Abstract
Polymethylmethacrylate (PMMA) Acrylic Bone Cement is a polymer used to anchor the prosthesis during Joint Replacement Surgery. Arthroplasty with Bone Cement is associated with late loosening, compromising prosthetic stability leading to Revision arthroplasty. Different irrigating solutions such as Hydrogen Peroxide or Saline are used during arthroplasty. The aim of the study was to analyse the effects of Hydrogen Peroxide on the mechanical properties of Bone Cement.
Materials and Methods: Cement was mixed as per standard methods used in theatre, in a vacuum and at a temp of 18 degrees centigrade. Once the cement was mixed it was then placed in conical moulds and the exposed surface was either exposed to saline or Hydrogen Peroxide solution (6% from a standard theatre preparation). We studied the effect of Hydrogen Peroxide on Dough time, Curing time, Surface Analysis and Hardness of PMMA. Dough time was performed with latex examination gloves. Curing time was measured at 15 seconds intervals using a Vickers hardness transistor. Cement hardness was assessed using the same machine. Surface analysis was performed by preparing the samples using a grit rotaforce machine. Palacos Bone Cement was used and tests were conducted according to ASTM F-451 and ISO 5833 standards.
Results: The samples exposed to hydrogen peroxide showed an increase in the dough time in comparison to the controls from 3.5 minutes to 5 minutes. Curing time showed a difference of 13.5 minutes for the controls as opposed to 17 minutes for the HP contaminated samples. Surface hardness reduced from a mean of 17.5hv to 14.3hv after exposure to hydrogen peroxide (p< 0.05). There was increased staining of the Hydrogen Peroxide sample, with surface irregularities, and an associated increase in surface porosity. Surface porosity increased from 120um (SD 11.2) to 180um (SD 8.7) (p< 0.05).
Conclusion: We have shown that the use of hydrogen peroxide contamination of bone cement interferes with the biomechanical properties of the cement, leading to an overall reduction in strength and hardness of the cement. This may lead to an associated reduction in the strength of the bone cement interface and precipitate early micro-motion and loosening of the prosthesis.
The abstracts were prepared by Emer Agnew. Correspondence should be addressed to Irish Orthopaedic Association, Secretariat, c/o Cappagh National Orthopaedic Hospital, Finglas, Dublin 11, Ireland.
