Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement
<br/><strong>Objectives: </strong>The aim of this study was to determine the polyethylene wear rate of Phase 3 Oxford Unicompartmental Knee Replacement bearings and to investigate the effects of resin type and manufacturing process.<br/><strong>Methods: </strong>A...
| Main Authors: | , , , , , |
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| Format: | Journal article |
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British Editorial Society of Bone and Joint Surgery
2019
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| _version_ | 1797050999018356736 |
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| author | Mohammad, H Campi, S Kennedy, J Judge, A Murray, D Mellon, S |
| author_facet | Mohammad, H Campi, S Kennedy, J Judge, A Murray, D Mellon, S |
| author_sort | Mohammad, H |
| collection | OXFORD |
| description | <br/><strong>Objectives: </strong>The aim of this study was to determine the polyethylene wear rate of Phase 3 Oxford Unicompartmental Knee Replacement bearings and to investigate the effects of resin type and manufacturing process.<br/><strong>Methods: </strong>A total of 63 patients with at least ten years’ follow-up with three bearing types (1900 resin machined, 1050 resin machined, and 1050 resin moulded) were recruited. Patients underwent full weight-bearing model-based radiostereometric analysis to determine the bearing thickness. The linear wear rate was estimated from the change in thickness divided by the duration of implantation.<br/><strong>Results: </strong>The wear rate for 1900 resin machined (n = 19), 1050 machined (n = 21), and 1050 moulded bearings (n = 23) were 60 µm/year (sd 42), 76 µm/year (sd 32), and 57 µm/year (sd 30), respectively. There was no significant difference between 1900 machined and 1050 machined (p = 0.20), but 1050 moulded had significantly less wear than the 1050 machined (p = 0.05). Increasing femoral (p < 0.001) and tibial (p < 0.001) component size were associated with increasing wear.<br/><strong>Conclusion: </strong>Wear rate is similar with 1050 and 1900 resin, but lower with moulded bearings than machined bearings. The currently used Phase 3 bearings wear rate is low (1050 moulded, 57 µm/year), but higher than the previously reported Phase 2 bearings (1900 moulded, 20 µm/year). This is unlikely to be due to the change in polyethylene but may relate to the minimally invasive approach used with the Phase 3. This approach, as well as improving function and thus increasing activity levels, may increase the risk of surgical errors, such as impingement or bearing overhang, which can increase wear. Surgeons should aim to use 4 mm thick bearings rather than 3 mm thick bearings in young patients, unless they are small and need conservative bone resections. |
| first_indexed | 2024-03-06T18:13:32Z |
| format | Journal article |
| id | oxford-uuid:03d54ec3-e5a3-4f29-b0cc-53cdb1931214 |
| institution | University of Oxford |
| last_indexed | 2024-03-06T18:13:32Z |
| publishDate | 2019 |
| publisher | British Editorial Society of Bone and Joint Surgery |
| record_format | dspace |
| spelling | oxford-uuid:03d54ec3-e5a3-4f29-b0cc-53cdb19312142022-03-26T08:48:28ZLong term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee ReplacementJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:03d54ec3-e5a3-4f29-b0cc-53cdb1931214Symplectic Elements at OxfordBritish Editorial Society of Bone and Joint Surgery2019Mohammad, HCampi, SKennedy, JJudge, AMurray, DMellon, S<br/><strong>Objectives: </strong>The aim of this study was to determine the polyethylene wear rate of Phase 3 Oxford Unicompartmental Knee Replacement bearings and to investigate the effects of resin type and manufacturing process.<br/><strong>Methods: </strong>A total of 63 patients with at least ten years’ follow-up with three bearing types (1900 resin machined, 1050 resin machined, and 1050 resin moulded) were recruited. Patients underwent full weight-bearing model-based radiostereometric analysis to determine the bearing thickness. The linear wear rate was estimated from the change in thickness divided by the duration of implantation.<br/><strong>Results: </strong>The wear rate for 1900 resin machined (n = 19), 1050 machined (n = 21), and 1050 moulded bearings (n = 23) were 60 µm/year (sd 42), 76 µm/year (sd 32), and 57 µm/year (sd 30), respectively. There was no significant difference between 1900 machined and 1050 machined (p = 0.20), but 1050 moulded had significantly less wear than the 1050 machined (p = 0.05). Increasing femoral (p < 0.001) and tibial (p < 0.001) component size were associated with increasing wear.<br/><strong>Conclusion: </strong>Wear rate is similar with 1050 and 1900 resin, but lower with moulded bearings than machined bearings. The currently used Phase 3 bearings wear rate is low (1050 moulded, 57 µm/year), but higher than the previously reported Phase 2 bearings (1900 moulded, 20 µm/year). This is unlikely to be due to the change in polyethylene but may relate to the minimally invasive approach used with the Phase 3. This approach, as well as improving function and thus increasing activity levels, may increase the risk of surgical errors, such as impingement or bearing overhang, which can increase wear. Surgeons should aim to use 4 mm thick bearings rather than 3 mm thick bearings in young patients, unless they are small and need conservative bone resections. |
| spellingShingle | Mohammad, H Campi, S Kennedy, J Judge, A Murray, D Mellon, S Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement |
| title | Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement |
| title_full | Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement |
| title_fullStr | Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement |
| title_full_unstemmed | Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement |
| title_short | Long term in vivo wear of different bearing types used for the Oxford Unicompartmental Knee Replacement |
| title_sort | long term in vivo wear of different bearing types used for the oxford unicompartmental knee replacement |
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