Mechanical alignment of tibial stems in revision total knee arthroplasty

This multicenter, retrospective study evaluates the radiographic results of achieving optimal tibial alignment in revision total knee arthroplasty (TKA) using a single modular CoCr cemented or cementless stemmed implant design. Stem size and length also were evaluated. The hundred ninety-nine revision TKAs were performed between January 1993 and January 1996 by 13 experienced revision knee surgeons. The cases were subdivided into 5 comparative groups: (1) cemented stems, (2) 140-mm length canal-filling stems, (3) 140-mm length non-canal-filling stems, (4) 95-mm length canal-filling stems, and (5) 95-mm length non-canal-filling stems. The anteroposterior (AP) tibial alignment angle was measured. The canal-filling ratio (CFR) was determined by dividing the stem diameter by the endosteal diameter at the stem tip. Overall, the ability to achieve tibial alignment in the AP plane was more predictable when canal-filling (CFR >/= 0.85) cementless stems were used. This was further enhanced when long canal-filling cementless stems were selected. The least-predictable results and the highest probability of varus malalignment were achieved with cemented stems.