[Quantitative analysis of worn and torn particles in periprosthetic tissue of hip and knee with scanning electron microscopy].

Background: Arthroplasty is successful because biocompatible material is available, but its lifespan decreases due to inadequate fixation, mechanical wear and tear, or biological loss caused by osteolysis. This last is a tissue response to wear particles of the implanted material localized in the bone--prosthesis interface. We undertook this study to present the morphological analysis and characterization of the metal wear particles (MWP) in the periprosthetic tissue of patients with prosthetic loosening.

Methods: Interface tissue was studied in 63 patients with prosthetic loosening and was processed with the conventional histological technique, and tissues with wear and tear particles were subjected to chemical element determination by energydispersive X-ray analysis.

Results: Composition of the prosthesis placed in patients contained Cr-Co (30.2%), stainless steel (34.9%), Cr-Co/stainless steel (12.7%) and Ti (22.4%). Cellular response caused by wear and tear particles was classified according to three types. MWP were identified in only 19 membranes. Particle presence or absence was not significantly associated with clinical characteristics of the patient and worn and torn methacrylate or polyethylene particles. Periprosthetic membranes that showed MWP were the ones of older patients with a longer average time of graft use and those with severe necrosis.

Conclusions: No patients experienced infection at the same time with MWP probably because they were treated for prosthetic septic loosening; consequently, it is less probable that they were recruited in a cross-sectional study such as the present one.