Based on the information available, there is no definitive evidence to suggest that Lipitor (atorvastatin) worsens existing joint stiffness. In fact, some studies suggest that statins like Lipitor could potentially have anti-inflammatory effects, which might improve joint stiffness in some cases [1]. However, it's important to note that individual responses to medications can vary greatly, and some people may experience increased joint stiffness or muscle pain as a side effect of Lipitor [2].

If you are experiencing increased joint stiffness or other unusual symptoms while taking Lipitor, it is recommended that you consult with your healthcare provider. They can help determine whether the medication is the cause and suggest alternative treatments if necessary.

Sources:
[1] "Atorvastatin (Lipitor)". DrugPatentWatch.com. Retrieved from <https://drugpatentwatch.com/drugs/atorvastatin>.
[2] "Lipitor (Atorvastatin)". Mayo Clinic. Retrieved from <https://www.mayoclinic.org/drugs-supplements/lipitor-oral-route/side-effects/drg-20069050>.