PAPER 44: CANCELLOUS BONE OSSEOINTEGRATION IS ENHANCED BY LOADING

Abstract

The influence of controlled mechanical loading on osseointegration was investigated using an in vivo device implanted in the distal lateral femur of five male rabbits. Compressive loads (1 MPa, 1 Hz, 50 cycles/day, 4 weeks) were applied to a porous coated titanium cylindrical implant (5mm diameter, 2mm width, 75% porosity, 350ìm average pore diameter) and the underlying cancellous bone.. The contralateral limb served as an unloaded control. MicroCT scans at 28 μm resolution were taken of a 4 × 4mm cylindrical region of interest that included cancellous bone below the implant. A scanning electron microscope with a backscattered electron (BSE) detector was used to quantify the percent bone ingrowth and periprosthetic bone in undecalcified sections through the same region of interest. A mixed effects model was used to account for the correlation of the outcome measures within rabbits.. The percent bone ingrowth was significantly greater in the loaded limb (19 +/− 4%) compared to the unloaded control limb (16 +/− 4%, p=0.016) as measured by BSE imaging. The underlying cancellous periprosthetic tissue bone volume fraction was not different between the loaded (0.26 +/− 0.06) and unloaded control limb (0.27 +/− 0.07, p=0.81) by microCT. BSE imaging also showed no difference in the percent area of periprosthetic bone (27 +/− 10% loaded vs. 23 +/− 10% unloaded, p=0.25). Cyclic mechanical loading significantly enhanced bone ingrowth into a titanium porous coated surface compared to the unloaded controls.