Exasperated Sunderland boss Steve Bruce is to launch an inquiry into why so many of his players break down in games.
The Black Cats have been severely hampered in recent weeks by having to make early substitutions which have disrupted the plans on which they have worked on the training pitch.
Lee Cattermole and Kieran Richardson had both limped off after 23 minutes of the defeat by Liverpool on March 20 had elapsed, while both John Mensah and Richardson again failed to last beyond the half-time whistle on Saturday against West Brom.
Bruce said: "It isn't happening on the training ground, it happens out there all the time in the match."
Bruce has repeatedly insisted he does not want to make injuries an excuse for the club's disastrous run of form, which has seen them collect just a single point from their last eight Barclays Premier League games.
He added: "It's something we will have to analyse. It is not a coincidence. We have had five operations and all five of them have broken down, so it is hampering us. I am not trying to blame anybody - I will take the blame - but we will have to look into it as to the reason why it keeps recurring like it is at the moment."
Bruce's team on Saturday included two men - defender Michael Turner and striker Danny Welbeck - who have just returned from long-term knee injuries, while Fraizer Campbell is close to doing the same.
However, Titus Bramble is struggling to play again this season because of a cartilage problem and keeper Craig Gordon is currently fit enough only to sit on the bench as he continues with a specially-designed programme to help him avoid knee surgery.
In addition, midfielder David Meyler has managed only five appearances this season because of serious knee injuries, making Bruce's concern understandable.
He added: "It's been particularly frustrating from the offset, really, that we have had big trauma injuries to big players of ours. Unfortunately in the end, it does catch up with you.
"You can maybe get away with it for a couple of weeks, but when you are talking months like Michael Turner and Fraizer Campbell and David Meyler and Danny Welbeck.
"Everywhere I look, people have missed three and four months, which has been far, far too many, and that's why I have got to ask now why, why is it us? We will try to get to the bottom of that."
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