- The most widely used bone cement- acrylic bone cement i.e. polymethylmethaacrylate (PMMA).
- Two components- a liquid & a powder
- Liquid component: Methylmethaacrylate(MMA) monomer, N,N -dimethyl-p-toluidine ( as accelerator), Hydroquinone (prevent premature polymerization)
- Powder component: PMMA microspheres (prepolymerized), Barium sulphate/Zirconium oxide (for radio-opacification), Dibenzoyl peroxide (Initiator of polymerization)
- Some other components in Powder may be used: Tri-n -butylborane ( as Initiator), 2,5-dimethylhexane-2,5-hydroperoxide (as an accelerator), chlorophyll dye, ethanol, ascorbic acid, antibiotics, & dyes.
- Calcium phosphate cements: two components- Calcium orthophosphate and a liquid phase; these together form a paste & later harden.
- INDICATIONS: 1. Arthroplasty, 2. Kyphoplasty & Vertebroplasty, 3. For control of Infection as antibiotic cement beads, 4. Filling of Gap after tumor resection as in GCT, 5. Ca-phosphate in vertebral augmentation & osteoporotic fractures, unstable fractures, skull reconstruction & maxillofacial deformities, 6. Ca-sulfate in periodontal disease & maxillary sinus augmentation
- Process of Curing: 4 stages: Mixing, Sticky/Waiting, Working, & Hardening
Hand mixing- more porosity, can compromise mechanical properties &
Vacuum mixing- less porous & homogenous radio-opacifier particle mixing; also reduces exposure of surgical staffs to MMA monomer vapor.
- Complications: To patients:– Cardiopulmonary- Hypotension, Hypoxia due to toxic effects of MMA monomer/Anaphylaxis. Death & Pulmonary Infarction if embolization of PMMA when injected in liquid state e.g. during vertebral augmentation.
To surgical staffs:- Hypersensitivity, Asthmatic reactions, Local neurological symptoms, irritations & skin reactions.