A new analysis of data from a previous trial looked at how the angle of the knee after total knee replacement affects implant stability. The study included 93 patients who had knee replacements with different types of plastic inserts. Researchers measured the tibial slope, which is the angle of the top of the shinbone, and grouped patients into small, intermediate, or large slope groups.
After five years, the group with the largest tibial slope showed more tilting of the implant. However, there was no difference in wear of the plastic insert among the groups. Also, the slope did not affect how well patients felt or functioned.
This is an observational analysis, so it cannot prove that the slope caused the implant to shift. Other factors could be involved. The study did not report any safety concerns or side effects.
For now, the findings suggest that surgeons may want to pay attention to the angle of the knee during replacement. But more research is needed to confirm this link and to see if adjusting the slope leads to better long-term outcomes.