Assessment of stability during gait in patients with spinal deformity-A preliminary analysis using the dynamic stability margin.

Daily living activities are dynamic, requiring spinal motion through space. Current assessment of spinal deformities is based on static measurements from full-spine standing radiographs. Tools to assess dynamic stability during gait might be useful to enhance the standard evaluation. The aim of this study was to evaluate gait dynamic imbalance in patients with spinal deformity using the dynamic stability margin (DSM). Twelve normal subjects and 17 patients with spinal deformity were prospectively recruited. A kinematic 3D gait analysis was performed for the control group (CG) and the spinal deformity group (SDG). The DSM (distance between the extrapolated center of mass and the base of support) and time-distance parameters were calculated for the right and left side during gait. The relationship between DSM and step length was assessed using three variables: gait stability, symmetry, and consistency. Variables' accuracy was validated by a discriminant analysis. Patients with spinal deformity exhibited gait instability according to the DSM (0.25m versus 0.31m) with decreased velocity (1.1ms-1 versus 1.3ms-1) and decreased step length (0.32m versus 0.38m). According to the discriminant analysis, gait stability was the more accurate variable (area under the curve AUC=0.98) followed by gait symmetry and consistency. However, gait consistency showed 100% of specificity, sensitivity, and accuracy of precision. The DSM showed that patients with spinal malalignment exhibit decreased gait stability, symmetry, and consistency besides gait time-distance parameter changes. Additional work is required to determine how to apply the DSM for preoperative and postoperative spinal deformity management.

Video-assisted functional assessment of index pollicisation in congenital anomalies.

PURPOSE: Functional results of index pollicisation are usually assessed by the clinical score of Percival. This score is based on elementary hand movements and does not reflect the function of the neo thumb in daily life activities. The aim of this study was to develop a new video-assisted scoring system based on daily life activities to assess index pollicisation functional outcomes. METHODS: Twenty-two consecutive children, operated between 1998 and 2012, were examined with a mean of 77 months after surgery. The mean age at surgery was 34 months. Post-operative results were evaluated by a new video-assisted 14-point scoring system consisting of seven basic tasks that are frequently used in daily activities. The series of tasks was performed both on the request of the examiner and in real-life conditions with the use of a hidden camera. Each video recording was examined by three different examiners. Each examiner rated the video recordings three times, with an interval of one week between examinations. Inter- and intra-observer agreements were calculated. RESULTS: Inter- and intra-observer agreements were excellent both on request (κ = 0.87 [0.84-0.97] for inter-observer agreement and 0.92 [0.82-0.98] for intra-observer agreement) and on hidden camera (κ = 0.83 [0.78-0.91] for inter-observer agreement and 0.89 [0.83-0.96] for intra-observer agreement). The results were significantly better on request than on hidden camera (p = 0.045). The correlation between the video-assisted scoring system and the Percival score was poor. CONCLUSION: The video-assisted scoring system is a reliable tool to assess index pollicisation functional outcomes. The scoring system on hidden camera is more representative of the neo thumb use in daily life complex movements. LEVEL OF EVIDENCE: Level IV.

Action-FRET: probing the molecular conformation of mass-selected gas-phase peptides with Förster resonance energy transfer detected by acceptor-specific fragmentation.

The use of Förster resonance energy transfer (FRET) as a probe of the structure of biological molecules through fluorescence measurements in solution is well-attested. The transposition of this technique to the gas phase is appealing since it opens the perspective of combining the structural accuracy of FRET with the specificity and selectivity of mass spectrometry (MS). Here, we report FRET results on gas-phase polyalanine ions obtained by measuring FRET efficiency through specific photofragmentation rather than fluorescence. The structural sensitivity of the method was tested using commercially available chromophores (QSY 7 and carboxyrhodamine 575) grafted on a series of small, alanine-based peptides of differing sizes. The photofragmentation of these systems was investigated through action spectroscopy, and their conformations were probed using ion mobility spectrometry (IMS) and Monte Carlo minimization (MCM) simulations. We show that specific excitation of the donor chromophore results in the observation of fragments that are specific to the electronic excitation of the acceptor chromophore. This shows that energy transfer took place between the two chromophores and hence that the action-FRET technique can be used as a new and sensitive probe of the structure of gas-phase biomolecules, which opens perspectives as a new tool in structural biology.