Cement Mixing Technique for TJR

- See: Addition of Antibiotics to Cement

- Discussion:
    - mixing under vacuum reduces retained air & incr cement strength;
    - typically 2 bags are needed;
    - slower mixing of cement over a shorter time decreases air voids within cement and thus improves the strength characteristics;
    - characteristics of cement are markedly improved by centrifugation.
           - 24% increase in ultimate tensile strength;
           - 54% improvement in mean ultimate tensile strain;
           - 136% increase in mean fatigue life;
    - vaccum mixing:
           - in the study by MH Geiger et al (CORR 2001), the authors performed a controlled study compared the strength and porosity
                  of 48 polymethylmethacrylate cement-implant constructs prepared with open bowl versus vacuum mix technique;
                  - 48 blast finished stainless steel rods of 13 mm diameter were implanted with centralizers into 17-mm inner diameter tubes that had been retrograde
                          filled with polymethylmethacrylate cement;
                  - 8 cement preparations used were open bowl and vacuum mixed Simplex, Osteobond, Zimmer Dough Type, or Palacos R;
                  - 6 replications of each condition were performed.
                  - rod pushout data showed there was no significant difference between open bowl and vacuum mixed samples when all cement brands were combined;
                  - mean sheer force for Palacos R vacuum mixed samples was greater than open bowl (634 ± 47 versus 423 ± 171), whereas the force for
                          Zimmer Dough Type cement open bowl was greater than that of the vacuum mixed samples (901 ± 71 versus 705 ± 82);
                  - cycles to failure data did not show significant differences when open bowl and vacuum mixed samples were compared when cements
                          were analyzed individually or combined;
                  - image analysis of cement-implant interfaces showed that vacuum mixing reduced void area significantly compared with open bowl mixing in
                         Palacos R and Osteobond preparations.
                   - vacuum mixing does not appear to reduce cement prosthesis interface porosity or improve its mechanical properties in all cements.
           - references:
                   - The Clinical Significance of Vacuum Mixing Bone Cement. MH. Geiger.  Clin Orthop 2001 January;2001(382):258-266
                   - Do we need to vacuum mix or centrifuge cement
                   - Vacuum mixing of acrylic bone cement.  RL Wixson et al.  J. Arthroplasty. Vol 2. 1987. p 141-149.
                   - Bone cement improved by vacuum mixing and chilling.  L. Lidgren et al.  Acta Orthop. Scandinavica. Vol 57. 1987. p 27-32.

- Addition of Antibiotics to Cement:
       - Antibiotic Bone Cement and the Incidence of Deep Infection after Total Knee Arthroplasty
       -


- Cement Disease:
    - discussion:
          - in some cases, application of pressurized cement is associated w/ an embolization phenomena (either cement elements or fat) which may
                  result in hypoxia, cardiac arrest, or death;
          - risk factors include older age and a patent foramen ovale (paradoxical embolization);
          - use of pulsatile lavage may help to prevent this embolization phenomena, by removing fat  and marrow from the canal;
          - in older co-morbid patients, consider avoiding pressurization of the cement within the canal, since the risk of acute embolization may be higher than late loosening;
    - removal of debris from femur:
         - may begin cement mixing while preparing bone bed for cement;
         - loose cancellous bone debris, blood, and tissue are removed w/ water pick &  brush are helpful, & routine mechanical drying of both acetabular &
                 femoral surfaces is important (continue water pick until returning fluid is clear);
         - apply dilute solution of Epi w/ moist sponge (prevents blood interposition)
         - references:
                 - Medullary lavage reduces embolic phenomena and cardiopulmonary changes during cemented hemiarthroplasty.
                 - An in vitro study of femoral intramedullary pressures during hip replacement using modern cement technique.
                 - High-volume, high-pressure pulsatile lavage during cemented arthroplasty.
    - optimize hemodynamics:
         - some surgeons will infuse one unit of autologous pRBC at this point to optimize preload and Hct;
         - consider increasing FiO2 during the cement application;

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Optimum pore size for bone cement fixation.

Tissue response to particulate polymethylmethacrylate in mice with various immune deficiencies.

The effect of centrifuging bone cement.   JP Davies et al.  JBJS Vol 71-B. 1989.p 39-42.

Emboli observed with use of transesophageal echocardiography immediately after tourniquet release during total knee arthroplasty with cement.
    AT Berman et al.  JBJS. Vol 80-A. No 3. March 1998. p 389.