Club press officer Di Law told ManUtd.com on Monday, "John has undergone arthroscopy on his left knee and will be out for three to four weeks."
And what is Arthroscopy you might ask?
Red Issue's resident quack Dietmar Hipplegrubber explains:
Arthroscopy is a surgical procedure orthopaedic surgeons use to visualise, diagnose and treat problems inside a joint.
The term literally means, "to look within the joint." In an arthroscopic examination, an orthopaedic surgeon makes a small incision in the patient's skin and then inserts pencil-sized instruments that contain a small lens and lighting system to magnify and illuminate the structures inside the joint. Light is transmitted through fibre optics to the end of the arthroscope that is inserted into the joint. By attaching the arthroscope to a miniature television camera, the surgeon is able to see the interior of the joint through this very small incision rather than a large incision needed for surgery.
The television camera attached to the arthroscope displays the image of the joint on a television screen, allowing the surgeon to look, for example, throughout the knee at cartilage and ligaments, and under the kneecap. The surgeon can determine the amount or type of injury, and then repair or correct the problem, if it is necessary.'