49ers FB Kyle Juszczyk out 4-6 weeks with knee injury

SANTA CLARA, Calif. -- San Francisco 49ers fullbackKyle Juszczykis expected to miss four to six weeks due to a sprained left medial collateral ligament in his left knee.

The Niners announced the injury and time frame on Tuesday afternoon, less than 24 hours after Juszczyk suffered the injury in a 31-3 win against the Cleveland Browns on Monday night. Because the injury isn't expected to last as long as eight weeks, Juszczyk will avoid joining the injured reserve list with hopes of returning sooner than later.

With a little more than three minutes remaining in the third quarter, Juszczyk was blocking on a run play when he and Browns safetyJermaine Whiteheadcollided. Juszczyk lost his footing as Whitehead undercut him, and he landed awkwardly on his left knee. He was able to hobble to the sideline before a cart took him to the locker room, ending his night.

After the game, 49ers coach Kyle Shanahan indicated he thought it was a sprain rather than a serious, season-ending type of knee injury. Juszczyk told ESPN in the locker room that he wasn't yet sure of the severity but that he would have an MRI on Tuesday morning.

The additional tests confirmed the Niners' initial suspicions, leaving the team without an integral part of its offense for at least the next month. It's a big blow to an offense that ranks fourth in the league in yards per game (427.3) and yards per play (6.28), first in rushing yards per game (200) and second in points per game (31.8).

Juszcyk said via Twitter on Tuesday that he will be back soon.

"Obviously, Juice is a vital part to our offense and especially our running game," right tackleMike McGlincheysaid. "But we have a lot of guys that are capable of playing that position. All three of our other tight ends, includingGeorge Kittle, can do it if he's required to. But Juice is a mainstay in our offense. He's tied in with the five of us up front, six of us including George, and we don't go without him. Hopefully we can pick up the slack here coming up in the next week if he is out. But he is huge for us. He makes plays all over the field. He's the unsung hero. Other than the couple times he gets to catch a pass, he's got an O-line mindset."

Juszczyk is the only fullback on the roster as Shanahan has previously said he values having a versatile player like Juszczyk more than just having a fullback. So far this season, Juszczyk has lined up split wide (4 percent of snaps), in the slot (6 percent), tight to the formation on the line of scrimmage (16 percent) and in the backfield (74 percent).

Through four weeks, the 49ers have used two running backs more than any other team, with two backs on the field 51.5 percent of the time.

Those personnel groupings have come with plenty of success as San Francisco has averaged 7.3 yards per play, scored nine touchdowns, averaged 11.8 yards per pass attempt and picked up 13.8 first downs per game with two backs on the field, according to ESPN Stats & Information.

In Juszczyk's absence, it's unlikely the Niners will look to add a fullback because there are none on the market who can do everything Juszczyk does. Without Juszczyk, the Niners are likely to turn to tight ends Kittle,Ross Dwelley and Levine Toiloloto fill the void on a more regular basis or to go without a fullback more than they have through the first four games.

Juszczyk's injury is the latest in a string of bad luck in which the 49ers have lost a starter to injury for at least a pair of contests in each of their four games. Running back Tevin Coleman sprained his ankle in the opener against Tampa Bay and returned after missing two games. Left tackle Joe Staley (broken fibula) and cornerback Ahkello Witherspoon (sprained foot) are also out for extended time due to injuries suffered in Weeks 2 and 3, respectively.