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8 The effect of change of direction angle on knee mechanics – implications for ACL injury
  1. Ayman Alhammad,
  2. Lee Herrington,
  3. Paul Jones,
  4. Ritchard K Jones
  1. School of Health Sciences, University of Salford, UK


Introduction Change of direction (COD) manoeuvres are important for many field sports, however they are unfortunately associated with non-contact ACL injuries. Although players frequently COD at >90° angles, limited knowledge is available on knee joint kinematics and kinetics during COD at 90° and 135° and whether limb preference impacts knee mechanics during COD at these angles, which formed the aims of this study.

Methods Healthy male recreational soccer players were recruited to take part in the study. 3D kinematics and kinetics were collected during COD manoeuvres at 90° and 135°. Running speed was controlled at 4±0.4 m/s and 3.5±0.3 m/s, respectively. To determine differences on variables associated with ACL risk; knee abduction angle and moment, across cutting angles and preferred legs, a paired sample t-test was conducted using a Holm method correction, α=(0.05/ (8 comparisons – rank +1).

Results 36 individuals took part in the study (24.25±6.21 years, 1.72±0.06 m and 66.41±10.83 kg). COD at 135° showed greater knee abduction angles and moments than at 90° but with similar peak VGRF. There were no differences between preferred and non-preferred legs, apart from the increased knee flexion angle during COD manoeuvres at 90° in the non-preferred leg.

Conclusion In male recreational soccer players, sharper cutting angles place the knee at more risk for ACL injuries with little asymmetry between preferred and non-preferred limbs. Sharper angles of examination should be utilized in the evaluation of individuals.

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