The Black Cats have been plagued by injuries throughout the campaign, with a number of key players spending several months on the sidelines, something which hasn't helped their quest for a top-ten finish.
Fraizer Campbell, Michael Turner, David Meyler and Craig Gordon have all suffered knee trouble, with defender Titus Bramble the latest player to be ruled out with a cartilage problem.
What's even more worrying for Bruce is that four of those players, Campbell, Meyler, Turner and Bramble, have all suffered recurrences of their injuries.
The Black Cats boss believes it can't be down to coincidence and admits he is trying to get to the bottom of the lingering problem.
"I haven't got a clue about medicine, I haven't got a clue about physiotherapy or doctors," Bruce said.
"But I have asked the question as to why we've had four serious knee injuries and four recurrences. That can't be coincidence.
"We've asked that question, but it's very difficult. Is it a coincidence I really don't know. But certainly it's very frustrating.
"With Titus having a recurrence, that's four of them who have had knee operations and that's not healthy. To be fair, the pitches are absolutely fantastic to look at, but they are rock hard.
"It's the recurrences for me. You get injuries like Turner sliding and hitting the post, Fraizer's is a normal cruciate ligament, Meyler cruciate and Titus a cartilage. It's difficult.
"Craig has been unfortunate because he started the season so well - that's another recurrence. You've jogged my memory there - five operations, five recurrences."
After enjoying a strong first half of the season, The Wearsiders have found themselves in a similar situation to last year, when a 14-match winless run saw their chances of a top-half finish disappear.
And once again, after spending the whole season occupying a place in the top-ten, last weekend's mauling at the hands of Manchester City saw Bruce's side drop down into the bottom half of the Premier League, just six points off the relegation places.
Bruce believes there is a number of reasons behind his team's disappointing run of form but he pinpoints the loss of Danny Welbeck as a major factor.
The striker was ruled out for three months with a hamstring injury when the Black Cats were already dealing with the departure of Darren Bent and in the absence of both, Bruce was left severely short up front.
Now though, Welbeck is back and Bruce hopes the newly-capped England international's return can provide the cutting edge his side has been lacking for a while.
"There are all sorts of reasons (for their dip in form), but if you didn't have a bad run you'd win the league and finish in Europe," said the Black Cats boss.
"If Arsenal can go six (without a win) and Chelsea eight, anyone can, but for me, the loss of the strikers, Welbeck and Campbell, that was where we were better than half of the league.
"Unfortunately we've lost that, along with the other big injuries we've had. And with the fixtures we've had to play we've found it very very difficult, so there was no hiding place from it. You don't try to make excuses, but those are the facts.
"We had 37 points from our 24 games towards the end of January.
"We couldn't have asked for anything better. We were on a run then. We needed one win by the end of January to be safe.
"We haven't won since, although it is only eight games since January and six have been against the top-six.
"But we need to get the momentum back. When we lost Welbeck he was arguably our best striker, and we lost him for three months. That's coincided with not really having a cutting edge.
"But Danny is back and hopefully he'll get a run like before when he scored seven in nine or ten games."
Sunderland welcome Roy Hodgson's in-form West Bromich Albion to the Stadium of Light today, looking to put an end to their seven-match winless run.
Keen to rejuvenate his side, Bruce is expected to make a number of changes to the team that lost heavily at Eastlands last week, with Kieran Richardson and Nedum Onuoha set to return to the starting line-up.
Jordan Henderson is expected to be rested after making 39 consecutive starts for the Black Cats.
Since making his England debut last November, the 20-year-old has struggled to recapture the form that won him a place in Fabio Capello's squad, and with Richardson and Cattermole back from injury, it seems the ideal time for Bruce to take his young midfielder out of the firing line.