FEMORAL COMPONENT MIGRATION IN TOTAL KNEE ARTHROPLASTY - RANDOMIZED STUDY COMPARING CEMENTED AND UNCEMENTED FIXATION OF THE MILLER-GALANTE-I DESIGN

The Miller-Galante I knee replacement was inserted in 25 women and thr ee men (33 knees) with osteoarthrosis. All patients received a TiAIV f emoral component with a commercially pure titanium fiber-mesh undersur face. Cemented or cementless fixation was used based on a randomizatio n protocol. Micromotions of the femoral components were recorded with roentgen stereophotogrammetric analysis during the first 2 postoperati ve years. The magnitude of migration did not differ between cemented a nd uncemented fixation. The number of nonmigrating prostheses decrease d from 21 (12 cemented and nine uncemented) at 3 months to six (three cemented and three uncemented) at 24 months. In both groups, the magni tude of prosthetic tilting about the longitudinal axis (internal-exter nal rotation) was as large as that about the transverse axis (flexion- extension). Rotation into extension was as common as rotation into fle xion. The largest translations were recorded at either of the posterio r condyles. In 10 uncemented components, radiolucent lines were seen a t the distal interface postoperatively. Proximal migration of the femo ral component was recorded in these knees, and the width of the lines decreased or the lines disappeared totally at 24 months. After 2 years , lines were noted around four cemented and four uncemented replacemen ts, mainly anteriorly or distally. All of these prostheses migrated. O ne prosthesis, revised because of malalignment, displayed pronounced m igration after an initial period of stability. Bone ingrowth was obser ved anteriorly and anterodistally despite the presence of motions of 1 mm or more.