Micromotion of noncemented Freeman-Samuelson knee prostheses in gonarthrosis. A roentgen-stereophotogrammetric analysis of eight successful cases.

Micromotion of the tibial component of eight Freeman-Samuelson arthroplasties without cement for gonarthrosis were followed for two years and studied by roentgen-stereophotogrammetric analysis (RSA). In five cases, displacement over time was studied, and in all cases migration was found to range from 0.7 to 4.8 mm after two years. One tibial component migrated continuously during the period studied, while the remaining prostheses migrated mostly during the first six months. The direction of the migration was erratic. Inducible displacement ranging from 0.8 to 5.0 mm was found in all cases. Clinically, all of the patients were scored as successful although one with continuous migration had the lowest score. This degree of micromotion is compatible with good results after two years, and appears to be a characteristic of the immediate interlocking fixation used in the Freeman-Samuelson prosthesis.