# The Effect of Cement Aging on the Stability of a Cement-in-Cement Revision Construct
###### Abstract  
A revision surgery can be a complicated procedure. The prevention of the removal of a well-integrated cement mantle can minimize intraoperative complications. With the cement-in-cement technique, the implant will be fixated with a layer of bone cement onto the remaining cement mantle. In our experimental in vitro study, we investigated the effect of cement aging of a cement-in-cement revision construct and regular cement mantle on the bending strength. Two different types of bone cement were tested at four different stages of aging. The Palacos cement showed no significant difference in bending strength at any aging point, regardless of whether it was used primarily or as a cement-in-cement revision. In contrast, the SmartSet MV cement showed a significant difference between the primary and cement-in-cement applications depending on cement aging time. The comparison of the two cement-in-cement structures investigated showed significant differences between the manufacturers depending on the cement aging.  
cement-in-cement; revision; aging cement; joint arthroplasty; cement; bending strength 112814. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 11. 1. 11. 1. 11. 1. 1.  
considered a different approach than removing all the existing cement [9]. They suggested to remain the cement and implant the new stem with a thin layer of bone cement on the old cement mantle if the original bone cement mantle is well-fixed and integrated into the femur. This approach is known as the cement-in-cement technique (also known as in-cement or cement-within-cement). After removing the femoral stem, the existing cement mantle is checked for possible damage. If damage is found, a conventional method has to be used. If a fully intact cement mantle is present, the surface is prepared by a burr then cleaned and dried so that the new bone cement has no contamination and a stable connection can be formed. After all these preparations, the new stem can be cemented into the femur. The use of the cement-in-cement technique has increased over the years [10; 11; 12]. The advantages of this technique are less host bone stock loss, less blood loss and a lower risk of femoral perforation or even fracture [5; 6; 7]. In addition, a cement-in-cement revision needs less time because cement removal is time-consuming [5; 13; 14]. This is a medical as well as a financial advantage due to a shorter time under narcotics and also the personal and room resources are used less [8]. However, only a few biomechanical studies on the strength between two cement layers exist. Testing the bending strength of different cement combinations was done, concentrated on the shear strength between the two layers [15]. However, the influence of different aging points was not considered. [PERSON] et al. investigated the shear strength while using different techniques to prepare the cement-in-cement interface [16]. A preparation with an ultrasonic device showed lower shear bond strength. In an experimental in vitro study, we investigated the effect of cement aging on a cement-in-cement revision construct. For this purpose, we used a four-point bending test to compare the bending strength of different cement-in-cement constructs over different times of bone cement aging.