The bone-to-cement interface improvement by Ca-phosphate ceramics

Polymethylmethacrylate used in surgery is one of the first biomaterials. Conventional histology dissolves the resin; one of the reasons that only few complete histology is published. OBJECTIVES AND PURPOSE: The question is, whether a complete histology changes the understanding, influences the application and opens approaches for improvements. The dos and don'ts of the processing technology are presented in reproducible manner.

Ten femurs of giant rabbits were taken from running experiments of femur-canal filling with bone cement. Different stages were considered for high-resolution histology and electron microscopy: 4-weeks-stage (bone healing), 12-weeks-stage (remodelling) and one and two years. A human-cadaver specimen with a follow up of two years was processed. All animals were perfusion-fixated and the complete vasculature micro-casted. Serial cuts were performed with a stone saw, followed by a wet grinding processing. The fluorescence documentation in the High Intensity Incident Fluorescent Light (HIIFL) and Orthoplan Leitz Ploemopak(®) was applied and high resolution microradiography used the Siemens Kristalloflex(®) . The Scanning Electron Microscopy (SEM) was performed applying deep-freezing technology for the PSEM-500. The human specimen was embedded after sectioning using epoxy-resin.

All cement implants showed osseointegration and remodelling with a tangential adherence of bone onto the ceramic/PMMA surfaces. Intact cancellous structures after one and two years did not show any signs of heat necrosis. The human specimen confirmed the results from the animal experiments.

The complete bone-to-cement histology changed the understanding of the bone cements function, influenced its application and opened new ways for improvement.