BENDING AND FRACTURE-TOUGHNESS OF WOVEN SELF-REINFORCED COMPOSITE POLY(METHYL METHACRYLATE)

Loosening remains an impediment to the long-term success of total hip replacements despite numerous improvements in the materials used. In c emented prostheses, fatigue and fracture of bone cement have been impl icated in the failure of these devices. A new material, self-reinforce d composite poly(methyl methacrylate) (SRC-PMMA), has been developed. SRC-PMMA is formed by a novel processing method that will be described . The composite consists of high strength, highly oriented PMMA fibers embedded in a matrix of PMMA. Using a woven form of SRC-PMMA, an in v itro physical and mechanical evaluation was performed to assess the fe asibility of its use in an orthopedic prosthesis. Three different weav es of SRC-PMMA were evaluated in bending and fracture toughness in air , after immersion for 30 days in 37 degrees C saline, and after gamma irradiation followed by immersion. Bending modulus and strength were d ecreased by gamma irradiation followed by saline immersion. The effect of saline immersion alone on bending strength and modulus was negligi ble. Saline immersion and gamma irradiation followed by saline immersi on was shown to have little or no effect on the fracture toughness of woven SRC-PMMA. Differences in the fracture processes of the different weaves were found and can be related to the differing orientation of fibers to the fracture toughness pre-crack. Optimally incorporated SRC -PMMA absorbs the same amount of water as bone cement. Comparison to p revious and current work with bone cement controls shows that SRC-PMMA is a material equal to or better than bone cement in all tests perfor med. It deserves further consideration as a candidate biomaterial. (C) 1997 John Wiley & Sons, Inc.