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Technical Failures Causing Loosening

- See:
    - Radiographic Evaluation of Cemented Femoral Components:
    - Exam for THR Loosening:

- Discussion:
    - failure to remove soft cancellous bone from medial surface of femoral neck, so column of cement does not rest on dense cancellous or
            cortical bone & support stem;
    - failure to roughen the medullary canal sufficiently, especially smooth surface of the thin layer of dense bone that forms about stem of a 
            femoral head prosthesis;
    - failure to remove sufficient cancellous bone to permit an adequate column of cement about entire stem - thin column cracks easily;
    - tip of the stem should be supported by a plug of cement, since this part of the stem is subjected to axial loading;
    - failure to position componenet in a neutral or mildly valgus position
            - varus position increases the moment of bending of the stem