Pozorování mechanismů mazání v náhradách kyčelního kloubu

Observation of lubrication mechanisms within artificial hip joints

abstrakt

en

Despite the rapid improvement of hip joint replacements, limited longevity of implants still represents its substantial limitation. Therefore, it is necessary to ensure sufficient service life of replacements to avoid its failure and consequent revising operations. As the main cause leading to implant failure is aseptic loosening due to osteolysis, it is desired to clarify the tribological processes inside the joints. In the present paper, we aimed on the investigation of lubricant film formation between femoral head and transparent acetabular cup from optical glass. The effect of material, geometry and the composition of model synovial fluid was examined, while the experiments were realized using pendulum hip joint simulator (Fig. 1). The contact was lubricated by various model synovial fluids. The applied approach is based on the combination of the two optical methods; optical interferometry and fluorescent microscopy. Utilizing of the fluorescent method enabled to employ also poly(methyl methacrylate) cups; therefore, hard-on-soft bearing pairs could be investigated as well. In terms of material, metal femoral heads formed thicker lubricating film, in general. This fact is attributed to higher hydrophobicity causing that the proteins are rather attracted to the surfaces. Considering the effect of geometry, the fundamental parameter, influencing the film formation, is the size of the diametric clearance. Focusing on the effect of model synovial fluid composition, it is apparent that the content of hyaluronic acid and phospholipids is crucial regarding to lubrication performance. Finally, it should be highlighted that the present study revealed some fundamentals considering also hard-on-soft bearing pairs. As this combination represents most of the currently implanted replacements, it can be concluded that the developed methodology can substantially extend the knowledge about lubrication of artificial hip joints, thus leading to further development in an effort to improve the quality of life of patients.

Despite the rapid improvement of hip joint replacements, limited longevity of implants still represents its substantial limitation. Therefore, it is necessary to ensure sufficient service life of replacements to avoid its failure and consequent revising operations. As the main cause leading to implant failure is aseptic loosening due to osteolysis, it is desired to clarify the tribological processes inside the joints. In the present paper, we aimed on the investigation of lubricant film formation between femoral head and transparent acetabular cup from optical glass. The effect of material, geometry and the composition of model synovial fluid was examined, while the experiments were realized using pendulum hip joint simulator (Fig. 1). The contact was lubricated by various model synovial fluids. The applied approach is based on the combination of the two optical methods; optical interferometry and fluorescent microscopy. Utilizing of the fluorescent method enabled to employ also poly(methyl methacrylate) cups; therefore, hard-on-soft bearing pairs could be investigated as well. In terms of material, metal femoral heads formed thicker lubricating film, in general. This fact is attributed to higher hydrophobicity causing that the proteins are rather attracted to the surfaces. Considering the effect of geometry, the fundamental parameter, influencing the film formation, is the size of the diametric clearance. Focusing on the effect of model synovial fluid composition, it is apparent that the content of hyaluronic acid and phospholipids is crucial regarding to lubrication performance. Finally, it should be highlighted that the present study revealed some fundamentals considering also hard-on-soft bearing pairs. As this combination represents most of the currently implanted replacements, it can be concluded that the developed methodology can substantially extend the knowledge about lubrication of artificial hip joints, thus leading to further development in an effort to improve the quality of life of patients.

Despite the rapid improvement of hip joint replacements, limited longevity of implants still represents its substantial limitation. Therefore, it is necessary to ensure sufficient service life of replacements to avoid its failure and consequent revising operations. As the main cause leading to implant failure is aseptic loosening due to osteolysis, it is desired to clarify the tribological processes inside the joints. In the present paper, we aimed on the investigation of lubricant film formation between femoral head and transparent acetabular cup from optical glass. The effect of material, geometry and the composition of model synovial fluid was examined, while the experiments were realized using pendulum hip joint simulator (Fig. 1). The contact was lubricated by various model synovial fluids. The applied approach is based on the combination of the two optical methods; optical interferometry and fluorescent microscopy. Utilizing of the fluorescent method enabled to employ also poly(methyl methacrylate) cups; therefore, hard-on-soft bearing pairs could be investigated as well. In terms of material, metal femoral heads formed thicker lubricating film, in general. This fact is attributed to higher hydrophobicity causing that the proteins are rather attracted to the surfaces. Considering the effect of geometry, the fundamental parameter, influencing the film formation, is the size of the diametric clearance. Focusing on the effect of model synovial fluid composition, it is apparent that the content of hyaluronic acid and phospholipids is crucial regarding to lubrication performance. Finally, it should be highlighted that the present study revealed some fundamentals considering also hard-on-soft bearing pairs. As this combination represents most of the currently implanted replacements, it can be concluded that the developed methodology can substantially extend the knowledge about lubrication of artificial hip joints, thus leading to further development in an effort to improve the quality of life of patients.

Náhrada kyšelního kloubu; mazání; synoviální kapalina

Hip replacement; lubrication; synovial fluid

17.09.2017

Chinese Tribology Institute (CTI)

Peking

Sixth World Tribology Congress (WTC 2017)

1–4

4