MINERAL APPOSITION RATES OF HUMAN CANCELLOUS BONE AT THE INTERFACE OFPOROUS-COATED IMPLANTS

Human cancellous bone ingrowth studies were conducted on 19 consenting bilateral total knee arthroplasty (TKA) patients. Titanium porous coa ted cylinders were implanted into the medial femoral condyle of the co ntralateral knee during of two the Retrieval was performed at the TKA (6-131 weeks later), and fluorochrome analysis was conducted. Mean min eral apposition rates (MAR) at the interface measured 1.0 mu/day, wher eas 4 mm away, the peripheral bone had a mean MAR of 0.8 mu m/day. Thi s represented a 25% acceleration in the interface bone remodeling rate when compared with the periphery (P <.05). This study showed the bone advanced appositionally at the interface at a rate of approximate to 1 mu m/day. Analysis showed that when bone was over 50 mu m from the p orous coating, bone ingrowth did not occur. These results emphasize th e need for surgical precision and careful postoperative management to achieve bone ingrowth. (C) 1994 John Wiley and Sons, Inc.