Brian Schiff’s Blog

I had the pleasure of listening to Darin Padua, PhD, of UNC present some of his latest research on ACL injury prevention last week. He has been doing research for some time. One of his studies (JUMP ACL) in collaboration with the military and several others has looked at prospective data and injury occurrence among college age subjects.

Much of the research to date on injury prevention has been done by Timothy Hewett and his colleagues. It has concluded that drop landing with a valgus collapse (hip abduction/IR with valgus knee moment) is a risk factor for injury. Interstingly enough, despite that knowledge and the proliferation of prevention programs, Darin mentioned that overall these prevention programs have not slowed the rate of ACL tears in the last decade. Why is that?  He also relayed that much of what we know now is based on 15 total cases.

The Jump ACL Study in a nutshell lasted for 5 years at 3 different military academies:

N = 5,700 cadets with no prior ACL surgery

• Soccer players = 1,690
• Tested from 2005 to 2008
• 39% female; 25% NCAA athletes
• 14,653 person-years of follow-up

N = 113 incident ACL injuries

• Soccer players = 29
• Mean time from testing to injury = 3.1 yrs
• N = 92 one ACL injury; N = 11 two ACL injuries

Some data (will be published) he discussed based on his findings revealed the following about high risk profiles for ACL injury:

• Hip flexion > 40 degrees at landing = 1.76x increased risk
• Hip adduction plus knee valgus = 3x increased risk
• Hip adduction plus knee varus = 27x increased risk

He also mentioned that the high risk profile does not correspond to the ACL injury event profile of:

• Hip abduction
• Lateral trunk flexion
• Knee valgus collapse
• Small knee flexion
• Tibial ER/IR

In the end, he suggests we need to better understand who to target (high risk profile clients) and what to modify (injury event profile) so we can better customize injury prevention programs that optimize proper movement and meet the needs of each individual athlete.  He reminded us that using the uninjured side for comparison is insufficient as faulty movement patterns already likely existed contributing to the first ACL injury.

So, assessing movement continuously and striving for excellent movement quality is a MUST if we are going to both prevent initial ACL injuries and reduce the re-tear rates for our athletes we send back to play.  He reports that those at increased risk simply have bad biomechanics.  His message provides more weight to having an advanced algorithm to identify asymmetry, poor motor control and flawed movement patterns in order to effectively prescribe interventions to address these things.

At UNC they use a PRIME assessment.  I am excited to learn more about it and have referred one of my female higher level soccer players to their lab for assessment as I look at this return to play decision with her now that she is just past 7 months post-op.   I think the hip/core obviously play an important role as I see so much deficiency in my female patients recovering from injury.

Clearly his findings with hip adduction and varus as a big risk factor seem to indicate it could be a top down kinetic chain breakdown as well upon impact based on the risk profile.  Pelvic stability or the lack thereof seems to be significant, only NOT in the same manner we thought about it before based on previous research available.  Stay tuned, as we have lots more to learn about ACL injuries and how best to tailor our prevention efforts.

I just finished presenting at our our second ACL Symposium of the year at the Athletic Performance Center last Saturday.   Rehabbing and training female athletes has been a passion of mine for some time.  Over the years, I have also developed a love for research and reading it, particularly studies on the ACL.

In my practice, I have incorporated jump landing, single leg training and deceleration based training for some time.  While we all know females are 3-8 times more likely to suffer an ACL injury than males, we have not isolated the exact reason why. Researchers have offered some clues such as: wider pelvis, narrow femoral notch, smaller ACL, ligament dominance, limb dominance, natural laxity (hormonal factors), wider Q angles, and faulty muscle firing patterns to name a few.

Many of the structural factors are beyond our control.  So, as practitioners, we must focus on the training.  Consider the following study just published in the August 2011 edition of the American Journal of Sports Medicine that basically reveals females develop peak valgus moments during deceleration during a drop landing maneuver, whereas males develop peak valgus forces during acceleration on the way back up:

Click here for the abstract

Drop Landing

This article adds more evidence that females recruit and fire their muscles very differently than males.  More importantly, it reiterates that we as coaches, therapists and S & C professionals need to be working on deceleration mechanics.  I believe this starts with simple soft two legged drills such as:

1. Small squat jump and holds
2. Box drops and holds
3. Forward line jump, stick and hold
4. Lateral line jump, stick and hold
5. 90 degree jump turn, stick and hold

In addition, one of my favorite drills is a single leg forward leap (hop) and stick working on deceleration.  The athlete stands on the right leg and then pushes off forward landing on the left leg.  Coaching the athlete to land softly on a bent hip and knee while avoiding valgus is important.  I usually perform 2-3 sets of 5 reps on each side.  Cueing with a mirror, auditory corrections and tactile cues are useful in encouraging proper form.

SL Stick (start)

SL Stick (finish)

It is important to keep in mind that the majority of non-contact ACL tears occur between 0 and 30 degrees of knee flexion.  They also typically involve deceleration (landing, jump stop or change of direction), planting or cutting.  For this reason, deceleration training must also involve programming for agility and change of direction.

On Saturday, I led the break-out session on deceleration training and covered a few key exercises I use with my athletes.  These drills are layered on one another and the basic ones I begin with are:

1. Stops – I have athletes accelerate out and then decelerate to a controlled two legged stop after 10-20 yards.  Keep in mind allowing for a longer run will allow the athlete to gradually slow down, while decreasing the distance increases intensity and force on the knees.  I coach breaking down with small “pitter patter” steps versus a sudden hard stop.
2. 2 cone lateral shuffle stops – the athlete shuffles over 5-6 yards and then stops with good hip, knee and foot alignment working to keep the shoulders inside the knees (inside the box).  I progress to multiple cone shuffles to increase intensity and maximize repetitive deceleration.
3. Pro-agility drills – 3 cones are placed 5 yards apart and I combine linear and lateral movements between the cones layering #1 and #2 above in a continuous pattern to work on acceleration/deceleration combos and change of direction
4. Y drill (4 cones) – the athlete runs forward to a cone 5-15 yards out and then performs a 45 degree cut left/right.  The progression begins with directed and predictable movement and then advances to reactive cueing with auditory and visual cues.
5. Arrow drill (4 cones) – The athlete runs 5-15 yards forward and then performs a 135 degree cut left/right and runs past the cone that serves as the bottom edge of the arrow head.  This is much more demanding on the body (knee) and as such I only move to this after the Y drill has been mastered.  In addition, I teach a hip turn (from Lee Taft) to reposition the hips and minimize torsion on the lower leg.  I move from predictive to reactive agility as in the Y drill.

These exercises are a small sampling of my ACL prehab/rehab routine.  I also include an enormous amount of single leg PRE’s and balance training as well.  I believe the most important things we can currently do to reduce ACL risk in this population are:

• Screen our athletes to help identify risk (FMS, drop landing, dynamic strength,running/cutting analysis)
• Emphasize hamstring, gluteus medius and lateral rotator strengthening
• Teach landing mechanics and proper deceleration through neuromuscular exercise, biofeedback and repetitive cueing
• Refine proper cutting technique by teaching ideal angles and how to reposition the hips
• Empower coaches and athletes with simple yet effective body weight training routines that can be replicated on the field or court with the team

For now, the battle rages on.  I hope you will join me in the quest to prevent these catastrophic injuries.  I think as research evolves we will continue to see that the answer to promoting optimal stability at the knee will increasingly have more to do with addressing the hip and ankle.  For now, we need to teach soft bent knee landing/cutting that shifts the body’s center of mass forward, while eliminating valgus loading as much as possible in the danger zone.