matches in March before withdrawing when doctors told him that he would require kneecap surgery. Yokozuna ceremonies and traditions The formal birth of the rank from Tanikaze's time appears to have in part come from a desire to let the very best have a separate ring entry ceremony (dohyō-iri) from the remaining top division wrestlers. The dohyō-iri is a ceremonial presentation of all the top division wrestlers which is held before the competitive bouts of the day. The normal ceremony for top division wrestlers is to be introduced and form a circle around the wrestling ring (dohyō) wearing specially decorated heavy silk "aprons", called keshō-mawashi. A brief symbolic "dance" is carried out before filing off to change into their fighting mawashi and prepare for their bouts. A yokozuna, however, is introduced after the lower ranked wrestlers and is flanked by two other top division wrestler "assistants". The "dewsweeper" or tsuyuharai precedes the yokozuna, while the "sword bearer" or tachimochi follows him into the arena. The sword is a Japanese katana and symbolises the samurai status of the yokozuna. The tachimochi will always be the more highly ranked of the assisting wrestlers. As indicated above, during the ceremony the yokozuna will wear his tsuna around his waist. The ceremonial aprons of all three form a matching set. Once in the ring the yokozuna takes centre stage and performs a much more complex ritual dance. The dance can take one of two forms, one of which the yokozuna usually chooses when he is first promoted. In addition to the slightly different routine the choice of the yokozunas ritual can also be determined by the knot used to tie the rope around his waist: the "Unryū" style has only one loop at the back, while the "Shiranui" style has two. The styles are named after 10th yokozuna Unryū Kyūkichi and 11th yokozuna Shiranui Kōemon of the Edo period, although there is no historical proof that they actually carried out the dances that have been attributed to them. Indeed there are some scholars who believe that in fact the two concerned have had their ring entering rituals mixed up by earlier historians. When a former yokozuna reaches the age of 60, he usually performs a special ring-entering ceremony known as kanreki dohyō-iri, wearing a red tsuna, in celebration of his longevity. This ceremony first started with the former yokozuna Tachiyama in 1937. As of