Postoperative Thoracic Kyphosis Research Articles

The Influence of Increased Pedicle Screw Diameter and Thicker Rods on Surgical Results in Adolescents Undergoing Posterior Spinal Fusion for Idiopathic Scoliosis.

Background: Modern surgical techniques allow for the correction of spinal deformity, stopping its progression and improving pain relief and social and physical functioning. These instruments have different implant designs, screws, and rod diameters and can be composed of different metal alloys with different hardnesses, which can have a significant impact on the effect of correcting spinal deformities. We designed a retrospective cohort study based on the same surgical technique and spine system using different implant sizes, and compared the results across them. Methods: This is a retrospective review of adolescent idiopathic scoliosis (AIS) patients who underwent posterior spinal fusion (PSF) between 2016 and 2022 with a minimum two-year follow-up (FU) using two spinal implant systems: 5.5 and 6.0 mm diameter screws with double 5.5 mm titanium rods (Group 1 (G1)), and 6.0 and 6.5 mm diameter pedicle screws with double 6.0 mm cobalt-chromium rods (Group 2 (G2)). The evaluated data were as follows: preoperative personal data, radiographic outcomes, complications, and health-related quality of life questionnaire (HRQoL). The parameters were reviewed preoperatively, after the final fusion, and during the FU. Results: The mean age of all 260 patients at surgery was 14.8 years. The average BMI was also similar in both groups and was noted as 21. The mean levels of fusion and screw density were similar in both groups. The mean preoperative major curves (MCs) were 57.6° and 62.5° in G1 and G2, respectively. The mean flexibility of the curves was noted as 35% in G1 and 33% in G2. After definitive surgery, the mean percentage correction of the MC was better in G2 vs. G1, with 74.5% vs. 69.8%, respectively (p < 0.001). At the final FU, the average loss of correction was 5.9° for G1 and 3.2° for G2 (p < 0.001). The mean preoperative (TK) thoracic kyphosis (T2-T5) was 12.2° in G1 and 10.8° in G2. It was corrected to 15.2° in G1 and to 13° in G2. At the FFU, we noted a significant difference in the TK (T2-T5) between the groups, with 16.7° vs. 9.6° for G1 vs. G2, respectively (p < 0.001). Statistical significance was observed between the preoperative sagittal balance and the final follow-up for both groups (p < 0.001). Conclusions: AIS patients surgically treated with screws with a larger diameter and thicker and stiffer rods showed greater correction and postoperative thoracic kyphosis without implant failure. The complication rates, implant density, and clinical outcomes remained similar. The radiographic benefits reported in this cohort study suggest that large-sized screws and stiffer rods for the correction of pediatric spinal deformities are safe and very effective.

Costs of revision operations for distal junctional kyphosis following thoracic posterior spinal fusion for adolescent idiopathic scoliosis.

To assess direct costs and risks associated with revision operations for distal junctional kyphosis/failure (DJK) following thoracic posterior spinal instrumented fusions (TPSF) for adolescent idiopathic scoliosis (AIS). Children who underwent TPSF for AIS by a single surgeon (2014-2020) were reviewed. Inclusion criteria were minimum follow-up of 2years, thoracolumbar posterior instrumented fusion with a lower instrumented vertebra (LIV) cranial to L2. Patients who developed DJK requiring revision operations were identified and compared with those who did not develop DJK. Seventy-nine children were included for analysis. Of these, 6.3% developed DJK. Average time to revision was 20.8 ± 16.2months. Comparing index operations, children who developed DJK had significantly greater BMIs, significantly lower thoracic kyphosis postoperatively, greater post-operative lumbar Cobb angles, and significantly more LIVs cranial to the sagittal stable vertebrae (SSV), despite having statistically similar pre-operative coronal and sagittal alignment parameters and operative details compared with non-DJK patients. Revision operations for DJK, when compared with index operations, involved significantly fewer levels, longer operative times, greater blood loss, and longer hospital lengths of stay. These factors resulted in significantly greater direct costs for revision operations for DJK ($76,883 v. $46,595; p < 0.01). In this single-center experience, risk factors for development of DJK were greater BMI, lower post-operative thoracic kyphosis, and LIV cranial to SSV. As revision operations for DJK were significantly more costly than index operations, all efforts should be aimed at strategies to prevent DJK in the AIS population.

Patient-Specific Surgical Correction of Adolescent Idiopathic Scoliosis: A Systematic Review.

The restoration of sagittal alignment is fundamental to the surgical correction of adolescent idiopathic scoliosis (AIS). Despite established techniques, some patients present with inadequate postoperative thoracic kyphosis (TK), which may increase the risk of proximal junctional kyphosis (PJK) and imbalance. There is a lack of knowledge concerning the effectiveness of patient-specific rods (PSR) with measured sagittal curves in achieving a TK similar to that planned in AIS surgery, the factors influencing this congruence, and the incidence of PJK after PSR use. This is a systematic review of all types of studies reporting on the PSR surgical correction of AIS, including research articles, proceedings, and gray literature between 2013 and December 2023. From the 28,459 titles identified in the literature search, 81 were assessed for full-text reading, and 7 studies were selected. These included six cohort studies and a comparative study versus standard rods, six monocentric and one multicentric, three prospective and four retrospective studies, all with a scientific evidence level of 4 or 3. They reported a combined total of 355 AIS patients treated with PSR. The minimum follow-up was between 4 and 24 months. These studies all reported a good match between predicted and achieved TK, with the main difference ranging from 0 to 5 degrees, p > 0.05, despite the variability in surgical techniques and the rods' properties. There was no proximal junctional kyphosis, whereas the current rate from the literature is between 15 and 46% with standard rods. There are no specific complications related to PSR. The exact role of the type of implants is still unknown. The preliminary results are, therefore, encouraging and support the use of PSR in AIS surgery.

Comparative Analysis of Hounsfield Units and Vertebral Bone Quality Scores for Predicting Proximal Junctional Failure in Female Adult Spinal Deformity Patients Undergoing Planned 2-Stage Corrective Surgery with Lateral Lumbar Interbody Fusion

This study aimed to evaluate the utility of computed tomography (CT)-based Hounsfield units (HUs) and magnetic resonance imaging-based Vertebral Bone Quality (VBQ) scores as alternatives to dual-energy x-ray absorptiometry for predicting the risk of proximal junctional failure (PJF) in female patients with adult spinal deformity (ASD) undergoing 2-stage corrective surgery with lateral lumbar interbody fusion (LLIF). The study included 53 female patients with ASD who underwent 2-stage corrective surgery with LLIF from January 2016 to April 2022 with a minimum follow-up of 1year. CT and magnetic resonance imaging scans were evaluated for their correlation with PJF. Of the 53 patients (mean age 70.2years), 14 had PJF. Patients with PJF had significantly lower HU values at the upper instrumented vertebra (UIV) (113.0±29.4 vs. 141.1±41.5, P=0.036) and L4 (113.4±59.5 vs. 160.0±64.9, P=0.026) than those without PJF. However, there was no difference in VBQ scores between the 2 groups. PJF correlated with HU values at UIV and L4 but not with VBQ scores. Patients with PJF also had significantly different pre- and postoperative thoracic kyphosis, postoperative pelvic tilt, pelvic incidence minus lumbar lordosis, and proximal junctional angle compared to those without PJF. The findings suggest that measuring HU values at UIV or L4 by CT may be useful for predicting the risk of PJF in female ASD patients undergoing 2-stage corrective surgery with LLIF. Therefore, CT-based HUs should be considered in ASD surgery planning to reduce the risk of PJF.

Prediction of Post-Operative Clinical Parameters in Posterior Scoliosis Surgery Through An Adaptive Neuro-Fuzzy Interface System

Background and Objective: Postoperative clinical indices should be estimated accurately in scoliosis correction surgeries, which have been analyzed in various studies such as experimental (in vitro or in vivo) trials through different modeling methods (finite element or multibody analysis). These costly and time-consuming methods can only be conducted on a large number of scoliotic patients. An adaptive neuro-fuzzy interface system (ANFIS) is used in this study to estimate the postoperative cobb and thoracic kyphosis angles in adolescent idiopathic scoliosis patients undergoing posterior scoliosis correction surgeries. Methods: Four groups of 55 patients with distinct preoperative clinical indices (thoracic cobb and pelvic incidence) were considered the ANFIS inputs, whereas postoperative thoracic cobb and kyphosis angles were used as the outputs. For robustness evaluation, the predicted values of postoperative angles were compared with measurements by calculating the root mean square errors and clinical correction deviation indices (the relative deviation of postoperative predicted angles from the real angles). Results: The least root mean square errors (3.0º and 6.3° for the main thoracic cobb and thoracic kyphosis estimations, respectively) were recorded in the group with the main thoracic cobb, pelvic incidence, thoracic kyphosis, and T1 spinopelvic inclination used as inputs. The clinical correction deviation indices were calculated 0.0086 and 0.0641 for cobb angles in two cases and 0.0534 and 0.2879 for thoracic kyphosis in two other cases. Conclusion: Greater differences between preoperative and postoperative cobb angles compared with those of thoracic kyphosis decreased the root-mean-square errors and clinical deviation indices but improved accuracy

Influence of posterior instrumented correction with pedicle screw dual rod systems on thoracic kyphosis in Lenke 1 and 2 curves: minimum 2years follow-up.

Adolescent idiopathic scoliosis (AIS) often correspond with hypo thoracic kyphosis (TK) or even lordosis. The aim of this study was to analyze the influence of posterior instrumentation in thoracic AIS. Analysis of prospectively collected AIS-data with structural thoracic curves (Lenke type 1 & 2), operated 2010-2019 with pedicle screw dual rod systems in one scoliosis center. Follow-up (FU) minimum 24months. Coronal and sagittal angles measured based on standing long-cassette-X-rays: thoracic major (MC), proximal thoracic (PC) and lumbar curve (LC), TK, lumbar lordosis (LL). values as mean ± SD, differences by student's t-test (significancy a = 0.05), Pearson's correlation, sub-analysis with sagittal modifier (-, N, +). A total of 127 AIS could be identified (63% type 1, 37% type 2). Mean FU 32.2 ± 16.6months, mean age 14 ± 1.5years. Mean Correction of MC 73 ± 12%, PC 51 ± 17%, LC 69 ± 21% with a significantly better correction of PC in Lenke 2 curves(p < 0.05). On average, TK (FU-preop) decreased by -2.1 ± 12.1°(p < 0.05) in all AIS. Whereas TK in type 1 was unchanged (p = 0.9), TK significantly decreased by - 6.0 ± 12.7°(p < 0.05) in type 2. No significant difference in LL. TK in hypokyphotic cases increased by 9.5 ± 5.5°(p < 0.05), stayed almost unchanged (- 1.4 ± 9.1°,p = 0.2) in normokyphotic, decreased by - 17.2 ± 14.2°(p < 0.05) in hyperkyphotic cases. Only hypokyphotic cases had a moderately strong correlation between correction of LC (r = 0.6) and PC (r = - 0.4) (frontal plane) and change from pre- to postoperative TK (sagittal plane) (r = 0.6). No relevant correlations for normo- and hyperkyphotic AIS. Postoperative hypokyphosis was significantly more often in Lenke 2 (16.3% vs. 2.6%, p < 0.05). Rod diameter (5,5mm versus 6mm) had no significant influence. Significant correction of hypo- and hyperkyphosis can be achieved with posterior spinal fusion (pedicle screw dual rod systems), whereas normokyphotic spines stay unchanged. However, Lenke 2 curves have a significantly higher risk for a postoperative thoracic hypokyphosis.

A comparison of three- and two-rod constructs in the correction of severe pediatric scoliosis.

Managing severe scoliosis is challenging and risky with a significant complication rate regardless of treatment strategy. In this retrospective comparative study, we report our results using a three-rod compared to two-rod construct in the surgical treatment of severe spine deformities to investigate which technique is safer, and which provides superior radiological outcomes. Forty-six consecutive patients undergoing posterior spine fusion for scoliosis between 2006 and 2017 were identified in our institutional records. Inclusion criteria were minimum coronal deformity of 90°, age < 18 years at the time of surgery and a minimum 2 years of follow-up. Radiographic and clinical parameters, as well as post-operative complications were compared between the two groups. There were 21 patients in the three-rod group and 25 in the two-rod group. The mean preoperative major coronal deformity was 100°± 9 and 102°± 10 in the three-rod and two-rod, respectively (p = 0.6). The average major curve correction was 51% and 59% in three-rod and two-rod groups, respectively (p = 0.03). The post-operative thoracic kyphosis was 30°± 11 and 21°± 12 in the three-rod and the two-rod groups, respectively (p = 0.01). The surgical time was 476 ± 52 and 387 ± 84 min in three-rod and two-rod, respectively (p < 0.01). One patient in the two-rod cohort showed permanent post-operative sensory deficit. There were three unplanned returns to operating theater in the two-rod group. Coronal correction was better with two-rod, whereas sagittal balance was superior with three-rod. Both techniques achieved balanced spine treating severe scoliosis. The two-rod technique was associated with a higher likelihood of requiring revision surgery. level 3.

Low radius of curvature growth-friendly rib-based implants increase the risk of developing clinically significant proximal junctional kyphosis.

Clinically significant proximal junctional kyphosis (PJK) occurs in 20% of children with scoliosis treated with posterior distraction-based growth-friendly surgery. In an effort to identify modifiable risk factors, it has been theorized biomechanically that low radius of curvature (ROC) implants (i.e., more curved rods) may increase post-operative thoracic kyphosis, and thus may pose a higher risk of developing PJK. We sought to test the hypothesis that early onset scoliosis (EOS) patients treated with low ROC distraction-based implants will have a greater risk of developing clinically significant PJK as compared to those treated with high ROC (straighter) implants. We conducted a retrospective review of prospectively collected data obtained from a multi-centre EOS database on children treated with rib-based distraction with a minimum 2-year follow-up. Variables of interest included: implant ROC at index (220mm or 500mm), participant age, pre-operative scoliosis, pre-operative kyphosis, and scoliosis etiology. PJK was defined as clinically significant if revision surgery with a superior extension of the upper instrumented vertebrae was performed. In 148 participants with scoliosis, there was a higher risk of clinically significant PJK with low ROC (more curved) rods (OR: 2.6 (95% CI 1.09-5.99), χ2 (1, n = 148) = 4.8, p = 0.03). Participants had a mean pre-operative age of 5.3years (4.6y 220mm vs 6.2y 500mm, p = 0.002). A logistic regression model was created with age as a confounding variable, but it was determined to be not significant (p = 0.6). Scoliosis etiologies included 52 neuromuscular, 52 congenital, 27 idiopathic, 17 syndromic with no significant differences in PJK risk between etiologies (p = 0.07). Overall, participants had pre-op scoliosis of 69° (67° 220mm vs 72° 500mm, p = 0.2), and kyphosis of 48° (45° 220mm vs 51° 500mm, p = 0.1). The change in thoracic kyphosis pre-operatively to final follow-up (mean 4.0 ± 0.2years) was higher in participants treated with 220mm implants compared to 500mm implants (220mm: 7.5 ± 2.6° vs 500mm: - 4.0 ± 3.0°, p = 0.004). Use of low ROC (more curved) posterior distraction implants is associated with a significantly greater increase in thoracic kyphosis which likely led to a higher risk of developing clinically significant PJK in participants with EOS. Level III - retrospective comparative study.

Prediction of Post-operative Clinical Indices in Scoliosis Correction Surgery Using an Adaptive Neuro-fuzzy Interface System.

Accurate estimation of post-operative clinical parameters in scoliosis correction surgery is crucial. Different studies have been carried out to investigate scoliosis surgery results, which were costly, time-consuming, and with limited application. This study aims to estimate post-operative main thoracic cobb and thoracic kyphosis angles in adolescent idiopathic scoliosis patients using an adaptive neuro-fuzzy interface system. Distinct pre-operative clinical indices of fifty-five patients (e.g., thoracic cobb, kyphosis, lordosis, and pelvic incidence) were taken as the inputs of the adaptive neuro-fuzzy interface system in four categorized groups, and post-operative thoracic cobb and kyphosis angles were taken as the outputs. To evaluate the robustness of this adaptive system, the predicted values of post-operative angles were compared with the measured indices after the surgery by calculating the root mean square errors and clinical corrective deviation indices, including the relative deviation of post-operative angle prediction from the actual angle after the surgery. The group with inputs for main thoracic cobb, pelvic incidence, thoracic kyphosis, and T1 spinopelvic inclination angles had the lowest root mean square error among the four groups. The error values were 3.0° and 6.3° for the post-operative cobb and thoracic kyphosis angles, respectively. Moreover, the values of clinical corrective deviation indices were calculated for four sample cases, including 0.0086 and 0.0641 for the cobb angles of two cases and 0.0534 and 0.2879 for thoracic kyphosis of the other two cases. In all scoliotic cases, the post-operative cobb angles were lesser than the pre-operative ones; however, the post-operative thoracic kyphosis might be lesser or higher than the pre-operative ones. Therefore, the cobb angle correction is in a more regular pattern and is more straightforward to predict cobb angles. Consequently, their root-mean-squared errors become lesser values than thoracic kyphosis.

The effect of the caudal insertion angle of pedicle screws on postoperative thoracic kyphosis in adolescent idiopathic scoliosis: a pilot study.

The study was a prospective analysis of collected data to compare the effect of the insertion angle (parallel or oblique relative to the upper-end plates) of thoracic pedicle screws on postoperative thoracic kyphosis in patients with idiopathic thoracic scoliosis. This study was conducted on idiopathic adolescent scoliosis (AIS) patients. Two groups of patients were defined according to the insertion angle of thoracic pedicle screws in relation to the upper-end plate of the corresponding vertebra, the insertion angles being either oblique or parallel. Seven consecutive AIS patients were compared in each group. Pre- and postoperative standing X-rays were obtained. Cobb's angles, sagittal parameters such as thoracic kyphosis (TK) (T1-T12) and lumbar lordosis (LL) (L1-S1) were all measured. The average of the main curve or compensatory curve corrections showed no significant differences between the two groups. From a sagittal profile perspective, the mean TK in the oblique screw group was 39.3 ± 11.5 preoperatively, which was reduced to 30.9 ± 6.41 after surgery. The mean TK in the parallel group was 36.4 ± 14 preoperatively and 42.1 ± 13.9 postoperatively. There was a significant reduction in TK in the oblique screws group compared with the second group ( P = 0.038). The insertion angle of pedicle screws had no significant effect on Cobb's angle and lumbar lordosis changes. However, oblique insertion of thoracic screws decreased thoracic kyphosis postoperatively, which could be considered a negative point. As such, the insertion of thoracic screws in a caudal direction should not be routinely used because of its lordogenic effect.

Use of intra-operative internal distraction for the application of magnetically controlled growth rods (MCGR): a technique for maximizing correction in the rigid immature spine during index surgery.

Operative treatment of early onset scoliosis (EOS) with Magnetically Controlled Growing Rod (MCGR) in moderate-to-severe curves poses a challenge due to the limited amount of force and length available with the implant. The purpose of this study was to assess the use of the intra-operative internal spine distraction using Harrington Outrigger, before definitive implantation of MCGR, with regard to initial correction, maintenance of correction, truncal balance, and complication rates. 16 EOS patients treated with the application of MCGR using the intra-operative internal distractor technique were included in the study. More than 50% of cases were congenital scoliosis with multiple vertebral anomalies. All patients were followed up for a minimum of 2years. Radiological measurement of change in Cobb angle, thoracic kyphosis, lumbar lordosis, T1-S1 length, T1-T12l length, and sagittal balance were done at pre-op, immediate post-op, after 1year, and 2years. All the complications were noted and documented. The mean age of the operated patients was 8±1.7years, range (4-10years). Mean pre-operative Cobb angle was 70.4 degrees. The mean correction of major Cobb angle was 34.6°. The percentage correction achieved in post-operative Cobb angle was about 51%. Mean change in post-operative thoracic kyphosis was 18.5° (40%). The average gain in immediate post-operative spinal length (T1-S1) and thoracic height (T1-T12) was 46.7mm (18.3%) and 41mm (23%), respectively. Large and rigid curves in EOS can achieve a significant correction of Cobb angle and coronal imbalance during the index operation, by the use of intra-operative internal distraction at the time of MCGR insertion. Retrospective clinical study, level 4.

Multilevel non-contiguous thoracic pedicle subtraction osteotomy for fixed rounded hyperkyphotic deformity of the thoraco-lumbar junction with anterior bony fusion: technical note

BackgroundFixed severe hyperkyphotic deformities spread over more than five vertebral levels represent a therapeutic challenge, especially when the deformity apex is located at the thoraco-lumbar junction, thus requiring a huge amount of correction. The aim of this article is to describe an innovative all-posterior corrective technique based on multilevel non-contiguous thoracic pedicle subtraction ostoeotomy (PSO).Materials and methodsA retrospective review of three patients with fixed severe thoracic hyperkyphosis (a deformity angle of over 70°) with a thoraco-lumbar apex (between T11 and L1) treated by simultaneous two-level thoracic PSO and thoraco-lumbar posterior fusion was performed. Radiographic and clinical records were evaluated pre-operatively, post-operatively and at last follow-up (after a minimum of 2 years). Each variable was presented as mean ± SD (standard deviation). Statistical analyses were performed using paired t-tests (P value < 0.05 was considered significant).ResultsThe mean local deformity angle decreased by 75% (from 81.3° ± 2.1° to 20.7° ± 1.4°, p < 0.001), the post-operative thoracic kyphosis decreased by 46% (from 61.4° ± 2.4° to 33.2° ± 0.9°, p < 0.001) and the sagittal vertical axis decreased by 73% (from 14.7 cm ± 0.8 cm to 3.9 cm ± 0.3 cm, p < 0.001). No differences were observed in the radiological results between post-operative values and those at the final follow-up. The average Oswestry Disability Index (ODI) score reduced from 65.7 ± 1.8 pre-operatively to 17.3 ± 1.7 at last follow-up (p < 0.001). No neurological, mechanical nor infective complication occurred.ConclusionsThe presented technique, although technically demanding, proved to be a safe and effective alternative for the management of fixed severe thoraco-lumbar junction hyperkyphotic deformities.Level of evidence: IVTRIAL REGISTRATION Retrospectively registered

The postoperative course of mechanical complications in adult spinal deformity surgery.

(a) Describe the time course of each mechanical complication, and (b) compare radiographic measurements and preoperative patient-reported outcome measures (PROMs) among each mechanical complication type. A single-institution case-control study was undertaken of patients undergoing adult spinal deformity (ASD) surgery from 2009-2017. Exposure variables included patient demographics, operative variables, radiographic measurements, and preoperative PROMs, including Oswestry Disability Index (ODI), Numeric Rating Scale Back/Leg-pain scores (NRS-Back/Leg), and EuroQol-5D (EQ-5D). The primary outcomes were occurrence of a mechanical complication and time to complication. Due to overlapping occurrence, rod fracture and pseudarthrosis were grouped into one composite category. 145 patients underwent ASD surgery and were followed for at least 2 years. 30/47 (63.8%) patients with proximal junctional kyphosis (PJK) required reoperation, whereas 27/31 (87.1%) patients with pseudarthrosis/rod fracture required reoperation (63.8% vs. 87.1%, Χ2 = -0.23, 95% CI -0.41, -0.05, p = 0.023). Cox regression showed no significant difference in time to reoperation between PJK and rod fracture/pseudarthrosis (HR = 0.97, 95% CI 0.85-1.11, p = 0.686). Distal junctional kyphosis (DJK) (N = 3; 2 reoperation) and implant failures (N = 4; 0 reoperations) were rare. Patients with PJK had significantly lower Hounsfield Units preoperatively compared to those with pseudarthrosis/rod fracture (138.2 ± 43.8 vs. 160.3 ± 41.0, mean difference (MD) = -22.1, 95% CI -41.8, -2.4, p = 0.028), more prior fusions (51.1% vs. 25.8%, Χ2 = 0.253, 95% CI 0.41, 0.46, p = 0.026), fewer instrumented vertebrae (9.2 ± 2.6 vs. 10.7 ± 2.5, MD = -1.5, 95% CI -2.7, -0.31, p = 0.013), and higher postoperative thoracic kyphosis (TK) (46.3 ± 12.7 vs. 34.9 ± 10.6, MD = 11.4, 95% CI 5.9, 16.9, p < 0.001). Higher postoperative C7 sagittal vertical axis (SVA) did not achieve a significant difference (80.7 ± 72.1 vs. 51.9 ± 57.3, MD = 28.8, 95% CI -1.9, 59.5, p = 0.066). No differences were seen in preoperative PROMs. Patients with pseudarthrosis/rod fracture had ahigher reoperation rate compared to those withPJK with similar time to reoperation. Moreover,patients with PJK had higher postoperative TK, lower Hounsfield Units, more prior fusions, and fewer instrumented levelscompared to thosewith pseudarthrosis/rod fracture. The results of this single-institution study suggest that even though mechanical complications are often analyzed as a single group, important differences may exist between them. III.

Retrospective analysis of deformed complex vertebral osteotomy in children with severe thoracic post-tubercular angular kyphosis

BackgroundMany surgical options have been described to manage post-tubercular kyphosis, but the standard approach for treating severe post-tubercular angular kyphosis in children has not been established yet. The present study was performed to evaluate the safety and efficacy of deformed complex vertebral osteotomy (DCVO) for the treatment of severe thoracic post-tubercular angular kyphosis (> 70°) in children.MethodsDeformed complex vertebrae indicated that multiple deformed and fused vertebrae were usually involved with two or more vertebral bodies and the partial or total fusion of many segments' facet joints and intervertebral discs. Thus, DCVO indicated that a wider posterior wedge-shaped and three-column osteotomy was performed within deformed complex vertebrae to correct a more extensive range of angles. From 2010 to 2017, 15 children who suffered from severe thoracic post-tubercular angular kyphosis underwent DCVO. Deformed complex vertebrae involved two vertebral bodies in 9 patients and three vertebral bodies in 6 patients. The Visual Analogue Scale (VAS) and Oswestry Disability Index (ODI) were assessed preoperatively and at the final follow up. This was a retrospective study analysing the outcome after grade 4/5 spinal osteotomies in deformed complex vertebrae.ResultsThe mean duration of surgery was 239 ± 37.81 min. The average period of follow-up was 31.6 ± 6.98 months. The preoperative mean kyphosis of deformed complex vertebrae was 83.39° ± 9.04°; the mean thoracic kyphosis (TK) and lumbar lordosis (LL) were 81.09° ± 8.51° and 80.51° ± 7.64°, respectively; the mean sagittal vertical axis (SVA) was 3.83 cm ± 1.43 cm. The postoperative mean kyphosis of deformed complex vertebrae was reduced to 19.98° ± 2.47° (P < 0.001) with a mean kyphosis correction of 63.41°; at the final follow up, it was 18.4° ± 2.29° (P < 0.001) without obvious loss of correction. The postoperative mean TK, LL, and SVA were reduced to 24.05° ± 3.84°, 46.9° ± 3.53°, and 0.6 cm ± 0.34 cm, respectively (P < 0.001 for all); and there was no obvious loss of sagittal alignment and balance at the final follow up (p = 0.982, p = 0.604, p = 0.754). Complicated with neural dysfunction preoperatively, 5 Frankel's grade D cases showed complete neurological recovery at final follow up. VAS score reduced from 3.6 ± 1.18 to 0.87 ± 0.64 (P < 0.001); and ODI score reduced from 22.21 ± 6.93 to 5.02 ± 2.6 (P < 0.001) at the final follow up.ConclusionsDCVO was an individualized osteotomy for treating severe thoracic post-tubercular angular kyphosis in children and could be safe and effective in reducing the incidence of complications and significantly improving kyphosis correction.

Relationship Between Hounsfield Units of Upper Instrumented Vertebrae, Proximal Junctional Failure, and Global Alignment and Proportion Score in Female Patients with Adult Spinal Deformity

This was a retrospective observational study. The purpose of this study was to evaluate bone mineral density using Hounsfield unit (HU) values at the upper instrumented vertebrae (UIV), UIV+1, and UIV+2 and to investigate the association with proximal junctional failure (PJF) in female patients with adult spinal deformity (ASD). We also evaluated the relationship between the global alignment and proportion (GAP) score and the HU value of patients after ASD surgery. Fifty-two patients (52 females, mean age=70.2years) who underwent multiple-level lateral lumbar interbody fusion combined with posterior instrumentation for ASD were included. The patients were divided into 2 groups, PJF and non-PJF. The demographics, surgical characteristics, and radiographic parameters were compared. Vertebral HU values at UIV, UIV+1, and UIV+2 using preoperative computed tomography scans and immediate postoperative GAP scores were also compared. PJF was found in 13 of 52 patients (25.0%). Preoperative and postoperative thoracic kyphosis was large in PJF patients. Based on the total GAP score, there was no significant difference among the categories of GAP scores (P=0.514). The statistically significant difference in mean HU values (116.6±28.1 vs. 141.8±41.8, P=0.049) between the two groupsat UIV. Further correlation analysis showed that the mean HU values in UIV and UIV+1 showed a significantly negative correlation coefficient with the total GAP score. Our study suggests that preoperative HU values at UIV may affect the development of PJF for female ASD patients. HU evaluation by preoperative computed tomography may help reduce the incidence of PJF.

Anterior versus posterior approach in Lenke type 1 adolescent idiopathic scoliosis: a comparison of long-term follow-up outcomes.

BackgroundAfter surgical treatment of adolescent idiopathic scoliosis (AIS), doctors should not only focus on the short-term surgical effect, but also pay special attention to whether the patients can live normally in the long-term. This work compared the long-term effects of thoracoscopy-assisted anterior spinal fusion (ASF) and posterior spinal fusion (PSF) in AIS.MethodsTwenty-two patients underwent thoracoscopy-assisted ASF, and twenty-three patients underwent PSF from 2004 to 2009 were involved , including 14 males and 31 females with an average age of 14.8±2.6 years, and all patients suffered from only Lenke type 1 AIS. The mean follow-up time was 102 months, the radiographic parameters and operation time, hospitalization time, fusion segments and estimated blood loss were evaluated. Comparisons between groups were made such as Cobb’s angle, thoracic kyphosis, the instrumented levels, curve correction, preoperative parameters, SF-36/SRS-22 questionnaire scores, and pulmonary function.ResultsThere was no significant difference in age, gender, Risser sign and follow-up period between two groups. The instrumentation level had an average of 6 in the thoracoscopy-assisted ASF group and 9.7 in the PSF group (P<0.001). The average correction rate of the main curve was 67.4% in ASF group versus 79.2% in PSF group (P>0.05). The postoperative thoracic kyphosis was 16.2°±3.9° in ASF group and 25.6°±4.4° in PSF group (P=0.023). Patients had momentous advancement in self-image, vitality and mental health in the SRS-22 and SF-36 questionnaires. Compared to preoperatively, the pulmonary function of both groups was satisfactorily improved at the final follow-up.ConclusionsSince there was no statistically significant difference in the general conditions of the two groups selected for this study, so we finally concluded that thoracoscopy-assisted ASF had a satisfactory correction rate, famous long-term radiography outcomes and desirable pulmonary function results. However, compared to PSF, it has a longer operation time, a more complicated surgical procedure and a weaker three-dimensional correction effect, and PSF has affirmative long-term outcomes, fewer complications, and satisfactory sagittal balance, all of which make PSF the standard operation to treat AIS.

Risk Factors and Three Radiological Predictor Models for the Progression of Proximal Junctional Kyphosis in Adult Degenerative Scoliosis Following Posterior Corrective Surgery: 113 Cases With 2-years Minimum Follow-Up.

Retrospective cohort study. To identify risk factors and predictive models for proximal junctional kyphosis (PJK) in a long-term follow-up of patients with adult degenerative scoliosis (ADS) following posterior corrective surgeries. A consecutive 113 ADS patients undergoing posterior corrective surgery between January 2008 and April 2019 with minimum 2-year follow-up were included. All patients underwent preoperative, postoperative, and final follow-up by X-ray imaging. Multivariate logistic analysis was performed on various risk factors and radiological predictor models. PJK was identified radiographically in 46.9% of patients. Potential risk factors for PJK included postoperative thoracic kyphosis (TK) (P < .05), final follow-up Pelvic Tilt (PT) (P < .05), PT changes at final follow-up (P < .05), age over 55 years old at the surgery (P < .05), theoretical thoracic kyphosis-actual thoracic kyphosis mismatch (TK mismatch) (P < .05) and theoretical lumbar lordosis-acutal lumbar lordosis mismatch (LL mismatch) (P < .05). As for the predictive models, PJK was predictive by the following indicators: preoperative global sagittal alignment ≥45° (Model 1), postoperative pelvic incidence-lumbar lordosis mismatch (PI-LL)≤10° and postoperative PI-LL overcorrection (Model 2), and TK+LL≥0° (Model 3) (P < .05). Postoperative TK mismatch (OR = 1.064) was independent as risk factors for PJK, with the cut-off values respectively set at -28.56° to predict occurrence of PJK. The risk of radiographic PJK increases with an age over 55 years old and higher postoperative TK. In addition, postoperative TK mismatch is an independent risk factor for developing PJK. All three predictive models could effectively indicate the occurrence of PJK.

Four-Dimensional Anatomical Spinal Reconstruction in Thoracic Adolescent Idiopathic Scoliosis.

Background:Recent surgical techniques involve 3-dimensional (3D) deformity correction of adolescent idiopathic scoliosis (AIS)1-4. However, next-generation surgical strategies should ensure that the final corrected spine is not only “non-scoliotic,” but has an anatomically correct shape. We developed a 4D anatomical spinal reconstruction technique that involves the use of spatiotemporal deformity prediction to preoperatively calculate the postoperative apex of thoracic kyphosis in order to achieve an anatomically correct spinal curvature5-7.Description:During the technique, facetectomies are performed at all levels except the lowest instrumented level in order to avoid pseudarthrosis at that site. Two rods are identically bent according to the desired postoperative anatomical thoracic kyphosis, with the apex often anticipated to be between T6 and T85-7. Two different categories of spinal rod shapes have been created to cover all presenting anatomies. The single-curve rod is utilized when the lowest instrumented vertebra is L1 or above and the thoracolumbar region remains straight. The double-curve rod is utilized when the lowest instrumented vertebra is L2 or L3. With both rod types, the cranial apex is created. There are 11 shapes of pre-bent, notch-free, cobalt-chromium alloy rods available in Japan7-9. Once the 2 spinal rods are connected to all polyaxial screw heads, the rods are simultaneously rotated1,2,5,7.Alternatives:Typical thoracic AIS exhibits thoracic hypokyphosis. Therefore, correction of the thoracic kyphosis and adjustment of the main thoracic curve are the 2 most important surgical goals for achieving an anatomically correct spine. Furthermore, hypokyphosis of the thoracic spine secondary to pedicle screw instrumentations can be reduced or prevented by utilizing the posterior-approach surgical strategies that we have previously described1-4.Rationale:In a healthy human population, the apex of the thoracic kyphosis is normally located at T6 to T8 as viewed on viewing standing sagittal radiographs10. However, for some patients with AIS, the postoperative apex of the thoracic kyphosis is almost identical to the apex of the preoperative thoracic scoliosis5, which is not anatomically correct. This insufficient correction is often a result of the spinal rods being bent to match the curvature of the scoliosis5. In addition, about 70% of cases of thoracic AIS do not have identical preoperative apices of the main thoracic scoliosis and thoracic kyphosis, and about 33% of cases have the apex of the scoliosis at the lower thoracic spine (i.e., T10 and T11)5. Performing sufficient multilevel facetectomies and utilizing the proper spinal rod curvature have been reported to greatly improve postoperative sagittal curve correction11-13. This proposed technique could be especially helpful in cases in which the apex of scoliosis is located in the lower thoracic spine, which is often seen in patients with Lenke 1AR scoliosis14.Expected Outcomes:When performed with proper shaping of the spinal rods and multilevel facetectomies, the present technique is expected to result in an anatomically correct thoracic spine. The use of this technique has been reported to increase the proportion of patients with a thoracic kyphosis apex at T6 to T8, from 51.3% preoperatively to 87.2% postoperatively5. Furthermore, patients who underwent this procedure with notch-free, pre-bent rods had a significantly higher postoperative thoracic kyphosis than patients who underwent the procedure with conventional, manually bent rods7.Important Tips: Mobilization of the spine by releasing the facet joints is more important than using a rigid implant.Two rods are bent identically to the desired postoperative anatomical thoracic kyphosis; the bending is not based on the preoperative scoliosis spinal curvature.This technique is applicable for Lenke 1, 1AR, and 2 through 6 curves except for Lenke 5 curves. However, the technique for producing pre-bent rods can also be utilized for Lenke 5 curves because the initial configuration leads to sagittal alignment of the spine. Acronyms & Abbreviations: TL/L = thoracolumbar/lumbarUIV = upper instrumented vertebraUEV = upper end vertebraSD = standard deviation

Correlation of Acetabular Anteversion and Thoracic Kyphosis Postoperatively with Proximal Junctional Failure in Adult Spinal Deformity Fused to Pelvis.

ObjectivesTo investigate whether the immediate thoracic kyphosis (TK) and acetabular anteversion (AA) postoperatively are correlated with proximal junctional failure (PJF) in adult spinal deformity (ASD) patients underwent surgical treatment.MethodsThis is a retrospective study. Following institutional ethics approval, a total of 57 patients (49 Female, eight Male) with ASD underwent surgery fused to sacroiliac bone (S1, S2, or ilium) from March 2014 to January 2019 were included. All of those patients were followed up for at least 2 years. Demographic, radiographic and surgical data were recorded. The maximum range of flexion motion (F‐ROM) and extension motion (E‐ROM) actively of hip joints was measured and recorded at pre‐ and postoperation. The sum of F‐ROM and E‐ROM was defined as the range of hip motion (H‐ROM). Receiver operating characteristic (ROC) curve analysis was used to obtain the cut off value of parameters for PJF. A Kaplan–Meier curve and log‐rank test were used to analyze the differences in PJF‐free survival.ResultsIn all, 14 patients developed PJF during follow‐up. Comparisons between patients with and without PJF showed significant differences in immediate TK (P < 0.001) and AA (P = 0.027) postoperatively. ROC curve analysis determined an optimal threshold of 13° for immediate AA postoperatively (sensitivity = 74.3%, specificity = 85.7%, area under the ROC curve [AUC] = 0.806, 95% CI [0.686–0.926]). Nineteen patients with post‐AA ≤13° were assigned into the observational group, and 38 patients with post‐AA >13° were being as the control group. Patients in the observational group had smaller H‐ROM (P = 0.016) and F‐ROM (P < 0.001), but much larger E‐ROM (P < 0.001). There were 10 patients showing PJF in the observational group and four in the control group (10/9 vs 4/34, P < 0.001). PJF‐free survival time significantly decreased in the observational group (P = 0.001, log‐rank test). Furthermore, patients in the observational group had much larger TK (post‐TK, P = 0.015). The optimal threshold for post‐TK (sensitivity = 85.7%, specificity = 76.7%; AUC = 0.823, 95% CI [0.672–0.974]) was 28.1° after the ROC curve was analyzed. In the observational group, those patients with post‐TK ≥28.1° had significantly higher incidence of PJF (9/2 vs 1/7, P < 0.001) than those with post‐TK < 28.1°. Moreover, PJF‐free survival time in those patients significantly decreased (P = 0.001, log‐rank test).ConclusionsASD patients with acetabular anteversion of ≤13° at early postoperation may suffer significantly restricted hip motion and much higher incidence of PJF during follow‐up, moreover, in those patients, postoperative TK ≥28.1° would be a significant risk factor for PJF developing.

Determining the validity and reliability of spinopelvic parameters through comparing standing whole spinal radiographs and upright computed tomography images

BackgroundStanding whole spinal radiographs are used to evaluate spinal alignment in adult spinal deformity (ASD), yet some studies have reported that pelvic incidence, pelvic tilt, and thoracic kyphosis (TK) intra- and inter-observer reliability is low. This study aimed to evaluate the accuracy of spinopelvic parameters through comparing standing whole spinal radiographs and upright CT images.MethodsWe enrolled 26 patients with ASD. All standing whole spinal posterior/anterior and lateral radiographs and upright whole spinal CT had been obtained in a natural standing position. Two examiners independently measured 13 radiographic parameters. Interclass correlation coefficients (ICCs) were used to analyze measurement intra- and inter-observer reliability. Paired t- and Pearson’s correlation tests were used to analyze validity of the standing whole spinal radiographs.ResultsICCs of upright CT were excellent in both intra- and inter-observer reliability. However, intra-observer ICCs for TK2–12, TK1–5, TK2–5, and TK5–12 on standing lateral radiographs were relatively low, as were inter-observer ICCs for TK2–12, TK1–5, TK2–5, and TK5–12. Concerning TK values, the difference between the radiographs and CT in TK1–12 and TK2–12 were 4.4 ± 3.1 and 6.6 ± 4.6, respectively, and TK values from T2 showed greater measurement error (p < 0.05).ConclusionsUpright CT showed excellent intra- and inter-observer reliability in the measurement of spinopelvic parameters. Measurement of TK with T2 on standing whole spinal radiographs resulted in a greater measurement error of up to 6.6°. Surgeons need to consider this when planning surgery and measuring postoperative TK changes in patients with ASD.