIV) was T12 in 22 patients, L1 in 55, L2 in 32, and L3 in 3. Distal to the main thoracic curve, the end vertebra, neutral vertebra, stable vertebra (SV), and the last vertebra touching the central sacral vertical line (last touching vertebra, LTV) were determined. The occurrence and factors associated with distal adding-on were investigated. The mean Cobb angle and apical translation of the main thoracic curve were 54.6° ± 9.6° and 53.1 ± 20.4 mm before surgery, and 14.2 ± 7.4 and 16.2 ± 12.7 at follow-up, respectively. Distal adding-on was observed in 21 patients (18.8%) at follow-up. Univariate analyses identified several factors significantly associated with adding-on, including the preoperative proximal thoracic curve, the apical translation of the main thoracic curve, Miyanji's subclassification, the postsurgical proximal and main thoracic curves, the postsurgical apical translation of the main thoracic curve, the correction rate of the main thoracic curve and the clavicle angle immediately after surgery and at follow-up, and the difference in levels between the LIV and the end vertebra, neutral vertebra, LTV, and stable vertebra. Logistic regression analysis showed that the apical translation of the main thoracic curve immediately after surgery (apical translation >25 mm, odds ratio: 10.7, 95% confidence interval: 3.1-37.0, P = 0.001) and the difference in levels between LIV and LTV (LIV-LTV) (LIV-LTV <0, odds ratio: 6.7, 95% confidence interval: 1.9-23.9, P = 0.003) were significantly associated with adding-on. Since the residual apical translation of the main thoracic curve and the lowest instrumented vertebra more cranial to the last touching vertebra were significantly associated with adding-on, surgeons may need to obtain the maximum reduction of the apical translation of the main thoracic curve and to extend the LIV at least to the LTV to avoid postoperative adding-on.

Distal Adding-on in Lenke 1A Scoliosis

A radiographical follow-up and analysis. To identify appropriate radiographical parameters for measuring the extent of distal adding-on and to discuss criteria for determining the onset of distal adding-on. There is no consensus on how to determine the onset of distal adding-on in Lenke 1A scoliosis. Such questions as: "Which radiographical parameters should be used for measuring the extent of distal adding-on?" and "What criteria should be applied in determining the onset of distal adding-on?" need to be answered. We reviewed all the AIS cases surgically treated in an institution from 2003 through 2009. Inclusion criteria were as follows: (1) patients with Lenke 1A curves who were treated with selective thoracic fusion; (2) age less than 30 years; (3) 2-year radiographical follow-up. Eight radiographical parameters were tested to see if they are potential instruments in the detection of distal adding-on. Fifty-three patients met the inclusion criteria. No pseudarthrosis or crankshaft phenomenon was observed in the current cohort. Five out of 8 radiographical parameters: thoracic Cobb, LIV-CSVL distance, LIV + 1-CSVL distance, thoracic AV-CSVL distance and LIV + 1 tilt angle, in the 2 years after surgery, showed significant increase. The remaining 3 parameters: LIV tilt angle, T1-CSVL distance and number of vertebrae within Cobb, however, did not show significant increase. In regard to the 5 parameters that have the potential to detect the onset of distal adding-on, we found a high correlation between every 2 of them. The correlation coefficients range from 0.504 to 0.962 (P = 0.001), suggesting that all of them are in a positive linear relationship. Regarding the criterion for determining the onset of distal adding-on, an increase of more than 10 mm in LIV-CSVL distance in the postoperative period can be considered as a the main criterion because it is unlikely to be induced by measurement errors. LIV-CSVL distance could be an ideal parameter for measuring the extent of distal adding-on. Distal adding-on can be determined when the LIV-CSVL distance increases by 10 mm in the postoperative period.

Posterior decompression with transforaminal interbody fusion for thoracic myelopathy due to ossification of the posterior longitudinal ligament and the ligamentum flavum at the same level

Our objective was to evaluate the clinical efficacy and feasibility of posterior decompression with transforaminal thoracic interbody fusion (PTTIF) for thoracic myelopathy caused by ossification of the ligamentum flavum (OLF) and ossification of the posterior longitudinal ligament (OPLL) at the same level. Between March 2004 and December 2008, 13 patients (five men and eight women, average age: 56years, range: 39–72years) who underwent PTTIF for concurrent OLF and OPLL were studied retrospectively. The clinical efficacy, operative time, blood loss, sagittal alignment and complications were investigated. Cerebrospinal fluid leakage occurred in three patients, all of whom healed well after repair. One patient developed a urinary tract infection and one developed a wound infection, but both were cured with appropriate antibiotic therapy. Neurological symptom deterioration occurred in one patient, but she returned to her preoperative baseline after completing methylprednisolone therapy. After an average 36.8months follow up, the mean Japanese Orthopaedic Association (JOA) score significantly increased from 4.3±1.3 preoperatively to 7.2±1.8 at 3months after the operation and 8.5±1.7 at the final follow-up (P<0.01), with an overall recovery rate of 63.2±21.8%. Postoperative imaging demonstrated an improvement in the local kyphosis (P<0.01), and as of the final follow up no cases of spinal instability or instrument loosening had occurred. We conclude that PTTIF provides satisfactory neurological recovery and stabilises the thoracic fusion through a single posterior approach. However, this procedure is not complication free and demands advanced technical expertise on the part of practitioners, particularly to avoid catastrophic spinal cord injuries.

Adding Thoracic Fusion Levels in Lenke 5 Curves

Multicenter; review of prospectively collected data. To determine the risks and potential benefits of nonselective versus selective fusion in a matched set of patients with Lenke 5 curves. The Lenke classification suggests a limited thoracolumbar/lumbar fusion for type 5 curves, although many experienced adolescent idiopathic scoliosis surgeons, at times, include a fusion of the thoracic curve. METHODS.: Prospectively collected cases from a multicenter database were analyzed. Patients with Lenke type 5 scoliosis curves were divided into 2 groups: 109 selective or short (only thoracolumbar/lumbar curve fused), and 41 nonselective or long (both thoracolumbar/lumbar and thoracic curves fused). Patients were then matched on the basis of the preoperative radiographical and clinical measures. Two-year postoperative radiographical and clinical outcomes were compared, using analysis of variance, with Bonferroni correction (P < 0.008). Twenty-nine matched pairs (58 patients) with Lenke 5 curves were identified. There were no preoperative differences between groups in age, thoracic or lumbar Cobb angle, curve flexibility, thoracic kyphosis, clinical trunk flexibility, or Scoliosis Research Society outcomes questionnaire scores. Postoperatively, patients in the nonselective group exhibited greater coronal correction for thoracic (residual Cobb; 22° vs. 12°) and lumbar curves (residual Cobb; 19° vs. 13°). However, the longer fusions had significantly less thoracic kyphosis (27° vs. 18°), truncal side bending (14 vs. 10 cm), and rotational flexibility (53° vs. 42°). There was no difference in clinical balance or Scoliosis Research Society questionnaire, version 22, scores. Adolescent idiopathic scoliosis surgeons attempt to achieve balanced correction with the fewest motion segments fused. Our data suggest that fusion of the thoracic curve in primary thoracolumbar scoliosis may improve coronal correction, but at the cost of decreased thoracic kyphosis and clinical flexibility 2 years postoperatively.

Secondary Curve Behavior in Lenke Type 1C Adolescent Idiopathic Scoliosis After Thoracoscopic Selective Anterior Thoracic Fusion

Analysis of a case series of 24 patients with Lenke 1C adolescent idiopathic scoliosis (AIS) receiving selective thoracoscopic anterior scoliosis correction. To report the behavior of the compensatory lumbar curve in a group of patients with Lenke IC AIS after thoracoscopic anterior scoliosis correction and to compare the results of this study with previously published data. Several prior studies have reported spontaneous lumbar curve correction for both anterior and posterior selective fusions in patients with Lenke 1C/King-Moe 2; however, to our knowledge no previous studies have reported outcomes of thoracoscopic anterior correction for this curve type. All patients with AIS with a curve classification of Lenke 1C and a minimum of 24-month follow-up were obtained from a consecutive series of 190 patients with AIS who underwent thoracoscopic anterior instrumented fusion. Cobb angles of the major curve, instrumented levels, compensatory lumbar curve, and T5-T12 kyphosis were recorded, as well as coronal spinal balance, T1 tilt angle, and shoulder balance. All radiographical parameters were measured before surgery and at 2, 6, 12, and 24 months after surgery. Twenty-four female patients with right thoracic curves had a mean thoracic Cobb angle of 53.0° before surgery, decreasing to 24.9° 2 years after surgery. The mean lumbar compensatory Cobb angle was 43.5° before surgery, spontaneously correcting to 25.4° 2 years after surgery, indicating balance between the thoracic and lumbar scoliotic curves. The lumbar correction achieved (41.8%) compares favorably to previous studies. Selective thoracoscopic anterior fusion allows spontaneous lumbar curve correction and achieves coronal balance of main thoracic and compensatory lumbar curves, good cosmesis, and patient satisfaction. Correction and balance are maintained 24 months after surgery.

Silicate-Substituted Calcium Phosphate Ceramic Bone Graft Replacement for Spinal Fusion Procedures

Retrospective study. To assess the clinical and radiographical outcomes in spinal fusion procedures using silicate-substituted calcium phosphate (Si-CaP). Si-CaP is a newer-generation synthetic ceramic designed to maximize osteoinduction and osteoconduction. This is a retrospective analysis of a prospectively collected patient database including 108 patients (204 individual spinal levels). Different surgical procedures performed included 25 anterior cervical discectomy and fusions, 17 posterior cervical fusions, 7 combined anterior and posterior cervical fusions, 10 thoracic fusion surgeries, 18 transforaminal lumbar interbody fusions with 12 axial lumbar interbody fusions, 11 transpsoas discectomy and fusions, and 8 combined thoracolumbar fusion procedures. Si-CaP was used as bone extender without any additional graft material, bone marrow aspirate, or bone morphogenetic protein. Clinical outcomes were assessed using the visual analogue scale (VAS), Oswestry Disability Index, and Neck Disability Index. Fusion was determined by the presence of bony bridging on 2 consecutive sections in at least 2 planes on computed tomographic imaging. At a follow-up of 12 (± 4.7) months, 90% of all patients demonstrated radiographical fusion. Fusion rates were highest in the cervical spine (97%) followed by thoracic and lumbar spines (86% and 81%, respectively). There were significant improvements in all clinical outcome measures-Oswestry Disability Index, 11.1 (± 10.2) and Neck Disability Index, 9.0 (± 11.4); VAS-back, 3.1(± 3.0); VAS-leg, 3.5 (± 3.6); VAS-neck, 3.7 (± 2.5); and VAS-arm 4.0 (± 3.2). There was no radiographical loosening of instrumentation due to infection or nonunion in this series, and no subsequent revisions for nonunion were required. Si-CaP is an alternative to autogenous bone graft in spinal arthrodesis procedures. At 12-month follow-up, we detected high levels of bony fusion using Si-CaP in combination with various surgical spinal techniques.

Postoperative Trunk Shift in Lenke 1C Scoliosis

A risk factor analysis study. To identify the causative factors for postoperative trunk shift in Lenke 1C scoliosis and investigate how to prevent it. When selective thoracic fusion is performed, postoperative trunk shift is a significant problem in the management of Lenke 1C scoliosis. It is often accompanied by unsatisfactory clinical outcomes and a risk of reoperation. We reviewed all the patients with adolescent idiopathic scoliosis (AIS) surgically treated in our institution from 2002 through 2008. Inclusion criteria were as follows: (1) patients with Lenke 1C curves who were treated with selective thoracic fusion using posterior pedicle screw-only constructs; (2) the lowest instrumented vertebra (LIV) ending at L1 level or above; and (3) 2-year radiographical follow-up. Eighteen radiographical parameters were chosen as potential risk factors. The 18 parameters measured (1) amount of correction obtained by surgery; (2) preoperative position of LIV; (3) magnitude of major thoracic and thoracolumbar/lumbar (MT and TL/L) curves and ratio of MT: TL/L curve; and (4) curve flexibility. Both comparative and correlation analyses were performed. Those parameters that had shown highest correlation with the 2-year thoracic apical vertebra-center sacral vertical line (AV-CSVL) distance were selected to form a linear regression model, by which the correlations were quantified. Of the 278 patients reviewed, 44 met the inclusion criteria. The parameters that measured the preoperative position of LIV and ratio of MT: TL/L curve showed high correlation with the 2-year thoracic AV-CSVL distance. With regard to the parameters that measured the amount of correction obtained by surgery, only the correction of the thoracic AV-T1 distance showed low correlation. Among the 18 parameters, preoperative lowest instrumented vertebra-lower end vertebra (LIV-LEV) difference and ratio of MT: TL/L Cobb angle were selected to form a formula to help predict postoperative trunk shift. The formula was as follows: 2-year thoracic AV-CSVL distance = -26.6 + 22.7 (ratio of MT: TL/L Cobb angle) - 3.9 (preoperative LIV-LEV difference). The model R2 = 0.55. Both LIV selection and ratio of MT: TL/L curve were found to be highly correlated with the onset of postoperative trunk shift in Lenke 1C scoliosis. Amount of correction obtained by surgery, however, did not seem to be an independent causative factor. Postoperative trunk shift is less likely to occur when selecting LEV as LIV and the ratio of MT: TL/L Cobb angle of 1.2° or more.

Lumbar Curve Is Stable After Selective Thoracic Fusion for Adolescent Idiopathic Scoliosis

A retrospective cohort study comparing long-term clinical and radiographical outcomes using selective thoracic instrumented fusion versus long instrumented fusion for the treatment of adolescent idiopathic scoliosis (AIS). To evaluate long-term behavior of the lumbar curve in patients with AIS treated with selective thoracic fusion and to assess clinical outcome measures in this patient population compared with those patients treated with fusion in the lumbar spine. Selective thoracic fusion for the treatment of AIS preserves motion segments, but leaves residual lumbar deformity. Long-term results of selective fusion using segmental fixation are limited. Nineteen patients with AIS treated with selective thoracic fusion and 9 patients treated with a long fusion returned at a mean 20 years (range, 14-24 years) postoperatively for radiographs, clinical evaluation, and outcome surveys (Short Form-12, Scoliosis Research Society-24, Spinal Appearance Questionnaire, Oswestry Disability Index, and visual analogue scale for pain and stiffness). Curve types were Lenke 1B, 1C, or 3C. All patients underwent posterior fusion with Texas Scottish Rite Hospital or Cotrel-Dubousset hook-rod instrumentation. The selective thoracic fusion group had no significant progression in the lumbar curve magnitude and no worsening of L4 obliquity to the pelvis between initial postoperative and 20-year follow-up. Mean preoperative lumbar curve magnitude (mean, 44°; range, 32-64) corrected 43% on initial postoperative films versus 38% at latest follow-up. Mean L4 obliquity to the pelvis, trunk shift, sagittal balance, and coronal balance were stable over time. Outcome scores between the 2 groups were similar. Scores in long fusion group, when compared with the selective group, were higher for 2 Scoliosis Research Society domains: self-image after surgery (P = 0.005) and function after surgery (P = 0.0006). Spinal balance and correction of the lumbar curve remain stable over time in selective thoracic fusion. Those with selective fusions have outcome measures comparable with those with long fusions.

Spontaneous lumbar curve correction in selective anterior instrumentation and fusion of idiopathic thoracic scoliosis of Lenke type C

Posterior pedicle screw instrumented correction and fusion have become the gold standard in the surgical treatment of thoracic scoliosis. However, in thoracic Lenke type C curves selective posterior fusion of the thoracic curve may lead to spinal imbalance. The aim of the study was to analyse the radiological results of selective anterior thoracic fusion using a standard open dual rod technique with special respect to spontaneous lumbar curve correction (SLCC). Twenty-eight patients (26 patients with Lenke 1C and 2 patients with Lenke 2C curves) with an average age of 15 years were surgically treated with an anterior dual rod system through a standard open double thoracotomy approach. Average clinical and radiological follow-up was 4 years (24-84 months). Fusion was carried out mostly from end-to-end vertebra. The primary curve was corrected from 61.6° (average correction on reverse bending films 42.9 %) to 27.1° (56.0 % correction) with an average loss of correction of 2.2°. The secondary lumbar curve measured 47.7° preoperatively (40-56°, average correction on reverse bending films 66.2 %) and corrected spontaneously to 30.1° (36 % SLCC) and remained stable without any cases of deterioration or decompensation during follow-up. Lumbar apical vertebral translation increased minimally by an average of 4 mm directly, postoperatively, and returned to an average of preoperative values during follow-up. All but two curves remained as type C lumbar modifier at follow-up. Preoperatively, three patients showed a marked coronal imbalance of more than 3 cm (all left, average 4.0 cm); at follow-up, two patients were still out of balance by more than 3 cm (all to the left, average 3.4 cm). Preoperatively, a marked shoulder imbalance of more than 1.0 cm was found in 11 patients; this was corrected in all patients to <1.0 cm at follow-up. The apical vertebral rotation measured according to Perdriolle was corrected from 23.5° to 15.0° in the thoracic spine (36.2 % correction) with an average clinical reduction of the rib hump of 63.2 %. In the lumbar spine, there was no relevant radiological derotation; however, clinically, the lumbar hump corrected spontaneously by 44.3 %. Thoracic kyphosis measured 28.5° preoperatively and 32.3° at follow-up. All six patients with a preoperative hypokyphosis (<20°) of an average of 9.5° were successfully corrected to an average thoracic kyphosis of 23.8° at follow-up. There were no cases of junctional thoracolumbar kyphosis. There were neither reoperations nor implant failures with pseudarthrosis. Selective anterior correction and fusion in primary thoracic curves with lumbar modifier type Lenke C resulted in a reliable and satisfactory SLCC. Advantages of anterior versus posterior techniques are the true segmental derotation with excellent rib hump correction and a superior restoration of thoracic kyphosis.

Anterior short correction in thoracic adolescent idiopathic scoliosis with mini-open thoracotomy approach: prospective clinical, radiological and pulmonary function results

This is a prospective study of adolescent patients in whom idiopathic thoracic scoliosis was corrected by short anterior fusion through a mini-open thoracotomy approach. Clinical, radiological and pulmonary function results of minimal 2-year (2-6) follow-up are presented. Consecutive 62 patients with Lenke 1 and 2 curves, having main thoracic scoliosis of up to 75°, were prospectively included. The shoulder imbalance in Lenke 2 patients was less than 20 mm. Thoracic scoliosis was corrected by short anterior fusion. The thoracic spine was exposed by an 8-cm mini-open thoracotomy incision. The operation technique and choosing of fusion levels are thoroughly described. Complete 360° discectomies and convex side vertebral endplates osteotomies are essential for deformity corrections with short fusions. Single-rod 5.5-mm titanium implants were used. The age at the time of operation was mean 15.2 years; 56 patients had a single thoracic curve and 6 patients had a double thoracic curve. There were almost equal numbers of patients with lumbar modifier A, B or C. The average length of fusion was 5.5 (4-7) vertebrae. The average length of fusion was 3.5 (2-6) vertebrae shorter than the average curve length. The instrumented thoracic curves improved by 58.3% at 6 weeks and 56.3% at the last follow-up. Apex thoracic vertebral rotation improved by 73.78% at 6 weeks and 76.24% at the last follow-up. The non-instrumented upper thoracic curve improved by 25% in double thoracic scoliosis, where the mid-thoracic curve was selectively fused, and the non-instrumented lumbar curves improved by 33.9% at the last follow-up. The radiological changes from 6 weeks to the last follow-up were statistically not significant. The clinical rib hump improved by 54% at the last follow-up. There were no significant changes in the pulmonary function. FVC% was 81.04% preoperatively, 76.41% at 6 months and 80.38% at the 2-year follow-up. The results of SRS 24 questionnaire improved from a total of 61.40 points preoperatively to 100.50 points at 6 months and 98.62 points at the 2-year follow-up. There were no neurological or thoracotomy related complications, no pseudarthrosis, no implant pullout or breakage. A good deformity correction without loss of correction or adding on, a good cosmetic result and good patient's satisfaction were achieved through shorter than end-to-end thoracic fusions. The radiological residual deformity is acceptable. Anterior correction of thoracic scoliosis with a short spinal fusion is recommended to keep the large part of the spine mobile. A very short fusion, small thoracotomy incision, low-profile implants and complete closure of parietal pleura are keys to prevent reduction in postoperative lung function.

Commentary: Postoperative spinal alignment remodeling in Lenke 1C scoliosis treated with selective thoracic fusion

COMMENTARY ON Wang Y, Bunger CE, Zhang Y, et al. Postoperative spinal alignment remodeling in Lenke 1C scoliosis treated with selective thoracic fusion. Spine J 2012;12:73–80 ( in this issue ).

A clinical study of internal fixation, debridement and interbody thoracic fusion to treat thoracic tuberculosis via posterior approach only

We evaluated the clinical efficacy and feasibility of one-stage posterior internal fixation, debridement and interbody thoracic fusion in the treatment of thoracic tuberculosis. Sixty adult patients with monosegmental thoracic tuberculosis were studied retrospectively: 34 men and 26 women with an average age of 37.5 years. Operating time, blood loss, time in bed, complications, neurological function, rate of deformity correction and rate of interbody fusion were investigated. All cases were followed up for 27.5 months on average. Average mean operating time was 251 min, evaluated blood loss during operation 780 ml, rate of kyphosis correction 79%, corrected kyphosis angle 25° and loss of corrected angle 1.2°. Patients whose neurological function improved accounted for 90.1%. Erythrocyte sedimentation rate (ESR) or C-reactive protein (CRP) decreased to normal levels three months after operation. The rate of bone fusion was 100%, with a 100% cure rate. No severe complications or spinal cord injury occurred. This approach can successfully remove the focus of tuberculosis with complete interbody thoracic fusion after operation, which restores spinal stability.

Postoperative spinal alignment remodeling in Lenke 1C scoliosis treated with selective thoracic fusion

Selective thoracic fusion may cause spinal imbalance in certain patients; how the spinal alignment changes over time after surgery is highly correlated with the final spinal balance. To investigate how spinal alignment changes over time after selective thoracic fusion and how spinal alignment remodeling affects spinal balance. All adolescent idiopathic scoliosis (AIS) cases surgically treated in our institution between 2002 and 2008 were reviewed. Inclusion criteria were as follows: Lenke 1C scoliosis patients treated with posterior pedicle screw-only constructs; the lowest instrumented vertebra (LIV) ended at L1 level or above; and 2-year radiographic follow-up. Standing anteroposterior and lateral digital radiographs from four different time points (preoperatively, immediately, 3 months, and 2 years postoperatively) were reviewed. In each standing anteroposterior radiograph, the center sacral vertical line (CSVL, the vertical line that bisects the proximal sacrum) was first drawn, and the translation (deviation from the CSVL) of some key vertebrae was measured, such as the LIV, LIV+1 (the first vertebra below LIV), LIV+2 (the second vertebra below LIV), LIV+3 (the third vertebra below LIV), lumbar apical vertebra (AV), thoracic AV, and T1. Additionally, the Cobb angles of the major thoracic and lumbar curves were measured at different time points, and the correction rates were calculated. Furthermore, clinical photographs of the patients from the back were taken preoperatively and postoperatively. Of 278 AIS patients reviewed, 29 met the inclusion criteria. The continuous follow-up of our present study revealed an interesting phenomenon: postoperative spinal alignment remodeling. A hypothetical criterion was established to determine the onset of the phenomenon. By means of a series of analyses, the criterion was validated. The results of our present study showed that selective thoracic fusion tended to cause leftward spinal imbalance in these Lenke 1C AIS patients. Twenty of the 29 patients had leftward spinal imbalance immediately after surgery. Although some patients regained spinal balance through postoperative spinal alignment remodeling, 11 patients remained imbalanced at 2-year follow-up. Selective thoracic fusion is prone to cause leftward spinal imbalance in Lenke 1C scoliosis patients. Postoperative spinal alignment remodeling can facilitate recovery of spinal balance in some patients. Postoperative spinal imbalance in Lenke 1C scoliosis patients could be prevented by selecting stable vertebra or the vertebrae above as LIV, checking the balance condition during surgery, or considering ratio criteria when selecting candidates for selective thoracic fusion.

Changes of Upper Thoracic Curve and Shoulder Balance in Thoracic Adolescent Idiopathic Scoliosis Treated by Anterior Selective Thoracic Fusion Using VATS

A retrospective radiographic analysis. To evaluate changes of upper thoracic curve and shoulder balance in thoracic adolescent idiopathic scoliosis patients treated by anterior selective thoracic fusion using video-assisted thoracoscopic surgery and to identify adequacy of earlier criteria of double thoracic (DT) curve for anterior correction. Although anterior and posterior scoliosis correction show many differences in correction mechanisms, fusion levels, loss of correction etc., the criteria of DT curve was applied without differences. There are no reports about these differences. Forty patients were followed for a minimum of 3 years (range, 3-8 y). The magnitude and flexibility of upper thoracic, lower thoracic, and the superior portion of the lower thoracic curve were measured using full length standing and side-bending radiographs before surgery, at 1 week postoperatively, and at last follow-up. The correction rate and loss of correction of these curves were calculated and preoperative and postoperative radiographic shoulder heights (RSHs) were measured. RSH was defined as balanced (shoulder height difference <10 mm), mildly imbalanced (10-20 mm), or moderately imbalanced (>20 mm). T1 tilt and coronal balance were also evaluated. Patients were divided into groups based on these factors and postoperative RSH was compared. Flexibility of the upper thoracic curve was 46% and magnitude of the upper thoracic curve was corrected spontaneously from 28.6±7.8 degrees to 17.9±7.0 degrees with a 37.4% correction rate that did not change during follow-up. On average, preoperative left shoulder was 6.3±10.5 mm lower than right shoulder and this changed to 10.4±11.8 mm and 6.0±8.2 mm higher than right shoulder at 1 week postoperatively and at last follow-up, respectively. The group with an upper thoracic curve of ≥30 degrees or a superior portion of the lower thoracic curve of ≥30 degrees preoperatively had a higher left shoulder postoperatively (P=0.016, 0.040). Of the 12 patients with a symmetric or higher left shoulder (≥0 mm) preoperatively, 9 patients had a balanced shoulder (-10-10 mm) and 3 patients showed mild shoulder imbalance (<20 mm) at last follow-up. Among patients who have DT curve, patients with mild left shoulder elevation (<20 mm) can be treated by anterior correction unless the magnitude of upper thoracic curve or superior portion of lower thoracic curve are ≥30 degrees. For anterior correction, criteria of DT curve might be applied less strictly.

Which Factors Influence Spontaneous Lumbar Curve Correction After Selective Thoracic Fusion In Lenke Type IB And C Curves?

Which Factors Influence Spontaneous Lumbar Curve Correction After Selective Thoracic Fusion In Lenke Type IB And C Curves?

Broader Curve Criteria for Selective Thoracic Fusion

Retrospective radiographic review. To evaluate the outcome of selective thoracic fusion (STF) by using cantilever bending technique (CBT) and the direct vertebral rotation (DVR) technique for major thoracic-compensatory lumbar (MTCL) curves selected by new curve criteria, which are broader than Lenke curve criteria for STF. Surgical treatment of MTCL curves aims to maximize the number of MTCL curves that can be treated with STF and optimize instrumented thoracic and spontaneous lumbar correction. Comparing current guidelines for STF shows that the surgical technique utilized for STF may affect the curve criteria for MTCL curves for successful STF and thoracic and lumbar correction. Seventy-eight consecutive idiopathic scoliosis patients with major thoracic-compensatory "C" modifier lumbar curves who met the following three criteria: (1) main thoracic curve (MT) to compensatory lumbar curve (CL) ratios of Cobb magnitude and apical vertebral translation (AVT) greater than one; (2) MT/CL ratio of flexibility less than one; (3) Cobb magnitude of lumbar curve less than 35° on side bending, were treated with STF by using CBT and DVR. Radiographs were analyzed before surgery, immediately after surgery, and at the most recent follow-up (range, 2-5 years). All 78 MTCL curves were successfully treated with STF by using CBT and DVR. A mean 61% thoracic correction was matched by 55% lumbar correction at the most recent follow-up. Spontaneous correction of lumbar AVT occurred in all patients. Global coronal imbalance was common before surgery (mean, 14 mm) and remained so after surgery (mean, 12 mm). There were 49 MTCL curves that did not meet Lenke curve criteria for STF. All were successfully treated with STF by using CBT and DVR. Among these 49 MTCL curves, there were 14 Lenke 1C and 18 Lenke 2C curves with one or two, or all of MT/CL ratios of Cobb magnitude, AVT, and apical vertebral rotation of 1.2 or less, and 6 Lenke 3C and 11 Lenke 4C curves with the Cobb magnitude of residual lumbar curve on side bending between 25° and 35°. CBT and DVR can broaden the current curve criteria of MTCL curves for STF to have more MTCL curves treatable with STF and optimize instrumented thoracic and spontaneous lumbar correction. A more effective surgical technique can not only improve instrumented thoracic and spontaneous lumbar correction but also can broaden the MTCL curve criteria for STF to have more MTCL curves treatable with STF.

Selective thoracic fusion in the scoliosis associated with syringomyelia

To evaluate the surgical results of selective thoracic fusion (STF) for scoliosis associated with syringomyelia. From January 2001 to January 2009, 93 cases of scoliosis associated with syringomyelia were retrospectively reviewed. There were 11 cases who underwent STF and were followed up more than 2 years, which included 8 female and 3 male, the mean age was 14.9 years (9 - 21 years). Curve type, coronal and sagittal Cobb angle, apical vertebral rotation apical vertebral translation, flexibility, trunk shift were recorded and analyzed. There were 9 double curves and 2 triple curves, the Lenke type of thoracolumbar/lumbar curve included Lenke A in 2 cases, Lenke B in 7 cases and Lenke C in 2 cases. The average coronal Cobb angle of thoracic curve before and after surgery were 62.6° and 19.0° respectively, and the average correction rate was 69.6%. The average coronal Cobb angle of thoracolumbar/lumbar curve before and after surgery were 36.1° and 11.6° respectively, and the average spontaneous correction rate was 67.9%. The followed up time ranged from 24 to 48 months (mean 29.5 months), the average loss of correction rate was 6.8%. Only one trunk decompensation was noted at final follow-up. Pedicle screw nut loosening occurred in one patient and this patient underwent revision surgery, no neurological complication was noted at final follow-up. STF could be safely performed in scoliosis associated with syringomyelia. Thoracolumbar/lumbar curve in these patients has similar spontaneous correction ability compared with idiopathic scoliosis patients. The satisfactory result could be achieved according to the STF criteria for IS.

Selective Thoracic Fusion in Adolescent Idiopathic Scoliosis

Analysis of multicenter, prospectively collected data. To determine how selection of the lowest instrumented vertebra (LIV) relative to the stable vertebra (SV) and the end vertebra (EV) effects correction of the main thoracic curve, compensatory lumbar curve, and incidence of coronal decompensation after selective thoracic fusion. Traditionally, in Lenke type 1B and 1C curves, the LIV is selected as the SV; however, selecting the LIV continues to be controversial. Inclusion criteria were patients with adolescent idiopathic scoliosis (AIS) with Lenke type 1B, 1C, or 3C curves that had a selective thoracic fusion with the LIV from T11 to L1 (n=172). The patients were divided into three curve patterns on the basis of the relative position of SV and EV. Group SBE (stable below end) (n=93) had SV below EV, group SAE (stable at end) (n=66) had SV at the EV, and group EBS (end below stable) (n=13) has EV below SV. In addition, each group was divided into six subgroups based on the selected LIV: LIV above SV, at the SV, below SV, above EV, at the EV, and below EV. Each was compared for preoperative and 2-year postoperative radiographic parameters and clinical data. In group SBE, the 2-year postoperative thoracic curve correction rate when the LIV was below the EV (64%+16%) was significantly greater than when the LIV was at the EV (54%+13%; P<0.001). The 2-year postoperative spontaneous lumbar curve correction (SLCC) rate similarly correlated with the LIV selection subgroups, 52%+20% and 43%+19%, respectively (P=0.03). In group SAE, the 2-year postoperative thoracic curve correction rate when the LIV was below the EV/SV (64%+14%) was significantly greater than when the LIV was at the EV/SV (52%+14%; P=0.004). The 2-year postoperative SLCC rate for group SAE similarly correlated with the LIV selection subgroup, 56%+16% and 38%+21%, respectively (P<0.01). In group EBS, the 2-year postoperative thoracic curve correction and SLCC rates were not significantly different among the LIV selection subgroups; however, the incidence of decompensation was 38%. When performing a selective thoracic fusion of Lenke type 1B, 1C, and 3C AIS curves in which the SV was at/or below the EV, the greatest correction of the main thoracic and compensatory lumbar curves occurred when the LIV was at/or at least one level distal to the SV. This more distal LIV did not result in an increased rate of truncal imbalance.