The mini bottle brush--a new fastening device in cancellous bone.

A new design for bone implants, the bottle brush, was recently presented in a pilot study on marrow cavities in the femur of rabbits. In this study, the concept is further evaluated on a mini bottle brush. The fixture, 5 x 7 mm, with an implant shaft made of CP-titanium and bristles of nylon coated with sputtered titanium, was inserted into the cancellous bone of the medial femoral condyle in 15 adult rabbits. The titanium fixture was compared with a similar brush without the titanium sputtered surface. The animals were sacrificed after 4 months and the quantity and quality of bone integration were evaluated with pull-out tests and histological examination. In both parameters, the values were significantly higher for the titanium-sputtered brushes, with removal forces similar to titanium cylinders of the same size and with a bone-to-metal contact area of about 50%.