Seven additional families with spondylocarpotarsal synostosis syndrome with novel biallelic deleterious variants in FLNB.

The location and/or type of variants in FLNB result in a spectrum of osteochondrodysplasias ranging from mild forms, like spondylocarpotarsal synostosis syndrome and Larsen syndrome, to severe perinatal lethal forms, such as atelosteogenesis I and III and Boomerang dysplasia. Spondylocarpotarsal synostosis syndrome is characterized by disproportionate short stature, vertebral anomalies and fusion of carpal and tarsal bones. Biallelic loss-of-function variants in FLNB are known to cause spondylocarpotarsal synostosis syndrome and 9 families and 9 pathogenic variants have been reported so far. We report clinical features of 10 additional patients from 7 families with spondylocarpotarsal synostosis syndrome due to 7 novel deleterious variants in FLNB, thus expanding the clinical and molecular repertoire of spondylocarpotarsal synostosis syndrome. Our report validates key clinical (fused thoracic vertebrae and carpal and tarsal coalition) and molecular (truncating variants in FLNB) characteristics of this condition.

ESR evidence for 2 coexisting liquid phases in deeply supercooled bulk water.

Using electron spin resonance spectroscopy (ESR), we measure the rotational mobility of probe molecules highly diluted in deeply supercooled bulk water and negligibly constrained by the possible ice fraction. The mobility increases above the putative glass transition temperature of water, T(g) = 136 K, and smoothly connects to the thermodynamically stable region by traversing the so called "no man's land" (the range 150-235 K), where it is believed that the homogeneous nucleation of ice suppresses the liquid water. Two coexisting fractions of the probe molecules are evidenced. The 2 fractions exhibit different mobility and fragility; the slower one is thermally activated (low fragility) and is larger at low temperatures below a fragile-to-strong dynamic cross-over at approximately 225 K. The reorientation of the probe molecules decouples from the viscosity below approximately 225 K. The translational diffusion of water exhibits a corresponding decoupling at the same temperature [Chen S-H, et al. (2006) The violation of the Stokes-Einstein relation in supercooled water. Proc Natl Acad Sci USA 103:12974-12978]. The present findings are consistent with key issues concerning both the statics and the dynamics of supercooled water, namely the large structural fluctuations [Poole PH, Sciortino F, Essmann U, Stanley HE (1992) Phase behavior of metastable water. Nature 360:324-328] and the fragile-to-strong dynamic cross-over at approximately 228 K [Ito K, Moynihan CT, Angell CA (1999) Thermodynamic determination of fragility in liquids and a fragile-to-strong liquid transition in water. Nature 398:492-494].

Morphometry of the lower thoracic and lumbar pedicles and its relevance in pedicle fixation.

PURPOSE: To assess the pedicle morphology in the lower thoracic and lumbar spine in an Indian population and to determine the causes of pedicle wall violation by pedicle screws. METHODS: Computerised tomographic scans of 135 consecutive patients with thoracolumbar and lumbar spine fractures were prospectively analysed to determine the pedicle morphology. The transverse pedicle angle, pedicle diameter and screw path length at 527 uninjured levels were measured. Post-operative CT scans of 117 patients were analysed to determine the accuracy of 468 pedicle screws at 234 vertebrae. RESULTS: The lowest (mean ± SD) transverse pedicle width in the lower thoracic spine was 5.4 ± 0.70 mm, whereas in the lumbar spine it was 7.2 ± 0.87 mm. The shortest (mean ± SD) screw path length in lower thoracic pedicles was 35.8 ± 2.10 and 41.9 ± 2.18 mm in the lumbar spine. The mean transverse pedicle angle in the lower thoracic spine was consistently less than 5°, whereas it gradually increased from L1 through L5 from 8.5° to 30°. Forty-one screws violated the pedicle wall, due to erroneous angle of screw insertion. CONCLUSIONS: In the current study, pedicle dimensions were smaller compared to the Western population. In Indian patients, pedicle screws of 5 mm diameter and 30 mm length, and 6 mm diameter and 35 mm length can safely be used in the lower thoracic and lumbar spine, respectively. However, it is important to assess the pedicle morphology on imaging prior to pedicle fixation.

Pedicle screw fixation in thoracolumbar and lumbar spine assisted by lateral fluoroscopic imaging: a study to evaluate the accuracy of screw placement.

BACKGROUND: The purpose of this study was to evaluate the accuracy of pedicle screw placement, its advantages, and limitations in posterior instrumentation of thoracolumbar and lumbar burst fractures assisted only by lateral fluoroscopic imaging. MATERIALS AND METHODS: Pre- and postoperative computerized tomographic (CT) scans of 117 patients with thoracolumbar and lumbar burst fractures, who underwent posterior instrumentation with pedicle screw fixation, were prospectively analyzed. Accuracy of screw placement, reconstruction of the vertebral height, and correction of the kyphotic angle were studied. Position of the pedicle screws were determined, and cortical breach was graded on the postoperative axial CT scans. Percentage of vertebral height reconstruction and kyphotic angle correction were calculated from the postoperative midsagittal CT scans. RESULTS: Four hundred and sixty-eight pedicle screws in 234 motion segments were included in this study. 427 screws were centrally placed with an accuracy rate of 91.24%. Out of the 41 (8.76%) screws that breached the pedicle wall, 32 (6.84%) screws had violated the medial wall, while 9 (1.92%) screws breached the lateral wall. There were no "air-ball" screws. No screw penetrated the anterior wall. Postoperatively, none of the patients deteriorated neurologically, and no screw required revision. Postoperatively, there was significant restoration of vertebral height and correction of kyphosis (P < 0.05). CONCLUSION: Pedicle fixation performed on a Relton-Hall frame is relatively simple and, when performed carefully using only lateral fluoroscopic imaging, has a lower potential for complications due to cortical breach.