Knee and Ankle Position, Anterior Drawer Laxity, and Stiffness of the Ankle Complex

Abstract

AbstractContext:Anterior drawer testing of the ankle is commonly used to diagnose lateral ligamentous instability. Our hypothesis was that changing knee and ankle positions would change the stability of the ankle complex during anterior drawer testing.Objectives:To assess the effects of knee and ankle position on anterior drawer laxity and stiffness of the ankle complex.Design:A repeated-measures design with knee and ankle position as independent variables.Setting:University research laboratory.Patients or Other Participants:Bilateral ankles of 10 female (age  =  19.8 ± 1.1 years) and 10 male (age  =  20.8 ± 1.2 years) collegiate athletes were tested.Intervention(s):Each ankle complex underwent loading using an ankle arthrometer under 4 test conditions consisting of 2 knee positions (90° and 0° of flexion) and 2 ankle positions (0° and 10° of plantar flexion [PF]).Main Outcome Measure(s):Recorded anterior laxity (mm) and stiffness (N/mm).Results:Anterior laxity of the ankle complex was maximal with the knee positioned at 90° of flexion and the ankle at 10° of PF when compared with the knee positioned at 0° of flexion and the ankle at 10° or 0° of PF (P < .001), whereas ankle complex stiffness was greatest with the knee positioned at 0° of flexion and the ankle at 0° of PF (P < .009).Conclusions:Anterior drawer testing of the ankle complex with the knee positioned at 90° of flexion and the ankle at 10° of PF produced the most laxity and the least stiffness. These findings indicate that anterior drawer testing with the knee at 90° of flexion and the ankle at 10° of PF may permit better isolation of the ankle capsuloligamentous structures.