The Yakult Swallows announced today that Yasuhiro Ogawa was examined at a hospital in Yokohama on September 20 and diagnosed with a stress fracture in his right elbow. He will not be allowed to do anything throwing for a while. There is currently no timetable for his recovery.
[UPDATE 9/26 @ 8:04pm]
The Swallows announced today that Ogawa will have surgery at a hospital in Yokohama on October 2.
[UPDATE 10/4 @ 12:43am]
The Swallows announced that Ogawa had surgery on his elbow at a hospital in Yokohama on October 2.
Source: Daily Sports 10/3/2017
[UPDATE 10/15 @ 6:14am]
Ogawa will not do anything throwing for the rest of the year. He did resume his training on October 14. He is planning to take his time, with the ultimate goal of being ready for opening day.
[UPDATE 10/15 @ 10:59pm]
Ogawa will not be able to do anything throwing practices for about three months.
Source: Sponichi 10/15/2017
[UPDATE 1/11/2018 @ 11:40am]
Ogawa resumed throwing exercises on January 10. He threw about sixty baseballs into a net fifteen meters away from him. He is hoping to toss a bullpen session some time in February. This was the first time he threw a ball in about three months.
[UPDATE 1/16 @ 9:58pm]
Ogawa played catch on January 16 for the first time since he went under the knife in October last year. He threw the ball around for around fifteen minutes at a distance of about twenty meters.
Source: Daily Sports 1/16/2018