While meeting with members of the Trinitarian order on Monday, Pope Francis referred to his knee ailment, which kept him from standing to greet all of them.

“After the photo I will greet you, but excuse me, I have to do it sitting, not on foot, because of the knee ... It is that malady that was once called ‘nun's pain’, because it was the time in which the nuns prayed, and for so much praying on their knees they got sick! This will heal, but in the meantime we have to do things right,” he said April 25 in the Vatican’s Clementine Hall to participants in the International Trinitarian Solidarity Conference.

The Trinitarians are a mendicant order founded in the 12th century by St. John of Matha to ransom Christian captives.

Francis, 85, has been suffering from pain in his right knee, causing him to take smaller roles in some liturgies and to remain seated more often.

His agenda was cleared April 22 for medical checkups, and he preached at, but did not preside over, Mass for the Octave Day of Easter on April 24.

The pope’s movements have been visibly more limited since the start of the year.

At the general audience on Jan. 26, he said the reason he was unable to greet pilgrims as usual was because of a temporary “problem with my right leg,” an inflamed knee ligament.

With a smile, he added: “They say this only comes to old people, and I don’t know why it has come to me, but ... I don’t know.”

On Good Friday, Pope Francis did not prostrate himself before the cross.

The pope also opted to not celebrate the Easter Vigil Mass, though he attended, delivered the homily, and performed several baptism.

And on Easter Sunday, he had to sit down part way through his delivery of the Urbi et Orbi message and blessing.

Pope Francis has also received more assistance walking and going up and down stairs in recent weeks.