Intramedullary fixation of artificial hip joints with bone cement-precoated implants. I. Interfacial strengths.

In order to minimize the problems associated with implant fixation using acrylic bone cement, a new technique has been investigated. Canine hip prostheses were precoated with self-curing acrylic bone cement and implanted in random source dogs using the same cement for fixation, a precoated prosthesis on one side and an uncoated (control) on the other. After 1, 3, and 6 months, both femora were excised and sectioned for mechanical assessment of the interfaces among bone, cement, and implant. It was found that the precoated implants had much higher interfacial shear strengths than the uncoated ones (average 14.2 and 6.8 MPa for implant-cement interface; 2.0 and 1.2 MPa for the cement-bone interface for all implant periods). The precoated "old" cement and the "new" cement's interfacial shear strength was the strongest with an average of 15.1 MPa for all implant periods. The present results indicate that the precoated hemiarthroplastic implants provide a firmer intramedullary fixation than the traditional, uncoated implants.