ABSTRACT
BACKGROUND: Ultra-high molecular weight polyethylene (UHMWPE) is widely used as acetabulum. The hip joint will produce lots of grind particles and lead to loosening of artificial joint because of alternating load and bad lubricate condition.OBJECTIVE: To learn about the lubricate mechanism of joint, introduce the present situation on artificial hip joint of UHMWPE including wear behavior and wear resistance properties, and grope for scientific evaluate method of tribological properties in artificial joints.RETRIEVAL STRATEGY: The articles published between January 2000 and October 2007 were searched by using computer with the key terms "hip joint, ultra-high molecular weight polyethylene, tribology" in CNKI, Weipu Science and Technology Database, Wanfang Database, and its language was limited to Chinese. Meanwhile, the English articles were searched in IEEE/IEE Electronic Library and Elsevier Electronic Journal Database with the key terms "hip simulators, ultra-high molecular weight polyethylene, tribology ". Those referring to the friction and wear property of the joints were included, whereas repeated researches were deleted.LITERATURE EVALUATION: Totally 729 articles were received. After the primary screening of the titles and abstracts, 601 repeated or similar researches were excluded, and other 128 articles were adopted for further analysis, finally 22 articles in accordance with the inclusion criteria were included as references.DATA SYNTHESIS: The study about UHMWPE focused two points, one is surface modification, the other is wear and friction mechanism.①The study indicates that wear properties of UHMWPE can be improved by surface modification, such as ion implantation and nanometer padding have a remarkable elevating ability of the wear and mechanical properties.②At recent years, scholars do many basal experiences about the tribology of hip joints, and have approved that wear rate of friction pairs would reduce under biological lubricate condition using artificial joint simulators or traditional tester in various conditions.CONCLUSION: The study about hip joint in China drops behind the developed counties, this traditional method can not really reflect wear and friction properties in vivo. Therefore, the following research should include making clear the relationships of load, environmental condition and wear of artificial joint in vivo, as well as groping for a scientific evaluate method of tribological properties in hip joints.
ABSTRACT
Objective To investigate the relationship between transient ischemic attack(TIA) and intracranial or extracranial artery stenosis.Methods Digital subtraction angiography (DSA) was further used in 56 cases with cerebral artery stenosis from 68 TIA patients after examinations of B ultrasound of neck, transcranial color doppler(TCD) and cardiac ultrasound. Results 6 cases were shown stenosis or occlusion in middle cerebral arteries(MCA), 21 cases were shown stenosis or occlusion in arteria carotis interna,8 cases were shown stenosis in subclavian arteries and 28 cases were shown stenosis or occlusion in vertebral arteries or basal arteries. 44 cases with TIA were related to stenosis of large arteties, 16 cases of which were intracarotid TIA, and 28 cases were vertebrobasilar TIA; 18 cases were embotic TIA, 15 cases of which were intracarotid TIA, and 3 cases were vertebrobasilar TIA. 4 casea were lacunar TIA; and 2 cases were related to vascular spasm. Conclusions Most patients with TIA have cerebral artery stenosis.There is a positive correlation between TIA and intracranial or extracranial artery stenosis.