Biomedical subjects

S Kourosh

Publications and source records attributed to S Kourosh.

4 recordsLinked to original sources

PubMed1992

Fibrillar collagen-biphasic calcium phosphate composite as a bone graft substitute for spinal fusion.

The osteoconductive capacity of fibrillar collagen-biphasic calcium phosphate composition was compared to autogenous bone in a canine spinal fusion model. All animals underwent a standard intervertebral body fusion (L2-L4) with rigid internal fixation and received either autogenous bone alone or a mixture of the ceramic and autogenous bone (3:1) as the graft material. Animals were followed for 12 months and the quality of fusion in each animal assessed by biomechanical testing and histological analysis. The fused L2-L4 segment of each dog was embedded in bone cement and mounted in a specially designed mechanical tester for testing in flexion, extension, and side bending. Overall, the mean rigidity of the fusion mass was not significantly different between the two groups [10.5 +/- 4.1 (SD) for autogenous bone vs. 11.3 +/- 1.7 for the ceramic plus autogenous bone, p greater than 0.05]. Similar findings were obtained for mean bending moment, compressive load, angular deformation, and energy absorbed for the two groups. Histological analysis was performed on transverse nondecalcified specimens. Quantitation of bone ingrowth using back-scattered electron imaging disclosed no significant differences in the amount of new bone formed at the graft site between autogenous bone and the ceramic plus autogenous bone recipients (23.4 +/- 10% vs. 25.8 +/- 8.8%) when correction for the autogenous bone volumes was performed. Light microscopic analysis of toluidine blue-stained transverse sections demonstrated new bone growth around and through the ceramic bone graft material. These results suggest that use of a collagen-biphasic calcium phosphate ceramic and autogenous bone mixture (3:1) provides a suitable osteoconductive alternative to the use of autogenous bone and results in the formation of a mechanically competent fusion mass not significantly different from that obtained with autogenous bone alone.

Animals↗

PubMed1989

The functional anatomy of tensor fasciae latae and gluteus medius and minimus.

The more accurate description of the anatomy of the glutei and the new biomechanical theory that has been presented describe the abductor mechanism as a system in which the tensor fasciae latae has the primary function of balancing the weight of the body and the non-weight-bearing leg during walking. Gluteus medius with its three parts and phasic functions is responsible for the stabilisation of the hip joint in the initial phase of the gait cycle. It is important also in initiating the major gait determinant of pelvic rotation. Gluteus minimus functions as a primary hip stabiliser during the mid- and late phase of the gait cycle.

Biomechanical Phenomena↗

PubMed1988

Objective evaluation of insert material for diabetic and athletic footwear.

Five of the most commonly used materials for shoe inserts (soft Plastazote, medium Pelite, PPT, Spenco, and Sorbothane) were objectively evaluated in the laboratory to characterize their behavior in the following three specific functions that correspond to clinical use: (1) the effect on the materials of repeated compression. (2) the effect of a combination of repetitive shear and compression. (3) the force-distribution (force-attenuation) properties of these materials, both when new and after repeated compression. The last function represents a model for relief of pressure beneath plantar bony prominences, a topic of special concern for the insensitive foot. All materials were effective in reducing transmitted force over the simulated bony prominence with a rank order of effectiveness. Other factors considered were: amount and rate of permanent deformation offset by considerations of enhanced moldability when comparing the neoprene and urethane materials with the polyethylene foams. The ideal insert represents a combination of material to achieve both durability and moldability.

Foot Diseases↗

PubMed1984

A unidirectional temperature gradient stage for solidification studies in aqueous solutions.

A low temperature light microscope stage has been designed and fabricated for quantitative analysis of the solidification of aqueous solutions. Thermal boundary conditions are controlled during freezing so as to enable direct comparison of data with complementary theoretical models. Evolution of the temperature distribution within the system is monitored by a one-dimensional thermocouple array, and growth of the phase interface is measured via a displacement transducer. The two-dimensional solution concentration field is assessed by computer densitometric analysis of the grey scale distribution for a light absorbing solute. Experimental and theoretical analyses of freezing processes with the stage correlate well, and the data base is shown to be internally consistent by independent thermal and mechanical measures of the interface velocity.

Computers↗