Aside from saying he's hopeful Breshad Perriman will be back on the field at some point during training camp, Ravens coach John Harbaugh declined to give a definitive timeline last week for the return of the young receiver.
Last year, Harbaugh initially downplayed a right knee injury Perriman sustained during the first full-squad practice of training camp, calling it a "day-to-day" situation. Much to the team's surprise, the 2015 first-round pick missed his entire rookie season with a partially-torn posterior cruciate ligament.
A year later, Perriman is dealing with a partially-torn anterior cruciate ligament in his left knee. The good news is that renowned orthopedist Dr. James Andrews, who performed arthroscopic surgery on Perriman early last week, didn't believe season-ending reconstructive knee surgery was necessary. Instead, he gave the player a stem cell injection to speed the healing.
The bad news is there remains plenty of uncertainty about when the wide receiver will return.
According to two doctors who didn't treat Perriman but spoke in general about the treatment of knee injuries, it might still be a while before the wide receiver knows when he'll be back on the field.
"In a situation like that, you still need to recover and heal and allow the ACL be completely healed so there is no risk for retearing it once he returns to the field," said Dr. Steve Yoon, a physiatrist (rehab physician) at Kerlan-Jobe Orthopaedic Clinic in Los Angeles. "It's also possible there were some other minor issues with the knee, whether it's debris from years of playing football or maybe even a small, frayed meniscus. Those things you can clean up during an arthroscopic procedure."
Yoon said that the effect of the stem cells could be felt by Perriman as soon as this week. However, the 22-year-old Raven will still need plenty of time beyond that to heal.
"A three-month period is a good time to undergo healing," Yoon said. "If there was no major issues found during the arthroscopic surgery and the knee is stable, then three months should be plenty of time to recover from a mild sprain or any type of arthroscopic surgery or cleanout. That amount of time would be adequate."
The Ravens have their first full-squad workout of training camp on July 28, which is about five weeks away. Their regular-season opener against the Buffalo Bills is on Sept. 11, which is in about 2 ½ months.
"Either way, you're looking at 10-to-12 weeks of a healing process before you know whether or not [the injection] is going to work," said Dr. Steven Bleckner, who practices with the Orthopaedic Specialists of Metropolitan Washington, a division of The Centers for Advanced Orthopaedics.
Bleckner, a former Ravens team physician, said it's a good sign Perriman avoided surgery, "but he'll still have lots of rehab in front of him."
That certainly beats the alternative for Perriman, who would have missed a second straight season if the ACL tear was significant enough to require reconstructive surgery. That surgery would have sidelined him for nine months to a year.
Still, Perriman's prognosis isn't clear.
"The partial ACL injury is one of the more difficult things to make a decision on," Bleckner said. "It's all about stability. You could scope the knee and look at the ligament and say, 'It looks fine,' until you poke and probe on it and it's loose. There's some folks that have the mindset that any ACL injury, partial or not, is probably not stable. They've already damaged the ligament. It becomes more of an all or none thing."
Perriman "may have a slight strain and there's no disruption," Bleckner added. "It's kind of just a little bit stretched or strained. That's probably why they scoped him and decided to try stem cell. But it still puts him on the clock for about three months until you know whether this is going to be a salvageable ACL."
Stem cell injections have become more common in recent years as quarterback Peyton Manning and golfer Tiger Woods are among the high-profile athletes to use the course of treatment in an effort to return to action.
"If you really want to try and calm a knee down and you don't want to put in something detrimental like cortisone, you can put something healthy in there like stem cells," Yoon said. "With these stem cell injections, there are a lot of other things that are in that injection – growth factors, anti-inflammatories, material that can help with tissue healing. It's becoming more and more popular. As every year goes on, especially in professional sports, physicians and providers are realizing there's a lot of upside with these injections and there's very little downside."
Yoon cautioned that Perriman will still be at risk of an ACL injury in the future.
"There's always a risk of an injury happening again," he said. "You can always retear the ACL. There's always risks involved, especially in football. It's a hard decision to make, but usually if the tear is small and the knee is stable upon examination, then you can conservatively manage it."