TKA is a reliable form of treatment to relieve pain and improve function in patients with RA. Factors that influence prosthetic survival include the design of the component, the method of fixation (cemented or cementless), and the preservation or excision of the PCL [15–18]. It remains unclear whether it is best to retain or excise the PCL, and whether cement should or should not be used for implant fixation.
There have been several reports describing good long-term results of cementless TKA for RA, with prosthetic survival rate of over 90% with follow-up periods of more than 10 years [2–5]. However, there have been few reports regarding the long-term outcome of cementless CR-type TKA [6–8]. The results of the present study suggested that the clinical results of Hi-Tech Knee II CR-type cementless TKA in RA patients are satisfactory.
Cement has disadvantages related to toxicity , reduced bone stock at revision, and difficulty in treating infections . However, early fixation after cementless TKA is the main problem related to stability of the prosthesis compared with cemented fixation . The Hi-Tech Knee II CR-type component is coated with fiber mesh consisting of ten layers of titanium, designed to promote mechanical fixation by bone ingrowth . The radiolucent line indicates the results of incorrect cutting of the femur and tibia. The width of this line is not progressive, and none of the patients in the present study had loosening, suggesting that adequate fixation can be achieved due to bony ingrowth.
The choice of whether to use a PCL-retaining design or posterior-stabilized design for TKA is based on limited data. It has been reported that there are no difference in clinical outcome between PCL retention and PCL removal, and conversely that the PS design results in a better range of motion and easier operation technique. Conditt  reported that substitution of the PCL with a spine and cam mechanism may not fully restore the functional capacity of the PCL, particularly in high-demand activities that involve deep flexion, squatting, kneeling, and gardening.
PCL substitution is believed to prevent posterior subluxation of the tibia in addition to enhancing roll-back during deep knee flexion. It has been suggested that PCL substitution allows greater conformity, which in turn results in less stress in the polyethylene tibial base plate. In this study, there were no cases of subluxation or loosening of the tibial base plate. Shai  reported the prosthesis survival rate of 97% at 13 years in the PCL-retaining procedure, and Rodriguez  also reported the rate of 91% at 15 years.
The disease state of the RA knee at the time of arthroplasty dictates whether the PCL is retained or sacrificed and whether cement is or is not used. Therefore, we did not use this prosthesis for all RA knees. The contraindications for use of this prosthesis include cases with mutilating type RA, severe deformity, severe knee stiffness, and severe instability of the knee. We did not consider metaphyseal tibial defect as a contraindication for use of this prosthesis.
There were some limitations in this study. First, this study was performed in a select patient population, and selection bias may have influenced the clinical outcomes. Second, the number of patients was small, which may have led to small-sample bias. Third, we did not perform blinded radiographic analysis. Fourth, the follow-up period was relatively short. Finally, this was a retrospective study.
In this study, there were no indications of problems associated with retention of the PCL and cementless fixation. However, attention should be paid to cases with large bony defects of the knee and with mutilating types of joint destruction. Appropriate selection of patient, prosthesis, and operative technique may lead to good clinical results, even using a CR-type prosthesis and cementless fixation.