Adult Acquired Flatfoot/PTTD (PCFD)

Adult Acquired Flatfoot/PTTD (PCFD)

Terminology

• PTTD refers to Posterior Tibial Tendon Dysfunction.
• PCFD is Progressive Collapsing Foot Deformity
• AAFD is an antiquated name for Adult Acquired Flatfoot

Lecture Overview

• The lecture covers normal and pathological anatomy, etiology, clinical exam, plantar dominance, and classification systems.
• Imaging, non-surgical management, surgical management, post-op care, and complications are also discussed.

Key Point

• PTTD is the most common cause of acquired unilateral adult flatfoot deformity.

Normal Anatomy

• Components include the tendon, tendon sheath, flexor retinaculum, watershed, insertion, and biomechanical function.
• The spring ligament, deltoid ligament complex, and interosseous talocalcaneal ligament (ITL) are also components.

The Watershed

• The watershed begins 40mm from the medial tubercle of the navicular.
• It extends an average of 14mm proximally.

Pathological Anatomy

• Pathological anatomy includes tendon edema, synovitis, and fusiform swelling of the tendon.
• Longitudinal rents in the tendon with yellow mucoid discoloration, attenuation/tendon rupture, tendon adhesions, and tendon end atrophy and cell death are also elements of pathological anatomy.

Etiology

• Etiology includes acute trauma and inflammatory synovitis.
• Predisposing factors include hypertension, obesity, diabetes mellitus (DM), previous surgery (sx), and steroid use (according to Holmes + Mann (F+A.1992) study).
• Michelson (FAI.1995) found that 11% of RA patients have PTTD.
• Other factors include the presence of an accessory navicular, middle-age obese females, and intrinsic abnormality of tendon (most common)

History & Physical

• History includes unilateral or insidious onset, recall of trauma, and presentation months to years.
• Bilateral cases could suggest rheumatology

Physical

• Classic presentation of PTTD: heel valgus, talar plantarflexion, flattened medial arch, abduction at Chopart's articulation, and sinus tarsi pain.
• The classic presentation is not always present, and the diagnosis is often missed.

Symptoms

• Symptoms vary depending upon the degree of tendon injury, including tenosynovitis, partial rupture, and complete rupture.
• Sinus tarsi pain and gait alterations may not be seen for up to 12 months.
• Chronic PTTD can lead to CCJ, TNJ, or STJ DJD (degenerative joint disease).

Clinical Tests and Findings

• Findings may include swelling/fullness of medial ankle and the "too many toes" sign.
• Single and double limb heel raise tests, manual muscle testing, and the Silfverskiold test can be utilized.

Planar Dominance (Surgical Biomechanics)

• Frontal plane dominance involves increased superimposition on lesser tarsus on lateral view and decreased 1st metatarsal declination angle and decreased height of sustentaculum tali.
• Transverse plane dominance involves an increase in D/P talocalcaneal and cuboid abduction angle, and a decrease in forefoot adductus angle and % of TN congruency.
• Sagittal plane dominance involves increased talar declination angle and T-C angle on lateral view, decreased CIA (calcaneal inclination angle), and NCJ breach.

Classification Systems

• Johnson & Strom classification system is important to know.
• Stage I includes tendon length normal to mild degeneration, mobile and normal hindfoot alignment, mild and focal medial pain, mild weakness on single-heel rise test, normal "too many toes" sign, synovitis pathology, and conservative treatment for 3 months.
• Stage II includes supple flatfoot, valgus position, tendon may be ruptured, hindfoot alignment along with TPT, moderate medial pain, marked weakness of single-heel rise, positive "too many toes" sign with forefoot abduction, marked degeneration pathology, and transfer FDL for TPT with synovectomy, tendon debridement, and rest (surgical, 3 months) treatment.
• Stage III includes rigid flatfoot, complete degeneration, fixed valgus position, possibly moderate medial/lateral pain, marked weakness on single-heel rise, positive "too many toes" sign, marked degeneration pathology, and subtalar arthrodesis treatment.
• Myerson added a 4th stage to Johnson and Strom, then Bluman and Myerson expanded it even more.

New Terminology and Classification (PCFD)

• PCFD (Progressive Collapsing Foot Deformity) was adopted in 2019 as new terminology for AAFD because the antiquated name can affect kids.
• Five position statements from the meeting: The name AAFD is antiquated (100% adoption of PCFD), classification systems are antiquated, include MRI findings (33%), add WBCT (56%), and adopt the new classification system (89%).

Imaging

• Lateral view X-rays help in evaluating Meary's line and calcaneal pitch; faults indicate sags or breaches.
• Meary-Tomeno Line is referred to as Meary's Line or Meary's Angle.
• Normal value is +/- 4 degrees, whether a flat foot or cavus foot.
• MRI: An MRI might not be needed, but can be the Gold Standard for diagnosis of PCFD.
• Representative MRI Findings: The Tendon, The Deltoid Complex, The Spring Ligament, The ITCL

FAO (Foot Ankle Offset)

• The FAO is a 3-D measurement that determines the alignment of the foot using a cone beam WBCT and measures hindfoot alignment.
• It uses 3D coordinates of the foot tripod and center of the ankle joint.
• FAO is calculated by taking the percentage distance between these two areas and dividing by foot length assessing torque on the foot.
• The "sweet spot" is between -1.64% and +2.71%.
• More negative values indicate a more varus attitude (talus is lateral), and more positive values indicate a valgus alignment (talus is medial).
• FAO is a percentage: offset distance / foot length (M1-M5 line) x 100.
• An important finding: the MIDDLE FACET of the STJ is most responsible for subluxation, not the posterior facet.

Relevant Studies

• A safe zone, -1.64% and +2.71%, for FAO was described in Francois Lintz et al. Arch Orthop Trauma Surg. 2023 May, Level II.
• Cesar de Cesar Netto et al. FAI. 2020 July, Level III reported that 3D WBCT measurements of FAO correlated with traditional AAFD markers, and a simple biomechanical assessment representing 3D deformity components.

Take Home Points

• Although WBCT is not universally available, it's gaining traction in both research and clinical use.
• The MIDDLE FACET is a very specific early marker for peritalar subluxation in PCFD and PCFD is a 3-D disease so 3-D imaging is necessary.
• The 3-D biometric Foot Ankle Offset correlates with conventional measurements.
• The spring ligament may be as important as the TPT in PCFD, thus requiring an MRI.
• There's still a lot of work to be done explaining the data and Normal FAO% is still being determined.

Non-Surgical Management

• The goal of treatment seeks to control pain with analgesics, control inflammation with NSAIDs, stabilize joints with bracing, prevent progression with bracing, and avoid cortisone injections.

Surgical Management

• Casting and orthoses such as Richie Brace, Arizona Brace, Articulated AFO, and Patella Tendon-Bearing Brace are options.
• Considerations: amount of pain, amount and location of deformity, amount of dysfunction, and X-ray/MRI changes.

Options

• Direct repair, TPT repair/FDL Transfer/Spring ligament and deltoid repair, osteotomies, arthrodesis, arthroereisis, medial/lateral column procedures, and Stage IV tilted ankle.

Common Techniques

• Options seek to fix equinus; either a recession or TAL.
• PCDO [Koutsogiannis] +/- DCO [Evans], spring ligament and deltoid ligament repair, TPT repair and FDL transfer, medial column fusion (Usually a Hoke), Cotton.

Equinus

• Options are either a TAL OR GASTROCNEMIUS RECESSION, DEPENDING UPON THE RESULTS OF THE SILFVERSKIOLD TEST.
• A recession is preferred in the case of equinus which is defined as a lack of DF at the ankle
• Sobel: Less than 0 degrees DF w/ KE (knee extended).
• DiGiovanni and Root: Less than 10 degrees DF w/ KΕ.
• Sgarlato: 10 degrees with the STJ neutral and MTJ locked.
• The most profound causal agent in foot pathobiomechanics and the greatest symptom producer of the human foot is [DeHeer].
• The Silfverskiold test determines whether a gastrocnemius recession or tendo-Achilles lengthening is required.

Gastrocnemius Recession

• Zones for Recession utilizes the specific recession procedures: Vulpius and Tongue-in-Groove [Baker], Fulp & McGlamry, Strayer, and Endoscopic Gastrocnemius Recession.

Tendo-Achilles Lengthening

• Options include Open Z Lengthening: Incision is a straight linear medially just off the tendo-Achilles.
• Percutaneous TAL and Hoke or White. The tendo-Achilles spirals counterclockwise 30-150 degrees as it courses toward its insertion, allowing for elongation and elastic recoil.
  • Hoke Triple Hemi-Section or White Double Hemi-Section

Posterior Calcaneal Displacement Osteotomy (PCDO)

• Next, address the heel with a PCDO or DCO by moving the calcaneus to a position of mild varus provides static support to the TPT by positioning the tendo-Achilles to pull the heel into varus, which locks the TTJ during toe-off/
• Koutsogiannis and Percutaneous Koutsogiannis with a gigli saw are other options.

Other PCDOs

• Other options include Silver and a Reverse Dwyer.

Addressing the Medial Side

• Focuses on the TPT, medial supporting structures, and the FDL transfer using a long incision that starts several centimeters above the medial malleolus and curves around the medial malleolus, and extends to the distal first metatarsal.
• This utility incision allows for deltoid repair, spring ligament repair, TPT repair, FDL transfer, and medial column fusion.

Deltoid Ligament Function

• Limits talar abduction and pronation, deep deltoid prevents eversion and lateral displacement of the talus, and the superficial deltoid limits external rotation.
• Options include Direct Primary Repair of the SL and Internal Brace Augmentation, spring ligament repair with grafting, endoscopic repair of deltoid and spring ligament, and the ITL.

TPT Repair & FDL Transfer

• One must Find the Master Knot of Henry, tubularize the tendon, and Transfer the FDL tendon onto the navicular.

Medial Column Fusion

• A Hoke is described and a Lowman and Miller. (Johnson et al. FAI 2020)
• Hoke stabilizes the medial longitudinal column and the naviculocuneiform fusion and is critical for restoration of a balanced foot tripod.

Cotton

• Employs a first cuneiform osteotomy w/ bone graft. (Johnson et al. FAI 2020) Consensus on Indications for the Cotton Osteotomy in the Treatment of PCFD.
• The typical wedge size needed for correction ranges from 5-11 mm.
• Some clinical instability of the 1st ray does not preclude the Cotton.
• Gross clinical instability with plantar gapping on x-ray may require a 1st TMT fusion.

Post-Op Care

• Posterior mold for 7 days or bivalved cast in the OR with the foot in equinus and adduction, transitioning to NWB SLC up to 8-12 weeks depending on the procedures performed without maintaining equinus and adduction.
• Begin formal PT around 4-6 weeks, depending upon what's been done.
• Let the patient know of continued improvement after 18-24 months.

Complications

• Includes subtalar arthrosis w/ arthroereisis, skin necrosis w/ the calcaneal osteotomy, and FF supination w/ lateral column pain w/ Evans.
• Potential complications and considerations: need for bone work, progression of the flatfoot deformity, overcorrection of calcaneal osteotomy, sural neuritis, and failure to recognize spring and deltoid ligament pathology.

Arthroereisis

• Spelling it correctly and defining it have been asked in clerkships. Arthroereisis is a question.
• Does this really work for PCFD?
• Arthro-: From the Greek arthron meaning joint (even though the tarsal canal is not a joint).
• -ereisis: From the Greek root ereidein [to press a thing against]. A lifting up with an implant in the STJ to prevent pathological pronation.

Types

• Vogler: Self-Locking, Axis-Altering, Direct Impact.
  • Graham & Nikhil: Type I A and B, Type II. IA is a cylinder; IB is a cone. In Type II, medially its a cylinder and laterally its conical.
• Self-Locking Wedge and Axis-Altering: The STA-Peg
  • STA-=Subtalar Arthroereisis = An axis-altering device for a pathologically low STJ axis

Relevant Study

• Pablo Fernandez de Retana, et al. Foot Ankle Clin N Am 17 (2012)

Insurance Coverage

• Insurances includes Cigna Healthcare: Effective Date: 10/15/24: Subtalar joint implantation is considered experimental: Rigid or flexible pes planus [ie flatfoot], Posterior tibial tendon dysfunction, Talotarsal joint subluxation/dislocation.
• BC/BS of Michigan: 11/2025

Complications of Arthroereisis

• The most common complication.