Collagen changes in congenital and idiopathic scoliosis

Rare functional genetic variants in COL7A1, COL6A5, COL1A2 and COL5A2 frequently occur in Chiari Malformation Type 1

Chiari Malformation Type 1 (CM-1) is characterized by herniation of the cerebellar tonsils below the foramen magnum and the presence of headaches and other neurologic symptoms. Cranial bone constriction is suspected to be the most common biologic mechanism leading to CM-1. However, other mechanisms may also contribute, particularly in the presence of connective tissue disorders (CTDs), such as Ehlers Danlos Syndrome (EDS). Accumulating data suggest CM-1 with connective tissue disorders (CTD+) may have a different patho-mechanism and different genetic risk factors than CM-1 without CTDs (CTD-). To identify CM-1 genetic risk variants, we performed whole exome sequencing on a single large, multiplex family from Spain and targeted sequencing on a cohort of 186 unrelated adult, Caucasian females with CM-1. Targeted sequencing captured the coding regions of 21 CM-1 and EDS candidate genes, including two genes identified in the Spanish family. Using gene burden analysis, we compared the frequency of rare, functional variants detected in CM-1 cases versus publically available ethnically-matched controls from gnomAD. A secondary analysis compared the presence of rare variants in these genes between CTD+ and CTD- CM-1 cases. In the Spanish family, rare variants co-segregated with CM-1 in COL6A5, ADGRB3 and DST. A variant in COL7A1 was present in affected and unaffected family members. In the targeted sequencing analysis, rare variants in six genes (COL7A1, COL5A2, COL6A5, COL1A2, VEGFB, FLT1) were significantly more frequent in CM-1 cases compared to public controls. In total, 47% of CM-1 cases presented with rare variants in at least one of the four significant collagen genes and 10% of cases harbored variants in multiple significant collagen genes. Moreover, 26% of CM-1 cases presented with rare variants in the COL6A5 gene. We also identified two genes (COL7A1, COL3A1) for which the burden of rare variants differed significantly between CTD+ and CTD- CM-1 cases. A higher percentage of CTD+ patients had variants in COL7A1 compared to CTD+ patients, while CTD+ patients had fewer rare variants in COL3A1 than did CTD- patients. In summary, rare variants in several collagen genes are particularly frequent in CM-1 cases and those in COL6A5 co-segregated with CM-1 in a Spanish multiplex family. COL6A5 has been previously associated with musculoskeletal phenotypes, but this is the first association with CM-1. Our findings underscore the contribution of rare genetic variants in collagen genes to CM-1, and suggest that CM-1 in the presence and absence of CTD symptoms is driven by different genes.

Etiopathogenesis of adolescent idiopathic scoliosis: Review of the literature and new epigenetic hypothesis on altered neural crest cells migration in early embryogenesis as the key event

Adolescent idiopathic scoliosis (AIS) affects 2-3% of children. Numerous hypotheses on etiologic/causal factors of AIS were investigated, but all failed to identify therapeutic targets and hence failed to offer a cure. Therefore, currently there are only two options to minimize morbidity of the patients suffering AIS: bracing and spinal surgery. From the beginning of 1960th, spinal surgery, both fusion and rod placement, became the standard of management for progressive adolescent idiopathic spine deformity. However, spinal surgery is often associated with complications. These circumstances motivate AIS scientific community to continue the search for new etiologic and causal factors of AIS. While the role of the genetic factors in AIS pathogenesis was investigated intensively and universally recognized, these studies failed to nominate mutation of a particular gene or genes combination responsible for AIS development. More recently epigenetic factors were suggested to play causal role in AIS pathogenesis. Sharing this new approach, we investigated scoliotic vertebral growth plates removed during vertebral fusion (anterior surgery) for AIS correction. In recent publications we showed that cells from the convex side of human scoliotic deformities undergo normal chondrogenic/osteogenic differentiation, while cells from the concave side acquire a neuronal phenotype. Based on these facts we hypothesized that altered neural crest cell migration in early embryogenesis can be the etiological factor of AIS. In particular, we suggested that neural crest cells failed to migrate through the anterior half of somites and became deposited in sclerotome, which in turn produced chondrogenic/osteogenic-insufficient vertebral growth plates. To test this hypothesis we conducted experiments on chicken embryos with arrest neural crest cell migration by inhibiting expression of Paired-box 3 (Pax3) gene, a known enhancer and promoter of neural crest cells migration and differentiation. The results showed that chicken embryos treated with Pax3 siRNA (microinjection into the neural tube, 44 h post-fertilization) progressively developed scoliotic deformity during maturation. Therefore, this analysis suggests that although adolescent idiopathic scoliosis manifests in children around puberty, the real onset of the disease is of epigenetic nature and takes place in early embryogenesis and involves altered neural crest cells migration. If these results confirmed and further elaborated, the hypothesis may shed new light on the etiology and pathogenesis of AIS.

Postoperative epidural analgesia versus systemic analgesia for thoraco-lumbar spine surgery in children

BACKGROUND

Spine surgery may be associated with severe acute postoperative pain. Compared with systemic analgesia alone, epidural analgesia may offer better pain control. However, epidural analgesia has sometimes been associated with rare but serious complications. Therefore, it is critical to quantify the real benefits of epidural analgesia over other modes of pain treatment.

OBJECTIVES

To assess the effectiveness and safety of epidural analgesia compared with systemic analgesia for acute postoperative pain control after thoraco-lumbar spine surgery in children.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase and Cumulative Index to Nursing and Allied Health Literature on 14 November 2018, together with the references lists of related reviews and retained trials, and two trials registers.

SELECTION CRITERIA

We included all randomized controlled trials performed in children undergoing any type of thoraco-lumbar spine surgery comparing epidural analgesia with systemic analgesia for postoperative pain. We applied no language or publication status restriction.

DATA COLLECTION AND ANALYSIS

We assessed risk of bias of included trials using the Cochrane tool. We analysed data using random-effects models. We rated the quality of the evidence according to the GRADE scale.

MAIN RESULTS

We included 11 trials (559 participants) in the review, and seven trials (249 participants) in the analysis: 140 participants received epidural analgesia and 109 received systemic analgesia.Most studies included adolescents. Three trials included in the analysis contained some participants older than 18 years. The types of surgery were posterior spinal fusion for idiopathic scoliosis (nine trials), anterior correction for idiopathic scoliosis (one trial), or selective dorsal rhizotomy in children with cerebral palsy (one trial). The mean numbers of vertebrae operated on were between nine and 14.5 and the mean numbers of spinal levels were between three and four and a half. The length of surgery varied between three and six and a half hours.Compared with systemic analgesia, epidural analgesia reduced pain at rest at all time points. At six to eight hours, the mean pain score on a 0 to 10 scale with systemic analgesia was 3.1 (standard deviation 0.7) and with epidural analgesia was -1.32 points (95% confidence interval (CI) -1.83 to -0.82; 4 studies, 116 participants; moderate-quality evidence). At 72 hours, the mean pain score with epidural analgesia was equivalent to a -0.8 point reduction on a 0 to 10 scale (standardized mean difference (SMD) -0.65, 95% CI -1.19 to -0.10; 5 studies, 157 participants; moderate-quality evidence).Return of gastrointestinal functionThere was no difference for nausea and vomiting between groups (risk ratio (RR) 0.87, 95% CI 0.58 to 1.30; 6 studies, 215 participants; low-quality evidence). One study found epidural analgesia with local anaesthetics may have increased the number of participants who had their first flatus within 48 hours (RR 1.63, 95% CI 1.08 to 2.47; 30 participants; very low-quality evidence). Two studies found epidural analgesia with local anaesthetics may have increased the number of participants in whom first bowel movement occurred within 48 hours (RR 11.52, 95% CI 2.36 to 56.26; 60 participants; low-quality evidence). It was uncertain whether epidural analgesia reduced the time to first bowel movement (MD 0.09 days, 95% CI -0.32 to 0.50; 1 study, 60 participants; very low-quality evidence) and time to first liquid ingestion following epidural infusion of an opioid alone or a local anaesthetic plus an opioid (mean difference (MD) -5.02 hours, 95% CI -13.15 to 3.10; 2 studies, 56 participants; very low-quality evidence). Epidural analgesia with local anaesthetics may have increased the risk of having first solid food ingestion within 48 hours (RR 7.00, 95% CI 1.91 to 25.62; 1 study, 30 participants; very low-quality evidence).Secondary outcomesIt was uncertain whether there was a difference in time to ambulate (MD 0.08 days, 95% CI -0.24 to 0.39; 1 study, 60 participants; very low-quality evidence) and hospital length of stay (MD -0.29 days, 95% CI -0.69 to 0.10; 2 studies, 89 participants; very low-quality evidence). Two studies found participants were more satisfied when treated with epidural analgesia (MD 1.62 on a scale from 0 to 10, 95% CI 1.26 to 1.97; 60 participants; very low-quality evidence). It was unclear whether there was a difference in parent satisfaction for epidural analgesia with an opioid alone (MD 0.60, 95% CI -0.81 to 2.01; 1 trial, 27 participants; very low-quality evidence).ComplicationsIt was uncertain whether there was a difference in the risk of complications such as: respiratory depression (risk difference (RD) -0.05, 95% CI -0.16 to 0.05; 4 studies, 126 participants; very low-quality evidence); wound infection (RD 0.01, 95% CI -0.05 to 0.08; 2 trials, 93 participants; very low-quality evidence); epidural abscess (RD 0, 95% CI -0.05 to 0.05; 3 trials, 120 participants; very low-quality evidence); and neurological complications (RD 0.01, 95% CI -0.04 to 0.06; 4 studies, 151 participants; very low-quality evidence).

AUTHORS' CONCLUSIONS

There is moderate- and low-quality evidence that there may be a small additional reduction in pain up to 72 hours after surgery with epidural analgesia compared with systemic analgesia. Two very small studies showed epidural analgesia with local anaesthetic alone may accelerate the return of gastrointestinal function. The safety of this technique in children undergoing thoraco-lumbar surgery is uncertain due to the very low-quality of the evidence. The study in 'Studies awaiting classification' may alter the conclusions of the review once assessed.

Light and Scanning Electron Microscopy of Human Spinal Ligaments

Spinal ligaments were obtained from normal and scoliotic individuals. Detailed morphological studies were carried out on the yellow, interspinous and supraspinous ligaments by light and scanning electron microscopy. Normal yellow ligaments are mostly constituted of dense elastin fibers with only a few collagen fibers and sparse blood vessels, while in normal interspinous and supraspinous ligaments, the presence of collagen is highly dominant. In the latter structures, the collagen fascicles are characterized by a regular waviness morphology. The fibrils constituting the fascicles appear either parallel or helical with respect to the fascicle axis. Structural changes are observed in the spinal ligaments of patients with congenital as well as idiopathic scoliosis. For yellow ligaments, only slight differences are found between normal and scoliotic specimens. However, alterations in collagen waviness and architecture are observed mainly in the supraspinous ligaments and to a lesser extent in the interspinous ligaments. In addition, increases in the cellularity, loose connective tissue and vessels are found in both forgoing ligaments. These results indicate that the more pronounced scoliosis-related changes occur in ligaments having the farthest distance from the axis of flexion-rotation.

Impact of leg lengthening on viscoelastic properties of the deep fascia

Background

Despite the morphological alterations of the deep fascia subjected to leg lengthening have been investigated in cellular and extracellular aspects, the impact of leg lengthening on viscoelastic properties of the deep fascia remains largely unknown. This study aimed to address the changes of viscoelastic properties of the deep fascia during leg lengthening using uniaxial tensile test.

Methods

Animal model of leg lengthening was established in New Zealand white rabbits. Distraction was initiated at a rate of 1 mm/day and 2 mm/day in two steps, and preceded until increases of 10% and 20% in the initial length of tibia had been achieved. The deep fascia specimens of 30 mm × 10 mm were clamped with the Instron 1122 tensile tester at room temperature with a constant tensile rate of 5 mm/min. After 5 load-download tensile tests had been performed, the specimens were elongated until rupture. The load-displacement curves were automatically generated.

Results

The normal deep fascia showed typical viscoelastic rule of collagenous tissues. Each experimental group of the deep fascia after leg lengthening kept the properties. The curves of the deep fascia at a rate of 1 mm/day with 20% increase in tibia length were the closest to those of normal deep fascia. The ultimate tension strength and the strain at rupture on average of normal deep fascia were 2.69 N (8.97 mN/mm²) and 14.11%, respectively. The increases in ultimate tension strength and strain at rupture of the deep fascia after leg lengthening were statistically significant.

Conclusion

The deep fascia subjected to leg lengthening exhibits viscoelastic properties as collagenous tissues without lengthening other than increased strain and strength. Notwithstanding different lengthening schemes result in varied viscoelastic properties changes, the most comparable viscoelastic properties to be demonstrated are under the scheme of a distraction rate of 1 mm/day and 20% increase in tibia length.

A study on platelet function in idiopathic scoliosis

Because platelets and muscle cells share the same contractile proteins--actin and myosin--platelets may serve as a model for muscle research. To study the functional abnormalities and ultrastructural changes of platelets and to determine whether or not abnormalities in muscle contractile proteins and collagen play an important role in the pathogenesis of idiopathic scoliosis, the bleeding time, the platelet aggregation test, and the titers of platelet plasminogen activator inhibitors were measured and the electron microscopic findings were examined in 52 idiopathic scoliosis patients aged 7 to 28 years and in 49 normal individuals aged 8 to 38 years as a control group. We found no statistically significant difference between the two groups in the bleeding time, the platelet aggregation test, and the titers of platelet plasminogen activator inhibitors. In the electron microscopic findings, no specific abnormalities were found in platelets of idiopathic scoliosis patients. We concluded that idiopathic scoliotic patients have normal morphology and function of platelets, and there is no important role of contractile proteins in the pathogenesis of idiopathic scoliosis. In addition, since the bleeding time was in the normal range, no evidence of subendothelial collagen dysfunction was found in the idiopathic scoliosis patients.

Collagen crosslinking and cartilage glycosaminoglycan composition in normal and scoliotic chickens

The amounts of lysine-derived crosslinks in collagens from tendon, cartilage, intervertebral disc, and bone and changes in the composition of sternal cartilage glycosaminoglycans were estimated in two lines of chickens, a control-isogenic line and a line that develops scoliosis. In the scoliotic line, scoliosis first appears at 3-4 weeks and progressively increases in severity and incidence so that 90% of the birds express the lesion by week 10. We have reported previously that cartilage, tendon, and bone collagens from scoliotic birds are more soluble than corresponding collagens from normal birds. Herein, collagen crosslinking and altered proteoglycan metabolism are examined as possible mechanisms for the differences in collagen solubility. At 1 week of age there were fewer reducible crosslinking amino acids (hydroxylysinonorleucine, dihydroxylysinonorleucine, and lysinonorleucine) in collagens from sternal cartilage and tendon in the scoliotic line than in the isogenic line. However, by week 3 and at weeks 5 or 7 values were similar in both groups. The amounts of hydroxypyridinium in vertebral bone and intervertebral disc collagen were also similar in both groups of birds. Consequently, differences in collagen crosslinking do not appear to be a persistent developmental defect underlying the expression of scoliosis in the model. However, differences were observed in cartilage proteoglycans and glycosaminoglycans from the scoliotic line that were not present in cartilage from the isogenic line. The average molecular weight of the uronide-containing glycosaminoglycans was 30% less in the scoliotic line than in the isogenic line, i.e., 12,000 compared to 18,000. The size distribution of cartilage proteoglycans from the scoliotic line also differed from that of proteoglycans from the isogenic line.(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital spine deformities. A review of 47 cases

Forty-two cases of congenital scoliosis, four cases of congenital kyphosis and one case of congenital lordosis were reviewed retrospectively from 1975 through 1982, with an average follow-up of 5.09 years. Associated anomalies occurred in 62.5% of the cases, with Sprengel's deformity and Klippel-Feil syndrome being the most common musculoskeletal anomalies. The rate of abnormal intravenous pyelography was 21.8%, and absent kidneys or duplication of collecting systems accounted for the majority of renal abnormalities. Myelographic abnormalities were noted in eight of twenty-five studies and included two cases of diastematomyelia and one tethered cord syndrome. Initial treatment was observation (11), bracing (11), and surgery in the remaining 25 cases. The surgical complication rate was 22.8%. Progressive deformities led to additional surgical procedures in six cases which had previous in situ fusions.

Bleeding time and scoliosis

Collagen abnormalities in idiopathic scoliosis are on record. Since there is a correlation between the platelet aggregating power of the collagen and the bleeding time in patients with scoliosis, the bleeding time was studied in 195 cases with scoliosis and in 318 controls. The bleeding time was longer in the females, especially in those with idiopathic scoliosis (n = 149). Patients with paralytic scoliosis (n = 5) also had a significantly longer bleeding time than non-scoliotic controls. The patients with congenital scoliosis (n = 13) did not differ significantly from the controls or from patients with idiopathic scoliosis. The bleeding time in idiopathic scoliosis did not vary with age or magnitude of the scoliosis. Our data support the view that collagen abnormalities play a role not only in the aetiology of idiopathic scoliosis, but also in other forms of scoliosis.

Structural properties of Type I collagen isolated from chickens with scoliosis

This study examines biochemically the Type I collagen isolated from skin of chickens that develop idiopathic scoliosis. Previous studies indicate a defect in collagen exists in these chickens. Alpha 1 (I) and alpha 2 chains were separated by gel filtration and carboxymethyl cellulose column chromatography and were then subjected to the analytical techniques of sodium dodecyl sulfate gel electrophoresis, Staphylococcus aureus V8 protease digestion, cyanogen bromide peptide mapping and amino acid analyses. In all categories, the scoliotic alpha 1 (I) and alpha 2 chains were identical to alpha chains isolated from normal chickens. These data suggest that the altered properties of collagen solubility and connective tissue stress relaxation seen in these scoliotic chickens are not a manifestation of an altered primary structure of the alpha chains or post-translational modification affecting chromatographic elution profiles or electrophoretic migration patterns.

Study of biochemical and hormonal data in idiopathic scoliosis in girls

Basic cause and factors determining the progression of idiopathic scoliosis are assumed to be multifarious. A deviating growth pattern has also been suspected. The influence of certain bone and growth-stimulating hormones and related biochemical values has been studied in girls with idiopathic scoliosis compared to controls. The mineral content (S-Ca, S-P and S-Alp) did not differ between idiopathic scoliosis and controls. a2-macroglobulin was slightly increased in the scoliotic group in all ages. Morning fast GH and Somatomedin A level in serum were also increased in the scoliotic group. Even a significant increase of 17-oxosteroids are metabolites of androgens in girls. 17-oxosteroids in urine mainly metabolites of cortisol, neither calcitonin or parathyroid hormone, in contrary, did not differ between scoliosis and controls.