Lonard, the defending Australian Open champion and world's No. 42 ranked player, suffered the setback while doing stretching exercises prior to a off-season training session.
He will probably miss four scheduled events, two in his native Australia and two events on the PGA Tour.
Lonard, a member of the PGA Tour, had three top 10s in 2003 including a fourth place finish at the WGC-Accenture Match Play Championship. He finished the year 50th on the money list.