JOINT IMPLANT SURFACES

PRESS-FIT AND POROUS COATED JOINT REPLACEMENT IMPLANTS OFTENFAIL DUE TO FORMATION OF A FIBROUS CAPSULE CAUSING LOOSENINGAND PAIN, EVENTUALLY REQUIRING REVISION. EARLY IN VITRO ANDIN VIVO EXPERIMENTS SUGGEST THAT SURFACE MICROGEOMETRY SIGNIFICANTLY MODULATES RATE AND DIRECTION OF GROWTH OF CONNECTIVE TISSUE CELL COLONIES. PHASE I WILL QUANTIFY THESE IN VITRO EFFECTS ON COLONY FORMATION KINETICS AND CELL FUNCTION OF RAT TENDON FIBROBLAST AND RAT BONE MARROW CELLS. CELLS WILL BE CULTURED ON A SELECTED RANGE OF SURFACE MICROGEOMETRIES, CONSTRUCTED FROM TITANIUM-COATED TEMPLATES. A CELL COLONY FORMATION MODEL DEVELOPED BY THE INVESTIGATORS TO PERMIT ACCURATE ANALYSIS OF THESE EFFECTS WILL PERMIT QUANTIFICATION. RESULTS WILL BE USED TO DESIGN, FABRICATE, AND TEST IMPROVEDIMPLANT SURFACES DURING PHASE II. IMPLANT SURFACES WILL BE TAILORED TO WITHER ENHANCE OR RETARD BONE ATTACHMENT AS DESIGN CRITERIA DICTATE. E.G., FOR HIP ARTHROPLASTY IMPLANTS, A CUSTOM BONE ATTACHMENT SURFACE ON THE STEM PROXIMAL PORTION WILL EFFECT GOOD LOAD TRANSFER TO FEMORAL CORTICAL BONE. SIMULTANEOUSLY, THE DISTAL SURFACE WILL BE FASHIONED TO PREVENT DISTAL FIXATION THAT COULD RESULT IN PROXIMAL BONE RESORPTION. AN IMPLANT CHAMBER MODEL WILL BE UTILIZED FOR THE IN VIVO STUDIES IN PHASE II.