To obtain reliable NMR quantitation, experimental cautions concerning data acquisition must be taken when using automatic predictive calculations. For this study, 2000 31P in vitro and in vivo spectra were processed, using the enhancement procedure with linear prediction using singular value decomposition (EPLPSVD) method, and analyzed. The effects of quadrature detection modes (simultaneous or sequential), of the number of time-domain samples used are investigated and experimental conditions such as sample motions and spectral width are discussed.

Algorithms↗

PubMedDate not supplied

An in vitro biomechanical study of bone plate and interlocking nail in a canine diaphyseal femoral fracture model.

OBJECTIVE: To compare the structural properties and the interfragmentary motion in ostectomized canine femurs stabilized with either an 8-mm interlocking nail system (IN) or a 10-hole dynamic compression broad plate (DCP). ANIMAL OR SAMPLE POPULATION: Ten pairs of adult canine femurs with a 25-mm mid-diaphyseal gap. METHODS: Bone specimens were divided into 2 groups (10 femurs each). Left femurs were stabilized with a DCP and 8 bicortical screws; right femurs were stabilized with an IN and 3 screws. Mechanical tests were performed in eccentric axial loading and in craniocaudal bending. The testing was first conducted nondestructively and then until breakage. Structural properties, ie, stiffness, yield limits, and failure limits, were determined. Interfragmentary motion was measured during nondestructive tests with the use of an optoelectronic device. Axial, transverse, and rotational motions were calculated. Mean values of stiffness, yield and failure limits, and axial and shear motions for each fixation method were compared using a paired t test within each group (P <.05). RESULTS: Mean (+/-SD) values of stiffness and failure limit were significantly higher for IN constructs than for DCP constructs in compression, while there was little difference in the results between each tested group in bending. Mean yield load values were significantly higher for IN than for DCP specimens in compression as well as in bending. The axial-motion analysis revealed significant differences between IN and DCP groups during bending tests only. The highest score of transverse motion at the gap was recorded during bending tests, and was higher for DCP than for IN specimens. There were insignificant differences between the two groups with regard to rotation around the diaphyseal axis. CONCLUSIONS AND CLINICAL RELEVANCE: Structural properties and interfragmentary shear motion analysis demonstrated a much higher rigidity in the IN-bone than in the DCP-bone constructs.

Animals↗

PubMedDate not supplied

[Multi-segment ventral stabilization of the lumbar spine: a comparative biomechanical study].

The stability provided by three anterior spinal fixation devices (VDS, TSRH, CDH) designed for multisegmental instrumentation have been studied in an in-vitro model using L1-L5 sections of six human cadaveric spines for each instrumentation. Three-dimensional measurement of rotation and translation for the intact and instrumented spine under physiological loads in flexion/extension, lateral bending, and axial rotation were determined. After measuring the intact spine the destabilization was performed by complete intersection of the intervertebral disc, all spines were instrumented for 3 segments. TSRH was found to be significantly (p < 0.05) higher in stiffness in flexion/extension and torsion than VDS. In bending there was no statistical difference. In all tests CDH was significantly more stable than VDS. In flexion/extension it proved higher in stiffness than TSRH, no statistical difference was observed in bending and rotation.

Biomechanical Phenomena↗

PubMedDate not supplied

Growth of tracheal sutures with absorbable sutures in primates.

Postoperative wound healing is studied after tracheal suturing in 5 primates operated on in two stages. First by double level hemisection comparing continuous and interrupted sutures with polydioxanone. In a second stage: comparison of continuous sutures after tracheal segmental resection. The tracheas were harvested sequentially to study the evolution of the sutured zone by measuring its diameter and by histopathologic examination. The reduction of the tracheal diameter observed was not statistically significant after hemisection using continuous (p = 0.7) or interrupted sutures (p = 0.6). But after tracheal resection the stenosis was significant with continuous sutures (p < 0.05). Histologic study revealed that polydioxanone is well tolerated and is absorbed within 26 weeks. The authors recommend the use of continuous sutures to repair simple wounds and of interrupted sutures after tracheal resection anastomosis.

Animals↗