The 29-year-old centre-back, who joined Rangers for £12.5m from Anzhi Makhachkala on transfer deadline day, played in the 2-0 home defeat on April 20 but has missed the last two matches.
Redknapp said after the 0-0 draw at Reading that sealed QPR's relegation that the former Blackburn defender was suffering from a knee problem, although there were suggestions of Samba missing out due to a difference of opinions with his manager.
"It's just an injury, nothing more to him than that," said Redknapp.
"He's got several little injuries. I think maybe when he came here he wasn't probably up to speed with the Russian season and he has picked up loads of little niggles.
"That's the problem for him. We could force him out to play but we don't know whether he'd break down and set him back.
"When he's fit I still think he's a top player. It's been disappointing that he has picked up these injuries and hasn't shown the form that we know he is capable of."