If proximal fixation of a femoral uncemented stem cannot be achieved, stem diameter should provide maximum cortical contact to reduce sheer stress. Longer stems do not necessarily provide additional stability. By using this prosthesis and selection method, a good outcome at first follow-up was observed.

Summary: The development and clinical indications of a new modular femoral endoprosthesis consisting of a head and shaft component is discribed. Components are available in different lengths and diameters and therefore can be joined individually depending on the patients anatomy and surgery required. Both parts are joined by a unique optimized taper socket with a groove, avoiding fretting and corosion. Fatigue tests showed no loosening of the tapered connection and no prosthesis fracture. The material and surface structure as weU as the philosophie of the distal fixation are discussed.

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