1. 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

2. “This is the cancer of the knee!!!”

3. What this IS about….

4. Objectives Epidemiology/Prevalence Factors influencing ACL injury
Screening programs
Injury prevention programs
Return to play
Things to consider….

5. First…..

6. Yikes….

7. Epidemiology
WE ALREADY KNOW THIS
>

8. Factors Influencing ACL Injury
Non-modifiable
Anatomic
Hormonal
Neuromuscular
Quasi-modifiable
Modifiable

9. 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

10. Anatomic/Developmental Factors
Geometric Profile  More important than we thought?

11. 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)
These findings consistently found in cadevarice studies, and increase in vivo ACL strain with similar geometric profiles
McLean et al 2010: 20 female recreational athletes, SL land and cut maneuver, LTS correlated with peak anterior knee joint reaction forces, explaining 60.9 of variance, TPW:ICD and MTS:LTS correlated with peak knee abduction angles, MTS:LTS correlated with peak in knee internal rotation angle
Schultz and Schmitz 2010: No correlation with hip/knee moments, lower CTS predicted greater hip adduction and knee valgus angles, Drop vertical jump, 23 female participants
Todd et al 2010: Greater PTS in NC-ACL injured patients than matched controls, when examined sex-dependent, only statistically significant in females
Hashemi et al 2010: Females ACL injuries had increased LTS and shallower MTD, male cases had increase LTS, MTS, and MTD, shallower MTD an improtant risk factor, followed by LTS
Beynnon 2014: Differences in articular cartilage surfaces between injured subjects, so unaffected knee compared to matched controls, 1) increased posterior LTS, 2) ACL injuries may result in acute changes in the articular surface of patients, when sex analyzed independently, females different, males not

12. Anatomic Factors

13. What We Still Don’t Know….
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?

14. HORMONES
Research suggests females suffer most ACL injuries during the pre-ovulatory (follicular) phase, compared to post-ovulatory (luteal) phase

15. HORMONES
Risk 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
-Mechanical and molecular properties of ACL likely influenced not only by estrogen, but by the interaction of other sex hormones, secondary messengers, remodeling proteins, and mechanical stresses
-Relaxin produced by the Corpus Luteum, rises to peak levels within approximately 14 days of ovulation, then declines in the absence of pregnancy, resulting in menstruation
-Effects collagen turnover, and is collagenolytic
Cyclic variations in knee laxity may result in altered knee biomechanics throughout the menstrual cycle

16. Question is….what DO we know?!?!?!
HORMONES
What we still don’t know……
Question is….what DO we know?!?!?!

17. Neuromuscular/Biomechanical
Extensively researched Neuromuscular measures + Biomechanical measures = Neuromechanics

18. Neuromuscular/Biomechanical
What we THINK we know…
Move differently than….

19. Neuromuscular/Biomechanical
Knee ABD moment predicte Acl injury with 78% sensitiviy and 73% specificity, greater knee ABD angle at initial and peak contact, 20% greater VGR forces and 16% shorter stance time, meaning more force, motion, and moments more quickly

20. 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
This data has been shoved down our throats for years….this is all we hear about….but is this really what is going on?

21. Neuromuscular/Biomechanical
McLean: Only consencus was with knee abduction angles, rest of kinetic and kinematic variable were equivocal, with the majority showing no difference. Variations in methodology, task performed, and do these tasks even correlate to on-field movement patterns?
Fox: Frontal plane knee motion of Hewett study fell within normal range of motion in this review/pooled data. Also, hip and knee flexion angles thought to contribute to “high-risk” movement also fell within “normal” motion in this review.
Different methodology, females inherently different in their biomechanical profile, thus hard to truly say that females that move differently than males are at increased risk of ACL injury, because they are EXPECTED to move differently, to some degree.

22. Practicality….

23. 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

24. 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.”
Hewett et al. study prospectively predicted ACL injury with baseline motion analysis, and kinetic/kinematic data
Dynamic Athletic Research Institute
100,000 dollars
The Carlton Blues, an Australian Rules Football team in Melbourne, are in their second year with DARI, and this past season "was a zero-ACL (injury) year," Patrick says. "We're talking the first time in 100 years they've had an ACL-free season."

25. Landing Error Scoring System (LESS)
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)

26. Landing Error Scoring System (LESS)…BUT…
Screening Programs
Landing Error Scoring System (LESS)…BUT…
Like Movement Screens….Hard to target specific stability/mobility/NM Control deficits with the FMS alone….need the SFMA to really tease out what is going on
Smith et al., 2012

27. Injury Prevention Programs

28. 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

29. Injury Prevention Programs
Hewett and colleagues, AJSM, 1999 Sportsmetrics program 6 week pre-season program 1,263 basketball, soccer, and volleyball athletes for 1 season
Non-randomized
Possible selection bias
Male control?????
Author’s developed and are selling their program….bias?

30. Injury Prevention Programs
Mandelbaum and colleagues, AJSM, 2005 Prevent injury, Enhance Performance (PEP) Program
Non-randomized
Possible selection bias
At least one of the authors involved in development and distribution of program for financial gain….bias?

31. 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?
Randomized
Good Level I study
No statistical significance, but clinical significance?
Again, authors were involved in development of PEP program, but deny any financial kick-back from the program itself

32. 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
867 control, 577 treatment, twice per week for 20 minutes, no pre-season training, no strength/flexibility training

33. Injury Prevention Programs

34. Injury Prevention Programs
Things 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)

35. Do we need to include 3-D motion analysis in our RTS criteria?
Return to Sport
Ryan 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)
Paterno 2010: Uninvolved limb transverse plane hip net moment impulse (internal rotation), knee abduction, and asymmetries in sagittal plane net moments (extensor moment), did not discuss ipsilateral vs. contralateral knee injuries, and if their data suggested biomechanics predicted one over the other.
Di Stasi 2013: Both groups demonstrated less knee flexion at IC on involved limb, both groups demonstrated more power absorption in uninvolved limb with weight acceptance
Do we need to include 3-D motion analysis in our RTS criteria?

36. 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)
Paterno et al 2012: Followed for one year, Level III
Paterno et al: 2014: Followed for 2 years, Level II
Webster et al 2014: 561 patients, 29% of those under 20 suffered second ACL injury, 3.9 times more likely to suffer ACL graft rupture, 5 times more likely to suffer contralateral ACL injury

37. 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

38. THANK YOU