RESUMO
BACKGROUND: Quantitative bone re-modelling theories suggest that bones adapt to mechanical loading conditions. Follow-up studies have shown that total disc replacement (TDR) modifies stress patterns in the bones, leading to heterotopic ossification (HO). Although there are a few studies on HO using finite element models (FEM), its effect on the adjacent levels and change in range of motion (ROM) have not been adequately investigated. This study interfaces the HO using bone re-modelling algorithm with a finite element solution and investigates the subsequent changes in segmental ROM. METHODS: A FEM of the human cervical spine (C3-C7) was developed for this study, with material properties obtained from literature. The motion of the segments in the sagittal, frontal and transverse planes under combined loading conditions of 1 Nm moment and 73.6 N compression were validated against experimental corridors. The natural disc between the C5-C6 segment was replaced with the Bryan artificial cervical disc, and changes in sagittal ROM were compared before and after HO. The process of HO was simulated using a bone remodelling algorithm using strain energy density (SED) as the mechanical stimuli. RESULTS AND CONCLUSION: Our study demonstrates the feasibility of using SED calculations from the flexion-extension loading conditions for prediction of HO after ADR. The current findings suggest that the nature of trabecular stresses, and the subsequent rate and location of HO formation could differ based on the geometric design and nature of constraint for different artificial discs. The Bryan disc significantly reduced ROM at the implanted level in flexion. However, in extension, ROM increased at the implanted level and decreased slightly at the adjacent levels. After HO, ROM drastically reduced at the implanted level in both extension and flexion, and showed a minor increase in the adjacent levels, indicating that biomechanical behavior of high-grade HO is similar to a fused segment, thereby reducing the intended and initial motion preservation.
RESUMO
Hot water epilepsy (HWE) is a form of reflex or sensory epilepsy wherein seizures are precipitated by an unusual stimulus, the contact of hot water over the head and body. Genome-wide linkage analysis of a large family with ten affected members, provided evidence of linkage (Z (max) = 3.17 at theta = 0 for D10S412) to chromosome 10q21. Analysis of five additional HWE families, for markers on chromosome 10, further strengthened the evidence of linkage to the same chromosomal region with three out of five families showing concordance for the disease haplotype and providing a two-point LOD score of 4.86 at theta = 0 and 60% penetrance for D10S412. The centromere-proximal and -distal boundaries of the critical genetic interval of about 15 Mb at 10q21.3-q22.3 were defined by D10S581 and D10S201, respectively. Sequence analysis of a group of functional candidate genes, the ion channels KCNMA1, VDAC2 and solute carriers SLC25A16, SLC29A3 revealed no potentially pathogenic mutation. We propose to carry out further analysis of positional candidate genes from this region to identify the gene responsible for this unusual neurobehavioral phenotype.