A former D.C. United goalkeeper is suing an ex-teammate, as well as Coach Ben Olsen, the team and Major League Soccer, for an incident last year that he says left him with a concussion and forced him to retire at age 22.

Charlie Horton, who was on United’s roster for nine months and did not appear in any matches, said in court documents filed in D.C. Superior Court this week that forward Fabian Espindola elbowed him in the head following a team meeting at RFK Stadium last spring.

Horton is seeking compensatory and punitive damages to be determined at trial.

Horton referred questions to his attorney, who was not immediately available to comment. United, MLS and Olsen, through his agent, said they did not want to comment. Espindola is now playing in Mexico and couldn’t be reached.

Courthouse News Service was first to report about the 18-page complaint.

United did not exercise the option on Horton’s contract after last season but invited him to training camp. He was medically cleared to participate and reported to workouts in Florida but cut about a month later.

The incident allegedly took place March 29, 2016, following a video session. According to the complaint, Espindola engaged Horton in conversation stemming from an incident between the two at practice two weeks earlier.

Horton claimed he did not want to continue the discussion and, when he turned away, Espindola elbowed him in the left temple. Teammates and staff witnessed the incident, the suit alleges, and pulled Espindola away.

Horton experienced “dizziness, shakiness, visual disturbances, nausea, sensitivity to light and sound and other symptoms,” according to court papers. The next day, United’s medical staff diagnosed a concussion.

At the time, the team said he had suffered the injury during practice.

One person familiar with the situation, who requested anonymity because of the legal nature, said the incident “happened and was pretty upset about it. apologized, but the damage was done.”

United did not suspend Espindola but, according to a source, fined him. He played all 90 minutes of the April 2 match at San Jose and, a week later, scored two goals against the Vancouver Whitecaps.

Horton was sidelined for about two months, then assigned to United’s third-division affiliates, the Richmond Kickers. He made 10 appearances before fracturing a finger. That injury, combined with issues related to the concussion, prevented him from playing again last year, he claimed in the court filing.

It also said his attempt to make the team this year was undermined by post-concussive symptoms. Horton was vying for the third-string role behind Bill Hamid and Travis Worra. United, instead, signed Eric Klenofsky, a second-round draft pick.

The severity of the neurological symptoms, Horton alleged, left him unable to “perform at a level necessary to continue his career.”

The suit claims “all or some” of Horton’s ailments are “permanent in nature” and that he will “continue to incur expenses related to medical treatment and rehabilitation.”

It also cited emotional and psychological distress and quality-of-life issues.

Espindola, 31, played 10 seasons in MLS, the last three with United. The Argentina native was D.C.’s top performer in 2014 with 11 goals and nine assists and, in the subsequent two years, totaled nine goals and eight assists in 32 matches.

In the final year of his contract and carrying one of the team’s top salaries, United traded him last summer to Vancouver for general allocation money. Instead of reporting to the Whitecaps, however, he signed with Mexican club Necaxa.

Espindola’s temper marred his stint in Washington. In the 2014 playoffs, he shoved an assistant referee at the end of a match and was suspended for the first six games of the 2015 season, one of the longest bans in league history.

Earlier in 2014, Espindola was suspended two games and fined by MLS for violent conduct against Montreal’s Felipe Martins. It was in retaliation for Martins’s unnecessary contact seconds into the match, a play that damaged Espindola’s knee and sidelined him for several months.

In the suit, Horton cites Olsen and United for negligent supervision, claiming they were “on notice of history of violent conduct.” Horton claimed Olsen told him it was “only a matter of time before Espindola caused physical harm to a teammate.”

MLS is liable, the suit says, because, in its centralized business structure, the league owns all teams and player contracts.