Definition

Sinus tarsi syndrome is characterized by lateral rearfoot pain at the sinus tarsi, its ligaments, and the peroneal tendons.

Overview

Sinus tarsi syndrome most often occurs after an inversion ankle sprain (70-80%). It can also result from soft tissue impingement in the sinus tarsi due to a very pronated foot (20-30%). Patients present with localize pain at the lateral subtalar region with a feeling of instability and aggravation upon weightbearing.

No clinical trials have evaluated the effect of custom orthoses for treatment of sinus tarsi syndrome. However, studies have demonstrated the effectiveness of custom orthoses in limiting excessive pronation.

Clinical Goal for Orthotic Treatment

When sinus tarsi syndrome is due to a very pronated foot, the goal of orthotic therapy is to decrease pronation. Refer to lateral ankle instability pathology specific orthosis if sinus tarsi syndrome results from an inversion ankle sprain.

Prescription

To prescribe this device, check “Sinus Tarsi Syndrome” under the Pathology Specific Orthoses section (Part A) of the prescription form.

Sinus Tarsi Syndrome Prescription Recommendations

• Polypropylene Shell – semirigid
• Deep Heel Cup
  • A deep cup helps limit heel eversion
• Wide Width
  • A wider width through the arch increases surface area under the arch preventing arch collapse
• Minimum Cast Fill
  • Minimum cast fill allows the orthosis to conform closely to the arch of the foot and helps prevent medial arch collapse
• Medial Heel Skive – 4mm
  • The medial heel skive creates a greater force medial to the axis of the subtalar joint helping to reduce excessive STJ pronation and heel eversion
• 4/4 Rearpost Post
  • The rearfoot post stabilizes the orthosis in the shoe
• EVA Cover to Toes

Summary

This orthosis is designed to reduce excessive pronatory forces that contribute to sinus tarsi syndrome. It is essential that practitioners determine the etiology of sinus tarsi syndrome in each patient and adjust their prescription accordingly. Refer to lateral ankle instability Pathology Specific Orthoses if sinus tarsi syndrome results from an inversion ankle sprain. If you have further questions, ProLab clients can contact a Medical Consultant.

References

1. Shear MS, Baitch SP, Shear DB. Sinus tarsi syndrome: the importance of biomechanically-based evaluation and treatment. Arch Phys Med Rehabil. 1993 Jul;74(7):777-81.
2. Conrad KJ, J Clin Epidemiol. 1996 Jan;49(1):1-7. Impacts of foot orthoses on pain and disability in rheumatoid arthritics.
3. Kirby KA. Rotational equilibrium across the subtalar joint axis. J Am Podiatr Med Assoc. 1989 Jan;79(1):1-14.
4. Hertel J. Functional instability following lateral ankle sprain. Sports Med. 2000 May;29(5):361-71. Review.
5. Richie, DH; Effects of Foot Orthoses on Patients with Chronic Ankle Instability. J Am Podiatr Med Assoc 2007 97: 19-30skadfj.
6. Kirby KA; Subtalar Joint Axis Location and Rotational Equilibrium Theory of Foot Function J Am Podiatric Med Assoc 2001 91: 465-487
7. Kirby KA. Rotational equilibrium across the subtalar joint axis, JAPMA Jan: 79(1) 1-14, 1989