Non-instrumented correction of cervicothoracic kyphosis in ankylosing spondylitis: a critical analysis on the results of open-wedge osteotomy C7-T1 with gradual Halo-Thoracic-Cast based correction

Introduction

With progression of cervicothoracic kyphosis (CTK), ankylosing spondylitis (AS) patients suffer functional disability. Surgical correction still poses neurologic risks, while evidence of an ideal technique preventing its complications is weak.

Materials and methods

We report our results with non-instrumented correction in perspective of a review of literature, serving as an important historical control. Database review identified 18 AS patients with CTK correction. After application of a Halo-Thoracic-Cast (HTC) patients underwent posterior non-instrumented open-wedge osteotomy at C7/T1 and osteotomy closure by threaded HTC-rod adjustments. Postoperative gradual HTC correction was continued for 2–4 weeks. Patients were invited for follow-up and medical charts were reviewed for demographics, surgical details, complications and outcomes. The patients’ preoperative, postoperative, before HTC removal and follow-up photographs were analyzed for the Chin-Brow-Vertical-Angle (CBVA), radiographs for the CTK angle.

Results

Patients’ age was 50 ± 11 years, follow-up was 37 ± 47 months and CBVA correction was 25° ± 9° (p < 0.000001). The final radiographic correction at follow-up was 20° ± 11° (p = 0.00002). At the latest follow-up, three patients judged their outcome as excellent, nine good, three moderate and one poor. Upon invitation, seven patients appeared with follow-up averaging 87 months. Neck-pain disability index was 8 ± 14 %. Two patients died, three were lost, one had revision elsewhere and five just had a routine follow-up. Six patients sustained a minor and ten a major complication. Revisions were indicated in five patients including infection, C8-radiculopathy and neurologic events by translation at the osteotomy. A total of 44 % of patients showed translation at the osteotomy indicating acute surgery with instrumentation twice after osteotomy closure, three patients had a revision posterior decompression and instrumented fusion for sequels related to translation.

Conclusion

With the non-instrumented HTC-based technique, average CBVA correction of 25° was achieved and all patients were ambulatory at follow-up. However, regarding translation at the osteotomy, loss of correction, morbidity of the HTC and lack of control at the osteotomy instrumentation-based correction and instrumented fusion seem to be preferable.     

Can acetabular orientation be restored by lumbar pedicle subtraction osteotomy in ankylosing spondylitis patients with thoracolumbar kyphosis?

Purpose

To evaluate whether acetabular orientation (abduction and anteversion) can be restored by lumbar pedicle subtraction osteotomy (PSO) in ankylosing spondylitis (AS) patients with thoracolumbar kyphosis.

Materials and methods

A total of 33 consecutive AS patients with thoracolumbar kyphosis undergoing one-level lumbar PSO were retrospectively reviewed. Radiographical measurements included sagittal vertical axis, global kyphosis, thoracic kyphosis, local kyphosis, lumbar lordosis, pelvic incidence, sacral slope, and pelvic tilt. Acetabular abduction and anteversion were measured on CT scans of the pelvis before and after lumbar PSO. The preoperative and postoperative parameters were compared by the paired samples t test. Pearson’s correlation analysis was conducted to determine the correlations between the changes in acetabular abduction and anteversion and the changes in sagittal spinopelvic parameters.

Results

After lumbar PSO, sagittal vertical axis, global kyphosis, and pelvic tilt were corrected from 15.7 ± 6.7 cm, 66.8° ± 17.5°, and 38.6° ± 9.0° to 2.9 ± 4.9 cm, 21.3° ± 8.2°, and 23.2° ± 8.2°, respectively (p < 0.001). Of note, acetabular abduction and anteversion decreased from 59.6° ± 4.6° to 31.4° ± 6.5° before surgery to 51.4° ± 6.5° and 20.2° ± 4.4° after surgery, respectively (p < 0.001). Moreover, the changes in acetabular abduction and anteversion were observed significantly correlated with the change in pelvic tilt (r = 0.527, p = 0.002; r = 0.586, p < 0.001).

Conclusion

Abnormal acetabular abduction and anteversion could be corrected by lumbar PSO in AS patients with thoracolumbar kyphosis. Consequently, a relatively normal acetabular orientation could be achieved after lumbar PSO, which might decrease the potential risk of dislocation in AS patients with spine and hip deformities requiring subsequent THR surgery.

     

The use of posterior vertebral column resection in the management of severe posttuberculous kyphosis: a retrospective study and literature review

Purpose

We present a retrospective study of 15 cases with severe posttuberculous kyphosis of thoracolumbar region that underwent posterior vertebral column resection.

Methods

From 2004 to 2009, 15 consecutive patients with posttubercular kyphotic deformity underwent posterior vertebral resection osteotomy. Six subjects were females and nine were males with an average age of 35.8 years (range 20–60 years) at the time of surgery. None of the patients had neurological deficits. The mean preoperative visual analogue scale was 8.7 (range 3–9), and the average preoperative Oswestry Disability Index was 46.5 (range 40–56).

Results

The average duration of postoperative follow-up was 36.1 ± 10.7 months (range 24–62 months). The number of vertebra resected was 1.3 (range 1–2) on average. There were ten patients with one-level osteotomy and five patients with two-level osteotomy. The average operation time was 446.0 ± 92.5 min (range 300–640 min) with an average blood loss of 1,653.3 ± 777.9 ml (range 800–3000 ml). The focal kyphosis before surgery averaged 92.3 ± 8.9° (range 74–105°), and the kyphotic angle decreased to 34.5 ± 8.7° on average after the surgical correction. The average kyphotic angle at the last follow-up was 36.9 ± 8.5°, loss of correction was 2.4 ± 1.4° on average. All patients postoperatively received bony fusion within 6–9 months.

Conclusions

Our results showed that although posterior vertebral resection is a highly technical procedure, it can be used safely and effectively in the management of severe posttuberculous kyphosis. It is imperative that operations be performed by an experienced surgical team to prevent operation-related complications.     

The posterior surgical correction of congenital kyphosis and kyphoscoliosis: 23 cases with minimum 2 years follow-up

Purpose

The purpose of this study is to review our operative experience of congenital kyphosis or kyphoscoliosis undergoing either pedicle subtraction osteotomy (PSO) or posterior vertebral column resection (pVCR) according to certain criteria we have established.

Methods

From December 2003 to 2009, 23 consecutive patients of congenital kyphosis or kyphoscoliosis were treated by means of PSO or pVCR procedure in a single institution. The average preoperative kyphosis angle was 74.3º. The C7 plumb line was 12.6 mm posterior to the posterior–superior corner of S1 on average, showing negative imbalance. In the 11 cases who had accompanied scoliosis, the average preoperative scoliosis angle was 42.6º. The average Oswestry Deficiency Index (ODI) for back pain was 14.6 before surgery. Eleven patients had compromise of neurological functions.

Results

After PSO or pVCR procedure, the average kyphosis angle decreased to 20.0º, and the accompanied scoliosis also decreased to 15.8º. The average follow-up time after surgery was 34.3 months. At the last follow-up, the average kyphosis corrective rate was 73.7 %, and the average scoliosis corrective rate was 61.7 %. The negative imbalance improved, with the C7 plumb line being 1.5 mm posterior to the posterior–superior corner of S1 on average. After surgery, the average ODI for back pain had 40.6 % improvement, and most patients who had neurological symptoms before surgery had varying degrees of relief. The total satisfactory rate to corrective surgery was 91.3 %. No permanent neurological damage was observed.

Conclusions

If selected appropriately, both PSO and pVCR procedures can achieve compatible and satisfactory correction results in the surgical treatment of congenital kyphosis or kyphoscoliosis.     

The results of closing wedge osteotomy with posterior instrumented fusion for the surgical treatment of congenital kyphosis

Purpose

There exist not much data regarding the surgical treatment of pure congenital kyphosis (CK) in the literature. The purpose of this study was to evaluate the results of closing wedge osteotomy with posterior instrumented fusion in patients with congenital kyphotic deformity.

Methods

We retrospectively evaluated the radiographical results of 10 patients who were subject to closing wedge vertebral osteotomy and posterior instrumented fusion due to CK. The mean age of the patients at surgery was 12.6 ± 3.72 years (range 8–18 years). Radiographical measurements including local kyphosis, correction loss, global kyphosis and sagittal balance values were noted for the preoperative, postoperative and final follow up periods, respectively. The data obtained from those periods underwent statistical analysis.

Results

Average follow-up period was 51.8 ± 29.32 months (range 26–96 months). The mean local kyphosis angle was 67.7° ± 15.64° (range 42°–88°) prior to the surgery, 31.5° ± 17.12 (range 14°–73°) following the surgery and 31.9° ± 15.98° (range 14°–71°) during the follow up-period, respectively (p < 0.05). A correction rate of 53.5 % was reported at the final follow up. Average sagittal balance was measured as 33.1 ± 24.48 mm (range 2–77 mm) prior to the surgery, 20.8 ± 15.46 mm (range 5–46 mm) following the surgery (p < 0.05) and 14.1 ± 9.2 mm (range 0–30 mm) during follow-up period (p > 0.05). Complications consisted of a rod fracture due to pseudoarthrosis, an implant failure with loosening of screws and a proximal junctional kyphosis. No neurological deficit or deep infection were encountered in any of the patients in the study group.

Conclusion

Closing wedge osteotomy with posterior instrumented fusion is an efficient method of surgical treatment in terms of sagittal balance restoration and deformity correction in patients with congenital kyphosis.     

Role of thoracoscopy for the sagittal correction of hypokyphotic adolescent idiopathic scoliosis patients

Purpose

Thoracic adolescent idiopathic scoliosis (AIS) curves (Lenke 1–4) are often characterized by hypokyphosis. Sagittal alignment remains challenging to correct, even with recent posterior segmental instrumentation. Some authors recommend anterior endoscopic release (AER) to reduce anterior column height, and facilitate thoracic kyphosis correction. The aim of this study was to assess the contribution of AER to sagittal correction in hypokyphotic AIS.

Methods

Fifty-six hypokyphotic (T4T12<20°) AIS patients were included. In group 1 (28 patients), patients first underwent AER, followed by posterior instrumentation and correction 5–7 days later. In group 2 (28 patients), patients underwent the same posterior procedure without AER. Posterior correction was performed in all cases using posteromedial translation and hybrid constructs consisting of lumbar pedicle screws and thoracic sublaminar bands. From radiological measurements performed using low-dose EOS radiographs, the correction of thoracic kyphosis was compared between the two groups.

Results

Groups 1 and 2 were comparable regarding demographic data and preoperative thoracic kyphosis (group 1: 11.7° ± 6.9° vs group 2: 12.1° ± 6.3°, p = 0.89). Postoperative thoracic kyphosis increase averaged 18.3° ± 13.6° in group 1 and 15.2° ± 9.0° in group 2. The benefit of anterior release was not statistically significant (p = 0.35).

Conclusion

Although previous studies have suggested that thoracoscopic release improved correction compared to posterior surgery alone, the current study did not confirm this finding. Moreover, results of the current series showed that no significant benefit can be expected from AER in terms of sagittal plane improvement when the posteromedial translation technique is used, even in challenging hypokyphotic patients.     

Adolescent idiopathic scoliosis treated with posteromedial translation: radiologic evaluation with a 3D low-dose system

Purpose

Computed tomography can be used for three-dimensional (3D) evaluation of adolescent idiopathic scoliosis (AIS) patients, but at the expense of high radiation exposure, and with the limitation of being performed in the supine position. These drawbacks can now be avoided with low-dose stereoradiography, even in routine clinical use. The purpose of this study was to determine the 3D postoperative correction of AIS patients treated by posteromedial translation.

Methods

Forty-nine consecutive patients operated for AIS (Lenke 1–4) using posteromedial translation were included. Corrections were evaluated preoperatively, postoperatively and after at least 2 years using the EOS imaging system. 3D angles were measured in the plane of maximum deformity.

Results

Mean number of levels fused and operative time were 13.5 ± 1 and 215 ± 25 min, respectively. Main thoracic, proximal thoracic, and lumbar curves corrections averaged 64.4 ± 18, 31 ± 10 and 69 ± 20 %, respectively. Mean T4–T12 kyphosis increased 18.8° ± 9° in the subgroup of hypokyphotic patients. Mean apical vertebral rotation reduction was 48.3 ± 20 %. Trunk height gain averaged 27.8 ± 14 mm. There was no pseudarthrosis or significant loss of correction in any plane during follow-up. Two patients (4 %) developed asymptomatic proximal junctional kyphosis, despite having normal thoracic kyphosis. Their sagittal balance was shifted posteriorly by 36 and 47 mm, respectively, by the operation, but revision surgery was not performed.

Conclusions

Low-dose stereoradiography provided 3D reconstructions of the fused and unfused spine in routine clinical use. Postoperative 3D analysis showed that posteromedial translation enhanced sagittal balance correction, without sacrificing frontal or axial correction of the deformity.     

Posterior-only correction of Scheuermann kyphosis using pedicle screws: economical optimization through screw density reduction

Introduction

Posterior-only approach using pedicle screws’ fixation has emerged as the preferred surgical technique for Scheuermann kyphosis (SK) correction. Insertion of multiple pedicle screws while increasing stability increases also the risk of complications related to screw malpositioning and surgical cost. The optimal screw density required in surgical correction of SK remains unclear. This study compares the safety and efficacy of low screw density (LSD) versus high screw density (HSD) technique used in posterior-only correction of SK.

Methods

Twenty-one patients underwent surgical correction of SK between 2007 and 2011 and were reviewed after a mean of 29 months. HSD technique (i.e., 100 % of available pedicles, averaged 25.2 ± 4 screws) was used in 10 cases and LSD technique (i.e., 54–69 % of available pedicles in a pre-determined pattern, averaged 16.8 ± 1.3 screws; p < 0.001) was used in 11 cases. Kyphosis correction was assessed by comparing thoracic kyphosis, lumbar lordosis and sagittal balance on preoperative and postoperative radiographs. Cost saving analysis was performed for each group.

Results

Preoperative thoracic kyphosis, lumbar lordosis and sagittal balance were similar for both groups. The average postoperative kyphosis correction was similar in both HSD and LSD groups (29° ± 9° vs. 34° ± 6°, respectively; p = 0.14). Complication occurred in four patients (19 %) in the HSD group and in two patients (9 %) in the LSD group (p = 0.56). Three patients required re-operation. Compared to HSD using LSD saves 4,200£ per patient in hardware and 88,200£ for the entire cohort.

Conclusion

LSD technique is as safe and effective as HSD technique in posterior-only correction of SK. Implant-related cost could be reduced by 32 %.     

Skip pedicle screw fixation combined with Ponte osteotomy for adolescent idiopathic scoliosis

Purpose

This study aimed to determine whether Ponte osteotomy combined with skip pedicle screw fixation (SPSF) can improve the correction rate and restore thoracic kyphosis for patients with adolescent idiopathic scoliosis.

Methods

Surgical time, blood loss, preoperative Cobb angle of the main thoracic curve, flexibility, Cobb angle at 1 year after surgery, thoracic curve correction rate, and Cincinnati correction index (CCI) were determined for both the Ponte (n = 17) and non-Ponte (control; n = 21) groups. Furthermore, kyphotic angles at T5–T12 before and 1 year after the surgery were measured.

Results

The following measurements were obtained for the Ponte and control groups, respectively: surgical time, 236 ± 13 and 187 ± 9 min; blood loss, 1,141 ± 150 and 745 ± 120 g; preoperative Cobb angle of the main thoracic curve, 52.5° ± 10.4° and 51.5° ± 9.2°; flexibility, 31.7 ± 13.2 and 45.1 ± 12.3 % (p = 0.003); thoracic curve correction rate, 62.0 ± 2.5 and 63.6 ± 2.5 %; CCI, 2.2 ± 0.2 and 1.5 ± 0.1 (p = 0.003); preoperative kyphotic angle at T5–T12, 11.3° ± 11.2° and 13.0° ± 9.0°; and kyphotic angle at T5–T12 at 1 year after the surgery, 21.8° ± 1.7° and 24.2° ± 1.9°.

Conclusion

Ponte osteotomy was combined with SPSF in case of rigid curve. CCI was significantly greater in the Ponte group. Postoperative thoracic kyphotic angles were identical in both groups.     

Combined spinal arthrodesis with instrumentation for the management of progressive thoracolumbar kyphosis in children with mucopolysaccharidosis

Purpose

To evaluate the outcome and complications of a novel technique for the treatment of progressive thoracolumbar kyphosis in children with mucopolysaccharidosis (MPS).

Methods

The medical records and spinal imaging of four consecutive paediatric patients who underwent a single stage anteroposterior spinal fusion with segmental pedicle screw instrumentation were reviewed.

Results

Patients underwent spinal deformity correction at the mean age of 3 years (2.4–3.7) with mean clinical follow-up of 3.2 years (2.1–4.5) and mean postoperative radiographic follow-up was 2.4 years (0.8–3). Preoperative kyphosis was corrected from a mean angle of 65º (63º–70º) to 6.5º (–12º–13º). Vertebral subluxation at the apex of the deformity was corrected from an average 64 % (56–83 %) to 12 % (0–24 %). Spinal cord monitoring with somatosensory evoked potentials (SSEP) was successfully obtained and stable throughout surgery. No instrumentation failure, loss of correction or junctional problems occurred at final follow-up.

Conclusions

Anterior and posterior spinal arthrodesis with segmental pedicle screw instrumentation is a safety and reliable technique for the treatment of severe thoracolumbar kyphosis in children with MPS. This technique achieves excellent correction of the deformity with adequate decompression of the spinal canal. The fusion is limited to the thoracolumbar junction and interferes minimally with the longitudinal growth of the thorax. No neurological complications or intraoperative spinal cord monitoring events occurred. No loss of correction or junctional kyphosis was observed.     

An exon polymorphism of programmed cell death 1 gene is associated with both the susceptibility and thoracolumbar kyphosis severity of ankylosing spondylitis in a Chinese Han population

Background

Although human leukocyte antigen (HLA)-B27 gene is the major susceptible gene associated with ankylosing spondylitis (AS), it has been recognized that non-HLA-B27 genes also play key roles in the development of AS. The purpose of this study is to investigate whether a single nucleotide polymorphism (SNP) in the exon region of the programmed cell death 1 (PDCD-1) gene is associated with the susceptibility or the thoracolumbar kyphosis severity of AS in a Chinese Han population.

Methods

A total of 255 AS patients between January 2008 and October 2012 were recruited in this study. Two hundred and three healthy patients were recruited as normal controls. According to the severity of thoracolumbar kyphosis, the AS patients were further divided into group A (patients with kyphosis <70°, n = 135) and group B (patients with kyphosis ≥70°, n = 120). One exon polymorphism, rs2227982 (C/T) of PDCD-1 gene, was selected for analysis. Genotyping was performed by TaqMan probe assays in all the subjects.

Results

There were significant differences of genotype distributions of rs2227982 between AS patients and normal controls. The frequency of the T allele was significantly higher in AS patients when compared with normal controls. The frequency of the T allele in group B was significantly higher than that in group A. Carriage of the TT genotype increased the risk of severe thoracolumbar kyphosis 1.9-fold in AS patients.

Conclusions

Our study confirms a significant association between the SNP rs2227982 of PDCD-1 gene and the susceptibility of AS in a Chinese Han population. Moreover, the TT genotype is suggested to be associated with the severity of thoracolumbar kyphosis secondary to AS.     

The posterior surgical treatment for focal kyphosis in upper-middle thoracic spine

Purpose

To analyze the clinical characteristics of focal kyphosis in upper thoracic spine, and observe the outcome of the posterior corrective surgical procedures.

Methods

Thirteen patients of focal kyphosis were treated with posterior surgical procedures in our medical center. The kyphosis apex was above T6 in all cases. The surgical procedures performed in this study included pedicle subtraction osteotomy (PSO) in six cases and vertebral column resection (VCR) in seven cases. For each case, the kyphosis angle, curvature of lower thoracic spine, lumbar lordosis angle, cervical lordosis angle, pelvic parameters, and the sagittal plane balance of the spine were compared before and after surgery. Neurological function change was assessed based on Frankel grading system and oswestry disability index (ODI).

Results

The average follow-up time of this study was 28.3 months. The average kyphosis angle was reduced from 73.5º before surgery to 32.7º immediately after surgery, and remained at 33.5º at follow-up. The average ODI improved from 22.5 before surgery to 15.5 at follow-up. The neurological function improved after surgery in eight cases. There were two cases of transient neurological deficiency in the lower extremities after VCR procedure, who eventually recovered under postoperative care. One case had recurrent kyphosis due to implant failure after VCR procedure, and recovered after the revision surgery.

Conclusions

Although high risk needs to be warned, the corrective surgery for focal kyphosis in upper thoracic spine still can achieve satisfactory results. Given the comparative surgical results yet less complications, PSO seems to be a preferable procedure over VCR for kyphosis at this region.     

Pedicle subtraction osteotomy in the thoracic spine and thoracolumbar junction: a retrospective series of 28 cases

Purpose

Pedicle subtraction osteotomy is a well-described surgical technique for treatment of kyphotic deformity in the spine. It is not widely used for treatment of thoracic kyphosis. We present the first documented series of 28 patients who underwent this procedure in 3 international centers. These patients presented with severe deformity with a wide range of aetiologies.

Indications

Kyphosis larger than 70 degrees, which is demonstrably rigid based on dynamic imaging.

Materials and methods

28 patients underwent surgery following pre-op neurological and radiographic assessment to fully assess the deformity. A triangular osteotomy was carried out using intraoperative navigation techniques. The patients were assessed post-operatively again with clinical and radiographic parameters at regular follow-up.

Results

The mean ODI score after surgery was 24.7 (16–42) while the pre-op was 53.4 (38–76). Mean thoracic kyphosis was improved from 64.2° (±20.1°) to 41.1° (±17.4°) resulting in a mean sagittal correction of 23.1°. Mean segmental correction at the PSO for all 28 cases was 17.8° (±8.1°). Stratified by region we found different values for the PSO correction: between T1 and T5 (6 cases) it was 17.5° (±5.4°) and between T6 and T9 (4 cases) 18.2° (±4.7°) and between T10 and L1 (18 cases) 26.2° (±5.2°). FBI index was 22.3° pre-op and improved to 7.8° post-op. Calculations were performed with Microsoft excel (2011 Microsoft, Redmond, WA).

Conclusions

Global sagittal balance was statistically improved in this series as demonstrated by FBI and C7 SVA correction.

     

3D rod shape changes in adolescent idiopathic scoliosis instrumentation: how much does it impact correction?

Purpose

Flattening of rods is known to reduce the correction capability of the instrumentation, but has not been studied in 3D. The aim is to evaluate the rods shape 3D changes during and immediately after instrumentation, and its effect on 3D correction.

Methods

The 5.5 mm CoCr rods of 35 right thoracic adolescent idiopathic scoliosis patients were measured from rod tracings prior to insertion, and reconstructed in 3D from bi-planar radiographs taken intra-operatively after the correction maneuvers and 1 week post-operatively. The rod bending curvature, maximal deflection and orientation of the rod’s plane of maximum curvature (RPMC) were computed at each stage. The relation between rod contour, kyphosis and apical vertebral rotation (AVR) was assessed.

Results

Main thoracic Cobb angle was corrected from 58° ± 10° to 15° ± 8°. Prior to insertion, rods were more bent on the concave side (curvature/deflection: 39° ± 8°/25 ± 6 mm) than the convex side (26° ± 5°/17 ± 3 mm). Only the concave rod shape changed after the correction maneuvers execution (flattening of 21° ± 9°/13 ± 7 mm; p < 0.001) and stayed unchanged post-operatively. After instrumentation, the RPMC was deviated from the sagittal plane (concave side: 27° ± 19°/convex side: 15° ± 12°). There was a significant association between kyphosis change and the relative concave rod to spine contour (rod curvature—pre-operative kyphosis) (R ² = 0.58) and between AVR correction and initial differential concave/convex rods deflection (R ² = 0.28).

Conclusions

Correction maneuvers induce a significant change of the concave rod profile. Both rods end in a plane deviated from the sagittal plane which is representative of the spinal curvature 3D orientation. Differential rod contouring technique has a significant impact on the resulting thoracic kyphosis and transverse plane correction.

     

Vertebral subluxation during three-column osteotomy in surgical correction of adult spine deformity: incidence,risk factors,and complications

Purpose

To investigate incidence, risk factors, and complications of vertebral subluxation (VS) during three-column osteotomy in surgical correction of adult spine deformity.

Methods

Adult spine deformity patients who underwent three-column osteotomies including VCR, PSO, and other modified types from March 2000 to December 2014 in our center were retrospectively reviewed. The following parameters were measured pre- and postoperatively: Cobb angle of main curve, global kyphosis, sagittal vertical axis, and kyphosis flexibility. Radiographic parameters between groups (VCR vs. PSO and subluxation vs. non-subluxation) were compared.

Results

171 ASD patients were recruited, 18 of which (10.5%) developed sagittal vertebral subluxation at the osteotomy site. 5 of 18 patients (27.8%) developed neurological complications after surgery. For these five patients, two patients got partial recovery, and three got complete recovery at 2-year follow-up. 116 patients underwent PSO, 12 of which (10.3%) developed sagittal vertebral subluxation. In 55 patients receiving VCR, 6 (10.9%) developed sagittal vertebral subluxation. No significant difference was noted between the two groups (P > 0.05). The mean age of VS group was larger than that of non-VS group (46.2 vs. 34.2, P < 0.05). VS group had less kyphosis flexibility (11 vs. 23%, P < 0.05). More patients in VS group had preoperative sagittal VS as compared to non-VS group (77.8 vs. 20.9%, P < 0.05). VS group had more neurological complications than non-VS group (25 vs. 5.4%, P < 0.05).

Conclusion

VS occurred in one-tenth of patients receiving three-column osteotomies, one-fourth of which would develop neurological deficits. Older age, rigid kyphosis, and the pre-existence of VS were risk factors for developing VS.

     

Effectiveness of pedicle screw-based ligamentotaxis in reducing preoperative kyphosis in thoracolumbar spinal fractures: a retrospective analytical study based on injury surgery interval

Objectives

Although there is an agreement of using long-level construct than short-level construct to correct the kyphosis, no literature mentioned the success of this treatment based on timing of surgery after the injury. Objective of this paper was to study the effect of ligamentotaxis on preventing the development of postoperative kyphosis in unstable thoracolumbar burst fractures based on injury surgery interval (ISI).

Study design

This is a retrospective analysis in 67 patients with unstable thoracolumbar burst fractures operated with posterior-only pedicle screw fixation.

Methods

A retrospective analytical study was conducted in 67 patients who had unstable thoracolumbar fracture and operated with posterior-only pedicle screw construct two levels above and one level below the fractured vertebra. Results were analyzed based on ISI: group 1 (34 patients) was operated within 7 days; group 2 (19 patients) operated between 7 and 14 days; and group 3(14 patients) operated after 14 days of injury. Immediate postoperative and final follow-up kyphotic angles were analyzed among all three groups using Kruskal–Wallis test. Complications regarding implant failure were also noted at final follow-up.

Results

Average follow-up was 37 ± 8.1 months. Average preoperative kyphosis at thoracolumbar junction was 26.3° ± 3.9°, 26.3° ± 2.9° and 26.3° ± 2.8° in groups 1, 2 and 3, respectively, which did not show any difference (P = 0.98). Immediate postoperatively kyphotic angle was improved to 4.3° ± 1.9°, 5.4° ± 1.7° and 10.1° ± 3.0° in groups 1, 2 and 3, respectively, which exhibited statistically significant difference (P < 0.001); and at final follow-up kyphotic angles were 5.4° ± 1.9°, 7.2° ± 1.7° and 15.0° ± 1.6° in groups 1, 2 and 3, respectively showing 1.1°, 1.7° and 4.9° loss in correction at final follow-up. Comparison of kyphotic angles and loss of kyphotic angles amongst the three groups showed statistically significant difference (P < 0.001). Two patients from group 3 had implant failure that required implant extraction.

Conclusion

Posterior-only pedicle screw fixation in unstable thoracolumbar fractures would correct and maintain the postoperative correction in kyphosis, at least at 3-year follow-up, without increasing implant failure if ISI is less than 2 weeks. While patients operated after 2 weeks of injury would require additional anterior procedure.     

Minimally invasive fixation techniques for thoracolumbar fractures: comparison between percutaneous pedicle screw with intermediate screw (PPSIS) and percutaneous pedicle screw with kyphoplasty (PPSK)

Purpose

To assess and compare the efficacy of two minimally invasive techniques (percutaneous pedicle screw with intermediate screw vs. percutaneous pedicle screw with kyphoplasty) for spinal fracture fixation by comparing the segmental kyphosis and vertebral kyphosis angles after trauma before surgery, after surgery, and at 4-month and 12-month follow-up.

Methods

Data from 49 patients without neurological deficit treated by either percutaneous pedicle screw with intermediate screw or percutaneous pedicle screw with kyphoplasty were retrospectively analysed. The segmental kyphosis and vertebral kyphosis angles over time were calculated and correlated with the type of procedure, AO classification, lumbar or thoracic site and the age and sex of the patients.

Results

After surgery, both techniques were found to be efficacious means of bringing about a significant correction of the segmental kyphosis angle (p = 0.002) and a just significant correction of the vertebral kyphosis angle (p = 0.06), although less effectively in thoracic fractures (p = 0.004). At follow-up, the vertebral kyphosis angle was stable in both groups, while there was a significant loss of segmental kyphosis angle stability in the percutaneous pedicle screw with kyphoplasty group at 1 year (p = 0.004); fractured thoracic vertebrae maintained a greater vertebral kyphosis angle (p = 0.06) and segmental kyphosis angle (p < 0.001), than the lumbar.

Conclusion

At 1 year after surgery, the use of intermediate screws in fractured vertebrae seemed to maintain a more efficacious correction with respect to kyphoplasty, although thoracic fracture sites appear to be associated with greater post-traumatic segmental kyphosis and lesser stability in the long term after both percutaneous surgical techniques.

     

Hilus pulmonis as the center of gravity for AS thoracolumbar kyphosis

Introduction

The sagittal vertical axis (SVA) is a meaningful measurement and widely used for evaluating sagittal balance, and is considered a design standard for surgery, including most ankylosing spondylitis (AS) kyphotic deformity planning. However, recent research indicates that the C7 plumb line is actually not the center of gravity (CG) line. Therefore, whether there is a better radiological marker as the CG of the trunk for AS thoracolumbar kyphosis remains unknown. This research is to investigate a radiological marker for the CG of the trunk in lateral radiographs for AS thoracolumbar kyphosis.

Materials and methods

The center of gravity of an irregular object can be obtained by hanging or supporting it in different points and directions, and the CG will be on the point of intersection. According to this principle of mechanics, we could use the pre- and post-operative hip axis vertical lines to locate the CG of the trunk. We evaluated 38 AS-fixed thoracolumbar kyphotic patients with pedicle subtraction osteotomies. Full-length, free-standing lateral radiographs, including the spine and pelvis, were available for all patients. Pre- and post-operative radiological parameters were measured, including SVA, horizontal distance between hip axis and C7 (HDHC), horizontal distance between hip axis and T5 (HDHT5), horizontal distance between hip axis and T9 (HDHT9), and horizontal distance between hip axis and hilus pulmonis (HDHH). Pre- and post-operative radiological parameter changes were compared by paired samples t tests. The intraclass correlation coefficient (ICC) was used to determine the intra- and interobserver reliabilities of HDHH.

Results

Pre-operative SVA, HDHC, HDHT5, HDHT9, and HDHH values were, respectively, 21.1, 12.7, 3.5, ?3.8, and 2.7 cm, and their post-operative values were, respectively, 9.1, 4.2, ?2.1, ?5.6, and 0.9 cm. Changes in SVA, HDHC, HDHT5, and HDHT9 were significant (p < 0.05), while the change in HDHH was not (p > 0.05). The ICC for overall interobserver reliability was 0.958 (p < 0.001), and it was 0.963 (p < 0.001) for overall intraobserver reliability.

Conclusion

The hilus pulmonis fell approximately on the hip axis both pre- and post-operatively. It was a better marker as the center of gravity of the trunk for deformity planning for AS thoracolumbar kyphosis.     

Reversing the concept: correction of adolescent idiopathic scoliosis using the convex rod de-rotation maneuver

Purpose

To show the radiological results of adolescent idiopathic scoliosis (AIS) patients treated with posterior fusion using all-pedicle-screw construct with correction carried out using a convex rod reduction technique.

Methods

Between October 2004 and June 2007, 42 AIS patients were treated with posterior fusion using all-pedicle-screw construct with correction done through the convex side. Two patients were lost to follow-up and were not included in the study. Forty patients had a minimum follow-up of 2 years. Patients were evaluated for the deformity correction in coronal and sagittal planes and for spinal balance.

Results

The mean preoperative Cobb angle of the major curve and secondary minor curves was 60° and 41°, respectively. Immediate postoperative mean Cobb angle of the major curve and secondary minor curves was 17° and 13°, respectively. Postoperative 2-year average major curve loss of correction was 7 %. Postoperative 2-year average minor curve loss of correction was 5 %. Preoperative thoracic kyphosis of 28° was changed to 22° in 2-years follow-up. The loss of thoracic kyphosis was most noted in hyperkyphotic patients.

Conclusions

The correction of AIS by convex-sided pedicular screws yields a coronal correction comparable to what is described in the literature for segmental concave-sided screws.