Interfacial strength between molded UHMWPE and PMMA-MMA monomer treated UHMWPE

To solve aseptic loosening of cemented acetabular cup and tibial plateaus of hips and knee joint prostheses in total joint replacement, adhesion between the polymeric prostheses made of ultra-high molecular weight polyethylene (UHMWPE) and bone cement made of polymethyl-methacrylate (PMMA) has been investigated. Previous studies using xylene, PMMA, and MMA monomer solution to treat bulk surfaces of UHMWPE resulted in 11.5 +/- 0.65 MPa as the maximum interfacial strength between the treated UHMWPE and bone cement. The present study eliminates the use of xylene; instead, UHMWPE powders were treated with MMA monomer and PMMA-MMA solution, dried, and then compression-molded with untreated UHMWPE powders. The interfacial tensile strengths were measured and the best molding conditions investigated by varying temperature, pressure, and time. Temperature was the predominant factor when compared to that of pressure or time. The maximum interfacial strength between the treated UHMWPE and untreated UHMWPE was 16.3 +/- 0.94 MPa with the molding conditions of 166.5 degrees C, 38.7 MPa, and 1 h. Scanning electron microscopic (SEM) pictures show the coating of the nodules and fibrils of UHMWPE powder with PMMA. Pulled out aggregated nodular space and coated PMMA after fracture could be seen easily from PMMA-MMA treated UHMWPE powder.