Pittard last played against the Gold Coast Suns in Round 4.
He pulled up with general soreness after that game before further investigation revealed a hip flexor issue.
It saw him withdrawn from the team that defeated West Coast in Round 5.
He has been listed for assessment in the past two weeks, however Hinkley conceded the hip had not recovered in the way club fitness staff expected.
"Jasper has had his best pre-season ever," Hinkley said.
"We thought he'd be only a week (out), now it looks like he could possibly be another two or three weeks.
"Like with any injury, you expect them (injuries) to behave a certain way, but then there's the ones that come from nowhere and cause you a little grief.
"We're not going to take a risk (in bringing Pittard back early)."
Hinkley confirmed that Jackson Trengove's recovery from a foot injury continues to progress well, despite him being projected to return in eight weeks.
He also suggested Dom Cassisi would firm for a recall to the side if he successfully completed the club's main training session today.
Cassisi missed last week's loss to Richmond with a hamstring complaint.
He has been listed for assessment in the past two weeks, however Hinkley conceded the hip had not recovered in the way club fitness staff expected.
"Jasper has had his best pre-season ever," Hinkley said.
"We thought he'd be only a week (out), now it looks like he could possibly be another two or three weeks.
"Like with any injury, you expect them (injuries) to behave a certain way, but then there's the ones that come from nowhere and cause you a little grief.
"We're not going to take a risk (in bringing Pittard back early)."
Hinkley confirmed that Jackson Trengove's recovery from a foot injury continues to progress well, despite him being projected to return in eight weeks.
He also suggested Dom Cassisi would firm for a recall to the side if he successfully completed the club's main training session today.
Cassisi missed last week's loss to Richmond with a hamstring complaint.
