Abstract
Aim
To undertake a biomechanical study to determine the existence of any difference in the early tibial component fixation to bone, between two widely used techniques of cementation, which may confer an influence on implant survival.
Method
20 tibial saw bones were prepared by standard methods using extramedullary instrumentation to receive a fixed bearingtibial component (PFC, DePuy). Under controlled laboratory conditions, thetibial trayswere implanted with CMW cement using either of the two following cementation techniques (10 implants in each group): Full cementation–application of cement to the undersurface of the tibial tray, the keel, the cut surface of the tibia and its stem hole. Surface cementation – application of cement only to the undersurface of thetibial tray and the cut surface of the tibia. 72 hours after implantation, the fixation of the cemented components was assessed by determining the load to failure under controlled tensile stresses (using an Instron Electro-mechanical tensile tester).
Results
The data suggested a two-stage process to failure with an initial de-bonding load preceding a peak load before failure. Highly significant differences between the two techniques were observed. The mean initial de-bond load for fully cemented implants was 1115N, compared to 590N for the surface cemented group (p<0.00005). The mean peak load before failure was also significantly greater in the fully cemented group (1830N vs 1370N, p<0.001)
Conclusion
Full cementation of the tibial component in total knee arthroplasty confers greater initial fixation to bone than surface cementation and may therefore positively influence implant longevity.
