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

Human cancellous bone ingrowth studies were conducted on 19 consenting bilateral total knee arthroplasty (TKA) patients. Titanium porous coated cylinders were implanted into the medial femoral condyle of the contralateral knee during of two the Retrieval was performed at the TKA (6-131 weeks later), and fluorochrome analysis was conducted. Mean mineral apposition rates (MAR) at the interface measured 1.0 mu/day, whereas 4 mm away, the peripheral bone had a mean MAR of 0.8 mu m/day. This 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 porous coating, bone ingrowth did not occur. These results emphasize the need for surgical precision and careful postoperative management to achieve bone ingrowth. (C) 1994 John Wiley and Sons, Inc.