Predisposing Factors for non-contact ACL injury: is there a relationship between the hip and the knee?
In the last 30 years, the elevated risk of ACL injury in females coupled with the 10-fold increase in high school and 5-fold increase in collegiate sport participation5,14. The risk of re-injury after ACL reconstruction surgery is 15 times greater when compared to athletes who did not sustain an ACL injury15. Reduction in ACL injuries in young, active individuals continues to be a major goal in sports medicine. Reduction can be done through understanding the contributing factors and patient education via ACL prevention programs.
What is the mechanism of an ACL injury?1
The most common non-contact ACL injury mechanism includes a deceleration task with knee going into excessive extension and buckling in as the body shifts over the injured knee while the foot is fixed on the playing surface.
Contributing Factors to an ACL injury
There are many factors that can play role in an ACL injury. Looking at the big picture, we can classify these factors as extrinsic (factors outside of our body ex. shoe wear, surface played etc.) and intrinsic factors (factors inside of our body such as. muscle strength, flexibility etc.) We can further classify intrinsic factors as Biomechanical, Anatomical, Neuromuscular, Developmental and Humeral.
- Anteriorly tilted pelvis can inhibit Glut max activation: Glut Max is a powerful extensor and external rotator of the lower extremity.
- Decreased relative hamstring strength & recruitment: can cause excessive activation of the Quads and therefore knee extension.
- Reduced trunk, hip, knee and ankle flexion angles during deceleration tasks and landing from a jump would cause more extension in the knee and decreased ability to absorb shock.
- A weak gluteus medius and lateral trunk displacement would more the trunk lateral in relationship to knee.
- Increased hip internal rotation would inhibit glut medius, and glut max.
Paterno MV SL, Ford KR, Rauh MJ, Myer GD, Huang B, Hewett TE. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sports. Am J Sports Med. 2010;38:1968-1978. Cohort study; Level of evidence, 2
Method: Biomechanical screening of N=56 after ACLR using 3-D motion analysis during a drop vertical jump maneuver and postural stability assessment before return to sports. LE joint kinematics, kinetics, and postural stability were assessed and analyzed.12 months follow up. Analysis of variance & logistic regression were used to identify predictors of a second anterior cruciate ligament injury. Results: 13 re-injuries. Transverse plane hip kinetics and frontal plane knee kinematics during landing, sagittal plane knee moments at landing, and deficits in postural stability predicted a second injury in this population with excellent sensitivity (0.92) and specificity (0.88). Hip rotation moment independently predicted second anterior cruciate ligament injury with high sensitivity (0.77) and specificity (0.81).
- Females activate the hip musculature different than men do in response to sudden loading.
- Glut Max+Med s role in mediating muscular protection to control of hip adduction & femoral internal rotation in helping female athletes avoid “at-risk” positions.
- Female soccer, basketball, and volleyball players perform playing actions with
- Increased adduction & internal rotation of the femur.
- Reduced hip and knee flexion angles.
- Increased dynamic knee valgus.
- Increased Quad & decreased hamstring activity.
- Decreased muscle stiffness around the knee joint.
- Muscular fatigue increases knee abduction and hip internal rotation at initial contact which were significantly more pronounced during unanticipated vs. anticipated land-jump tasks.
Zazulak BT, Hewett TE, Reeves NP. Deficits in neuromuscular control of the trunk predict injury risk. Am J Sports Med. 2007;35(7): 1123-1130. Cohort study; Level of evidence, 2.
Method: 277 collegiate athletes (140 F +137 M) were prospectively tested for trunk displacement after a sudden force release. Results: 25 athletes (11 F +14 M) sustained knee injuries over a 3-year period. Trunk displacement was greater in athletes with knee, ligament, and ACL injuries than in uninjured athletes (P < .05). Lateral displacement was the strongest predictor of ligament injury (P = .009). A logistic regression model, consisting of trunk displacements, proprioception, and history of LBP, predicted knee ligament injury with 91% sensitivity and 68% specificity (P = .001). Core strength and Glut Med are important since increased lateral trunk lean moves the ground reaction forces lateral to knee which is same as dynamic knee valgus.
Philippon M, Dewing C, Briggs K, Steadman JR. Decreased femoral head-neck offset: a possible risk factor for ACL injury. Knee Surg Sport Tr A. 2012: 20:2585–2589. Level of evidence Prognostic study, Level III
Purpose :To determine the head–neck offset, as measured by AP pelvis alpha angles, in patients with isolated non-contact ACL knee injuries. Methods: N= 48 patients with complete primary ACL rupture. Control N= 42 with non-ACL injury. A single surgeon, blinded to the diagnosis, took radiographic measures of the AP alpha angle of both hips and the weight-bearing line at both knees. Results: No difference in gender distribution, height, BMI or age between groups. ACL-injured patients had a significantly higher alpha angle on the injured side than the controls. 94% of the ACL- injured group had alpha angles over 60°, while only 35% of the non-ACL-injured group had alpha angles over 60°. Those patients with alpha angle over 60° were 27 times more likely to be in the ACL injury group than those patients with alpha angle 60° or less. Conclusion: There is a correlation between ACL injury and diminished femoral head–neck offset, as characterized by abnormal, elevated alpha angles.
Gomes JLE, Palma HM, Becker R. Radiographic findings in restrained hip joints associated with ACL rupture. Knee Surg Sport Tr A. 2010; 18:1562–1567.
Purpose: To investigate abnormal radiographic findings in soccer players with limited hip ROM and non-contact ACL injury. Methods: 50 male soccer players with restricted hip ROM and non-contact ACL injury were subjected to radiographic examination to identify bone changes that could be associated with decreased hip ROM. Conclusion: Soccer players with ACL ruptures and restricted hip joint mobility may have bone alterations, which can lead to unpredictable results from conventional surgical techniques; therefore, they may benefit from new protocols that contemplate this abnormal situation.
Take Home Points
- Elevated alpha angles >60 will predispose to ACL.
- Players with ACL ruptures and restricted hip joint mobility may have bone alterations.
- Transverse plane hip kinetics & frontal plane knee kinematics during landing, sagittal plane knee moments at landing, and postural stability deficits can predict an ACL injury.
- Hip rotation moment independently predicted second anterior cruciate ligament injury with high sensitivity (0.77) and specificity (0.81).
– Proximal Strengthening such as core, Glut Max and medius can decrease risk for an ACL injury.
– Hamstring strengthening can improve shock absorption during deceleration and landing tasks and would decrease the likelihood of stiffening of the knee due to Quad over-use.
– Dynamic Tests such as step down and/or single limb squat can be used to assess to neuromuscular control and proper lower extremity alignment.
– Return to Sports Assessment is a sport specific tool that can evaluate if athlete is ready for return to play.
- Alentorn-Geli E, Myer GD, Silvers G+HJ, Samitier G, Romero D, La zaro-Haro C, Cugat R. Prevention of non-contact anterior cruciate ligament injuries in soccer players. Part 1: Mechanisms of injury and underlying risk factors. Knee Surg Sports Tr A. 2009;17:705–729.
- Beynnon BD, Shultz SJ. Anatomic Alignment, Menstrual Cycle Phase, and the Risk of Anterior Cruciate Ligament Injury. J Athl Training 2008;43(5):541–542
- Martineau PA, Al-Jassir F, Lenczner E, Burman ML (2004) Effect of the oral contraceptive pill on ligamentous laxity. Clin J Sport Med 14:281–286
- Shimokochi Y, Yong Lee S, Shultz SJ, Schmitz RJ. The Relationships Among Sagittal-Plane Lower Extremity Moments: Implications for Landing Strategy in Anterior Cruciate Ligament Injury Prevention. J Athl Training 2009;44(1):33–38.
- Hewett TE, Ford KR, Hoogenboom BJ, Myer GD. Understanding and Preventing ACL injuries: Current biomechanical and epidemiologic considerations. N Am J Sports Phys Ther. 2010 ; 5(4): 234–251.
- Hudek R, Fuchs B, Regenfelder F, Koch PP. Is noncontact ACL injury associated with the posterior tibial and meniscal slope? Clin Orthop Relat Res. 2011. 469:2377–2384.
- Chandrashekar N, Slauterbeck J, Hashemi J (2005) Sex-based differences in the anthropometric characteristics of the anterior cruciate ligament and its relation to intercondylar notch geometry. Am J Sports Med 33:1492–1498.
- Hashemi J, Chandrashekar N, Mansouri H, Slauterbeck JR, Hardy DM (2008) The human anterior cruciate ligament: sex differences in ultrastructural and correlation with biomechanical properties. J Orthop Res 26:945–950
- Uhorchak JM, Scoville CR, Williams GN, Arciero RA, St Pierre P, Taylor DC. Risk factors associated with noncontact injury of the anteriorcruciate ligament: a prospective four-year evaluation of 859 West Point cadets. Am J Sports Med. 2003: 31:831– 842
- Bien DP. Rationale and implementation of anterior cruciate ligament prevention warm-up programs in female athletes. J Strength Cond Res 2011;25(1):271-285.
- Borotikar BS, Newcomer R, Koppes R, McLean SG. Combined Effects of fatigue and decision making on female lower limb landing postures: Central and peripheral contributions to ACL injury risk. Clin Biomech. 2008;23:81-92.
- Zazulak BT, Hewett TE, Reeves NP. Deficits in neuromuscular control of the trunk predict injury risk. Am J Sports Med. 2007;35(7): 1123-1130.
- Blackburn JT, Padua DA. Sagittal-plane trunk position, landing forces and forces, and quadriceps electromyographic activity. J Athl Train. 2009;44:174-179.
- Paterno MV SL, Ford KR, Rauh MJ, Myer GD, Huang B, Hewett TE. Biomechanical measures during landing and postural stability predict second anterior cruciate ligament injury after anterior cruciate ligament reconstruction and return to sports. Am J Sports Med. 2010;38:1968-1978.
- Paterno MV, Rauh, MJ, Schmitt LC, Ford KR, Hewett TE. Incidence of Contralateral and Ipsilateral Anterior Cruciate Ligament (ACL) Injury After Primary ACL Reconstruction and Return to Sport. Clin J Sports Med. 2012; 22(2): 116-121.
- Philippon M, Dewing C, Briggs K, Steadman JR. Decreased femoral head-neck offset: a possible risk factor for ACL injury. Knee Surg Sport Tr A. 2012: 20:2585–2589.
- Gomes JLE, Palma HM, Becker R. Radiographic findings in restrained hip joints associated with ACL rupture. Knee Surg Sport Tr A. 2010; 18:1562–1567.