Definition

Lateral ankle instability originates from a hypermobile and unstable ankle with a history of lateral ankle ligament disruption. This instability leaves the ankle susceptible to further injury.

Overview

Numerous studies have shown that foot orthoses play a significant role in the treatment of lateral ankle instability, although the exact mechanism of their function is debated. This pathology specific orthosis is appropriate for the patient who has ankle instability that produces excessive supination of the foot. This can be a complicated orthotic prescription due to the large variety of foot types that demonstrate this problem.

Clinical Goal for Orthotic Treatment

The goal of an orthosis for lateral ankle instability is to resist excessive supination by applying a pronatory force to the foot.

Prescription

To prescribe this device check “Lateral Ankle Instability/Peroneal Tendinitis” under the Pathology Specific Orthoses section (Part A) of the prescription form.

Lateral Ankle Instability Prescription Recommendations

• Polypropylene Shell – semirigid
• Standard Heel Cup Depth
• Wide Width
  • A wider width increases surface area contact for better control
• Standard Cast Fill
  • Standard fill allows mild pronation
• 0/0 Rearfoot Post with no Lateral Bevel
  • “No lateral bevel” increases the rearfoot post contact area with the ground to increase orthotic stability
• Valgus Extension
  • Increases pronatory torque under the metatarsal heads in order to reduce supinatory torque and can lead to lateral ankle instability

Summary

This orthosis is designed to reduce excessive supinatory forces that can lead to lateral ankle instability. If excessive supination is not the mechanism of the lateral instability, do not use these prescription recommendations. ProLab clients are encouraged to discuss any questions with a Medical Consultant.

References

1. Guskiewicz KM, Perrin DH: Effect of orthotics on postural sway following inversion ankle sprain. J Orthop Sports Phys Ther 23: 326, 1996
2. Hertel J, Denegar CR, Buckley WE, et al: Effect of rearfoot orthotics on postural control in healthy subjects. J Sport Rehabil 10: 36, 2001.
3. Hertel J: Functional anatomy, pathomechanics, and pathophysiology of lateral ankle instability. J Athl Train 37: 364, 2002
4. Kirby KA: Subtalar joint axis location and rotational equilibrium theory of foot function. J Am Podiat Med Assoc, 91:465-487, 2001
5. Munn J, Beard DJ, Refshauge KM, et al. Eccentric muscle strength in functional ankle instability. Med Sci Sports Exerc. 35(2): 245. 2003.
6. Ochsendorf DT, Mattacola CG, Arnold BL. Effect of orthotics on postural sway after fatigue of the plantar flexors and dorsiflexors. J Athl Train 35(1):26, 2000.
7. Orteza LC, Vogelbach WD, Denegar CR: The effect of molded and unmolded orthotics on balance and pain while jogging following inversion ankle sprain. J Athl Train 27: 80, 1992
8. Richie, DH: Effects of foot orthoses on patients with chronic ankle instability. J Am Podiat Med Assoc 97:19-30, 2007
9. Tropp H, Odenick P, Gillquist J: Stabilometry recordings in functional and mechanical instability of the ankle joint. Int J Spt Med 6:180, 1985