Development and analysis of modular uniaxial leg adapter.

The adapters of modular prostheses are the structural components mostly likely to fail during the use of prostheses because of the high forces and moments occurring during the human gait. In this study, structural performance of a modular uniaxial leg adapter during gait is analysed utilizing computer software. By analysing the results, the relevant product was redesigned in order to prevent possible failures. Subsequently, the developed modular uniaxial leg adapter was tested in accordance with ISO 10328 in order to ensure the safety of the design. Further, the test results are compared with a finite element analysis to evaluate the performance of the numerical analysis.

Correlation of right atrial pressure and blood flow velocities in the common femoral vein obtained by duplex Doppler sonography.

PURPOSE: The purpose of this study was to correlate the right atrial pressure with the blood flow velocity and pulsatility index (PI) values obtained with duplex Doppler sonography of the common femoral vein. METHODS: Thirty consecutive patients with suspected right-sided heart failure who had right atrial pressure measurements for correlation were included in the study. The common femoral veins were examined with duplex Doppler sonography. Irrespective of the presence or absence of clinical right-sided heart failure, patients were divided into 2 groups on the basis of their right atrial pressures. The mean flow velocities and PIs in the common femoral veins of the 2 groups were compared. RESULTS: In patients with elevated right atrial pressure (> or = 8 mm Hg), the mean minimum flow velocity + standard deviation (-0.15 +/- 0.11 m/second) in the common femoral vein was significantly lower than that in patients with normal right atrial pressure (< 8 mm Hg) (0.01 +/- 0.10 m/second) (p < 0.001). There was no significant difference in the mean maximum flow velocities in the common femoral vein between the patients with elevated right atrial pressure (0.25 +/- 0.08 m/second) and the patients with normal right atrial pressure (0.21 +/- 0.09 m/second). The mean PI in patients with elevated right atrial pressure (7.75 +/- 3.19) was significantly higher than the mean PI in patients with normal right atrial pressure (1.55 +/- 1.30; p < 0.001). There was a weak negative correlation between the minimum flow velocity and the pressure in the right atrium in patients with elevated right atrial pressure (p = 0.05; r = -0.4760). The amplitude of retrograde waves seen in patients with normal right atrial pressure was significantly smaller than in patients with elevated right atrial pressure (p < 0.05). CONCLUSIONS: The association of a decreased minimum velocity, especially a negative value, and an increase in PI in the common femoral vein may indicate an elevated right atrial pressure. Sonographic assessment of retrograde flow velocity in the common femoral vein may be useful in monitoring the response to medical treatment to decrease atrial pressure.