PTTD - Posterior Tibial Tendon Dysfunction

🧠 Introduction

Posterior Tibial Tendon Dysfunction (PTTD) is a progressive condition primarily seen in adults over 40—particularly women, but men are not immune here—and is the most common cause of acquired (adult) flatfoot deformity. It begins with tendon inflammation or wear and can evolve into structural foot deformities and joint degeneration. This summary integrates classic clinical staging (Johnson & Strom, Myerson) with advanced imaging and pathological insights to support improved diagnosis and treatment.

📌 Classification: Clinical Stages & Tendon Pathology

1. Clinical Staging (Based on Johnson–Strom / Myerson)

  • Stage I

    • Tendon intact but shows tenosynovitis or tendinosis—patients present with medial ankle pain and swelling.

    • Foot structure normal, single-leg heel-raise retained.

    • X-rays appear normal

  • Stage II (Flexible flatfoot develops)

    • Tendon becomes dysfunctional or partially torn; foot collapses but remains flexible.

    • IIa: hindfoot valgus, arch collapse without forefoot abduction.

    • IIb: flexible flatfoot plus forefoot abduction (positive “too many toes” sign).

    • Single-leg heel-raise often fails.

    • Imaging: talonavicular uncovering, subtalar joint preserved

  • Stage III (Rigid deformity)

    • Foot becomes rigid due to tendon rupture and subtalar joint arthritis.

    • Single-leg heel-raise fails; sinus tarsi pain present.

    • Radiographs show fixed hindfoot valgus and degenerative joint changes

  • Stage IV (Ankle involvement)

    • Medial ankle ligaments (deltoid) and talocrural joint are compromised.

    • Rigid flatfoot plus ankle arthritis and talar tilt.

    • Advanced stages may require ankle fusion

2. Pathological and Imaging-Based Classification

  • Spectrum of tendinopathy: tendon pathology ranges from tenosynovitis/tendinosis → partial tear → elongation/rupture .

  • Tear locations (MRI/ultrasound):

    • Most common: retromalleolar region with hypovascularity and mechanical stress.

    • Tears may occur at supramalleolar, retromalleolar, or inframalleolar sites

  • Associated findings: spring ligament damage (92%), sinus tarsi syndrome, plantar fascia strain, joint degeneration

  • Histopathology: shows chronic degeneration and synovitis (termed “pantendinopathy”) rather than acute inflammation

3. Terminology: TPT vs. PTTD vs. PCFD

  • Tibialis posterior tendinopathy (TPT) refers to early tendon pathology (Stage I–IIa) without structural collapse

  • Adult acquired flatfoot deformity (AAFD) and PTTD overlap structurally, with AAFD emphasizing defect and PTTD including tendon changes

  • Progressive Collapsing Foot Deformity (PCFD) is a newer classification describing the entire deformity spectrum; it often excludes tendon-only mild cases like TPT

💡 Mechanisms & Risk Factors

  • Hypovascular zone: behind medial malleolus, prone to ischemic degeneration

  • Mechanical overload: repetitive stress due to foot misalignment (e.g. overpronation, flatfoot, accessory navicular)

  • Demographics & comorbidities: most common in obese, hypertensive, diabetic women over 40; steroid use and inflammatory arthropathies contribute

🛠 Treatment Insights (Early vs Advanced)

  • Conservative (Early / Flexible Stages I–II):

    • Rest, NSAIDs, immobilization, custom orthotics/bracing, PT focused on strengthening/inversion and proprioception.

    • Modalities like PRP and shockwave therapy show emerging promise

  • Surgical (Advanced / Rigid Deformity Stages IIb–IV):

    • Tendon debridement, FDL tendon transfer, osteotomies (medializing calcaneal, lateral column lengthening), spring ligament repair; arthrodesis in severe cases.

    • Outcomes: FDL transfer and Cobb procedure improve AOFAS scores and alignment; orthotic + exercise proven superior to orthotic alone

🧾 Summary

PTTD is a progressive spectrum from early tendinopathy to severe structural foot deformity with arthritis. Proper classification—recognizing early tendon-only changes (TPT)—enables timely intervention with conservative strategies like orthosis, physiotherapy, and emerging biologics. As the condition advances to rigid deformities, surgical reconstruction is usually required. Multi-modal imaging and consensus-based terminology (PCFD) are improving diagnostic precision and treatment planning.