This Preseason's Wave of ACL Tears: What's Actually Happening to the Knee

NFL training camp has been rough on knees this August. Falcons edge rusher Jalon Walker, Cowboys tight end Princeton Fant, and Panthers linebacker Nic Scourton have all been diagnosed with torn ACLs in practice within the same stretch of camp, each expected to miss the coming season.^1,2,3 None of this is unusual for the calendar — late-summer training camps and preseason conditioning reliably produce a cluster of ACL injuries across every level of sport, from the NFL down to high school fields. It's a good moment to look at what the ACL actually does, how it typically fails, and what the research says about recovery.

What the ACL Does

The anterior cruciate ligament is one of four main ligaments stabilizing the knee, running diagonally through the joint to resist forward sliding of the shin bone relative to the thigh bone and to help control rotation. It's not built primarily to absorb straight-line contact — it's built to control the knee during cutting, pivoting, and deceleration, which is exactly why so many tears happen without anyone touching the athlete at all.

Most ACL Tears Aren't Caused By Contact

Across sports, roughly 70–75% of ACL injuries occur via non-contact mechanisms — a sudden deceleration, a plant-and-cut, or an awkward landing — rather than a direct hit to the knee.⁴ Research has identified anatomical factors (like the shape of the femoral notch or the slope of the tibial plateau), biomechanical patterns (particularly a "valgus collapse," where the knee caves inward during landing or cutting), and neuromuscular factors that combine to put a given knee at higher risk in a given moment.⁴ Female athletes are also consistently shown in the literature to be at meaningfully higher risk of non-contact ACL injury than their male counterparts, a difference thought to reflect a combination of anatomical, hormonal, and biomechanical factors that researchers are still working to fully untangle.⁵

Recovery Is Measured in Months, Not Weeks

For a competitive athlete, ACL reconstruction is typically followed by a criterion-based rehabilitation process — meaning the athlete progresses through phases based on hitting specific strength and movement benchmarks, not just a calendar date. Full return to sport generally falls somewhere between 9 and 12 months post-surgery, with strength symmetry targets (often 90% or greater compared to the uninjured leg) required before an athlete is cleared for cutting and pivoting sports.⁶ That timeline is also why season-ending really does mean season-ending for an August training camp injury — there's no version of the rehab process that compresses safely into a few months.

It's also worth noting that a first ACL reconstruction isn't necessarily the end of the story. A widely cited meta-analysis found that younger athletes who return to pivoting sports after ACL reconstruction have roughly a 1-in-4 chance of a second ACL injury, either to the reconstructed knee or the opposite one, within the following years — a statistic that has helped push return-to-sport testing toward stricter, more objective criteria rather than a fixed timeline alone.⁷

What Actually Reduces Risk

The most encouraging research here isn't about treatment — it's about prevention. Structured neuromuscular training programs, which combine strength, balance, and landing-mechanics work into a team's regular warm-up, have repeatedly been shown to reduce ACL and other lower-extremity injury rates in youth and adolescent athletes, with meta-analyses reporting meaningful reductions in injury incidence for teams that adopt them consistently.⁸ These programs work best with good adherence and coach buy-in, which is part of why they're a routine recommendation from sports medicine and athletic training organizations heading into any preseason.