The mechanical properties of recovered PMMA bone cement: a preliminary study. 
Samples of polymethylmethacrylate (PMMA) bone cement, used in the fixation of hip prostheses, have been recovered from 11 patients after in service life spans of between 15 and 24 years.  Eighteen samples in total have been recovered from the acetabular and/or femoral cement.  Samples were subjected to three point bending tests, their density, porosity and microhardness determined and all specimens were examined using EDX and X-ray techniques.  Since the porosity of many of the samples is very high, the continuous matrix properties are inferred from the performance of individual specimens.  No evidence has been found to suggest that the PMMA has deteriorated whilst in-vivo and the mechanical properties of the cement matrices appear to be comparable to freshly made PMMA.