Measurement of ankle dorsiflexion: a comparison of active and passive techniques in multiple positions.

CONTEXT Limited ankle DF (DF) range of motion (ROM) resulting from restricted gastrocnemius and soleus mobility is associated with a variety of lower extremity pathologies. Several techniques are used clinically to measure ankle DF. OBJECTIVES To evaluate the reliability and minimal detectable change of DF ROM measurement, determine whether there is a difference in measured DF between techniques, and quantify the electromyographic (EMG) activity of the soleus and tibialis anterior muscles associated with the techniques. DESIGN Repeated measures. SETTING Controlled laboratory setting. PARTICIPANTS 39 healthy subjects, age 22-33. MAIN OUTCOME MEASURES DF measurements using 5 different techniques including active and passive DF with the knee extended and flexed to 90° and a modified lunge. EMG activity of the soleus and anterior tibialis muscles. RESULTS Intrarater reliability values (ICC3,1) ranged from .68 to .89. Interrater reliability (ICC2,1) ranged from .55 to .82. ICCs were the greatest with the modified lunge. The minimal detectable change (MDC95) ranged from 6° to 8° among the different techniques. A significant difference in DF ROM was found between all methods. Measurements taken with active DF were greater than the same measures taken passively. The lunge position resulted in greater DF ROM than both active and passive techniques. EMG activity of the soleus was greater with active DF and the lunge than with passive DF. CONCLUSIONS The modified lunge, which demonstrated excellent intrarater and interrater reliability, may best represent maximal DF. Active end-range DF was significantly greater than passive end-range DF when measured at either 0° or 90° knee flexion. Greater active DF was not explained by inhibition of the soleus. Finally, using the modified lunge, a difference between 2 measurements over time of 6° or more suggests that a meaningful change has occurred.