Former Washington Redskins defensive end Dexter Manley has joined the list of former NFL players who are suing the league over the effects of concussions.

Manley, 53, played for the Redskins between the 1981 and ’89 seasons. He also spent time with the Phoenix Cardinals and Tampa Bay Buccaneers.

Manley and a group of former players filed their lawsuit last week in U.S. District Court for the Eastern District of Pennsylvania. It claims that the NFL “continuously and fervently denied that it knew, should have known or believed there to be any relationship between NFL players suffering concussions while playing, the NFL policies concerning tackling methodology or the NFL policies about return-to-play, and long-term physical, neurological, mental and cognitive problems… that many players have experienced.”

Manley’s participation in the concussion-related litigation was first reported by the Washington Times.

Approximately 100 similar lawsuits have been filed by other former players. The NFL has denied the allegations.

The league, in response to the lawsuits, issued a recent written statement that said: “The NFL has long made player safety a priority and continues to do so. Any allegation that the NFL intentionally sought to mislead players has no merit. It stands in contrast to the league’s actions to better protect players and advance the science and medical understanding of the management and treatment of concussions.”

Manley was one of the Redskins’ most popular and productive players, amassing 91 sacks during his tenure with the team. But he battled substance abuse problems during and after his playing career and spent time in prison on drug-related charges after leaving the NFL. Manley reportedly experienced minor memory loss after undergoing brain surgery in 2006 for a cyst.