- Discussion:
- by definition, is a decrease of more than 5 mm in the verticle distance of the femoral stem;
- subsidence of 1 mm or less is within limits of measurement;
- subsidence of cement mass & stem or migration of stem into cement mass resulting in more distal position of collar or platform in relation to proximal surface of cement & femoral neck;
- subsidence may not be noted unless relationship of stem & cement mass to proximal femur is carefully evaluated in serial x-rays;
- stem may subside in cement, in which case there is usually frx of cement near tip of stem, or entire cement mass & stem may subside