• Bernd Rappe
  • Heinz Lohrer
  • Albert Gollhofer
  • Wilfried Alt
Keywords: ankle joint instability, functional instability, risk factors, stress x-ray


INTRODUCTION: In this study biomechanical, clinical and radiological parameters of the lower extremity were investigated with regard to their importance as risk factors for ankle sprains in basketball. The relation of all these results should allow a special individual forecast of a higher risk of ankle injury. Those players who belong to a high injury-risk group should be advised to wear an external support such as an orthosis or obtain special training for a sufficient ankle sprain prophylaxis. METHODS: For this study 36 German second division basketball players were examined with at least one recent ankle sprain in their histories. A complex clinical investigation of the lower extremity including several torsional parameters like femoral anteversion, tibial torsion and the malleolar detorsion measured by the Lerat method was followed by the measurement of a modified Naviculareindex by Debrunner. On a visual analogical scale the players indicated their subjective feeling of ankle instability for both joints. A stress radiography followed a clinical investigation of talar tilt and anterior drawer sign. The EMG activity of the m. peroneus was measured during a sudden combined inversion-plantarflexion movement on a specially constructed tilt platform with and without an orthosis. RESULTS: The player’s subjective feeling of functional ankle instability did not correlate with clinical or radiological instability parameters. The torsional parameters, especially a high malleolar detorsion angle, seem to influence a player’s higher risk of suffering an ankle sprain. The modified Naviculareindex has no significant correlation to a high injury risk group. The integrated EMG during the tilt movement was reduced significantly by an average of 20% by wearing an orthosis. The amplitude and velocity of the inversion movement was decreased by an average of 30% compared to the baseline value without orthosis. DISCUSSION: Most of the parameters measured in this investigation were insufficient to explain a player’s subjective feeling of functional instability, and further research is needed, especially in psychological and physiological aspects. Most of the clinical, radiological and biomechanical parameters did not correlate with higher injury risk. Only torsional parameters seem to affect a player’s risk. These results should be regarded in further studies to detect risk factors for ankle injuries.