Intramedullary fixation of artificial hip joints with bone cement-precoated implants. II. Density and histological study.

Bilateral coxofemoral hemiarthroplasties were performed in dogs using experimental and control implants, which were fixed with bone cement. The stem of the experimental implant was precoated with bone cement, about 2 mm thick. After 1, 3, and 6 months the femora with implant specimens were harvested and sectioned for mechanical and histological evaluation. Histological observations on the implant-bone interface and density measurements of the bone cement are reported. The density of the precoated bone cement was higher than the same cement used for implant fixation at the time of implantation (1.202 vs. 1.188 g/mL). The precoating also resulted in milder histological reactions, including thinner fibrous tissue capsule and smaller gap between bone and cement. The present results and the previously reported mechanical findings strongly support our hypothesis that a better and longer lasting prosthesis fixation can be achieved using cement-precoated prosthesis combined with the customary cement fixation technique.