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Promising results seen with cementless unicompartmental knee replacement
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Cementless unicompartmental knee replacement provides better fixation and is associated with less radiolucency than cemented unicompartmental knee replacement according to a presentation at a recent meeting.
“Compared to cemented, cementless UKR [unicompartmental knee replacement] provides better functional outcome, better fixation and a similar level of complications,” David W. Murray, MD, FRCS, of Nuffield Orthopaedic Center in Oxford England, said.
Murray noted UKRs have many advantages over total knee replacements: They provide better function and satisfaction, and are associated with a more rapid recovery and less morbidity and mortality. They do, however, have a higher revision rate. If this could be addressed then UKR would be much more widely used. Murray noted that loosening, pain associated with radiolucent lines and cementing errors were common causes of revision of cemented UKR. Cementless UKR could probably address these issues, he added.
In his presentation, Murray described studies that were undertaken to assess the cementless Oxford UKR (Biomet; Warsaw, Ind., USA). In a randomized study, involving 43 patients, the migration of cemented and cementless UKR components were compared using radiostereometric analysis. During the second year, there was no significant difference in the amount of migration between the two designs, suggesting the fixation of the cementless is at least as good as the cemented.
A randomized study of 62 patients compared the clinical outcome of the cemented and cementless procedures. At 5 years, the Knee Society function score was significantly better in the cementless group. There were radiolucent lines under the tibial components, but all were 1 mm thick or less. The incidence of radiolucency was significantly lower in the cementless group (0% complete; 7% partial) than the cemented group (25% complete; 36% partial). To assess the complications and contraindications for cementless Oxford UKR a multicenter cohort study of 1,000 cases was undertaken. With a minimum follow-up of 1 year, there were 19 reoperations. If each reoperation is considered to be a failure, then the survival at 8 years was 97%. There were no complete radiolucencies and 7% had partial tibial radiolucent lines.
“These studies suggest the cementless components have better fixation than cemented and that the indications for the cementless are the same as the cemented,” Murray said.
The National Joint Registry of England and Wales and the National Registry of New Zealand report similar survival rates for the Oxford knee. In both registers, the 5-year survival of the cemented Oxford was 93%, whereas the 5-year survival of the cementless Oxford was 97% and 98%, respectively. These results suggest that the revision rate of the cementless Oxford is less than half that of the cemented. However some of the difference may be explained by the fact that most cementless components tend to be implanted by experienced surgeons and that this may not be the case for cemented components, Murray noted. – by Renee Blisard Buddle
- References:
- Murray DW. Paper #80. Presented at: Current Concepts in Joint Replacement Winter Meeting; Dec. 12-14, 2013; Orlando, Fla.
- Liddle AD. Bone Joint J. 2013;doi: 10.1302/0301-620X.95B2.30411.
- Pandit H. J Bone Joint Surg Am. 2013;doi: 10.2106/JBJS.L.01005.
- For more information:
- David W. Murray, MD, FRCSC, can be reached at Nuffield Orthopaedic Centre, University of Oxford, Oxford, OX3 7LD, United Kingdom; email: david.murray@ndorms.ox.ac.uk.
Disclosure: Murray receives consulting fees and royalties from Biomet Orthopedics.