Fraga sustained the injury when Simba locked horns with Mara's Biashara United in a Vodacom Premier League (VPL) duel, which took place at Benjamin Mkapa Stadium in Dar es Salaam recently.
There had earlier been reports the midfielder will be out of action for less than one month, he will for that matter miss Simba's coming four assignments.
Simba are expected to take on Gwambina, Mbeya City FC, Prisons and Yanga in the former's next four matches.
Vandenbroeck noted he and fellow coaches have not got medical report from Simba's doctor which details how long will Fraga be out of action.
"He is an important player in our side, although there are other players who can effectively play in his position,'' he disclosed.
''I have not got report from the doctor much as I have read news in some of the media saying the player will be out of action for one month, we are waiting for the report.''
Simba's Manager, Patrick Rweyemamu, as well disclosed the side's technical bench is now waiting for the doctor's report on an examination done on the player's injury.
"Honestly we have not got the doctor's report, the reports coming out of the media are mere rumours,'' he noted.
He also disclosed they are currently preparing for the VPL match against Gwambina FC, to be played in Dar es Salaam tomorrow.
"The rest of the players are in good shape and are following the head coach's training program,'' he disclosed.
In another development, Mtibwa Sugar's head coach, Zuberi Katwila, has disclosed his outfit's VPL duel with Yanga, slated for Sunday in Morogoro, will be more tactical.
Katwila stated lack of concetration by one of the two sides' will make the squad concede loss.
He was of the opinion the game, which will take place at Jamhuri Stadium, will see the two sides commit mistakes which will lead to victory for one of the teams.
"It will not be an easy game for either of us, I know Yanga will be keen on winning given they notched victory in their previous two clashes but we are unpertubed by their achievement, we know their weaknesses,'' Katwila disclosed.
He stated he believes Yanga will punish his players, if the latter will commit mistakes, noting the same will apply to his side.
"Better preparation is the most important thing for us, we are curently shaping up for the game, we appeciate the fixture will take place at our home venue,'' he noted.
Yanga have headed to Morogoro to participate in their second away clash in this season's VPL.
In Yanga's first away fixture, the squad posted 1-0 victory over Kagera Sugar at Kaitaba Stadium in Bukoba.
The victory has seen Yanga collect seven points from three games, winning two and posting draw in the other.