Rick Green, the big man of the Washington Capitals' defense, has joined his partner, Paul MacKinnon, on the disabled list.

Green Suffered a possible fracture of the right wrist Tuesday night when he tried to check Quebec's Peter Stastny and banged the Colisee boards instead.

The hope generated by the word "possible" should not be overrated. Although there was no evidence of a fracture when X-rays were taken yesterday, Dr. Pat Palumbo diagnosed it on the basis of his clinical examination.

Palumbo said he had to assume the bone is fractured on the basis of swelling, tenderness and clinical appearance. The bone involved, the carpal navicular frequently does not show immediate evidence of a fracture.

Green's wrist was placed in a cast for seven to 10 days, at which time it will be reexamined. Palumbo said that if it is definitely determined at that time that the bone is fractured, another cast would be applied for six weeks and Green would be out of action eight weeks.

If the wrist is merely sprained, as everyone hoped when Green revealed that the wrist hurt following the game, he would be out about two weeks.

Green broke the same bone in a practice collision with teammate Gord Smith in Montreal in January 1977. He missed the rest of that season and his play was affected the next year as well. However, that break caused considerably more damage, with serious displacement.

If the injury is disaster for the Capitals, it is tragedy for Green. He has been playing extremely well on regular shifts, on the power play and on the penalty killing shift. This year, he seemed ready to become one of the standout defensemen in the league.

"At first I thought he was joking, because I didn't even imagine there was a possible break in that bone after what I've been through," Green said. "I thought maybe it would just be ligaments. It's pretty sore, but I've had soreness there before.

"It's really frustrating. We're going pretty good. Throw that game in Quebec away. We've got something rolling. And I know it's going to drive me crazy sitting up there watching it.

"If there's any bright spot, it might be that it will heal quicker than that last one. It's a little higher up and it's not a complete displacement. I hope I'm not out long. It's owed to me or something. I think I've paid my dues as to missing games."

Green, who signed a four-year contract last summer, is in his fifth NHL season and has never played more than 71 games. Already this year he had been troubled by some painful bruises, forcing him to tape his left hand and use extra padding on his left elbow.

Before the season began, Green and MacKinnon were considered the two men the Capitals could not afford to lose. MacKinnon went out for the season when he tore knee ligaments in Denver Oct. 30, and the loss of Green puts tremendous pressure on the Capitals' thin defense.

"We'll just cross our fingers and hope that it's not a fracture," General Manager Max McNab said. "Rick was carrying a very heavy load both offensively and defensively, and now somebody else is just going to have to pull up to his standard.

"I'm confident somebody will step in there and play over his head. Rick has been a power and a tremendous factor in every situation. He's been lugging the puck, moving it, doing everything with tremendous confidence. He's been dominating some games for us.

"But we'll be there. That's the only way to look at it. Hank (Alan Hangsleben) will move back on defense and we'll just hope for the best."

Hangsleben, who twisted his back in Hartford and missed the 6-2 loss in Quebec, started the season at left wing, moved to defense, which he prefers, after MacKinnon's injury, and then was on the wing again in Hartford. He will be ready for tonight's 7:30 Capital Centre contest against Calgary. h

Also asked to bear a heavy load in the upcoming games will be defenseman Rick Smith, acquired from Detroit on waivers Nov. 7. Smith had played alongside Green in the games at Hartford and Quebec and will make his home debut with the Capitals tonight.