Pozorování mazacího filmu v umělých kyčelních kloubech

In Situ Observation of Lubricant Film within Artificial Hip Joints

abstrakt

en

The aim of this study is to clarify the interfacial lubrication processes within artificial hip joints. For this purpose, pendulum hip joint simulator in combination with thin film colorimetric interferometry was employed. The experimental device allows to study friction and lubrication of artificial hip joints with respect to real geometry of rubbing surfaces including diameteral clearance. The contact of metal femoral head and glass acetabular cup was observed using an optical test rig, while the chromatic interferograms of contact region were captured via high-speed CMOS camera. The contact was lubricated by 25% bovine serum solution. All the measurements were conducted under body temperature of 37 °C. To investigate the influence of kinematic conditions, two different types of motions were applied. Firstly, the pendulum deflected at an initial offset angle was allowed to oscillate freely in the flexion-extension plane, while the motion was damped naturally. Under these transient conditions the film thickness was stabilized in a few tens of seconds and reached around 90 nm at the end of the experiment. Secondly, active drive was used, therefore the motion was steady state without any damping. In this case, film thickness gradually increased with increasing time.

Cílem této studie je objasnit mazací procesy v umělých kyčelních kloubech. Pro tento účel byl použit kyvadlový simulátor kyčelního kloubu v kombinaci s kolorimetrickou interferometrií tenkých mazacích filmů. Experimentální zařízení umožňuje studium tření a mazání umělých kyčelních kloubů s ohledem na skutečnou geometrii třecích ploch, včetně průměrové vůle. Kontakt kovové kyčelní hlavice a skleněné acetabulární jamky byl pozorován optickou soustavou. Pomocí vysokorychlostní CMOS kamery byli tak získány chromatické interferogramy. Kontakt byl mazán 25% roztokem hovězího séra. Všechna měření byla provedena za tělesné teploty 37 °C. Pro vyšetření vlivu kinematických podmínek, byly použity dva různé typy pohybů. Za prvé, kyvadlo bylo vychýleno o počáteční úhel a ponecháno volně dokmitat v rovině flexe-extenze. Za těchto proměnných podmínek byla tloušťka filmu stabilizována během několika desítek sekund a dosáhl asi 90 nm na konci experimentu. Za druhé, byl použit aktivní pohon, pohyb byl tedy v ustáleném stavu bez tlumení. V tomto případě se tloušťka filmu postupně zvyšovala s přibývajícím časem.

The aim of this study is to clarify the interfacial lubrication processes within artificial hip joints. For this purpose, pendulum hip joint simulator in combination with thin film colorimetric interferometry was employed. The experimental device allows to study friction and lubrication of artificial hip joints with respect to real geometry of rubbing surfaces including diameteral clearance. The contact of metal femoral head and glass acetabular cup was observed using an optical test rig, while the chromatic interferograms of contact region were captured via high-speed CMOS camera. The contact was lubricated by 25% bovine serum solution. All the measurements were conducted under body temperature of 37 °C. To investigate the influence of kinematic conditions, two different types of motions were applied. Firstly, the pendulum deflected at an initial offset angle was allowed to oscillate freely in the flexion-extension plane, while the motion was damped naturally. Under these transient conditions the film thickness was stabilized in a few tens of seconds and reached around 90 nm at the end of the experiment. Secondly, active drive was used, therefore the motion was steady state without any damping. In this case, film thickness gradually increased with increasing time.

biotribology, total hip replacement, conformal surfaces, protein aggregation, colorimetric interferometry, film thickness

16.09.2015

Japanese Society of Tribologists

Tokyo

860–861

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