Knee injuries continue to mystify me. Some rikishi seem to be able to recover without significant loss of ability. Some seem to have improved. Baruto appears much more stable now after his injury and doesn't take as many nasty looking falls. Toyonoshima, Kotoshogiku, Aminishiki, and Kotooshu have all continued to be quite competitive after serious knee injuries. Kotooshu may not seem competitive right now, but unlike the other three listed with him, he did win a yusho in the last year.
Ichihara, on the other hand, seems to have degraded to the point of being totally uncompetitive. It's almost an untenable situation now, though. If he gets surgery now, by the time he recovers, he might be in jonidan.