ANTERIOR CRUCIATE LIGAMENT: A RESEARCH UPDATE ON THE CANCER OF THE KNEE

Luke Bahnmaier MS, ATC/L, OTC

Idaho Athletic Trainer’s Association Summer Symposium

July 26, 2014

Cancer of the Knee?

“This is the cancer of the knee!!!”

What this IS about….

Objectives

Epidemiology/Prevalence

Factors influencing ACL injury

Screening programs

Injury prevention programs

Return to play

Things to consider….

First…..

Yikes….

Epidemiology

WE ALREADY KNOW THIS

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Factors Influencing ACL Injury

Anatomic

Hormonal

NeuromuscularModifiable

Non-modifiable

Quasi-modifiable

Anatomic/Developmental Factors

Q-Angle

Static pelvis and hip alignment

Body Mass Index

Knee Joint Laxity

Femoral Notch Width/Height

ACL cross-sectional area/volume/length/ultrastructure

Tibiofemoral Joint Geometry/Morphology Medial and Lateral Posterior Tibial Slope (MTS and PTS) MTS:PTS ratio Tibial Plateau Width (TPW), and Depth

Anatomic/Developmental Factors

Geometric Profile More important than we thought?

Anatomic/Developmental Factors

Geometric Profile More important than we thought?

Tibial geometry influences hip and knee joint biomechanics and forces during drop-jump and SL land-and-cut tasks (Schultz and Schmitz, 2010, McLean et al., 2010)

Retrospective review of ACL injured patients shows increased posterior tibial slopes, and increased MTS: LTS ratio and shapes (Brandon et al., 2006, Todd et al., 2010)

Tibial sub-chondral bone geometry retrospectively predicted ACL injury (Hashemi et al., 2010)

Similar findings when tibial articular cartilage is mapped (Beynnon et al., 2014)

Anatomic Factors

Anatomic Factors

What We Still Don’t Know….

Large-scale, prospective studies to incorporate all LE alignment and

geometric measures to determine most susceptible profiles Interaction of joint laxity,

tibial geometry, and ACL size on knee joint

biomechanics and ACL load

Is there a practical tool that can be used to

elucidate these measures on the field or in the

training room?

HORMONESResearch suggests

females suffer most ACL injuries during the pre-

ovulatory (follicular) phase, compared to

post-ovulatory (luteal) phase

HORMONESRisk of ACL may be

higher in female athletes with elevated serum relaxin concentration

Sex hormone receptors present on the human ACL potential direct influence on structure

Cyclic variations in knee laxity may result in

altered knee biomechanics throughout the menstrual cycle

HORMONES

What we still don’t know……

Question is….what DO we know?!?!?!

Neuromuscular/Biomechanical

Extensively researched

Neuromuscular measures + Biomechanical measures = Neuromechanics

Neuromuscular/Biomechanical

What we THINK we know…

Move differently than….

Neuromuscular/Biomechanical

Neuromuscular/Biomechanical

ACL is loaded by combined sagittal and non-sagittal plane loads, compressive and shear forces

• Knee valgus, internal rotation, and anterior shear forces• “Dynamic Valgus” phenomenon…

Females vs. Males

Females land “stiff”, with less knee and hip flexion• Increased VGR forces…rely on passive restraints to absorb energy

More “quad dominant” landing patterns• Thought to increase anterior shear forces during “stiff” landing

Land with increased knee valgus angles

Neuromuscular/Biomechanical

Practicality….

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Screening Programs

What’s out there?• Laboratory 3D Motion Capture Programs

• Expensive laboratory equipment• Very accurate….Very expensive• Not practical for on-field utility

• 2D Video Analysis• Less expensive….• Still time intensive• Still not very practical (You already have ImPACT baselines…now you’re

telling me we need to do a 2D video jumping analysis?!?!?!)

• Landing Error Scoring System (LESS)• Recently developed, easy to implement, based off the BESS test• Still requires video analysis, however

Screening Programs

3D Motion Capture Systems

DARI System, University of Missouri

Brett Hayes

“It allows us to see the small changes in joint angles, joint torques and even muscular instabilities that are difficult — if not impossible — to measure with the naked eye,” said Brett Hayes, a physical therapist and physical rehabilitation manager for the Missouri Orthopaedic Institute. “We’re able to determine where that specific athlete may have a muscular imbalance, a joint imbalance or basically just a weakness that we can see is a detriment to performance or, in worst cases, we can see as potentially leading to injury if we don’t address it.”

Screening Programs

Landing Error Scoring System (LESS)• Valid and reliable (Padua et al., 2009)• Intra- and inter-rater reliability good to excellent (Padua et

al., 2009, Onate et al., 2010)• LESS scores higher in subjects s/p ACL-R (Bell et al., 2014)

Screening Programs

Landing Error Scoring System (LESS)…BUT…

Smith et al., 2012

Injury Prevention Programs

Injury Prevention Programs

Multiple studies have shown training programs correlate with changes in biomechanical profiles thought to be “high-

risk”

….So why wouldn’t these programs work to prevent, or reduce, ACL injury?

Short answer:…some have shown promising results, though study

design has been questionable

Long answer:…Talk to Dr. Shea and get his opinion

Injury Prevention ProgramsHewett and colleagues, AJSM, 1999

Sportsmetrics program

6 week pre-season program

1,263 basketball, soccer, and volleyball athletes for 1 season

Injury Prevention Programs

Mandelbaum and colleagues, AJSM, 2005

Prevent injury, Enhance Performance (PEP) Program

Injury Prevention Programs

Gilchrist et al., AJSM 2008

Prevent injury, Enhance Performance (PEP) Program

Prospective, RCT of D-1 collegiate female soccer athletes

Intervention athletes 3.3 times less likely to suffer NC-ACL

Only statistical significance was ACL injuries in practice…

Promising trend in a Level I study…how do we interpret?

Injury Prevention Programs

Pfeiffer and colleagues, JBJS 2006

Boise, Idaho Special!

Prospective, non-randomized, two year study

Program similar to Sportsmetrics, but less time-intensive

Injury Prevention Programs

Injury Prevention ProgramsThings to Consider…

Retention of movement patterns affected by program duration (Padua et al., AJSM 2012)

Current, commercially available training programs may not affect LE biomechanics for youth athletes under the age of 12 (DiStefano et al., AJSM 2011)

Numbers needed to treat to prevent 1 non-contact ACL injury over one season is estimated at 108 individuals (Sugimoto et al., Br J Sports Med. 2012)

Peripheral and central fatigue, with unanticipated landings, are shown to significantly affect LE biomechanics during landing and cutting….so WHY aren’t we incorporating these into our programs? (McLean and Samorezov 2009, Borotikar 2007, McLean 2007)

Return to SportRyan Mizner PT, PhD

University of Montana

Growing body of evidence showing significant asymmetries in landing biomechanics at time of RTS following ACL-R (Paterno et al., 2011, Di Stasi et al., 2013, Delahunt et al., 2012, Webster et al., 2014)

Asymmetries retrospectively predicted re-rupture or contra-lateral ACL tear upon RTS (Paterno et al., 2010)

Asymmetries present even in those who have passed RTS testing (Di Stasi et al., 2013)Do we need to include 3-D motion analysis in our

RTS criteria?

Return to Sport: Re-injury

Incidence rate of ACL injury following ACL-R 15 times greater than that of controls (Paterno et al., 2012)

• Females 4X more likely to suffer ACL graft rupture, 6X more likely to suffer contralateral ACL injury

29.5% of 78 patients who underwent ACL-R (Paterno et al., 2014)

• Risk of second ACL injury 6 times greater in ACL-R group• Twice as likely to suffer contralateral ACL injury

For patients under 20 s/p ACL-R, odds of suffering ipsilateral and contralateral ACL injury increased 6-, and 3-fold, respectively (Webster et al., 2014)

Clinical Take Home Points

Critically evaluate research, don’t swallow the “Blue Kool-Aid”

Consider modifying current prevention programs to include fatigue, with unanticipated movements

Consider assessing jump-landing movement patterns with return to play, access to 3-D motion

analysis?

Understand that geometric profiles of the tibia may be more important in ACL injury risk than we have

historically thought

THANK YOU