SANTA CLARA Justin Smith's triceps muscle is as big as a normal man's thigh. He can bench press a dump truck. He can chop down a redwood with one swing of an ax.
Point is, the 49ers defensive lineman is a powerful guy.
Ask Jermon Bushrod or Drew Brees. Last year in the playoffs, Smith shoved Bushrod, a 315-pound left tackle for the New Orleans Saints, backward as if he were on roller skates. While bull-rushing Bushrod with his left arm, Smith reached out and grabbed Brees by the collar with his right hand, then yanked both to the ground.
With apologies to quarterback Alex Smith and tight end Vernon Davis, Smith was the 49ers' most dominant player in the playoffs a year ago. He set the tone early in the Saints game, then brutalized Eli Manning and the New York Giants' offensive line the following week in the NFC Championship.
As the 49ers venture into the playoffs again next week, the biggest question is whether they will have the same Herculean, havoc-wreaking lineman they had last year at this time.
The problem is Smith's left triceps, which he uses to push and pull offensive linemen, often two at a time. He suffered a partial tear of the tendon that attaches the muscle to the elbow on Dec. 16 and hasn't played since.
Smith returned to practice Thursday and has said he will play in the 49ers' playoff opener Jan. 12.
Even Smith doesn't know how effective he can be.
"Hopefully, they run right at me and we find out quick," Smith said.
Two orthopedic surgeons said nearly every question about Smith's injury depends on how much of the tendon is torn, something the 49ers haven't divulged. If it's a high-grade tear more than 50 percent torn Smith wouldn't be close to full strength. There's a chance that even a small tear could rip completely, which would make his arm useless.
"It's something you definitely can't quantify," said UC Davis orthopedic surgeon Cassandra Lee. "But there's certainly a risk for a full tear."
Lee said St. Louis Rams receiver Danny Amendola was in a similar situation last year. He suffered a dislocated elbow early in the season, rested and rehabilitated for a couple of weeks but then aggravated the injury in practice and had to have season-ending surgery.
Another orthopedic surgeon, Dr. George "Rick" Hatch, said Smith probably has spent the past few weeks working on the range of motion in his elbow and making sure he doesn't lose strength in his left arm.
Still, Hatch said it would take six to 12 weeks for even a small tear to heal. If Smith starts next Saturday, it will be 27 days since he incurred the injury.
"He can probably expect to be 70, 80 percent of full strength," said Hatch, an assistant professor of orthopedic surgery at USC. "He's not going to be 100 percent."
Smith isn't interested in percentages.
He isn't much of a talker, but he spoke at length in June about windows of opportunity and how quickly they can slam shut.
Smith noted at the time that a 49ers defense that boasts six Pro Bowlers this season is full of youngsters except him.
Smith, 33, is closing out his 12th season, and his contract takes him only through next season.
"I figure I got three more good years in me, four more good years," Smith said in June. "I don't want to be the guy that becomes the third-down guy, plays 17 (snaps). I don't want to do that. I'm figuring, let's go.
"Time is of the essence for me, personally. Not everyone else. We have a young defense. But I think everyone feels the urgency, and we've got the guys right now. Let's not wait."
Translation: As long as his triceps is attached to his elbow, he'll be on the field.