Thoughts on the ACL – Rob Gronkowski, Jake Ballard, and Adrian Peterson’s “Baby Knee”

ACL injuries are mostly season-ending, not career-ending. Dr. Christopher Geary, Chief of Sports Medicine at Tufts Medical Center, explains why recovery is more certain and shorter than ever for NFL and college football players.

Nine months from the moment that his season came to an abrupt and traumatic end on the turf at Gillette and almost exactly eight months since he had his ACL reconstructed, Rob Gronkowski returned to the field on Sunday. Even with the look we got yesterday, questions abound. Is he going to be the old Gronk? Is he going to be limited, either with respect to playing time or ability?

Based on what we saw, the answer to the first question is “Not yet,” while the rejoinder to the second is “In the short-term, yes.” Taking a step back, though, the very idea that an NFL player might even be active for a game eight months after ACL surgery would have seemed ludicrous a decade ago. What has changed? Why is it even feasible for Gronk to trundle down the seam so soon after going under the knife — a period that used to take up to two years? The answer is multifactorial and encompasses both his own specific injury and the evolving science of rehabilitation and recovery.

First off, and probably most importantly, not every ACL injury is created equal. For the most part, if your ACL is torn, your ACL is torn – it’s like being pregnant, you either are or you are not. Partial ACL tears are almost nonexistent. What really differentiates one injury from another is the associated damage – is there an MCL tear, a meniscus tear, articular cartilage damage? That collateral damage is what can prolong a player’s recovery period and impact his overall prognosis. In Gronk’s case, he had a tear of his medial collateral ligament as well, which healed non-surgically but delayed his procedure by about a month to allow that healing to occur. Absent that, he might have had his surgery sooner.

In the case of Jake Ballard, he had a significant injury to the articular cartilage of his knee – that necessitated microfracture surgery in addition to his ACL reconstruction. The microfracture technique is used when there is a significant injury to the articular, or “surface” cartilage of the knee. The idea is that holes are drilled in the end of the bone in an attempt to grow new cartilage; it is a well-described technique with good results, but not as reliable or predictable as ACL surgery itself when it comes to recovery. Not only did Ballard’s need for microfracture prolong his recovery, it was probably the one factor which most impacted his ability to return successfully from his injury.

ACL reconstruction is a relatively reliable surgery with an 80-90% success rate for even elite athletes, but when you add in damage to the meniscus or especially the articular cartilage, the recovery becomes much more fraught with doubt. A contrast to Ballard is Adrian Peterson, who famously came back the year after his injury and surgery to have a phenomenal season. After performing the operation, Dr. James Andrews commented that aside from his ACL tear, Peterson had a “baby knee.” The joint showed no signs of wear and tear from his years of playing running back, and he had no other acute injury to his knee aside from his ACL tear. The pristine state of the remainder of Peterson’s knee is likely what allowed him to recover so quickly and successfully.

Other major factors in the decreased (and more successful) rehab time after ACL surgery is the development of more advanced surgical techniques and rehabilitation methods. Even in the 1990s, surgeries were much more invasive and rehab protocols much less aggressive. It was not uncommon for patients in previous decades to be placed in a cast and not even be able to bend their knee for 4-6 weeks after surgery. This usually resulted in a knee that was nice and stable but stiffer than a board. These days, patients, and especially elite athletes, start their rehab process in the days after surgery with methods such as early motion and passive stimulation of muscle groups that can’t be actively rehabilitated in the early post-op period. The end result of these advanced techniques are legs that are rehabilitated from this injury and subsequent surgery much more quickly and effectively.

So, over the course of the season, what can we expect from Gronk? He’s obviously going to play and he will likely feel good, but his knee and leg will continue to improve in subtle ways over the next 12-18 months. Almost every patient I have performed ACL surgery on has been cleared to resume playing the following year, and every one of them reported their knee felt good the first year back and even better the next year. As the leg continues to get stronger in imperceptible ways and the players get more used to their “new” knee, patients start becoming less and less conscious of the joint as an injured or rehabilitated body part. They begin using it normally and without paying undue attention to it. So if you have Gronk on your fantasy team, go ahead and start him. He and his new ACL might not play every play, but you can bet your own baby knee that he’ll be in there for the red zone.

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Inside The Pylon covers the NFL and college football, reviewing the film, breaking downmatchups, and looking at the issues, on and off the field.