Development of total hip arthroplasty (THA) now spans more than 5 decades encompassing combinations of metal-on-metal (MOM), ceramic-on-metal (COM), metal-on-plastic (MOP), ceramic-on-plastic (COM), and ceramic-on-cer...Development of total hip arthroplasty (THA) now spans more than 5 decades encompassing combinations of metal-on-metal (MOM), ceramic-on-metal (COM), metal-on-plastic (MOP), ceramic-on-plastic (COM), and ceramic-on-ceramic (COC). In every arena of extensive technical development, there exists a data set that when viewed in isolation seemed of little import, but when assembled in-toto may produce a generational shift in perception. Our review focused on two such THA events. Firstly, COC retrieval studies (1999-2001) noted habitual wear patterns on heads and peripheral wear stripes, along with femoral-neck impingement, and ceramic surfaces stained gray by metal debris. These COC<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">data indicated THA risks included, </span><span style="font-family:Verdana;">1</span><span style="font-family:Verdana;">) cup edge-loading (E/L) on heads producing </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">stripe wear</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 2</span><span style="font-family:Verdana;">) component impingement releasing metal particles resulting in </span><span style="font-family:Verdana;">3</span><span style="font-family:Verdana;">) tissues contaminated by metal debris. A corresponding MOM impingement-debris mechanism was only perceived by Howie (2005) in a McKee-Farrar retrieval study. Our anticipation at LLUMC was that MOM retrievals would provide superior wear details to those seen on COC retrievals. We noted stripe wear in the polar zone of CoCr heads and basal stripes in the non-wear areas. The basal-polar stripe combinations were </span><span style="font-family:Verdana;">found in all MOM retrievals. Basal-polar stripe combinations followed cup-rim</span><span style="font-family:Verdana;"> profiles in our LLUMC simulations of prosthetic impingement. LPUH videos demonstrated the formation of stripe wear in functional-standing and functional-sitting postures for both impingement and subluxation episodes using THA and RA designs. The stripes on CoCr heads revealed the large scratches we now term </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">microgrooves</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;">. Microgroove width varied from 40</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">400</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">um with 100</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">um being typical. The longitudinal striations in microgrooves, the raised jagged lips, scratches with shallow entry and exit termini, were</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">all indicative of a classic 3</span><sup><span style="vertical-align:super;font-family:Verdana;">rd</span></sup><span style="font-family:Verdana;">-body wear mechanism. The THA</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">impingement simulations denoted four sites of edge-loading, </span><i><span style="font-family:Verdana;">i.e.</span></i><i><span style="font-family:Verdana;"> </span></i><span style="font-family:Verdana;">neck-E/L, inferior cup-E/L, superior cup-E/l and head-E/L, and ingress of Ti64 particles as a contaminating-roughness effect. Individual MOM cases referred to LLUMC demonstrated dramatic evidence of neck notching. At one end of the debris spectrum, a Ti64-notch model predicting a 6</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">mm</span><sup><span style="vertical-align:super;font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> annual wear-rate represented the release of 5700 particles of 126</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">um-size (approximating daily release of 16 particles). At the other end of the spectrum, if metal particles were crushed between MOM surfaces to the equivalent nanometer size found in tissues, our notch model represented approximately 22-trillion Ti64 particles annually deposited in tissues. The anatomical THA models represented in LPUH videos demonstrated that even 1-degree of head subluxation from a rigid cup created a cup </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">lift-off</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;"> scenario (CLO) that would open a gap of 250</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">400 microns between femoral head and cup. This would void all lubrication potential and focus the total hip-joint force along the beveled cup rim</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> stripe wear. It is therefore interesting that MOM impingement/debris predictions by Howie </span><i><span style="font-family:Verdana;">et al</span></i><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> not been confirmed until now or discussed in contemporary literature. Therefore, this review of 50</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">years of THA data demonstrated that hip impingement was always the trigger for adverse wear and that metal-backed cups represent the potential for release of metal debris at extremes of functional standing and sitting postures.</span>展开更多
Dialkyldithiocarbamate (R<sub>2</sub>NCS<sup>-</sup><sub>2</sub>) acting as either bridging or terminal ligand plays an important role in modern coordination chemistry. The molecu...Dialkyldithiocarbamate (R<sub>2</sub>NCS<sup>-</sup><sub>2</sub>) acting as either bridging or terminal ligand plays an important role in modern coordination chemistry. The molecules of the univalent coinage metals (Cu, Ag, and Au) with dialkyldithiocarbamate ligands form a class of compounds in which the sterical restriction influences strongly the crystal structures, and several types of polymerizates were found. However, only a few structures in linear form展开更多
文摘Development of total hip arthroplasty (THA) now spans more than 5 decades encompassing combinations of metal-on-metal (MOM), ceramic-on-metal (COM), metal-on-plastic (MOP), ceramic-on-plastic (COM), and ceramic-on-ceramic (COC). In every arena of extensive technical development, there exists a data set that when viewed in isolation seemed of little import, but when assembled in-toto may produce a generational shift in perception. Our review focused on two such THA events. Firstly, COC retrieval studies (1999-2001) noted habitual wear patterns on heads and peripheral wear stripes, along with femoral-neck impingement, and ceramic surfaces stained gray by metal debris. These COC<span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">data indicated THA risks included, </span><span style="font-family:Verdana;">1</span><span style="font-family:Verdana;">) cup edge-loading (E/L) on heads producing </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">stripe wear</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> 2</span><span style="font-family:Verdana;">) component impingement releasing metal particles resulting in </span><span style="font-family:Verdana;">3</span><span style="font-family:Verdana;">) tissues contaminated by metal debris. A corresponding MOM impingement-debris mechanism was only perceived by Howie (2005) in a McKee-Farrar retrieval study. Our anticipation at LLUMC was that MOM retrievals would provide superior wear details to those seen on COC retrievals. We noted stripe wear in the polar zone of CoCr heads and basal stripes in the non-wear areas. The basal-polar stripe combinations were </span><span style="font-family:Verdana;">found in all MOM retrievals. Basal-polar stripe combinations followed cup-rim</span><span style="font-family:Verdana;"> profiles in our LLUMC simulations of prosthetic impingement. LPUH videos demonstrated the formation of stripe wear in functional-standing and functional-sitting postures for both impingement and subluxation episodes using THA and RA designs. The stripes on CoCr heads revealed the large scratches we now term </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">microgrooves</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;">. Microgroove width varied from 40</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">400</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">um with 100</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">um being typical. The longitudinal striations in microgrooves, the raised jagged lips, scratches with shallow entry and exit termini, were</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">all indicative of a classic 3</span><sup><span style="vertical-align:super;font-family:Verdana;">rd</span></sup><span style="font-family:Verdana;">-body wear mechanism. The THA</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">impingement simulations denoted four sites of edge-loading, </span><i><span style="font-family:Verdana;">i.e.</span></i><i><span style="font-family:Verdana;"> </span></i><span style="font-family:Verdana;">neck-E/L, inferior cup-E/L, superior cup-E/l and head-E/L, and ingress of Ti64 particles as a contaminating-roughness effect. Individual MOM cases referred to LLUMC demonstrated dramatic evidence of neck notching. At one end of the debris spectrum, a Ti64-notch model predicting a 6</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">mm</span><sup><span style="vertical-align:super;font-family:Verdana;">3</span></sup><span style="font-family:Verdana;"> annual wear-rate represented the release of 5700 particles of 126</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">um-size (approximating daily release of 16 particles). At the other end of the spectrum, if metal particles were crushed between MOM surfaces to the equivalent nanometer size found in tissues, our notch model represented approximately 22-trillion Ti64 particles annually deposited in tissues. The anatomical THA models represented in LPUH videos demonstrated that even 1-degree of head subluxation from a rigid cup created a cup </span><span style="font-family:Verdana;">“</span><span style="font-family:Verdana;">lift-off</span><span style="font-family:Verdana;">”</span><span style="font-family:Verdana;"> scenario (CLO) that would open a gap of 250</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">-</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">400 microns between femoral head and cup. This would void all lubrication potential and focus the total hip-joint force along the beveled cup rim</span><span style="font-family:Verdana;">,</span><span style="font-family:Verdana;"> </span><i><span style="font-family:Verdana;">i.e.</span></i><span style="font-family:Verdana;"> stripe wear. It is therefore interesting that MOM impingement/debris predictions by Howie </span><i><span style="font-family:Verdana;">et al</span></i><span style="font-family:Verdana;">.</span><span style="font-family:Verdana;"> ha</span><span style="font-family:Verdana;">ve</span><span style="font-family:Verdana;"> not been confirmed until now or discussed in contemporary literature. Therefore, this review of 50</span><span style="font-family:Verdana;"> </span><span style="font-family:Verdana;">years of THA data demonstrated that hip impingement was always the trigger for adverse wear and that metal-backed cups represent the potential for release of metal debris at extremes of functional standing and sitting postures.</span>
基金Project supported by the National Natural Science Foundation of China.
文摘Dialkyldithiocarbamate (R<sub>2</sub>NCS<sup>-</sup><sub>2</sub>) acting as either bridging or terminal ligand plays an important role in modern coordination chemistry. The molecules of the univalent coinage metals (Cu, Ag, and Au) with dialkyldithiocarbamate ligands form a class of compounds in which the sterical restriction influences strongly the crystal structures, and several types of polymerizates were found. However, only a few structures in linear form