An anatomical study of tibial metaphyseal/diaphyseal mismatch during revision total knee arthroplasty.

This cadaveric study determines the relationship of the tibial metaphysis and intramedullary canal of the tibia (diaphysis), particularly relating to revision knee arthroplasty. A total knee arthroplasty was performed in 20 cadaveric tibiae using revision instrumentation with a canal-filling uncemented stem. The offset, which is the distance between the center of the tibial canal and the center of the tibial metaphysis, was measured using the revision system offset bushing. The average distance between the center of the tibial metaphysis and the center of the tibial diaphysis was 4.1 mm (+/-2.9 mm) with an average angle of 105 degrees (0 degrees -70 degrees ). The mean offset was 4.1 mm (+/-2.9) and the mean offset angle was 105 degrees (0 degrees -350 degrees ). The study confirms the center of the tibial diaphysis is not congruous with the center of the metaphysis with wide variations in offsets among individuals. A wide range of offsets are necessary for optimum placement of implants.