What happened to gohan's arm in Dragon Ball Z?

I don't know which instance you're talking about but here are the two times that Gohan's arm got noticeably hurt. In the series Gohan is a teenager fighting Cell and his arm just gets broke in the last few little scruffs. In the movie "History of Trunks" the Androids 17 and 18 shot an Adult Gohan with a ki blast that took off his arm(In the alternate future where Trunks came from).