Patient Presentation: Inconsistent Ankle Modulation

This article is sixth in a series of seven that explores clinical groups of common bracing applications.

Neurological problems that affect the muscle control systems or proprioceptors of the lower leg can cause the movement and positioning of the foot (via the ankle joint) to be erratic. When combined with other tone-related problems, a variety of gait and posture problems can result. This presentation category is for ankle control problems that are typically variable, rather than constant.

More specifically, some of the ways inconsistent ankle modulation can present are unsteady or erratic movement and positioning of the foot. You may see mild to severe instability during standing and walking; inconsistencies in gait rhythm; inappropriate changes in position or posture such as momentary knee hyperextension or crouching; mild to severe ataxia; and drop-foot. Patients may also present with pronated or supinated feet.

Describing all the possible movement or positional problems would unnecessarily complicate the task of selecting an appropriate brace. As the movement at the ankle is the focus of the problem, we will try to gauge the severity based on the strength, degree, incidence and duration of the undesirable movement or position, and then choose a brace with the appropriate control capability to improve ankle movement and/or position.

For very mild cases, increasing proprioceptive stimuli may be sufficient to deter excessive ankle motion and/or improve positional awareness. This is seen especially in younger and smaller patients whose primary need is for improved alignment. These patients would also benefit from a small amount of added ankle control as they develop stance and gait.

The DAFO 4 brace, when two adjustable ankle straps are added, will provide stimulation and slight resistance to ankle movement. A posterior strap provides mild plantarflexion (PF) resistance, and an anterior strap provides mild dorsiflexion (DF) resistance. In some cases, both straps can be applied to provide PF and DF resistance.

In mild to moderate cases, the flexible proximal upright of the DAFO 3.5 will provide spring-like resistance to both PF and DF. The actual resistive force of the proximal upright is determined by the practitioner at casting and can vary from very flexible to semi-rigid. Thus, the DAFO 3.5 brace is particularly versatile for moderate presentations. (Note that the resistive force will be set at fabrication. From that point, only minimal alteration can be made.) To determine the best level of resistance, consider two factors: (1) the strength and degree of the ankle movement to be controlled and (2) the finished height of the upright portion of the brace. (Short braces tend to be stiffer, and tall braces tend to be more flexible.)

The ankle consistencies of some patients include relatively strong PF with concerns regarding DF range. To block ankle PF and allow full DF, the DAFO 2 has both a hinged proximal upright and wraparound foot control.

In moderate to severe cases, the FlexiSport^TM;—a Softy^TM Turbo brace with a more flexible proximal upright—will also provide spring-like resistance to both PF and DF. It’s generally best suited for larger, active patients.

DAFO 4 DAFO 3.5 DAFO 2 DAFO FlexiSport