- This study quantified the effect of cement type and cement application timepoint on the bone penetration of cement in an animal model of total knee arthroplasty
- Four bone cements (different manufacturers/viscosities) were tested at three timepoints (one, two and three minutes after dough time was reached); each combination was tested five times, for a total of 60 tests
- No cement type or application timepoint offered an advantage in terms of cement penetration depth into bone
- Other results did suggest, however, that it may be best to apply cement soon after dough time is reached to avoid an excessively thick cement mantle between the implant and bone
About a quarter of revisions after arthroplasty are needed because of aseptic loosening. Orthopedic surgeons debate how the penetration of cement into bone is affected by cement type and timing of application, but studies commonly involve plastic molds that don't accurately represent the biological environment.
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Researchers at Massachusetts General Hospital recently conducted the first study on this issue that used a porcine cadaveric model. Sourabh Boruah, PhD, research fellow in the Technology Implementation Research Center (TIRC), Orhun K. Muratoglu, PhD, director of the TIRC and the Harris Orthopaedics Laboratory, Kartik M. Varadarajan, PhD, former associate director of the TIRC, and colleagues published the findings and resultant clinical recommendations in Medical Engineering and Physics.
An orthopedic surgeon and staff tested four bone cements: Palacos R (high relative viscosity), Palacos MV (medium viscosity), Simplex P (low viscosity) and Smartset HV (high viscosity). Three application timepoints were tested (1, 2 and 3 minutes after dough time was reached).
To mimic preparation for cemented total knee arthroplasty, the surgeon removed about 5 mm of proximal bone from cadaveric porcine tibias, exposing the trabecular bone bed. The bone bed underwent saline pulse lavage and was dried with gauze.
Vacuum-mixed cement was applied to the resected surface using the same cement gun for all specimens. 60 tibias were tested—five replicates of each testing condition (four cement types x three application timepoints). The cemented specimens were imaged with computed tomography.
The depth of cement penetration into bone was not significantly associated with any cement type or application timepoint.
The statistically significant results were that:
- The percent area covered by cement at 2 mm depth was significantly higher at one minute than three minutes
- The thickness of the pure cement mantle above the bone resection plane was 0.25, 0.49 and 0.73 mm at one, two and three minutes (P<0.011)
It may be best to apply cement early in the working window after dough time is reached to avoid an excessively thick cement mantle between the implant and bone.
For successful fixation of implants during total knee arthroplasty, longstanding principles of good cement application technique seem to be more crucial than any particular cement viscosity or manufacturer.
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