Effect of bisphosphonates on selected markers of bone turnover in patients after total knee arthroplasty

Purpose Osteoporosis is a problem for many patients after total knee arthroplasty (TKA). The aseptic loosening of the prosthesis is also a significant problem. Therefore, in these patients, bisphosphonates (BPs) are used that, by influencing the level of bone turnover markers, reduce the risk of osteoporotic fractures and aseptic revisions in TKA. The purpose of the study was to assess whether the Pamifos® present in bone cement has any effect on the level of selected bone turnover markers and cytokines in patients after total knee arthroplasty. Methods The study group consisted of 30 women with degenerative changes of the knee joint, whose total knee prosthesis was stabilized with cement enriched with Pamifos®. The control group consisted of 30 women treated for degenerative changes of the knee joint without the use of bisphosphonate-enriched cement for prosthetic stabilization. Results In the study group, we found a decrease in tumour necrosis factor (TNF-α) levels 12 weeks after surgery, whereas the control group experienced an almost twofold increase in TNF-α level. The concentration of OPG, a natural RANKL antagonist, was highest in patients of the study group six weeks after surgery and was four times higher compared to the control group. Statistically significant differences were found in the RANKL level ( P < 0.05). In the control group, there was a continuous increase in RANKL concentration from the first to the 12th week after surgery. The highest level of RANKL in patients of the study group was found six weeks after the surgery, and 12 weeks after knee arthroplasty, it was significantly lower. It was found that the concentration of osteocalcin (OC) in the study group was the lowest three weeks after the surgery, then it increased and remained at a similar level after 12 weeks. The concentrations of selected cytokines (IL-1β, IL-2, IL-6, IL-10, IL-17AF) also showed statistically significant differences. Conclusions The BP-stimulated increase in the level of OPG and the decrease in the level of RANKL, as well as the impact on the level of the analyzed interleukins in the bone microenvironment, may be an important element of the mechanisms limiting bone resorption. Therefore, the use of BP-enriched cement implants appears to be justified.