Background In sports ankle sprains are responsible for most of the time lost in practice. In basketball, ankle sprains are not only a main injury but they also have a high tendency of re-injury. There is a special interest in finding risk factors that can be used to predict the ankle sprain occurrence and so prevent it. Joint position when contacting the ground is a main issue.

Objective The aim of this study is to examine the knee position on ground contact moment and its relationship with ankle sprain.

Design To reproduce the most common mechanism of ankle sprain in basketball players, landing in another player's foot, barefoot athletes with healthy (n=17) and already sprained ankles (n=28) were asked to jump from the floor to an unstable round surface placed 50 cm in front of them while kinematics was recorded using an electromagnetic tracking device with 3 sensors located in each segment of the lower limb and another on a round Freeman board.

Setting elite basketball players.

Patients (or Participants) 13 females, and 12 males accepted to perform five consecutive jumps in unipodal support.

Interventions (or Assessment of Risk Factors) Previous ankle sprain or never sprained ankle.

Main Outcome Measurements Knee range of motion on landing.

Results At contact knee angles did change significantly with previous ankle sprain. Never sprained subjects showed more knee flexion on contact. When separating results by gender we found that women landed with knees in an even more extension degree.

Conclusions Knee position on landing differs from healthy to previous sprained ankles. Previous sprained land in a more extension position and consequently a higher impact energy for lower limb and all the body must be absorbed. This difference is even more important among females.