Sinus Tarsi Syndrome

Sinus Tarsi Syndrome

🦶 Introduction

Sinus tarsi syndrome (STS) describes a clinical condition marked by lateral hindfoot pain and a sense of instability, rooted in pathology of the sinus tarsi, a small canal between the talus and calcaneus within the subtalar joint. Although first described by Denis O’Connor in 1957, STS remains a somewhat controversial and multifaceted diagnosis—the term often functioning as an umbrella for various underlying causes such as inflammation, impingement, synovitis, scar tissue, ligament tears, or subtle hindfoot instability 

✅ Scientific Summary

1. Definition

  • A syndrome marked by pain and tenderness localized to the sinus tarsi region, often accompanied by a sensation of subtalar instability 

  • Broadly descriptive rather than a precise pathological entity; synonyms include "sinus tarsi pain," "sinus tarsi impingement," and “tarsal sinus syndrome” 

2. Cause

  • Primary: Acute or recurrent inversion ankle sprains (~70–80% of cases) leading to injury of subtalar ligaments (interosseous talocalcaneal, cervical, etc.) and subsequent synovitis, hemorrhage, fibrosis, or scar tissue in the sinus tarsi Secondary: Biomechanical factors such as overpronation, flatfoot deformity, excessive joint eversion/inversion, or chronic subtalar instability (~20–30%) Less often linked to degenerative joint disease, ganglion cysts, or inflammatory arthritides (e.g., rheumatoid arthritis) 

3. Classification

  • No formal staging system exists; STS is best described as symptomatic sinus tarsi pain with or without mechanical instability 

  • A “canalis tarsi syndrome” variant may present with broader, medial hindfoot symptoms 

  • Suggested best practice is to identify underlying causes (e.g. ligament tear, impingement, synovitis) rather than rely on the general label 

4. Signs & Symptoms

  • Pain: Deep, lateral hindfoot ache or sharp stabbing at the sinus tarsi; exacerbated by palpation, inversion/eversion, weight-bearing, walking uneven terrain 

  • Tenderness to direct palpation over the sinus tarsi, reproducible with supination and adduction 

  • Instability: Reports of looseness, giving-way, especially with uneven surfaces or direction changes 

  • Associated findings: Subtalar range-of-motion restriction, potential peroneal spasms, valgus hindfoot posture in some cases 

  • Diagnostic injection: Pain resolution with local anaesthetic in the sinus tarsi is considered confirmatory 

5. Current Treatment Trends

A. Conservative First-line (~60–80% success)

  • Rest/immobilisation (e.g., ankle braces, crutches) to reduce irritation 

  • NSAIDs, cryotherapy, activity modification 

  • Physical therapy: Targeted proprioceptive and neuromuscular training, strengthening of calf, foot and ankle, joint mobilisations, balance/coordination drills, retraining motion patterns 

  • Supportive devices: Footwear modifications, off-the-shelf or custom orthoses, medial heel wedges 

  • Injections: Local corticosteroid/anaesthetic, platelet-rich plasma or ozone injections into the sinus tarsi space — effective for short-term relief 

B. Minimally Invasive / Interventional (~40–60% success)

  • Ultrasound- or fluoroscopy-guided injections of corticosteroid or biologicsSubtalar arthroscopy: Diagnostic and therapeutic debridement of synovitis, scar tissue, ligament repair — increasingly favored when imaging is inconclusive and conservative measures fail 

C. Surgical Intervention (rare; for refractory cases)

  • Open or arthroscopic debridement, removal of bony or soft-tissue impingement, ligament reconstruction, or in structural deformities, procedures such as subtalar arthroereisis for flatfoot correction 

  • Post-surgical rehab includes immobilization followed by progressive rehbilitation therapy, aiming for return to sport or full function in 4–6 months; full recovery by ~12 months 6. Prognosis

  • Excellent outcomes with early, comprehensive conservative care; persistent symptoms risk chronic instability and pain 

  • Minor relapse rates exist if only conservative methods are used.

  • Arthroscopy offers ~60–70% return-to-sport success; provides both diagnostic clarity and therapeutic effect