Based on the available information from Mayo Clinic and WebMD, there is no explicit mention of Lipitor increasing the risk of acute joint stiffness.

Lipitor, a type of statin, is a medication used to treat high cholesterol levels [1][2]. Statins are known to have several side effects, including muscle pain, liver damage, and increased blood sugar levels [1][3]. However, joint stiffness is not listed as a common side effect of Lipitor or other statins in the provided sources.

It is important to note that everyone's body reacts differently to medications, and some people may experience side effects not listed in the common side effects. If you are experiencing joint stiffness or any other unusual symptoms while taking Lipitor, it is recommended to consult with your healthcare provider [1].

In summary, based on the available information, there is no explicit mention of Lipitor increasing the risk of acute joint stiffness.

Sources:
[1] <https://www.mayoclinic.org/diseases-conditions/high-blood-cholesterol/in-depth/statin-side-effects/art-20046013>
[2] <https://www.drugpatentwatch.com/p/tradename/LIPITOR>
[3] <https://www.webmd.com/cholesterol-management/side-effects-of-statin-drugs>