MINNEAPOLIS — An arbiter appointed by the NFL ruled Friday that Minnesota Vikings star running back Adrian Peterson will remain suspended until at least next spring in the child-abuse case that has sidelined him for all but one game this season.

The decision by Harold Henderson, a former league official, upheld the NFL’s decision last month to suspend Peterson without pay for the remainder of the season and not consider him for reinstatement before April 15.

Peterson was paid during his appeal, but Henderson’s ruling means Peterson will forfeit checks from the team’s last six games. That amounts to a fine of more than $4.1 million.

The NFL Players Association called Henderson’s objectivity into question and said it was “considering immediate legal remedies” to the decision.

“The NFLPA expected this outcome, given the hearing officer’s relationship and financial ties to the NFL,” the union said in a statement. “The decision itself ignores the facts, the evidence and the collective bargaining agreement. This decision also represents the NFL’s repeated failure to adhere to due process and confirms its inconsistent treatment of players.”

The Vikings declined to comment. Peterson is a three-time, first-team Associated Press All-Pro and reached the Pro Bowl in six of his first seven NFL seasons, all with Minnesota. Peterson led the NFL in rushing twice, including 2012 when his 2,097 yards fell 9 short of breaking Eric Dickerson’s all-time record, but he may never play again for the Vikings after this mess.

Peterson was charged with felony child abuse in September for using a wooden switch to discipline his 4-year-old son, but he pleaded no contest to misdemeanor reckless assault in November. He had been on paid leave, on a special exempt list at the discretion of NFL Commissioner Roger Goodell, while his case moved through the court system.

At the crux of the NFLPA’s argument for reinstatement was what NFL executive vice president for football operations Troy Vincent told Peterson last month when the dispute was at its height. According to a person with knowledge of the conversation, Vincent told Peterson he would receive a two-game ban if he attended a hearing on Nov. 14 with Goodell.

Peterson declined to meet that day with Goodell, citing uncertainty about the NFL’s intent to question him. Goodell then announced on Nov. 18 that Peterson would be suspended for the six games that remained for the Vikings at the time and not be considered for reinstatement until April.

A recording and a transcript of what Vincent told Peterson was presented by the NFLPA to Henderson, who oversaw a hearing on Dec. 2. Peterson attended that and listened via telephone as the hearing continued on Dec. 4, when Vincent was questioned.