Structural vertebral changes in the horizontal plane in idiopathic scoliosis and the long-term corrective effect of spine instrumentation

Summary The rotation and structural changes of the apex vertebra in the horizontal plane as well as of the thoracic cage deformity were quantified by measurements on computed tomography (CT) scans from patients with right convex thoracic idiopathic scoliosis (IS). The CT scans were obtained from 12 patients with moderate scoliosis (mean Cobb angle 25.8°, r 13°–30°) and from 33 with severe scoliosis (mean Cobb angle 46.2°, r 35°–71°). In addition, CT scans of thoracic vertebrae from 15 patients without scoliosis were used as reference material. Ten of the scoliotic cases had had Cotrel-Dubousset instrumentation (CDI) and posterior fusion and had entered a longitudinal study on the effect of operative correction on the re-modelling of the apical vertebra. An increasingly asymmetrical vertebral body, transverse process angle, pedicle width and canal width were found in the groups with scoliosis as compared with the reference material. Vertebral rotation and rib hump index were significantly larger in patients with early and advanced scoliosis than in normal subjects. The modelling angle of the vertebral body, the transverse process angle index and the vertebral rotation in relation to the middle axis of the thoracic cage were significantly greater in patients with severe than with moderate scoliosis. The results of this longitudinal study suggest that the structural changes of the apical vertebra regress 2 years or more after CD instrumentation.     

Mid-term effects of Cotrel-Dubousset instrumentation on the configuration of the spine and the thoracic cage in thoracic idiopathic scoliosis

Summary The effect of Cotrel-Dubousset instrumentation (CDI) on the three-dimensional spinal deformity in 24 consecutive patients with idiopathic scoliosis was investigated by posteroanterior and lateral radiographs and by computed tomography preoperatively, postoperatively, and at a mean follow-up of 3.2 years (range 2.0–5.3 years). At follow-up the mean Cobb angle was decreased by 73%, and the translation of the apical vertebra was significantly decreased by 33%. The sagittal contour was significantly improved with thoracic kyphosis T5–12 increased by 46% (6.9°) and lumbar lordosis L1–5 increased by 28% (10.3°) at follow-up. The sagittal diameter was significantly improved by 5 mm at follow-up. Although the vertebral rotation and the size of rib hump was improved postoperatively, this was followed by significant loss of correction, and at follow-up the vertebral rotation and the size of rib hump were not significantly better than preoperatively. The study indicates that while CDI improves the coronal and sagittal plane deformity permanently, the effect on vertetebral rotation and the rib hump deteriorates with time.     

胸椎侧凸后路凸侧胸廓成形术后胸腔并发症及其预防

目的：探讨青少年特发性胸椎侧凸后路凸侧胸廓成形术的胸腔并发症原因,并提出预防措施。方法：对2003年12月至2007年9月行脊柱侧凸后路矫形内固定术和凸侧胸廓成形术,并有完整资料的胸椎侧凸患者548例进行回顾性分析。其中男167例,女381例;年龄12～38岁,平均16.1岁。术前剃刀背畸形16°～50°,平均35°。结果：凸侧胸廓成形的肋骨切除数平均4.1根。术后剃刀背畸形2°～17°,平均7°。1例（0.2%）术后呼吸困难需间歇性吸氧,29例（5.3%）术中发生壁层胸膜穿孔,其中5例术后胸腔积液,3例气胸。6例（1.1%）患者术中并无明显胸膜穿孔,但术后出现术侧胸腔积液。结论：提高手术技巧,术后严密监测呼吸状态,早期积极处理,可减少凸侧胸廓成形术后胸腔并发症的发生。     

Correction of flexible thoracic scoliosis below 65 degrees—A radiological comparison of anterior versus posterior segmental instrumentation applied to similar curves

Direct comparison of the correction of scoliosis achieved by different surgical methods is usually limited by the heterogeneity of the patients analyzed (their age, curve pattern, curve magnitude, etc.). The hypothesis is that an analysis of comparable scoliotic curves treated by different implant systems could detect subtle differences in outcome. The objective of this study was therefore: (1) to measure the 3D radiological parameters of scoliotic deformity and to quantify their postoperative changes, and (2) to compare the radiographic results achieved with one anterior and one posterior instrumentation methods applied to similar curves but representing different mechanisms of correction. Material and methods: The clinical notes and radiographs of 46 patients operated on for adolescent idiopathic scoliosis were reviewed. The inclusion criteria consisted of: a single thoracic curve, right convex, a frontal Cobb angle minimum of 45° and a maximum of 65°, flexibility on a lateral bending test of more than 30%, and a Risser test value of between 1 and 4. The operative procedures were: Cotrel-Dubousset instrumentation (CDI) for 25 patients (the CD group) and correction by anterior instrumentation (Pouliquen plate) for 21 patients (the ANT group). Preoperative and postoperative long cassette standing antero-posterior and lateral radiographs were examined. The frontal and sagittal thoracic Cobb angle, apical vertebra transposition (AVT), apical vertebra rotation (AVR), lowest instrumented vertebra (LIV) tilt, C7 vertebra shift and rib cage shift (RCS) were all compared. A computed reconstruction was produced with Rachis-91 software. Vertebral axial rotation angle was evaluated throughout the spine. Results: Postoperative assessment revealed a mean correction of the frontal Cobb angle of 37.0° for the CD group and 41.0° for the ANT group. The AVT operative correction was 45.8 and 42.7 mm, respectively, and AVR correction was 1.8 and 12.6°, respectively. The postoperative change of the sagittal Th4–Th12 Cobb angle was not significant for any method but it was significant (P=0.05) for the CD group if the curves were divided preoperatively into hypokyphotic and normokyphotic subgroups and then analyzed separately. Computed assessment demonstrated a correction of segmental axial rotation of more than 50% in the main thoracic curve in the ANT group, significantly more than that in the CD group (P<0.001). Conclusions: Anterior instrumentation provided better correction of the vertebral axial rotation and of the rib hump. CD instrumentation was more powerful in translation and more specifically addressed the sagittal plane: the postoperative thoracic kyphosis angle increased in the hypokyphotic curves and slightly decreased in the normokyphotic curves.     

Video-assisted thoracoscopic surgery (VATS) for the treatment of scolioticrib hump deformity

A retrospective study of 21 patients with idiopathic scoliosis who underwent endoscopic thoracoplasty was done. The objective of the study was to report and assess the morbidity and mid term outcomes of video-assisted thoracoplasty in idiopathic scoliosis. Patients with idiopathic scoliosis often present cosmetic complaints due to their rib deformity. This deformity may still exist after surgical correction of the main scoliotic curve. Endoscopic thoracoplasty has been reported as a safe method in limited cases of idiopathic scoliosis. Between 2002 and 2004, 21 patients underwent endoscopic anterior release and thoracoplasty for significant rib hump deformity associated with idiopathic scoliosis. Patients were operated on lateral position, with two endoscopic ports. Anterior release and rib resection were performed during the first stage, and instrumented posterior fusion was performed in a second stage. Patients were evaluated preoperatively, 1 week after surgery, 6 months after surgery and at their most recent follow-up with clinical and radiological measurement of the rib deformity. The mean age at surgery was 14.9 years old (range 13–17 years). The average Cobb’s angle of the main scoliotic curve was 70° (range 60°–85°). Average follow-up was 25 months (range 23–32 months). The mean number of resected ribs was five ribs (range 4–7) and the mean length of the resected rib was 4.2 cm (range 2.2–7 cm). Average operating time of endoscopic thoracoplasty (including anterior release) was 65 min (range 45–108 min). The mean preoperative height of rib hump deformity was 3.6 cm (range 2.5–5.5 cm). It was reduced to 1.5 cm at most recent follow-up. There was no significant thoracic pain necessitating medication postoperatively. No complications related to endoscopic anterior release and rib hump resection occurred in the series. Endoscopic thoracoplasty is a safe and reliable technique in idiopathic scoliosis. If indicated, the anterior release can be performed with video-assistance and the thoracoplasty can be performed on the same stage.     

Rip hump correction and rotation of the lumbar spine after selective thoracic fusion

In this study a series of 32 patients with idiopathic scoliosis, managed with selective thoracic fusion, was reviewed. Classified according to King and instrumented with the H-frame, the patients were evaluated for curve correction, rib hump correction and postoperative shift in lumbar rotation. Age and follow-up averaged 19.4 and 2.4 years, respectively. The 32 patients had an average primary and lumbar curve correction of, respectively, 66% (6.0% correction loss) and 53% (3.4% correction loss). The respective values for postoperative rib hump correction and shift in apical lumbar rotation averaged 8° and 9.4° in type II King curves, 4.4° and 3.5° in type III and 11° and-5° in Type IV. Significant differences were noted between the curve types in rib hump correction and shift in lumbar rotation. The study showed that en bloc postoperative rotation of the compensatory lumbar segment, directed towards the rib hump, positively influences rib hump correction. This en bloc rotation of the unfused lumbar segments is induced by the correcting forces applied by the instrumentation. The unfused lumbar spine of a patient with a King type II curve shows a larger lumbar rotation shift and subsequent rib hump correction than that of a patient with a King type III curve. Together with factors such as lateral angulation, rib-vertebra angles and structural limitations, the rotational dynamics of the unfused lumbar spine seem to form an important component in the understanding and surgical management of scoliosis.     

Short apical rib resections thoracoplasty compared to conventional thoracoplasty in adolescent idiopathic scoliosis surgery

Purpose

To introduce a modified technique of thoracoplasty (short apical rib resection thoracoplasty (SARRT)) and compare its clinical, functional radiological outcomes and postoperative lung functions with conventional thoracoplasty (CT) in scoliosis surgery.

Methods

Retrospectively review of adolescent idiopathic scoliosis patients who underwent corrective surgery with thoracoplasty from 2006 to 2010 was performed. Thoracoplasty was performed in 58 patients (CT in 31 and SARRT in 27 patients). 21 patients who underwent deformity correction only, without thoracoplasty were taken as control group (non-thoracoplasty, NT). To evaluate the outcome of SARRT, radiological parameters, pulmonary functions and clinical outcomes were compared among all the three groups.

Results

Age, sex and scoliosis types were evenly distributed between 3 groups (p = 0.66, 0.92, 0.31). Number of levels fused, change in Cobb angle, lordosis, kyphosis, coronal balance, sagittal balance, coronal translation and sagittal translation were not significantly different among the three groups (p > 0.05 for all). There was 38.6 % improvement in rib hump in NT, 44.04 % in CT and 60.9 % correction in SARRT group. Pulmonary complications were significantly higher in the CT group, especially in view of pleural rupture, pulmonary effusion and intercostal neuralgia (p = 0.041, 0.029, 0.049). There was no difference among three groups in postoperative pulmonary function but the score of satisfaction as sub-category in SRS-22 questionnaire was decreased in CT groups (p = 0.046).

Conclusions

SAART is effective in correcting the rib deformity without altering the pulmonary functions and SAART has less number of pulmonary complications as compared to CT.     

The segmental effect of Cotrel-Dubousset instrumentation on vertebral rotation,rib hump and the thoracic cage in idiopathic scoliosis

The segmental effect of Cotrel-Dubousset instrumentation (CDI) on the spine and thoracic cage was investigated in 38 patients with adolescent idiopathic scoliosis by preoperative and postoperative postero-anterior and lateral radiographs and computed tomography from T1 to S1. Mean Cobb angle decreased by 67%. The T5–T12 kyphosis in the hypokyphotic patients increased on average by 8.4° (P<0.001). Average preoperative as well as postoperative maximal vertebral rotation was located at the apex level, and was reduced from 19.0° to 14.3° (P<0.001). All vertebrae between the upper and lower instrumented vertebrae were significantly derotated. Average derotation for the apical zone was 4.8° (P<0.001), for the upper instrumented zone it was 2.5° (P<0.01), and for the lower instrumented zone it was 2.6° (P<0.01). Vertebral derotation was significantly higher in the apical zone than in the upper and lower instrumented zones. The apical rib hump index (RHi) decreased by 38% (P<0.001) and the cumulative RHi for the five apical levels decreased by 34% (P<0.001). The RHi for the two levels above and below the instrumentation each decreased by 20% (n.s.). No significant increase in sagittal or transverse rib cage diameter at any level was observed. The translation in the coronal plane of the apical vertebra of major right thoracic curves improved significantly (P<0.001). The preoperative flexibility index of the major curve correlated positively (r=0.47) with derotation at the apex level (P<0.01). However, no correlation was found between flexibility index and reduction of RHi at the apex level. Vertebral derotation did not correlate with reduction in RHi at any level. The study shows that CDI results in a postoperative three-dimensional improvement of the spine and a limited improvement of the thoracic cage, with no tendency towards a worsened deformity at any level within or outside the instrumentation.     

Colour Doppler ultrasonography for evaluation of anterior chest blood supply: the possible role of arterial blood supply to the costosternal junction in the aetiology of idiopathic scoliosis in female adolescents

This prospective comparative study was carried out to investigate the blood supply to the anterior chest wall by measurement of several anatomical and haemodynamic flow parameters of the internal mammary artery, with the use of colour Doppler ultrasonography, in female scoliotics with idiopathic right convex scoliosis in adolescence. Previous investigations have postulated that asymmetry of the breasts in female adolescents may be linked with the development of right convex thoracic scoliosis. This breast asymmetry is supposed to be linked with anatomical and functional asymmetry of the internal mammary artery that is the main supplier to the mammary gland. However, no measurements of anatomical and haemodynamic parameters of the internal mammary artery have been made to justify or reject the hypothesis of asymmetric blood flow volume to the breasts and costosternal junction in female adolescent scoliotics. Twenty female adolescents with right convex thoracic scoliosis and 16 comparable female individuals without spine deformity were examined with roentgenograms (scoliotics only) to measure scoliosis curve, vertebral rotation and concave and convex rib–vertebra angle at three vertebrae (the apical, one level above and one below the apical vertebra). Doppler ultrasonography was used to measure, at the origin of the internal mammary artery, its lumen diameter, cross-sectional area, time average mean flow and flow volume per minute in scoliotics and controls, which were compared with each other. The roentgenographic parameters were compared with the ultrasonographic parameters in the scoliotics to disclose any relationship. The reliability of colour Doppler ultrasonography was high and the intra-observer variability low (ANOVA, P=0.92–0.94). There was no statistically significant difference in the ultrasonographic parameters of the internal mammary artery between right and left side in each individual as well as between scoliotics and controls. In scoliotics the right mammary artery time average mean velocity increases with the convex (P<0.05) and concave (P<0.01) rib–vertebra angle one level above the apical vertebrae and with the apical convex rib–vertebra angle (P<0.05). The right internal mammary artery flow volume per minute increases with convex (P<0.01) and concave (P<0.01) rib–vertebra angle one level above the apical vertebrae and with the apical convex rib–vertebra angle (P<0.05). Left internal mammary artery cross-sectional area increases with convex apical rib–vertebra angle (P<0.01) and concave rib–vertebra angle one level above the apical vertebra (P<0.01). Conclusively, this investigation showed that haemodynamic flow parameters of the right internal mammary artery and anatomical parameters of the left internal mammary artery are significantly correlated with the magnitude of rib–vertebra angles close to the apex of right thoracic scoliosis in female adolescents. This study did not find any evidence for side-difference in vascularity of the anterior thorax wall and, thus, it could not clearly justify previous theories for development of right thoracic scoliosis in female adolescents.A reviewers comment to this paper can be found at     

Imbalance of electromyographic activity and physical rehabilitation of patients with idiopathic scoliosis

Summary In order to monitor changes in postural performance capacity in patients with idiopathic scoliosis after an intensive in-patient Schroth rehabilitation programme [17] lasting several weeks, we undertook electromyographic investigations in 316 patients with a mean age of 20 years (range 8–76 years) and a mean Cobb curvature angle of 38.2° (range 10°–147°). Electromyographic activity was recorded by means of surface electrodes in the thoracic and lumbar region at the level of the apical vertebra, paravertebrally on both sides of the erector spinae muscle during trunk lifting from the prone position. Two hundred and fifty-nine recordings without artefacts were evaluated. Significant reductions in muscle activity of 6.85% in the thoracic convex region (P<0.05) and of 14.2% (P<0.001) on the lumbar convex side were found. The activity quotient (convesx/concave) was reduced by 11.99% (P<0.001) in the thoracic region and by 7.91% (P<0.01) in the lumbar region. These findings confirm the improvement of postural performance capacity after an intensive in-patient Schroth rehabilitation programme. As the imbalance of electromyographic activity may be influenced by scoliosis-specific exercises leading to a highly significant reduction of the Cobb angle, it is assumed to be secondary to the development of the scoliotic curve and may not be a primary factor in the aetiology of idiopathic scoliosis.     

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

Purpose

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.

Methods

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 24 months. 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). Statistical analysis: values as mean ± SD, differences by student’s t-test (significancy a = 0.05), Pearson’s correlation, sub-analysis with sagittal modifier (−, N, +).

Results

A total of 127 AIS could be identified (63% type 1, 37% type 2). Mean FU 32.2 ± 16.6 months, mean age 14 ± 1.5 years. 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 (5,5 mm versus 6 mm) had no significant influence.

Conclusion

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.

     

Spinal growth and progression of adolescent idiopathic scoliosis

Summary The spinal growth in scoliotic segments (T4-L4) of 110 girls with untreated idiopathic scoliosis was measured from two successive radiographs taken at a mean interval of 1.1 years. At the first visit the mean age of the patients was 14 years (range 11–16 years), the mean magnitude of the major curves 24° (range 9°–38°) and that of the minor curves 14° (range 2°–38°). Spinal growth was most rapid at the age of 11–12 years. The progression of the curves (major plus minor) correlated with the spinal growth (r=0.384). The greater the initial curves were, the stronger the correlation was between the spinal growth and the progression of the curves (r=0.046–0.639), and the correlation was more significant in thoracic scoliosis (r=0.560) than in thoracolumbar and lumbar scoliosis (r=0.152).     

Selective posterior thoracic fusion by means of direct vertebral derotation in adolescent idiopathic scoliosis: effects on the sagittal alignment

The objectives of this retrospective study were to evaluate the effect of direct vertebral derotation on the sagittal alignment of the spine after selective posterior thoracic fusion for Lenke Type I adolescent idiopathic scoliosis (AIS). Preservation of the sagittal alignment has become critical in the management of spinal deformity. Better coronal and rotational corrections in posterior selective thoracic fusion for AIS have been reported with direct vertebral derotation as compared with the simple rod rotation technique. A greater lordogenic effect has been anticipated with direct vertebral derotation; however, data comparing those two techniques in terms of correction in the sagittal plane are still lacking. Standing full-spine PA and standard lateral serial X-rays of a total of 30 consecutive patients with adolescent idiopathic scoliosis treated between 2002 and 2008 at a single institution were evaluated. All the patients had Lenke Type I curves and underwent selective posterior thoracic fusion with pedicle screw instrumentation. Patients who were treated with additional osteotomies and concave or convex thoracoplasty or concomitant anterior releases were excluded. Minimum follow-up period was 24 months. Preoperative and postoperative coronal and sagittal spinal alignments in both the groups were compared. In 13 patients, the correction was achieved by means of a simple rod rotation (SRR). In 17 patients, the technique of direct vertebral derotation (DVD) was used. Scoliosis correction averaged 67 and 69%, respectively, and was similar in both groups (p > 0.05). Thoracic kyphosis and lumbar lordosis remained unchanged in the SRR group (p > 0.1). In the direct vertebral derotation group, a significant decrease of both thoracic kyphosis and lumbar lordosis of 8.1° and 11.8°, respectively, was observed (p < 0.0001). Global sagittal balance remained within normal limits in all the patients at the latest follow-up. Decrease in thoracic kyphosis and lumbar lordosis should be taken into account when using direct vertebral derotation for selective posterior thoracic fusion in AIS. In order to preserve sagittal alignment in these patients, ultra hard rods or maneuvers that pull posteriorly the concave side of the spine, thus avoiding the application of additional flattening forces should be considered.     

Computed tomographic-based volumetric reconstruction of the pulmonary system in scoliosis: trends in lung volume and lung volume asymmetry with spinal curve severity

BACKGROUND: Scoliosis has been associated with reduced pulmonary capacity; however, the source of the reduction in capacity (left, right, or both lungs) is not clear. The objective of this study was to investigate trends in left, right, and total lung volume and left/right lung volume asymmetry with spinal curve severity in scoliosis. METHODS: Three-dimensional volumetric reconstruction of the pulmonary system was performed on existing preoperative computed tomographic (CT) scans for 28 idiopathic scoliosis patients. Left, right, and total lung volumes, and left/right lung volume ratios were calculated and correlated with the following spinal curve parameters: major Cobb angle, rib hump, number of vertebrae in the major curve, most cephalad vertebra in the major curve, and thoracic kyphosis. RESULTS: Left/right lung volume ratio increases significantly with increasing rib hump. Left, right, and total lung volumes were significantly correlated with rib hump and number of vertebrae in the major curve (P < 0.05), and near-significantly correlated with most cephalad vertebra in the major curve (P < 0.10). Shorter, higher, more rotated thoracic curves therefore restrict lung volume more than longer, lower, less rotated curves. The mean lung volume ratio for scoliosis patients was lower than for age-matched controls (P < 0.10). CONCLUSION: CT-based volumetric reconstruction of the pulmonary system in scoliosis patients shows differences in both lung volumes and lung volume ratios compared with normal controls.     

Effect of Harrington instrumentation spondylodesis on scoliotic thoracic deformity. A retrospective 5-year analysis]

INTRODUCTION AND AIM OF THE STUDY: Harrington-Instrumentation (HI) was the golden standard of scoliosis surgery for more than two decades and is still frequently used. The effects of instrumentation on rib hump reduction in long term follow-up is not well documented. 104 patients with idiopathic thoracic scoliosis were studied with a minimum follow-up of five years (min. 5 y., max. 8 years). METHODS: The rib-cage deformity was determined as rib hump index (RHi) by measuring the rib hump to the depression. The long term effect of HI was investigated using full standing AP radiographs. Measuring cobb angle (CA), translation (TA) and rotation of apical vetebra (RA) were obtained for every patient preoperatively, postoperatively and at follow-up. Patient were analysed in 3 different groups. Single curve thoracic scoliosis (n = 54) (King III and IV), double curve thoracic/lumbar scoliosis (n = 35) (King I and II) and double curve thoracic scoliosis (n = 15) (King V). RESULTS: With an average preoperative measurement of 62.7 degrees and a postoperative measurement angle of 32.9 degrees the correction of CA achieved is 47.5% (23-73%). The mean thoracic translation improved by 50% (0-100%). Rotation of the scoliosis was not reduced significant. In follow up studies no loss of correction in frontal plane deformity was obtained. The mean RHi in all groups was seen to improve by 25-30% (min. 0%, max. 60%), depending on form of scoliosis. In group of patients King II/III scoliosis (n = 52) the mean RHi increased measurably to 11.5% (min. 0%, max. 50%) correction at long term follow up. In group of patients King I/II scoliosis average RHi was increased from 31% (5-100%) to 21% correction. The mean RHi correction in the group of patients King V scoliosis correction rate of 26% (0-50%) was unchanged at long term follow up. CONCLUSION: HI leads to a permanent and stable improvement of the frontal plane including apical vertebral translation. HI does not have derotational capabilities. The effect of the rib-cage deformity was less impressive with loss of correction at follow up.     

Rib length asymmetry in thoracic adolescent idiopathic scoliosis: is it primary or secondary?

The development of scoliosis in animal models after inducing asymmetric rib growth suggests the possible role of asymmetric rib growth in the etiopathogenesis of adolescent idiopathic scoliosis (AIS). Asymmetric rib length is well recognized in idiopathic scoliosis; however, whether this rib asymmetry is primary or secondary has not been clearly documented. The objectives of this study were to investigate any rib length asymmetry in patients with AIS and compare those with scoliosis with syringomyelia (SS) with the intention of elucidating any relationship between rib growth and pathogenesis of AIS. Forty-eight AIS and 29 SS with apical vertebrae located between T7 and T9 were recruited. The average age was 13.5 ± 2.3 versus 12.5 ± 3.4 years, and the average Cobb angle of thoracic curve was 43.3° ± 16.4° versus 45.6° ± 22.6° in patients with AIS or SS, respectively. The length of all ribs was measured from the tip of costal head to the end of the same rib by built-in software on spiral computed tomography. At the levels of the apical vertebrae, the vertebrae above and below the apex, the mean discrepancy in rib length (concave minus convex rib) was 7, 4 and 7 mm, respectively, in AIS group (p < 0.01), and 6, 5 and 7 mm in SS group, respectively (p < 0.01). The rib length discrepancy between concave and convex sides was significantly correlated with the magnitude of the Cobb angle of thoracic curve in both AIS and SS groups (p < 0.01). Similar findings of the asymmetry of rib length in both AIS and SS patients pointed strongly to the fact that the rib length asymmetry in apical region is most likely secondary to the scoliosis deformity rather than playing a primary role in the etiopathogenesis.     

Anterior surgery for adolescent idiopathic scoliosis

Anterior open scoliosis surgery using the dual rod system is a safe and rather effective procedure for the correction of scoliosis (50–60 %). Thoracic hypokyphosis and rib hump correction with open anterior rather than posterior instrumentation appear to be the better approaches, although the latter is somewhat controversial with current posterior vertebral column derotation devices. In patients with Risser grade 0, hyperkyphosis and adding-on may occur with anterior thoracic spine instrumentation. Anterior thoracoscopic instrumentation provides a similar correction (65 %) with good cosmetic outcomes, but it is associated with a rather high risk of instrumentation (pull-out, pseudoarthrosis) and pulmonary complications. Approximately 80 % of patients with adolescent idiopathic scoliosis (AIS) curves of >70° have restrictive lung disease or smaller than normal lung volumes. AIS patients undergoing anterior thoracotomy or anteroposterior surgery will demonstrate a significant decrease in percentage of predicted lung volumes during follow-up. The thoracoabdominal approach and thoracoscopic approach without thoracoplasty do not produce similar changes in detrimental lung volume. In patients with severe AIS (>90°), posterior-only surgery with TPS provides similar radiographic correction of the deformity (44 %) with better pulmonary function outcomes than anteroposterior surgery. Vascular spinal cord malfunction after segmental vessel ligation during anterior scoliosis surgery has been reported. Based on the current literature, the main indication for open anterior scoliosis instrumentation is Lenke 5C thoracolumbar or lumbar AIS curve with anterior instrumentation typically between T11 and L3.     

Thoracoplasty in scoliosis]

Since 1978, 108 cases of scoliosis with severe thoracic deformity have received thoracoplasty. Most of them were operated at the same time for correction of scoliosis. The resected ribs were served as bone graft for posterial spinal fusion. The rib prominence was reduced 2.5-6.9 cm after operation, and the costectomy also found to be beneficial to the correction of lateral curvature and axial rotation of the spine. The thoracoplasty showed no affect upon the pulmonary function. In this paper, three kinds of thoracoplasty and their indications are discussed and compared.     

Implant removal for late-developing infection after instrumented posterior spinal fusion for scoliosis: reinstrumentation reduces loss of correction. A retrospective analysis of 45 cases

A retrospective follow-up study of patients who, having undergone instrumented posterior spinal fusion for scoliosis, experienced late infection and then underwent either implant removal alone or implant removal and instrumented refusion. We conducted this study to determine whether it is possible to avoid loss of correction by a single-stage implant removal and reinstrumentation procedure. There have been a few reports of late-appearing infections after spinal instrumentation. Implant bulk, metallurgic reactions, and contamination with low-virulence microorganisms have been suggested as possible etiologic factors. The clinical symptoms include pain, swelling, redness, and spontaneous drainage of fluid. Complete instrumentation removal and systemic antibiotics is usually curative. We retrospectively reviewed 45 patients who underwent instrumented posterior spinal fusion for scoliosis and experienced development of late infections and, after a mean of 3 years after the initial procedure, either underwent implant removal alone [n=35, instrumentation removal (HR) group] or additionally underwent reinstrumentation and fusion [n=10, reinstrumentation and fusion (RI&F) group]. Three patients were reinstrumented 1.5 years after instrumentation removal, and seven underwent a one-stage rod removal and reinstrumentation/refusion procedure. Allergic predisposition, protracted postoperative fever, and pseudarthrosis appear to increase the risk of late-developing infection after posterior spinal fusion. All wounds in both groups healed uneventfully. Preoperative radiographic Cobb measurements showed no statistically significant between-group differences. At follow-up, however, outcome was clearly better in the RI&F group: Loss of correction was significantly smaller in reinstrumented patients. Thus, the thoracic Cobb angle was 28±16° (range 0–55°) in the RI&F group versus 42±15° (21–80°) in the HR group, and the lumbar Cobb angle was 22±11° (10–36°) in the RI&F group versus 29±12° (13–54°) in the HR group. The results of our study demonstrate that wound healing is usually uneventful after instrumentation removal for late infection, also when patients undergo instrumented refusion in a one-stage procedure. Reinstrumentation appears to achieve permanent correction of scoliosis.