SAN FRANCISCO linebacker Chris Borland has told ESPN's "Outside the Lines" that he is retiring following his standout rookie season because of concerns about head trauma.

The 24-year-old Borland had a team-leading 108 tackles in his stellar rookie season, emerging as a punishing defender. He also had a sack and two interceptions.

He told "Outside the Lines" yesterday he wants to do "what's best for my health."

This is yet another blow to the team that lost coach Jim Harbaugh after the season, then watched Frank Gore, Mike Iupati, Chris Culliver and Perrish Cox depart in free agency this past week.

Borland's big announcement comes less than a week after five-time All Pro linebacker Patrick Willis walked away from football at 29.

In other 49ers news, former San Francisco defensive lineman Ray McDonald filed a defamation lawsuit yesterday against a woman accusing him of rape.

McDonald says security camera footage will show a consensual sexual encounter occurred in his hot tub.

Police say the woman doesn't recall any sexual encounters and reported blacking out after drinking alcohol and falling at McDonald's home.

She said she went to police after waking up naked next to McDonald.

The 49ers cut McDonald in December after learning of the allegation. The Santa Clara County district attorney is considering whether to file criminal charges.

McDonald's lawyer says the unresolved accusations are preventing the defensive lineman from signing with an NFL team.

The 49ers released McDonald on Dec. 22, citing a pattern of behavior and off-field issues.

The lawsuit filed yesterday in Santa Clara County seeks unspecified damages.

Noteworthy

* Former Eagles safety Kurt Coleman signed a 2-year contract with Carolina as a free agent. Coleman started 27 games for Philadelphia in 2011 and '12, but has only three starts in the last two seasons with the Eagles and Kansas City. Coleman, 26, played for Panthers defensive coordinator Sean McDermott as an Eagles rookie.

* Longtime New England nose tackle Vince Wilfork signed with Houston. Wilfork, 33, had played his entire 11-year career with the Patriots. Houston also signed receiver Cecil Shorts III, who was with Jacksonville.

* The Raiders released Matt Schaub less than a year after acquiring him to be their starting quarterback. Schaub was beaten out for the starting job by rookie Derek Carr and was released just days after Oakland signed Christian Ponder as a backup.

* Cleveland signed former Packers cornerback Tramon Williams and former Dolphins defensive lineman Randy Starks.

* New England signed free agent Scott Chandler, a 6-7, 260-pound tight end who played for Buffalo the last five seasons.

* Tennessee agreed to terms with cornerback Perrish Cox, who had five interceptions for the 49ers last season.

* Dallas signed free-agent linebackers Jasper Brinkley (from Minnesota) and Andrew Gachkar (San Diego.)

* Safety Jeron Johnson signed with Washington after four seasons with Seattle.