The 28-year-old was taken off on a stretcher during Wales' win over South Africa in November.
Lydiate subsequently missed the rest of the 2016-17 campaign.
"Dan is continuing his rehab from knee and shoulder surgery having been out of action since November," Ospreys medical performance manager Chris Towers said.
"The objective now is to make every effort to have him available for selection at the start of the season."
Dafydd Howells will miss start of next season as the Wales wing recovers from injury.
"Daf failed to recover from a shoulder injury picked up in training at the end of the season, which meant he has gone on to have surgery," Towers added,
"As a result we expect him to miss the start of the season."
But there is better news on wing Jeff Hassler, who will miss part of pre-season after keyhole surgery on a knee problem but is expected to return for the start of the new season.
Hooker Sam Parry (neck) has returned to limited training, while senior players Dmitri Arhip, Ma'afu Fia, Ben John and Rob McCusker have all rejoined the squad after injury.
Hanno Dirksen (knee), James King (ankle), Brian Mujati (shoulder) and Eli Walker (back) have yet to return to training because of their injuries.
Ospreys' Wales flanker Dan Lydiate is battling to be fit for the start of the 2017-18 season as he recovers from knee and shoulder surgery.