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Hip Muscle Strength Predicts Non-‐contact ACL Injury in Male and Female Athletes: A Prospec@ve Study
Rachel K. Straub, MS, CSCS* Khalil Khayambashi, PT, PhD**
Navid Ghoddosi, MS**
Christopher M. Powers, PT, PhD, FACSM, FAPTA* University of Isfahan; Isfahan, Iran.**
University of Southern California; Los Angeles, CA.*
ACL Research Retreat: March 19-‐21, 2015
Introduc=on Methods Results Discussion Conclusion
Prospec@ve Studies • Abnormal movement paEerns at trunk, hip, and knee have been shown to be independent risk factors for non-‐contact ACL injuries in athletes (HeweE et al., 2005; Paterno et al., 2010; Zazulak et al., 2007).
Cross-‐sec@onal Studies • Impaired hip strength may underlie these abnormal movement paEerns (Claiborne et al., 2006; Hollman et al., 2009; Jacobs et al., 2007; Lawrence et al., 2008; Lee S-‐P and Powers, 2013; Willson et al., 2006).
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Introduc=on Methods Results Discussion Conclusion
So the ques@on is. . . Can hip strength predict non-‐contact ACL injury?
Why is this relevant? If hip strength can be shown to predict non-‐contact ACL tears, this may be an easier way to screen athletes at risk for injury (as opposed to more complicated kinema=c analyses).
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Introduc=on Methods Results Discussion Conclusion
Primary Aim • To determine whether baseline hip strength can predict future non-‐contact ACL injury in compe==ve athletes
Secondary Aim • To establish clinical cutoffs for baseline hip strength that predict future injury with high specificity & sensi=vity
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Introduc=on Methods Results Discussion Conclusion
Subjects • 501 compe==ve athletes
– 138 females and 363 males par=cipa=ng in various sports (futsal, soccer, volleyball, handball, basketball)
• No previous ACL injury or previous LE injury during the past 6 months
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Assessment (Preseason) • 10 raters trained to assess isometric hip strength (external rota=on & abduc=on) using a hand-‐held dynamometer
• Intra-‐rater reliability – Hip ER: 0.81 to 0.98 – Hip ABD: 0.95 to 0.99
• Inter-‐rater reliability – Hip ER: 0.99 – Hip ABD: 0.71
Introduc=on Methods Results Discussion Conclusion
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Introduc=on Methods Results Discussion Conclusion
Assessment (During Sports Season) • ACL injury status recorded.
– Non-‐injured – Injured
• Contact • Non-‐contact
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Introduc=on Methods Results Discussion Conclusion
Data Analysis (Postseason) • Preliminary analysis used to determine poten=al predictors of non-‐contact ACL injury. – Two-‐way ANOVAs (injury x sex) for con=nuous variables (age, ht, wt, hip ER strength, hip ABD strength)
– Fisher’s exact tests for categorical variables (sport, gender) • Variables that were significantly different between injured and non-‐injured groups were considered as predictors in logis=c models (p < 0.05).
• ROC curves constructed for each hip strength measure to determine clinical cut-‐off values.
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30 Males Excluded
• 5 ACL Contact Injuries • 25 Inconclusive Diagnoses
3 Females Excluded
• 3 ACL Contact Injuries
501 Subjects
363 Males 138 Females
333 Males Final Sample 135 Females Final Sample
468 Total Athletes
Introduc=on Methods Results Discussion Conclusion
Introduc=on Methods Results Discussion Conclusion
Annual Non-‐contact ACL Injury Rate • Overall injury rate 3.0% (15 of 501)
– Males: 2.5% (9 of 363) – Females: 4.3% (6 of 138)
hEp://sportskneetherapy.com/tag/acl-‐recovery/ 10
Introduc=on Methods Results Discussion Conclusion
Injuries by Sport & Gender
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Sport
Futsal
Soccer
Volleyball
Basketball
Handball
Male (n = 333)
Injured
(n = 9)
Non-‐injured
(n = 324)
3 (6.5%) 43 (93.5%)
3 (1.6%) 179 (98.4%)
1 (2.6%) 37 (97.4%)
0 24 (100%)
2 (4.7%) 41 (95.3%)
Female (n = 135)
Injured
(n = 6)
Non-‐injured
(n = 129)
2 (7.7%) 24 (92.3%)
0 0
0 33 (100%)
4 (7.1%) 52 (92.9%)
0 20 (100%)
Introduc=on Methods Results Discussion Conclusion
Baseline Variables • Two-‐way ANOVAs for con=nuous variables
– All interac=ons non-‐significant (p > 0.05). – All injury main effects non-‐significant (p > 0.05) except for hip ADB and ER strength
• Fisher’s exact test for categorical
– Neither sex nor sport associated with injury status (p > 0.05).
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22.1
37.8
17.2
30.8
0
5
10
15
20
25
30
35
40
45
50
%B
W
ER ABD
Non-injured Injured
Introduc=on Methods Results Discussion Conclusion
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Hip Strength: Non-‐injured vs. Injured
p = 0.003
p < 0.001
Introduc=on Methods Results Discussion Conclusion
Logis@c Models • Strength measures highly correlated
– (r = 0.66, p < 0.01) • Model 1:
– ER: OR = 1.23 (95% CI: 1.08, 1.38), p = 0.001, R2 = 11.2% • Model 2:
– ABD: OR = 1.12 (95% CI: 1.05, 1.20), p = 0.001, R2 = 10.2%
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Introduc=on Methods Results Discussion Conclusion
ROC Curves • High Risk Cutoffs
– ER: ≤ 20.3 %BW • Sensi@vity = 89% • Specificity = 59%
– ABD: ≤ 35.4 %BW • Sensi@vity = 87% • Specificity = 65%
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Probability of Future Injury Based on Preseason Hip Strength Test
• High Risk – ER: 3.0% à 6.6% – ABD: 3.0% à 7.2%
• Low Risk – ER: 3.0% à 0.34% – ABD: 3.0% à 0.65%
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Introduc=on Methods Results Discussion Conclusion
ER (%BW) Leetun Current 17.9 17.2
20.6 22.1
Introduc=on Methods Results Discussion Conclusion
• Female vs. male injury rate: 4.3% vs. 2.5% – Our results indicated sex did not impact injury status.
• Logis@c models as a whole explained only 10-‐11% of the varia@on in injury status.
• How do our strength values compare? – Leetun et al., 2004
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ABD (%BW) Leetun Current 28.6 30.8
31.6 37.8
Injured ê
Non-‐Injured é
• Preseason isometric hip strength (abduc@on and external rota@on) independently predict future non-‐contact ACL injury in compe@@ve athletes.
• Screening procedures to assess ACL injury risk should consider assessment of isometric hip abduc@on and/or hip external rota@on strength.
Introduc=on Methods Results Discussion Conclusion
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References
1. Claiborne TL, Armstrong CW, Gandhi V, Pincivero DM. Rela=onship between hip and knee strength and knee valgus during a single leg squat. J Appl Biomech. 2006;22(1):41-‐50.
2. HeweE TE, Myer GD, Ford KR, et al. Biomechanical measures of neuromuscular control and valgus loading of the knee predict anterior cruciate ligament injury risk in female athletes: a prospec=ve study. Am J Sports Med. 2005;33(4):492-‐501.
3. Hollman JH, Ginos BE, Kozuchowski J, Vaughn AS, Krause DA, Youdas JW. Rela=onships between knee valgus, hip-‐muscle strength, and hip-‐muscle recruitment during a single-‐limb step-‐down. J Sport Rehabil. 2009;18(1):104-‐117.
4. Jacobs CA, Uhl TL, MaEacola CG, Shapiro R, Rayens WS. Hip abductor func=on and lower extremity landing kinema=cs: sex differences. J Athl Train. 2007;42(1):76-‐83.
5. Lawrence RK, 3rd, Kernozek TW, Miller EJ, Torry MR, Reuteman P. Influences of hip external rota=on strength on knee mechanics during single-‐leg drop landings in females. Clin Biomech (Bristol, Avon). 2008;23(6):806-‐813.
6. Lee S-‐P, Powers CM. Individuals with Diminished Hip Abductor Muscle Strength Exhibit Altered Ankle Biomechanics & Neuromuscular Ac=va=on during Unipedal Balance Tasks. Gait & Posture. 2013.
7. Leetun DT, Ireland ML, Willson JD, Ballantyne BT, Davis IM. Core Stability Measures as Risk Factors for Lower Extremity Injury in Athletes. Medicine & Science in Sports & Exercise. 2004;36(6):926-‐934.
8. Paterno MV, SchmiE LC, Ford KR, et al. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury auer anterior cruciate ligament reconstruc=on and return to sport. Am J Sports Med. 2010;38(10):1968-‐1978.
9. Willson JD, Ireland ML, Davis I. Core strength and lower extremity alignment during single leg squats. Med Sci Sports Exerc. 2006;38(5):945-‐952.
10. Zazulak BT, HeweE TE, Reeves NP, Goldberg B, Cholewicki J. Deficits in neuromuscular control of the trunk predict knee injury risk: a prospec=ve biomechanical-‐epidemiologic study. Am J Sports Med. 2007;35(7):1123-‐1130.
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For Further Informa=on. . .
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Paper accepted at American Journal of Sports Medicine
September 1, 2015.
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