The Hip: Preservation, Replacement and Revision

Titanium


- See: Characteristics of Metals and Implants:

- Discussion:
    - titanium is often selected as a materalial for metal plates or femoral stem implants due to its lower modulus of elasticity (as compared to other alloys); 
    - elastic modulus of stainless steel is 12 times EM of cortical whereas EM of titanium is 6 times of cortical bone;
    - advantages:
          - resistance to fatigue is execellent;
          - it is easily worked, and 1/16 plates are radiolucent;
          - yield strength:
                 - metals ranked according to yeild strength (highest to lowest);
                 - cast cobalt chrome > titanium > wrought cobalt chrome, stainless steel;
          - resistance to corrosion:
                 - by itself titanium would have a high potential for oxidative corrosion;
                 - the titanium dioxide layer which coats the outer metal layer provide a major barrier to corrosion;
    - disadvantages: this metal has an extremely low modulus of elasticity & low tensile strength;
          - titanium plates and implants, therefore, have to be bulkier than stainless steel in order to provide same rigidity


- Corrosion:
    - it is the most inert of metals;
    - resistance of titanium to corrosion in a chloride environment is excellent;
    - titanium and its alloys form oxide passivation layers more rapidly than do substances that contain chromium, such as cobalt-chromium
           alloy and stainless steel;
    - while an active metal like titanium forms its oxide passivation layer spontaneously in any environment that contains oxygen, strength of 
           adhesion of the oxide layer to the underlying titanium metal is not as great as that of chromium oxide layer to its metal substrate;
           - in addition, chromium oxide passivation film is more dense than titanium oxide layer


- Wear of Modular Titanium Stems
    - known drawbacks of using titanium as a bearing include its poor resistance to wear, notch sensitivity, and reports that it is more
           susceptible to abrasive wear by particles of debris



Serum titanium levels in individuals undergoing intramedullary femoral nailing with a titanium implant.

The advantages of titanium alloy over stainless steel plates for internal fixation of fractures: an experimental study in dogs.  

Aseptic loosening in total hip arthroplasty secondary to osteolysis induced by wear debris from titanium-alloy modular femoral heads. 

Metallic wear in failed titanium alloy total hip replacements:  A histological and quantitative analysis.  

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Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Tuesday, August 6, 2013 10:46 am