Arena Football may have funky new rules that distinguish it from the regular game and the National Football League, but there is at least one similarity that remains.

Knee injuries.

A hit there, a misstep here, and it's see you next season. And playing every game on the artificial turf can make things even worse in the indoor league.

During the Washington Commandos' 36-20 victory over the Denver Dynamite Saturday night at Capital Centre, two players fell victim to knee injuries, and both will be out the rest of the six-game season. Washington running back/defensive back Richard DuPree tore ligaments in the fourth quarter while blocking, and Denver quarterback Marty Mornhinweg rolled over on his knee when he was sacked in the second quarter.

DuPree was upfield blocking Denver's Richard Prather when two teammates crashed into his leg -- including quarterback Richard Ingold, the ball carrier who got the two yards needed for a first down that set up a Washington field goal. DuPree said the injury could have happened anywhere.

"It was kind of a freak thing," said DuPree, who said he likely will return home to Seattle to have surgery. "But every time you put on pads, you take a chance something like that will happen."

When Chicago routed Pittsburgh, 60-23, Friday night in the Rosemont (Ill.) Horizon, two other players banged up knees badly enough to probably miss the rest of the season. One was Pittsburgh's Mike Hohensee, a quarterback from Germantown, Md., who once played for the USFL Washington Federals. Hohensee, who completed 25 of 39 passes for 354 yards last week in Pittsburgh's season-opening victory over the Commandos, was hit directly on his knee while being sacked in the second quarter. Chicago's Ken Sanders also damaged knee ligaments during the game when his foot caught in the turf.

"Hohensee is the best quarterback in the league," said Chicago assistant coach Gino Nudo. "That's the last thing anyone wants to see. He adds a lot of credibility to this league."

Mornhinweg's injury was "typical" for a game played on artificial turf, and probably wouldn't have happened on grass, according to Denver Coach Tim Marcum. The injury leaves Marcum in a tough spot, since he had just put in Mornhinweg to replace Stuart Mitchell, who completed only eight of 27 passing attempts. Marcum has only Mitchell at quarterback next Friday when Denver hosts Washington, although he said he will quickly sign another. However, he added, the signee likely won't be one who has been through the league's training camp, and therefore will need to learn the indoor game.

The surface the Commandos played on on Saturday, one layer padded only by another, face-down layer of artificial turf, originally was used by the Pittsburgh Spirit soccer team 12 years ago, according to Jerry Obie, head utility worker at Pittsburgh's Civic Arena. The turf is being shipped between Capital Centre and the Civic Arena for arena football games, while another one goes between Chicago and Denver.

Washington Coach Bob Harrison said the arena players have made "great adjustments" to avoid injury, by pulling off a hit at the right time and by watching the abrupt ending of the turf along the sideline.

During the game, Harrison made some adjustments to control the Dynamite, which had beaten Washington, 20-18, in a two-quarter exhibition two weeks ago. On films, he noticed Denver's frequent blitzing -- and the Dynamite blitzed even more than he expected Saturday -- so he worked in an option attack to throw the Dynamite off guard. The attack also allowed receiver Lenny Taylor to gain 115 yards on seven receptions.

"I've never really been one to think that the game plan can be a deciding factor, but Harrison really had a great one," said DuPree, who caught three passes for 26 yards before his injury. "Running the option really did open up the passing game and, once we were able to get the short passing game going, that opened things up for Taylor."

Marcum said blitzing was the best thing he could do, considering that Washington went up, 14-0, in a little more than three minutes. "We were just trying to do something to change the pace of the game," he said.

After scoring on their first drive, the Commandos got a break when Mitchell fumbled on Denver's 2-yard line, and Washington's Mike Witteck grabbed it to set up another touchdown. "They out-hit us, out-caught, out-threw, everything," Marcum said. Denver 7 0 13 0 20 Washington 17 7 6 6 36

W -- DuPree 10 pass from Ingold (Castro kick)

W -- Holman 2 pass from Ingold (Castro kick)

D -- Smith fumble recovery in end zone (Mike-Mayer kick)

W -- FG 50 Castro

W -- Taylor 8 pass from Ingold (Castro kick)

D -- Trimble 44 pass from Mitchell (Mike-Mayer kick)

W -- Holman 11 run (kick failed)

D -- Mitchell 8 run (kick failed)

W -- FG 27 Castro

W -- FG 31 Castro

A -- 13,507

Dynamite Commandos First downs 7 12 Rushes-yards 13-40 14-34 Passing yards 104 166 Return yards 85 16 Passing 11-31-0 17-28-0 Fumbles-lost 3-2 2-1 Penalties-yards 1-8 4-15 Time of possession 29:07 30:

RUSHING -- Denver: Brewer 4-16, Mitchell 6-11, Mornhinweg 1-9, Prather 1-7, Trimble 1-minus 3. Washington:

PASSING -- Denver: Mitchell 8-27-0, 113 yards, Mornhinweg 3-4-0, 30. Washington: Ingold 17-28-0, 195.

RECEIVING -- Denver: Trimble 5-102, Brewer 4-25, Mullen 2-16. Washington: Taylor 7-115, Dixon 5-31, DuPree