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Question

Please explain what constitutes are in bone cement and how is the bone cement prepared?

Answer

In our theatres the cement is prepared by the scrub nurse.  There are liquid and powder components which are added together and mixed in a vacuum.

First the powder is poured into the cylindrical container (between 1 and 4 bags depending on the amount of cement required, more in revision cases for example). Then the theatre runner is prepared with a timer and starts the clock as the liquid is poured into the container.

The components are mixed initially without vacuum and then with a vacuum. Once mixed for a pre-determined time the vacuum is removed and the cement tube is connected to the gun for implantation. 

The two main brands of cement used in the UK are Palacos and Simplex. 

Components are:

  • Liquid
    • Monomer (methylmethacrylate)
    • Activator (N, N-dimethyl-p-toluidine)
    • Stabiliser (hydroquinone)
    • Colourant (chlorophyll)
  • Powder
    • Co-polymer
    • Initialtor (benzoyl peroxide)
    • Radio-opaque material (zinc oxide or barium sulphate)
    • Antibiotics

PMMA is formed from polymerisation of the monomer by an exothermic reaction

Answer