Less than a week into preseason practice, Tennessee offensive lineman Nathan Niehaus left the team.

His decision marked the first attrition since the preseason started, but continued a trend for UT.

NIehaus is the eighth player to medically retire since last season ended, following the likes of linebacker Darrin Kirkland Jr. and tight end James Brown. The remaining six were all offensive lineman.

Here is a look at all six, listed in chronological order:

Tanner Antonutti

Antonuitti was the first offensive lineman in Pruitt's tenure to take a medical retirement.

Recurring herniated disc injuries forced him to give up football in December. Antonutti signed with Tennessee in 2018 as a three-star prospect out of Ensworth High School in Nashville. He redshirted this season. His injury kept him sidelined from practice.

He remains on medical exemption scholarship at UT as a student assistant.

Devante Brooks

Days after Antonutti left football, Brooks did the same. He retired in December.

The sophomore offensive lineman did not play in 2018, as an undisclosed injury prevented him from practicing.

Brooks started the final four games of the 2017 season at right tackle. He remains on medical scholarship.

Chance Hall

Hall would have been a fifth-year senior this season, but he retired from football, Pruitt said in February.

He had an injury-plagued run at Tennessee after a career that started with promise. Hall started seven games as a freshman, then six as a sophomore. He missed the entire 2017 season with a knee injury and had surgery in March 2018 before returning to play in eight games in 2018.

He remains on scholarship.

Eric Crosby

Crosby announced on May 1 that he would be ending his career and medically retiring. He cited "a knee injury that would not get right" and left him in "constant daily pain" as the reason for his retirement.

Crosby, a third-year sophomore, did not play in any games in his Tennessee career. He was named to the 2017-18 First-Year SEC Academic Honor Roll.

The 6-foot-1, 328-pound Crosby was ranked the No. 215 recruit in the nation for the class of 2017, according to the 247Sports Composite.

Melvin McBride

McBride committed to Tennessee in Aug. 2018, then arrived on campus this summer. The Vols discovered a "personal medical condition" during a pre-participation physical this summer.

He took a medical retirement before playing at Tennessee.

McBride committed to Tennessee in August 2018. He graduated from Whitehaven High School in Memphis.

The 6-foot-3, 312-pound McBride was ranked the No. 475 prospect nationally and No. 16 in the state of Tennessee, according to the 247Sports Composite.

He remains on scholarship.

Nathan Niehaus

Niehaus left UT on Wednesday, Pruitt said after the Vols practiced. The junior posted a statement on social media Thursday, pointing to "sustained injuries and the overlapping wear on my body" leading to his decision to retire from football.

Niehaus started six games in 2018, all at right guard. He played in 10 games last season after not playing as a redshirt freshman in 2017.

The 6-foot-6, 300-pound Niehaus was working as a backup right guard behind K'Rojhn Calbert during preseason practice. He was expected to provide depth to a group that has struggled in the past two seasons.