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Journal of Bone and Joint Surgery - British Volume, Vol 89-B, Issue 8,
1115-1121.
doi: 10.1302/0301-620X.89B8.19129 Copyright © 2007 by British Editorial Society of Bone and Joint Surgery Vacuum-mixing cement does not decrease overall porosity in cemented femoral stemsAN IN VITRO LABORATORY INVESTIGATIONK. J. Messick, MD, Orthopaedic Surgeon, Chief Resident1; M. A. Miller, MS, Research Engineer1; L. A. Damron, MS, Research Engineer1; A. Race, PhD, Assistant Professor1; M. T. Clarke, FRCS, Assistant Professor1; and K. A. Mann, PhD, Professor11 SUNY Upstate Medical University, 750 East Adams Street, Syracuse, New York, 13210, USA. Correspondence should be sent to Professor K. A. Mann; e-mail: mannk{at}upstate.edu
The role of vacuum mixing on the reduction of porosity and on the clinical performance of cemented total hip replacements remains uncertain. We have used paired femoral constructs prepared with either hand-mixed or vacuum-mixed cement in a cadaver model which simulated intra-operative conditions during cementing of the femoral component. After the cement had cured, the distribution of its porosity was determined, as was the strength of the cement-stem and cement-bone interfaces. The overall fraction of the pore area was similar for both hand-mixed and vacuum-mixed cement (hand 6%; vacuum 5.7%; paired t-test, p = 0.187). The linear pore fractions at the interfaces were also similar for the two techniques. The pore number-density was much higher for the hand-mixed cement (paired t-test, p = 0.0013). The strength of the cement-stem interface was greater with the hand-mixed cement (paired t-test, p = 0.0005), while the strength of the cement-bone interface was not affected by the conditions of mixing (paired t-test, p = 0.275). The reduction in porosity with vacuum mixing did not affect the porosity of the mantle, but the distribution of the porosity can be affected by the technique of mixing used.
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