[Comments on measuring the mobility of the upper ankle joint by the neutral-0-method].

The pivot and axes of the ankle joint not easily determined. Instruction and some experience are required to determine the values by the Neutral 0 Method as accurately and reproducibly as at all possible. The following recommendations are based on theoretical considerations and clinical experience: 1. The experienced physician can measure the correct angle by taking the patient's foot in his hand and asking the patient to raise and lower the foot. From the overall posture and reaction of the foot it is possible to correctly "feel" the neutral 0 position as initial value, and therefrom the raising and lowering. 2. A highly recommended procedure is to examine the patient in recumbent position on the couch with the heal upright as it touches the couch. The foot is then lowered until the sole touches the couch while the knee is bent, a small supporting board serving to determine the axis as the foot is raised. This is a safe method for both the beginners and the experienced. The angles can be determined even better than by the "free" method. 3. In patients who do not cooperate well, lowering and raising of the foot can be checked additionally with the patient standing and bending his knee as well as by standing on tiptoe. In this case the passive forces must be taken into consideration, especially during forward bending of the lower leg. Hence, with this method, it is necessary to distinguish clearly between active and passive function.