The Washington Redskins signed Coach Joe Gibbs to a new five-year contract today, extending through the end of the 1988 season. Gibbs was entering the final year of a three-year contract.

The Redskins also signed the entire staff of assistant coaches to new three-year contracts, retroactive to March 1, 1983.

"I can think of no man more deserving of this confidence than Joe Gibbs," Jack Kent Cooke, Redskins owner, said today. "He has been the patriarch of the great Redskin family, molding it into a potent force in professional sports."

In his first two years as Redskins coach, Gibbs has compiled a 16-9 record during the regular season (20-9 overall) and, in January, his Redskins defeated the Miami Dolphins, 27-17, to win Super Bowl XVII.

"It's a great feeling for me being a part of the Redskins' organization for the past two seasons. It has been personally and professionally gratifying," Gibbs, 42, said in a prepared statement.

Though figures were not disclosed on his new contract, Gibbs' base salary from his first contract escalated from $115,000 in 1981, to $125,000 last year, to $140,000 in 1983.

In other personnel matters, the Redskins picked up center Art Kuehn, an eight-year veteran waived by the Seattle Seahawks, and guard/tackle Roy Simmons, a fourth-year veteran waived by the New York Giants, in attempts to solve depth problems on the offensive line.

Kuehn is 6 feet 3, 255 pounds and can play every position on the offensive line, though he is primarily a center. Kuehn was drafted by the Redskins in the 15th round of the 1975 draft, but opted instead for the Southern California Sun of the World Football League. The following year, Kuehn's rights were awarded to Seattle in the NFL expansion draft. Kuehn, 30, had been with the Seahawks ever since. Last season, he played in six games, all in a reserve role. Simmons, 26, is 6-3, 264 pounds and a veteran of 48 NFL games.

The Redskins have developed depth problems on the offensive line because of an injury suffered by starting right guard Mark May (partial tear of right triceps) and because Fred Dean, who started at right guard in the Super Bowl, departed to the Tampa Bay Bandits of the U.S. Football League. May is expected back next week, at the earliest.

Bobby Beathard, general manager, said he will represent the Redskins Tuesday in St. Louis, in a meeting of representatives from each of the National Football League's 28 teams. The primary purpose of the meeting will be to take an official vote on whether to expand team rosters from 45 players to 49 players. The Redskins are strong advocates of the 49-man roster.