Electronic Letters to:

Research: K. J. Messick, M. A. Miller, L. A. Damron, A. Race, M. T. Clarke, and K. A. Mann Vacuum-mixing cement does not decrease overall porosity in cemented femoral stems: AN IN VITRO LABORATORY INVESTIGATION J Bone Joint Surg Br 2007; 89-B: 1115-1121 [Abstract] [Full text] [PDF]

eLetters: Submit a response to this article

Electronic letters published:

Author's reply:

Kenneth A Mann   (31 October 2007)

Cement mantle optimisation

William M. Murray   (18 October 2007)

Author's reply: 31 October 2007
Kenneth A Mann, Research Professor SUNY Upstate Medical University Send letter to journal: Re: Author's reply: mannk{at}upstate.edu Kenneth A Mann	Sir, We thank Dr Murray for his interest in our work. The stem and cement were maintained at room temperature (21°) prior to cementing. To the best of our knowledge, most surgeons use room temperature stems for cemented hip replacement, so we believe the comparison is valid. Contrary to the statement in your letter, we did not find increased porosity in the cement mantle when vacuum-mixing was used. Rather, the distribution of porosity was different for the hand- and vacuum-mixed cements. Repeating the same study with different thermal boundary conditions, such as a warmed stem or cooled bone would be interesting. As described in the discussion section of the manuscript, this may reduce porosity at the stem/cement interface but would be likely to do so for both the hand-mixed and vacuum-mixed conditions. K.A. Mann, Research Professor, SUNY Upstate Medical University, New York, USA.
Cement mantle optimisation 18 October 2007
William M. Murray, orthopaedic surgeon Harrisburg Hospital, Hbg. PA USA Send letter to journal: Re: Cement mantle optimisation murrayw{at}paonline.com William M. Murray	Sir, In the paper by Messick, Miller, et al, data are presented showing increased porosity in cement mantles of femoral stems, particularly at the stem-cement junction, when vacuum-mixed cement is employed. The temperature of stems when inserted is not provided. Presumably the stems were at room temperature, and thus colder than the bony canal. As acknowledged in their paper, there is published data1,2 showing that stem-cement interface porosity is very much lower when using vacuum-mixed cement if the temperature of the inserted stem is equal to, or higher than, that of the surface of the bony canal. A more useful comparison of the results of hand-mixing versus vacuum-mixing would be one using temperature parameters shown to enhance, rather than degrade, mantle quality with vacuum mixing. W.M. Murray, MD, Orthopaedic Surgeon, Harrisburg Hospital, Harrisburg, PA, USA. 1. Iesaka K, Jaffe WL, Jones CM, Kummer FJ. The effects of fluid penetration and interfacial porosity on the fixation of cemented femoral components. J Bone Joint Surg [Br] 2005;87-B:1298-1302. 2. Hsieh PH, Tai CL, Chang YH, et al. Precooling of the femoral canal enhances shear strength at the cement-prosthesis interface and reduces the polymerization temperature. J Orthop Res 2006;24:1809-14.