What does capsulitis mean in the knee joint?

Let me explain: Adhesive capsulitis is an inflammatory condition that restricts motion in a joint. It most often affects the shoulder joint, a condition called frozen shoulder syndrome.

-itis = inflammation: So knee capsulitis is inflammation of the membrane in the knee joint. May be due to trauma, infection, gout, pseudogout, auto-immune disease. Fp/orthopedics can evaluate & offer treatment options. Nsaids (if u tolerate them) may help. Other treatments depend on cause.