QUANTITATIVE STUDY OF THE EFFECT OF STRAIN REDISTRIBUTION ON BONE REMODELLING NEAR A POROUS SURFACED IMPLANT.

Bone resorption observed clinically in the vicinity of a stiff metallic implant is often attributed to a lack of stress in the resorbing region. This 'stress shielding' appears to be exaggerated by the use of porous coated implants. The objective of this work was to measure strain levels on the plated and unplated femurs of dogs throughout gait using in vivo strain gauging and FM radio telemetry to quantitatively assess the location of the region of low stress and compare it to the location of histologically observed resorption. A correlation was noted in the laterally plated limbs between a region of stress change from tension prior to plate application to compression after plate application and the region of most extensive resorption below the plate.