The undrafted free agent out of Illinois will have surgery on the knee this week. He could return later this season.
LaCosse, 23, had impressed this spring and summer, and it appeared he was going to play a significant role, especially considering his ability as an all-around tight end. The Giants have struggled badly with blocking at this position the past two weeks, and for much of the past few years.
LaCosse was splitting first-team reps with Will Tye and Larry Donnell up until tweaking his right knee while catching a pass from quarterback Eli Manning several weeks ago during practice. He tried to play through the problem, but the pain became increasingly worse. He was limping to the line of scrimmage last week against the Buffalo Bills and did not practice this past week. Instead, he worked on a side field with trainers.
It is possible the knee surgery could end LaCosse's season.
Malleck struggled when he worked with the first team Saturday night against the New York Jets. Johnson has been sidelined the past two weeks with a stinger but is expected back soon. Adams is a rookie seventh-round pick out of South Carolina.
LaCosse hurt his hamstring and was waived by the Giants last summer. He was re-signed during the season to the practice squad, before being elevated to the active roster late last season. LaCosse played in two games and had three receptions for 22 yards. His role was expected to increase significantly this season, and it appeared he made significant strides during the spring and early this summer.
"He brings a knowledge of the position, number one, and he's a big target," Giants tight ends coach Kevin M. Gilbride said earlier this summer. "I would say overall as far as him going into his second season, he does everything pretty well."
Tye and Donnell are both known as pass-catching tight ends. The Giants' search for a sufficient blocker at the position continues.