Primary thoracoplasty and pedicle screw instrumentation in thoracic idiopathic scoliosis

Thoracoplasty in combination with spine fusion is an established method to address the rib cage deformity in idiopathic scoliosis. Most reports about thoracoplasty and scoliosis correction focused on Harrington or CD instrumentation. We report a retrospective analysis of 21 consecutive patients, who were treated with pedicle screw instrumentation for idiopathic thoracic scoliosis and concomitant thoracoplasty. Minimal follow up was 24 (24–75) months. Indication for thoracoplasty was clinical rib prominence of more than 15°. In average there was a 44% correction of clinical rib hump, from 18 (15–25°) to 10° (0–18°) (p<0.0001) and a 40% correction of radiological rib hump, from 15 (5–20°) to 9°(2–15°) (p<0.0001). The preoperative pulmonary function, accessed by forced vital capacity (FVC) and one-second forced expiratory volume (FEV1), remained unchanged at the last follow up. The distal end of fusion was the end vertebra of the curve in 83.3% and the end vertebra plus one in 16.7% of the patients. There was a 68% correction of instrumented primary thoracic curves, from 60 (45–85°) to 19°(5–36°) (p<0.0001), and a 45% correction of non-instrumented secondary lumbar curves, from 40 (28–60°) to 22°(8–38°) (p<0.0001). Apical vertebral rotation (AVR) of the thoracic curves improved 54%, from 24 (10–35°) to 11° (5–20°) (p<0.0001). The tilt of lowest instrumented vertebra (LIV) improved 68%, from 28 (20–42°) to 9°(3–20°) (p<0.0001). There was no significant change in sagittal profile of the spine. Analysis with SRS-24 questionnaire showed that the majority of the patients were very satisfied with the outcome. A matched control group (n=21) operated by the same surgeon with the same operation technique but without concomitant thoracoplasty was chosen for comparison. The scoliosis correction in the two groups was comparable. The patients without thoracoplasty had 37% spontaneous improvement of the clinical rib hump.     

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.     

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.     

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.     

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.     

The rib deformity in adolescent idiopathic scoliosis. A prospective study to evaluate changes after Harrington distraction and posterior fusion

A prospective study to investigate changes in the rib hump or rib deformity after correction of the lateral curvature in adolescent idiopathic scoliosis is reported. The operative treatment for 47 patients was by a Harrington distraction rod and posterior fusion. Before operation and at follow-up, measurements of the Cobb angle, of vertebral rotation, and of the rib deformity were taken. Despite operative correction of the lateral curve, there was a progression of the rib deformity in 64% of the cases after four years. Correction of the lateral curve may thus have no effect on vertebral rotation and cannot be guaranteed to effect a permanent reduction of the rib hump.     

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.     

Evaluation of deformities and pulmonary function in adolescent idiopathic right thoracic scoliosis

Summary Seventy patients with adolescent idiopathic right thoracic scoliosis had full assessment of their pulmonary function using a computerised pulmonary function system. Their mean age at evaluation was 13.8 years. The following measurements were obtained from anteroposterior and lateral standing and antero-posterior supine bending radiographs: lateral curvature, vertebral rotation, kyphosis, maximum sterno-vertebral distance and apical rib-vertebral angles. Using the above measurements, the flexibility of curve, vertebral rotation and rib-vertebral angle asymmetry were calculated. Patients were classified into three groups on the basis of their predicted vital capacity, to determine whether radiological features of deformity can help identify patients with compromised pulmonary function. The mean Cobb angle and vertebral rotation for the 70 patients were 50° (range 35–100°) and 22° (range 1–44°) respectively. The mean flexibility of curve and vertebral rotation were 52% and 49% respectively. Mean thoracic kyphosis was 25%, ranging from -7 to 55%. Of the patients with Cobb angle less than 90%, 71% had vital capacity less than 80% of predicted values, and of these, 18% had marked compromise of vital capacity (less than 60% of predicted values). Mean values of Cobb angle, vertebral rotational flexibility, kyphosis, rib-vertebral angle asymmetry (in standing as well as supine bending radiographs) differed significantly between patients with more than 80% of predicted vital capacity and those with 60% or less of predicted values. Radiological features indicative of better pulmonary function were: rotational flexibility exceeding 55%, rib-vertebral angle asymmetry (standing) less than 25% and kyphosis greater than 15%. Two deformity parameters—that give a better prediction of pulmonary function than the widely used Cobb angle, vertebral rotational flexibility and rib-vertebral angle asymmetry—were identified in this study.     

Cotrel-Dubousset instrumentation and vertebral rotation in adolescent idiopathic scoliosis

We have studied 34 consecutive patients receiving Cotrel- Dubousset instrumentation for a single and flexible thoracic scoliotic curve, evaluating the rib hump deformity from a single CT scan through the apical vertebra of the curve. Using two measures of rotation we found a mean improvement of 25% in the rotation of the vertebra after operation. Any, usually minor, deterioration occurred in the first six months postoperatively, and there was no significant further deterioration in 19 patients assessed over two years after surgery. Cotrel-Dubousset instrumentation can produce a significant correction of vertebral rotation and of the associated rib hump deformity.     

Cotrel-Dubousset instrumentation in the treatment of unstable thoracic and lumbar spine fractures

The use of computed tomography and developments in spinal biomechanics have led to a better understanding of vertebral fractures. The disappointing results achieved with conservative treatment have led to an increasing popularity of surgical treatment in the last 15 years. The results of 20 unstable thoracic or lumbar spine fractures treated surgically with Cotrel-Dubousset instrumentation at the First Clinic of Orthopaedics and Traumatology of the Ankara Social Security Hospital between December 1988 and June 1991 were evaluated in this study. The mean follow-up was 31.9 months. The mean sagittal index angle was 23.7° ± 6.8° preoperatively and was corrected by 67.1 ± 29.9%, and the thoracolumbar junction angle was brought within physiological limits in 65% of the cases. Postoperatively, the neurological status improved in 15% of the patients and remained unchanged in the rest. It was concluded that the Cotrel-Dubousset instrumentation established vertebral stability in unstable vertebral fractures by forming a rigid frame and restored physiological thoracic and lumbar postural contours due to its highly corrective effect in the sagittal plane.     

Analysis of pulmonary function and axis rotation in adolescent and young adult idiopathic scoliosis patients treated with Cotrel-Dubousset instrumentation.

Forty-eight patients with idiopathic scoliosis underwent posterior spinal fusion with Cotrel-Dubousset instrumentation (CDI). Each patient was given preoperative and postoperative pulmonary function tests (PFTs). Pulmonary volume improved a mean 0.40 L (16%), and pulmonary flow improved a mean 0.33 L (15%). Differences between preoperative and postoperative PFT values were shown to be statistically significant and correlated well with coronal side-bending correction. Twenty patients had preoperative and postoperative CT scans through the apical vertebra. Vertebral rotation was assessed on CT scan by the method of Aaro and Dahlborn (1,2). At the apex, the mean percentage improvements in the longitudinal axis rotation relative to the midline (16%) and to the sagittal plane (10%), the rib hump index (8%), and the kyphosis-lordosis index (0%) were minimal. Radiographically, the 66% mean improvement in apical vertebral translation was more substantial and consistent than the 10% mean improvement in apical vertebral rotation. Therefore, at the apex the CDI "derotation maneuver" may be more of a "translational maneuver."     

Vertebral coplanar alignment technique: a surgical option for correction of adult thoracic idiopathic scoliosis

Purpose

Previous studies have demonstrated vertebral coplanar alignment (VCA) as an effective surgical option for adolescent idiopathic scoliosis (AIS). The purpose of this study is to analyze the outcome of VCA for the surgical correction of adult idiopathic scoliosis (AdIS).

Methods

35 AdIS patients (mean age: 24.2 years) undergoing VCA-instrumentation were reviewed. The main thoracic curve and thoracic kyphosis (TK, T5-T12) were evaluated preoperatively, immediate postoperatively, and at the final follow-up (>1 year). All patients were stratified by the TK modifier before surgery: “+” (TK, >40°), “?” (TK, <10°), and “N” (TK, 10°–40°) for normal. The apical vertebral body-to-rib ratio (AVB-R), rib hump (RH), and rotational angle to sacrum (RAsac) were measured to assess the correction of rotational deformity. Quality of life was evaluated with SRS-20 questionnaires.

Results

The main thoracic curve (59.1° vs. 19.3°, P < 0.001) and rotational deformity (AVB-R: 2.4 vs. 1.7 %, P < 0.001, RH: 34.9 vs. 19.1 mm, P < 0.001, RAsac: 19.6° vs. 11.9°, P < 0.001) were significantly reduced with surgery. Sagittal deformity improved significantly in group “+” (51.4° vs. 31.6°, P < 0.001) and group “?” (6.2° vs. 20.1°, P < 0.001), while no significant postoperative change in TK was observed in group “N” (23.5° vs. 26.3°, P = 0.270). Patients were followed for an average of 18.7 months with no significant loss of correction. SRS scores improved greatly from 57.7 preoperatively to 71.6 at the final follow-up.

Conclusions

VCA can be effectively used for the correction of the coronal and rotational deformity, with better sagittal profile restoration in adult thoracic idiopathic scoliosis with sagittal malalignment.

     

Adolescent idiopathic thoracic scoliosis: apical correction with specialized pedicle hooks

Forty-one patients with thoracic adolescent idiopathic scoliosis (AIS) treated with only a posterior spine fusion using specialized pedicle hooks (SPH) (hooks augmented with 3.2-mm screws) at the apex of the curve were reviewed in order to assess the effectiveness of this correction method. Inclusion in the study group required a minimum of 2 years’ follow-up and the same strategy of correction where the apical vertebrae (3 or 4 vertebrae on the concave side) were instrumented with SPH. The mean preoperative Cobb angle was corrected from 55° (42°–80°) to 18° (67%) postoperatively and to 23° (58%) at the last follow-up (28–50 months) for a flexibility index of 46%. Apical vertebral translation was corrected to 70% at the last follow-up. Thoracic kyphosis remained unchanged, from 23° to 26°, and the lumbar lordosis went from –53° to –59°. The lumbar curve was corrected from 38° to 18°. Coronal balance improved from 10 to 1 mm; shoulder balance was improved from 15 to 5 mm. The rib hump was improved from an average of 30 mm preoperatively to 15 mm postoperatively, but only to 25 mm at the last follow-up (17% of correction). One case of a spastic bladder was observed postoperatively, which resolved completely after 8 months. Three patients had to have their instrumentation removed because of pain. There was no complication related to the use of the SPH. The authors conclude that apical correction with SPH allows effective scoliosis correction without spinal distraction and does not require supra- or infralaminar hook in the spinal canal. Received: 1 July 1998 Revised: 25 March 1999 Accepted: 21 April 1999     

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.     

Cotrel-Dubousset and Harrington Instrumentation in idiopathic scoliosis: a comparison of long-term results

Summary Between 1968 and 1977, 72 patients with idiopathic scoliosis underwent Harrington Instrumentation (HI). Between 1985 and 1988, 21 patients with idiopathic scoliosis had posterior spinal fusion with Cotrel-Dubousset instrumentation (CDI). All patients were operated by the same orthopedic surgeon. None of the CDI patients had postoperative brace or cast protection, the HI group had on average 6 months' postoperative brace treatment. The two groups of patients were comparable in age, sex, and type of curves. The HI group and CDI group were reexamined with clinical and radiological assessment after mean periods of 148 months and 60 months respectively. The average preoperative Cobb angle in the CDI group was 59.9° (HI group 67.8°), which improved to 20.8° (HI group 33°) postoperatively — a correction of 66.3% (HI group 51.3%). The loss of correction on reassessment amounted to 5% in the CDI group and 20.7% in the HI group. In both groups, the mean rib hump height was reduced to 2.2 cm. In 40% of the Harrington patients, a flat back was found, but this was not related to clinical back pain. The rate of complications and reintervention was 9.5% in the CDI group and 8.3% in the HI group. There were no neurological complications. Subjectively, 86% of the Harrington patients and 95.2% of the CDI patients rated the results of their operation as good or very good. The CDI group showed better results in correction of the Cobb angle and loss of correction, while saving one mobile lumbar segment. The correction of the rib hump showed the same results for both techniques. Blood loss and operation time was much lower in the HI group. However, the rate of complications was similar in both groups.     

Minimally invasive osteosynthesis in septic conditions

Background and purpose

Management of pyogenic spondylodiscitis in adults remains controversial. The aim of this study was to evaluate the results of a minimally invasive method for deformity correction and stabilization of these lesions with percutaneous osteosynthesis.

Methods

Ten patients were included in this study and treated with a two-step procedure: posterior percutaneous osteosynthesis completed by complementary intervertebral grafting via an anterior access. Postoperative evaluation was clinical and radiological with measurement of local sagittal deformity and restitution of vertebral body height.

Results

In this series, bacteriologic identification was possible and pain was controlled in every case. On postoperative evaluation, the implants were always properly positioned. The mean local sagittal deformation was +2.1° preoperatively and −8.4° postoperatively. The mean increase in vertebral body height was measured at 8 mm postoperatively. At the last follow-up, a moderate loss of correction was noted (mean: 2° and 3 mm) and all patients but one showed solid bony fusion.

Conclusion

Percutaneous osteosynthesis in septic conditions in association with an anterior graft provides satisfactory clinical and radiographic results. It provides a valuable alternative for deformity correction and spinal stabilization with a minimally invasive access in patients with comorbidities.     

Anterior dual rod instrumentation in idiopathic thoracic scoliosis

For anterior correction and instrumentation of thoracic curves single rod techniques are widely used. Disadvantages of this technique include screw pullouts, rod fractures and limited control of kyphosis. This is a prospective study of 23 consecutive patients with idiopathic thoracic scoliosis treated with a new anterior dual rod system. Aim of the study was to evaluate the safety and efficacy of this new technique in the surgical treatment of idiopathic thoracic scoliosis. To the best knowledge of the authors, this is the largest series on dual rod dual screw instrumentation over the entire fusion length in thoracic scoliosis. Twenty-three patients with an average age of 15 years were surgically treated with a new anterior dual rod system through a standard open double thoracotomy approach. Average clinical and radiological follow-up was 28 months (24–46 months). Fusion was carried out mostly from end-to-end vertebra. The primary curve was corrected from 66.6° to 28.3° (57.5% correction) with an average loss of correction of 2.0° at Cobb levels and of 1.3° at fusion levels. Spontaneous correction of the secondary lumbar curve averaged 43.2% (preoperative Cobb angle 41.2°). The apical vertebral rotation was corrected by 41.1% with a consecutive correction of the rib hump of clinically 66.7%. The thoracic kyphosis measured 29.2° preoperatively and 33.6° at follow-up. In seven patients with a preoperative hyperkyphosis of on average 47.3° thoracic kyphosis was corrected to 41.0°. This new instrumentation enables an entire dual rod instrumentation over the whole thoracic fusion length. It offers primary stability without the need of postoperative bracing. Dual screw dual rod instrumentation offers the advantages of a high screw pullout resistance, an increased overall stability and satisfactory sagittal plane control.     

Variability of geometric measurements from three-dimensional reconstructions of scoliotic spines and rib cages

Summary Three-dimensional (3-D) reconstructions of the spine are being used with increasing frequency to describe scoliotic deformities, but the reproducibility of most of these techniques and the implication for the reliability of measurements made on the reconstructions has not been reported. How reliable are these reconstructions, and can a clinician interpret with confidence the results of studies based on such mathematical models? A reproducibility study of various computerised measurements obtained from 3-D reconstructions of the spine and rib cage for five subjects with adolescent idiopathic scoliosis was done to evaluate the errors associated with repeated measurements and compare them with inter-and intraobserver errors reported for similar commonly used clinical measurements. The mean variation for the Cobb angle differed according to the plane of computation from 0.6° in the frontal plane to 6.7° in the sagittal plane; vertebral axial rotation varied from 2.3° to 5.9° according to the vertebral level, and rib hump measurements displayed an average variation of 1.4°. All these variations are below or within the error levels reported for equivalent 2-D measurements used by clinicians, which suggests that this 3-D model of idiopathic scoliosis may be used with confidence for clinical evaluations.     

Texas Scottish Rite Hospital instrumentation for correction of idiopathic scoliosis: short-term results

Summary In this prospective study 27 consecutive patients of an average age of 20±8 years suffering from idiopathic scoliosis were operated on using the Texas Scottish Rite Hospital (TSRH) instrumentation in the period from 1992 to 1995 and were evaluated at a minimum follow-up of 26 months postoperatively. Curvature correction, derotation of the apical vertebra, frontal and sagittal trunk balance, and L3–L4 and L4–L5 disc-space wedging were evaluated prepostoperatively and at the maximum follow-up of 54 months. The average correction of the thoracic and lumbar scolioses that was obtained immediately postoperatively averaged 41% and 51% respectively. An average 2–4° and 4–5° loss of correction was dependent on King type in the thoracic and lumbar scoliotic curves respectively was observed at the longest follow-up. Thoracic kyphosis and lumbar lordosis did not significantly change. No significant derotation of thoracic and lumbar apical vertebral rotation was achieved by TSRH but the preoperatively laterally shifted apical vertebra was translated by TSRH instrumentation towards the midline (p<0.001). The position of the T1, and C7 vertebrae in the sagital frontal plane was not significantly changed by TSRH instrumentation postoperatively. The preoperative wedging of the intervertebral spaces L3–L4 and L4–L5 was simultaneously significantly (p<0.01) reduced by TSRH with subsequent horizontalization of the L3, L4 and L5 vertebrae. No trunk decompensation, neurologic complications, infection or pseudarthroses occurred. Lumbar hook dislodgment occurred in the early post-operative period in two patients because of insufficient TSRH rod contouring at the beginning of our learning curve. TSRH is a safe instrumentation that corects idiopathic scoliosis satisfactorily, maintains frontal and sagittal vertebral balance by translating the apical vertebra towards the midline and simultaneously correcting the lowermost lumbar vertebral tilting without associated infection, neurologic complications or decompensation.      

Excision of hemivertebrae in the management of congenital scoliosis involving the thoracic and thoracolumbar spine

We present a study of ten consecutive patients who underwent excision of thoracic or thoracolumbar hemivertebrae for either angular deformity in the coronal plane, or both coronal and sagittal deformity. Vertebral excision was carried out anteriorly alone in two patients. Seven patients had undergone previous posterior spinal fusion. Their mean age at surgery was 13.4 years (6 to 19). The mean follow-up was 78.5 months (20 to 180). The results were evaluated by radiological review of the preoperative, postoperative and most recent follow-up films. The mean preoperative coronal curve was 78.2 degrees (30 to 115) and was corrected to 33.9 degrees (7 to 58) postoperatively, a mean correction of 59%. Preoperative coronal decompensation of 35 mm was improved to 11 mm postoperatively. Seven patients had significant coronal decompensation preoperatively, which was corrected to a physiological range postoperatively. There were no major complications and no neurological damage. We have shown that resection of thoracic and thoracolumbar hemivertebrae can be performed safely, without undue risk of neurological compromise, in experienced hands.