Jimmy G ACL Injury: The Classic Non-Contact ACL Rupture

During week three of the Niners eventual loss to the Kansas City Chiefs, Niners starting QB Jimmy Garoppolo (aka Jimmy G) was scrambling on third and goal when he went to plant his left foot into the ground to take on an incoming defender.

Here’s the video of that moment:

Jimmy G was carted off the field and the medical staff likely performed a hands-on test known as the Lachmann test to test the looseness (laxity) of the ACL:

Based on the testing, the team feared an ACL rupture and those fears were confirmed on Monday through MRI imaging.  The team promptly announced that Jimmy G would miss the rest of the season.

After watching the replay, I was pretty sure he had ruptured the ACL. It was the classic mechanism, nearly to a tee, for a non-contact ACL injury.  In general, most ACL ruptures happen during a non-contact movement (click here, here and here for more info).

That classic non-contact mechanism for ACL rupture is an unanticipated/reaction cut on an extended (straight) leg followed by adduction (going inwards) and internal rotation (rotating towards midline) of the leg.

jimmy g
Credit – BJSM

Lets go through each phase of that mechanism:

I. Unanticipated/Reaction Cut

Reactionary movement relies on what is known as the neuromuscular system (it’s actually multiple integrated systems).  It provides unconscious feedback to your brain about where your body is in space. Through this feedback, muscles are timed and activated to optimize joint stability and promote efficient and effective movement.

The following schematic is a bit heavy (doc) but it’s the cleanest representation I’ve found of the complex neuromuscular system (and believe me, I’ve looked for hours):

jimmy g
Credit – Sheri Silfies

If we think of the physical components of the body (muscle, heart, ligaments, etc) as the “hardware”, then the neuromuscular system is part of the “software” that activates the hardware.  During reactionary and unanticipated movement, this software has to recognize body position and then maintain joint stability.

As Jimmy G was scrambling out of the pocket towards the sideline, looking for open targets and incoming defenders, and then finally cut towards a defender, his neuromuscular system was in overdrive – dealing with constant reaction movements and integrating all the information coming at it.

That’s a lot of information for any player to deal with but especially for a QB because they don’t train for these unstructured situations (what I refer to as “chaos” training). It’s quite possible his neuromuscular system was overwhelmed and unable to keep up, impairing his knee joint stability during the cut and increasing injury risk (to learn more about the neuromuscular system and it’s relationship to ACL injuries, I wrote this piece).

To make matters worse, his left leg was planted in an extended (straight) position during that last cut which added a huge risk of injury….

II. Extended (straight) knee during a cut

jimmy g
Credit – NFL on Fox

When the leg is straight like in this picture, the knee joint is at end range.  The closer the knee joint is to end range, the more the muscles are in a disadvantaged position and can’t complete one of their key roles – absorbing force.  Instead, this force now gets transferred into the joint and into what are known as “passive restraints”, including the knee ligaments.

This is why players are taught to cut and land with bent (soft) knees. In this position, the muscles are able to be shock absorbers and dissipate force.  Additionally, because Jimmy G (or any other football player) doesn’t train to cut in this extended knee position, the neuromuscular system is further impaired and unsure of what to do.

This leads to a “point of no return”….

III. Adduction and Internal Rotation

During any high speed inward cut, the plant leg is going to go into some adduction (inwards) and internal rotation (rotating towards midline).  That’s natural.  However, with an impaired neuromuscular system that can’t recognize joint position quickly and the leg extended which negates shock absorption by muscles, Jimmy’s leg is approaching what is called “a point of no return”:

jimmy g
Credit – NFL on Fox

That “point of no return” is the point at which the knee joint can’t move out of its current trajectory and the ACL experiences a level of stress that’s beyond it’s capacity to tolerate (like the “one more drink” that completely alters the course of the night).  At that point, the ACL snaps and the knee buckles:

jimmy g
Credit – NFL on Fox

And here’s the reverse angle which clearly shows Jimmy G looking at the defender and bracing while cutting which speaks to the multi-tasking nature of that final plant and cut movement:

jimmy g
Credit – NFL on Fox

As I said at the start of the piece, Jimmy G was subsequently carted off and his ACL rupture confirmed via MRI.

According to reports, he will be having ACL reconstruction surgery in the next week or two after the swelling in his knee diminishes.  Speaking of surgery…

IV. Jimmy G ACL Surgery

ACL ruptures are one of the most common injuries with upwards of 200,000 per year in the US alone (click here, here, here, here, or here for more info) so surgeons have it down to an exact science.  Here’s one example of how the reconstruction is done (if you’ve read any of my stuff recently, you should be very familiar with this video):

After surgery is completed, Jimmy G begins the long road back…

V. Timeline For Return

On average, NFL players return from an ACL injury in a little over 10 months and the outcomes on ACL repair in elite athletes, generally, are very good.  Recent high level evidence on return to sport after ACL surgery has shown that nearly 83% of elite athletes (irregardless of sport) returned to sport following an ACL surgery and most performed comparably to non-injured counterparts.

Further, evidence shows that early participation and accelerated ACL protocols, like are often used in the NFL, do carry some risk of re-injury. Athletes in accelerated rehab programs may have ongoing abnormal motion and relative weakness for up to 22 months following surgery, in addition to an increased risk for knee arthritis (click here and here for more info).

Generally, the consensus amongst medical providers I’ve spoken to is the longer the timeline the better – it allows for the ACL graft to heal more and for the player to reduce side to side asymmetries which is a key indicator of injury risk.  It would be very prudent of the Niners to let Jimmy G take his time but I expect he’ll be back on the field in nine or ten months, barring any setbacks (the most recent example is Carson Wentz who returned in a little over nine months).

Once he does get back to the field, what can we expect?

VI. Long-Term Ramifications

There are certainly some long-term consequences after an ACL rupture.  Like my NAU professor Dr. Carl DeRosa alway said, “it’s never the same model.”

First and foremost, there’s nearly a 25 percent chance of re-rupturing the same ACL after surgical repair . It’s no coincidence that prior ACL injury is the best predictor for future ACL injury.  Perhaps even more disconcerting, the risk of rupturing the other side (“contralateral”) ACL after surgical repair is upwards of 20.5 percent!  Bio-mechanics, proprioception, and compensation are quite sensitive to injury.

Further, research has found that side to side movement asymmetries (jumping distance, landing distance, mechanics) can exist for up to two years after ACL surgery.

Lastly, there’s potential ramifications for the knee cartilage.

jimmy g
Credit – MyHealthAlberta

For reference, femur = thigh bone, patella = knee cap, and tibia = shin bone.

After ACL injury, research shows a higher degeneration rate of knee cartilage and nearly a 3.6x increase in developing arthritis compared to an uninjured knee. Arthritis risk is even higher when the original ACL rupture also involves direct damage to the knee cartilage, which may or may not be the case for Jimmy G. Research shows anywhere from an 18% to 48% increase in osteoarthritis risk with this combined injury compared to only an ACL rupture.

To top it all off, we know that kinesphobia (aka fear of movement or re-injury) is one of the last things to dissipate for athletes (click here, here, and here for more info) returning from ACL ruptures. In other words, one of the last things to return is confidence of movement.

As a Niners fan or just someone concerned for Jimmy G, you might be thinking “oh crap, he’ll never be the same dude”.  However, that’s very likely NOT the case.

A research study specifically looked at NFL QB’s recovering from a torn ACL and it found that 92 percent returned to play with only one re-injuring the ACL and needing a re-repair. Additionally, the study found that these QB’s performed just as well after the ACL injury as they did before AND there was no difference between these QB’s who tore their ACL and their injury free counterparts.

VII. All in all

The reality with an ACL rupture is that it’s always crappy – nearly a year of rehab to get back on the field and potential long-term ramifications thereafter.  However, it’s not a death-knell by any means and the great news for Niners and Jimmy G is that QBs often come back at a level commensurate to their pre-injury levels.

Additionally, it’s pretty early in the season so he should be ready to go or almost back by OTAs and, for his mental piece of mind, he’s financially secure after signing that big contract.  One major takeaway for Jimmy G is a better understanding of risk/reward – there was no need for him to take on that last defender and it opened him up to all sorts of risk.  A very valuable, albeit painful, lesson.

In the meantime, he can keep hitting those photo shoots:

Jimmy g
Credit – GQ

Thanks for reading and until next time.  if you liked the piece, subscribe to the email list on the sidebar, join our facebook group, and follow us on twitter or IG to never miss an update.

Posted in NFL

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