"My knee is deteriorating in spite of intensive physical therapy. I'm heading for the knee replacement op," he wrote on July 27. "I have great trust in my knee Prof. I am in good hands."

"From a hospital bed, but I'm still on it rather than in it!," wrote May on Tuesday. "About 1pm I go down for the chop. I may be quiet after that."

Late Tuesday, the procedure was complete. "I'm THROUGH !!! With a shiny new knee," posted the guitarist. "This no walk in the park (!) but for 1st time in months I feel optimistic and free of that OLD pain. Thanks so much for the great messages - it means a lot."