Aims

Gram-negative infections are associated with comorbid patients, but outcomes are less well understood. This study reviewed diagnosis, management, and treatment for a cohort treated in a tertiary spinal centre.

Introduction

There is no consensus among scoliosis surgeons on which surface topography method and parameters may be used as an alternative to serial radiography to monitor scoliosis progression. The aim of this study was to evaluate the inter-correlation among surface rotation (4-D formetric II) with 3-D Quantec scan and 2-D cobb's angle measurements for assessing torso asymmetry in adolescent idiopathic scoliosis (AIS).

The side distribution of single spinal curves in our school screening referrals for 1988–99 (n=218) suggests that the mechanism(s) determining curve laterality for the upper spine differs from those for the lower spine. We address here the laterality of right thoracic AIS. In the search to understand the aetiology of AIS some workers focus on mechanisms initiated in embryonic life including a disturbance of bilateral symmetry. The normal external bilateral symmetry of the body, highly conserved in vertebrates, results from a default process involving mesodermal somites. The normal internal asymmetry of the heart, major blood vessels, lungs and gut with its glands is also highly conserved among vertebrates. There is recent evidence that vertebrates retain an archaic asymmetric visceral organization in thoracic and abdominal organs (Cooke). In early embryonic life the visceral asymmetry develops from the breaking of the initial bilateral symmetry by a binary asymmetry switch producing asymmetric gene expression around the embryonic node and/or in the lateral plate mesoderm. In the mouse this switch occurs during gastrulation by cilia driving a leftward flow of fluid and morphogen(s) at the embryonic node (nodal flow) favouring precursors of heart, great vessels and viscera on the left. Based on the non-random laterality of thoracic AIS curves, we suggest that the binary asymmetry switch – through genetic/environmental factors extending to involve anomalously left-sided mesodermal precursors of vertebrae, ribs and/or muscles (positively or negatively), explains the distribution of right/left thoracic AIS. Some support for this hypothesis is the prevalence of scoliosis curve laterality associated with situs inversus.

Most workers consider that ribcage changes in AIS are secondary to spinal deformity. Others claim that ribs are pathogenic in curve initiation or aggravation. In 117 consecutive patients referred from school screening in 1996–99 and routinely scanned by ultrasound, 24 had thoracic and 33 thoracolumbar scolioses (right 37, left 20; mean age 14.9 years, range 12–18 years, girls 44 postmenarcheal 37, boys 13). On anteroposterior standing radiographs, Cobb angle (CA), apical vertebral rotation (AVR, Perdriolle) and apical vertebral translation (AVT from the T1-S1 line) were measured (mean & range: CA 19°, 6–42°; AVR 15°, 0–39°; AVT 17 mm, 0–38 mm). Real-time ultrasound in the prone position recorded laminal rotation (LR) and rib rotation (RR) segmentally and the spine-rib rotation difference (SRRD) as LR minus RR to estimate the combined rib deformity in the transverse plane using for thoracic curves apical LR and RR and for thoracolumbar curves T12 LR and T12 RR (mean LR 8.3°, RR 3.8°, SRRD 5.2° absolute). All deformity parameters, radiological and ultrasound, are unrelated to age. SRRD correlates significantly with each of AVR (r=0.753 p< 0.0001), Cobb angle (r=0.738 p< 0.0001), and AVT (r=0.725 p< 0.0001). Partial correlation analysis shows AVR rather than AVT is associated with the transverse plane rib deformity (SRRD/AVR controlling for AVT r=0.386 p=0.004; SRRD/AVT controlling for AVR r=0.257 p=0.058; SRRD/CA controlling for AVR r=0.260 p=0.055 and for AVT r=0.223 p=0.101). These and other findings suggest that rib rotation in thoracic curves is associated with AVR and AVT and in thoracolumbar curves more with AVR than AVT each within the 4^th column of the spine.

Several workers consider that the aetiology of adolescent idiopathic scoliosis (AIS) involves undetected neu-romuscular dysfunction. During normal development the central nervous system (CNS) has to adapt to the rapidly growing skeleton of adolescence, and in AIS also to developing spinal asymmetry from whatever cause. A new etiologic concept is proposed after examining the following evidence:

anomalous extra-spinal left-right skeletal length asymmetries of upper arms, ribs, ilia and lower limbs suggesting that asymmetries may also involve vertebral body and costal growth plates;

The central of four requirements is maturational delay of the CNS body schema relative to skeletal maturation during the adolescent growth spurt that disturbs the normal neuro-osseous timing of maturation. With the development of an early AIS deformity at a time of rapid spinal growth the association of CNS maturational delay results in postural mechanisms failing to balance a lateral spinal deformity in an upright moving trunk that is larger than the information on personal space (self) established in the brain by that time of development. It is postulated that CNS maturational delay allows scoliosis curve progression to occur – unless the delay is temporary when curve progression would cease. The concept brings together many findings relating AIS to the nervous and musculoskeletal systems and suggests brain morphometric studies in subjects with progressive AIS.

Left-right skeletal length asymmetries in upper limbs related to curve side have been detected with adolescent thoracic idiopathic scoliosis (AIS). In school screening referrals with thoracic scoliosis we find apical vertebral rotation (AVR, Perdriolle) is associated significantly with upper arm length asymmetry. Sixty-nine of 218 consecutive adolescent patients referred routinely during 1988–1999 had idiopathic thoracic scoliosis of whom 61 had left and right upper arm lengths measured with a Holtain anthropometer (right curves 49, left curves 12, mean age 14.9 years, girls 38 postmenarcheal 34, boys 23). The controls are 278 normal girls and 281 boys (11–18 years, mean age 13.5 years). The mean value for Cobb angle is 18 degrees (range 4–42 degrees), AVR 13 (range 0–34 degrees), Cobb angle (CA) and AVR are each positively associated with upper arm length asymmetry (p=0.001 & p< 0.0001 respectively) and after correcting for each of Cobb side, apical level, sex and handedness, AVR and upper arm length asymmetry are still significantly associated (p=0.004 ANOVA). Partial correlation analysis shows AVR is associated with upper arm length asymmetry after controlling for CA (p=0.033); but not CA and upper arm length asymmetry after controlling for AVR (p=0.595). The reason why a larger AVR to the right is associated with a relatively longer right upper arm is unknown. Possibilities include neuromuscular and skeletal mechanisms, the latter relative concave overgrowth of neurocentral synchondrosis and/or of periapical ribs. We suggest consideration be given to combining convex vertebral body stapling (Betz) with concave periapical rib resection (Sevastik and Xiong) for right thoracic AIS in girls.

Objective. To evaluate the relation of ribs to the spine in the transverse plane (TP) at the curve apex in preoperative AIS using a real-time ultrasound method and radiographs (Burwell et al 2002).

Design. With the subject in a prone position and head supported, readings of laminal rotation (LR) and rib rotation (RR) were made on the back by one of two observers (RKA, ASK) using an Aloka SSD 500 portable u/s machine with a veterinary long (172mm) 3.5 MHz linear array transducer. The maximal difference between LR and RR about the curve apex was calculated as the apical spine-minus-rib rotation difference (SRRD). The SRRD eliminates the effect of any anterior chest wall asymmetry on the ultrasound measurements and, assuming no movement of ribs in the TP at the costotransverse joints, is considered to be a measure of TP rib deformity. The radiographic Cobb angle (CA), apical Perdriolle rotation (AR), and apical vertebral translation (AVT) were measured by one observer (RGB). In an attempt to separate mechanical axial vertebral rotation from axial vertebral deformity a derivative was calculated as Perdriolle rotation minus ultrasound LR with the latter corrected for the positional effect of lying prone and termed the axial vertebral difference (AVD) The correction factor (CF) used is maximal Scoliometer angle of trunk rotation obtained in the standing forward bending position minus that in the prone position.

Subjects. Thirty-three preoperative patients with AIS were studied (thoracic curves 20, thoracolumbar curves 8, double curves 5).

Results. The mean figures in degrees or mm (AVT) are shown in the Table.

All curves combined. The LR is significantly greater than the RR (p< 0.001) and correlates with RR (r=0.358, p=0.041), SRRD (r=0.713, P< 0.001) but not with CA (p=0.088), AR (p=0.166), AVT or AVD. AR does not correlate significantly with CA.

Thoracolumbar and thoracic curves. In the thoracolumbar curves the SRRDs are significantly greater than those in the thoracic curves (p=0.031) implying more TP rib deformity in the thoracolumbar curves. In the thoracic curves the SRRDs correlate negatively with the AVDs (r= −0.470, p=0.036) suggesting that rib deformity and intravertebral deformity contribute reciprocally and together with axial spinal rotation to determine the overall spinal deformity of AIS.

Conclusions. The findings are consistent with the hypothesis that in preoperative AIS the axial RR and TP rib deformities are adaptations to rotational and lateral forces imposed by the scoliotic spine (Wever et al 1999). Might surgical stiffening of the posterior ends of the apical convex ribs – in an attempt to prevent TP convex rib deformity – constrain axial spinal rotation, vertebral translation and intravertebral deformity and limit curve progression? #Supported by AO/ASIF Research Commission Project 96-W21

Objective: To evaluate the subjective clinical outcomes, radiographic results and complications associated with single solid rod anterior instrumentation in neuromuscular scoliosis.

Design: Retrospective clinical case series with a mean follow up of 30 months (range 24 – 42 months).

Subjects: 9 consecutive cases (6F, 3M) with a mean age 15 years (range 11 – 24 years), underwent single solid rod anterior instrumentation of their neuromuscular thoracolumbar scoliosis between 1994 and 2000. The heterogeneous patient group consisted of 5 spinal dysraphism, and 1 each of prune belly syndrome, arthrogryposis, myotonic dystrophy and congenital myopathic dystrophy (muscle eye brain syndrome). All patients were ambulatory and had minimal pelvic obliquity (< 15 degrees).

Outcome measures: Pre-operative, post-operative and final follow up measurements were collected for 1) Cobb angles, 2) apical vertebral translation (AVT), 3) thoracic kyphosis (T5-12) and 4) lumbar lordosis (L1-5). Operative complications, pseudarthrosis, metalwork failure and loss of correction were also recorded.

Results: There was 1 each of rod breakage and upper thoracic curve progression requiring supplementary posterior surgery. For the remaining 7 patients, the average follow-up corrections for Cobb angle was 56% (49 to 22 degrees), AVT was 49% (5.1 to 2.6 cms), and both the thoracic kyphosis and lumbar lordosis remained unchanged. No significant loss in correction occurred during the post-operative period to final follow-up in all the above parameters. No pseudarthrosis, vascular or neurological complications were encountered. Subjectively, there were 6 excellent and 1 good results.

Conclusions: In this limited case review, selective anterior instrumentation for neuromuscular scoliosis using a single solid rod system resulted in acceptable clinical and radiographic outcomes. Our results appear to compare favourably with those published for the recommended method of posterior instrumentation. Advantages include preservation of distal lumbar motion segments whilst maintaining segmental saggital and coronal alignment. We believe that this method of scoliosis correction has a definite yet select role in patients who are ambulatory, have minimal pelvic obliquity (< 15 degrees), non-progressive pathology and near normal mental function.