Bone remodeling around the tibial component of distal femoral expandable endoprosthesis.

Radiographs of 33 patients who had an expandable prosthesis inserted after tumor resection in the distal femur were evaluated. We hypothesized that, when a sleeve was present, there was greater stem migration and cortical reaction. The thickness of medial and lateral cortices of the tibia was measured at 6 months and on the last follow-up radiograph. The distance from the edge of the prosthesis to the cortical edge was also compared. When a sleeve was present, there was greater stem migration (P < .001) and a greater increase in lateral cortical thickness (P < .001). There was a higher revision rate when a sleeve was used, but this was not statistically significant. There was no difference in function according to the Toronto Extremity Salvage Score (TESS) between the 2 groups. This is the first study to demonstrate that the presence of a polyethylene sleeve is associated with a tendency for the tibial prosthesis to migrate laterally and cause a greater sclerotic reaction.