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Updated: May 31 2024

Posterior Tibial Tendon Insufficiency (PTTI)

Images
https://upload.orthobullets.com/topic/7020/images/xray.foot.lat.shows ptti.google.jpg
https://upload.orthobullets.com/topic/7020/images/stage 2b ptti xray lateral_moved.jpg
https://upload.orthobullets.com/topic/7020/images/ptt xray_moved.jpg
https://upload.orthobullets.com/topic/7020/images/731840e9-7e6b-4986-b591-d1de1e534b3f_ptti_stage_iv..jpg
https://upload.orthobullets.com/topic/7020/images/ptti stage i.jpg
https://upload.orthobullets.com/topic/7020/images/arch collapse.jpg
https://upload.orthobullets.com/topic/7020/images/forefoot abduction.jpg
https://upload.orthobullets.com/topic/7020/images/ap foot.jpg
  • summary
    • Posterior Tibial Tendon Insufficiency is the most common cause of adult-acquired flatfoot deformity, caused by attenuation and tenosynovitis of the posterior tibial tendon leading to medial arch collapse. 
    • Diagnosis can be made clinically with loss of medial arch of the foot which may progress to hindfoot valgus, forefoot abduction and subsequent development of midfoot osteoarthritis. 
    • Treatment is nonoperative with orthotics and ankle braces in early stages. A variety of surgical options are available and indicated for progressive and rigid deformities, subtalar or midfoot arthritis, and failure of nonoperative management. 
  • Epidemiology
    • Demographics
      • more common in women
      • often presents in the sixth decade
    • Risk factors
      • obesity
      • hypertension
      • diabetes
      • increased age
      • corticosteroid use
      • seronegative inflammatory disorders
  • Etiology
    • Mechanism
      • exact etiology is unknown
        • acute injury (e.g., ankle fractures caused by pronation and external rotation) vs. long-standing tendon degeneration
    • Pathoanatomy
      • early disease
        • early tenosynovitis progresses to PTTI
          • leads to loss of medial longitudinal arch dynamic stabilization
      • late disease
        • PTTI contributes to attritional failure of static hindfoot stabilizers and collapse of the medial longitudinal arch
          • spring ligament complex (e.g., superomedial calcaneonavicular ligament)
          • plantar fascia
          • plantar ligaments
        • fixed degenerative joint changes occur at late stages
      • foot deformity
        • pes planus
        • hindfoot valgus
        • forefoot varus
        • forefoot abduction
    • Associated conditions
      • inflammatory arthropathy
      • tarsal coalition
        • young person with rigid pes planus and/or recurrent ankle sprains
  • Anatomy
    • Muscle
      • tibialis posterior
        • originates from posterior fibula, tibia, and interosseous membrane
        • innervated by tibial nerve (L4-5)
    • Tendon
      • posterior tibial tendon (PTT) lies posterior to the medial malleolus before dividing into 3 limbs
        • anterior limb
          • inserts onto navicular tuberosity and first cuneiform
        • middle limb
          • inserts onto second and third cuneiforms, cuboid, and metatarsals 2-4
        • posterior limb
          • inserts on sustentaculum tali anteriorly
    • Blood supply
      • branches of the posterior tibial artery supply the tendon distally
      • a watershed area of poor intrinsic blood supply exists between the navicular and distal medial malleolus (2-6 cm proximal to navicular insertion)
    • Biomechanics
      • PTT lies in an axis posterior to the tibiotalar joint and medial to the axis of the subtalar joint
        • functions as a primary dynamic support for the arch
        • acts as a hindfoot invertor
        • adducts and supinates the forefoot during stance phase of gait
        • acts as secondary plantar flexor of the ankle
      • major antagonist to PTT is peroneus brevis
      • activation of PTT allows locking of the transverse tarsal joints creating a rigid lever arm for the toe-off phase of gait
  • Classification
      • Posterior Tibial Tendon Insufficiency Classification 
      • Deformity
      • Physical exam
      • Radiographs
      • Stage I
      • Tenosynovitis
      • No deformity
      • (+) single-heel raise
      • Normal
      • Stage IIA
      • Flatfoot deformity
      • Flexible hindfoot
      • Normal forefoot
      • (-) single-leg heel raise
      • Mild sinus tarsi pain
      • Arch collapse deformity
      • Stage IIB
      • Flatfoot deformity
      • Flexible hindfoot
      • Forefoot abduction ("too many toes", > 40% talonavicular uncoverage)
      • (-) single-leg heel raise
      • Mild sinus tarsi pain
      • Arch collapse deformity 
      • Stage III
      • Flatfoot deformity
      • Rigid forefoot abduction
      • Rigid hindfoot valgus
      • (-) single-leg heel raise
      • Severe sinus tarsi pain
      • Arch collapse deformity
      • Subtalar arthritis 
      • Stage IV
      • Flatfoot deformity
      • Rigid forefoot abduction
      • Rigid hindfoot valgus
      • Deltoid ligament compromise
      • (-) single-leg heel raise
      • Severe sinus tarsi pain
      • Ankle pain
      • Arch collapse deformity
      • Subtalar arthritis
      • Talar tilt in ankle mortise 
  • Presentation
    • Symptoms
      • medial ankle/foot pain and weakness is seen early
      • progressive loss of arch
      • lateral ankle pain due to subfibular impingement is a late symptom
    • Physical exam
      • inspection & palpation
        • pes planus
          • collapse of the medial longitudinal arch
        • hindfoot valgus deformity
          • flexible stage II
          • rigid stage III, IV
        • forefoot abduction (Stage IIB disease)
          • "too many toes" sign
          • >40% talonavicular uncoverage
        • forefoot varus
          • place flexible heel in neutral position
          • observe the relationship of metatarsal heads
            • flexible = MT heads perpendicular to long axis of tibia and calcaneus
            • fixed = lateral border of foot is more plantar flexed than medial border
        • tenderness just posterior to tip of medial malleolus
          • often associated with an equinus contracture
        • equinus contracture
          • positive Silfverskiöld test indicates contribution of gastrocnemius
      • range of motion
        • single-limb heel rise
          • unable to perform in stages II, III, and IV
        • PTT power
          • foot positioned in plantar and full inversion
          • unable to maintain foot position when examiner applies eversion force
        • determine whether deformity is flexible or fixed
          • flexible deformities are passively correctable to a plantigrade foot (stage II)
          • rigid deformities are not correctable (stages III and IV)
  • Imaging
    • Radiographs
      • recommended views
        • weight bearing AP and lateral foot
        • ankle mortise
      • findings
        • AP foot
          • increased talonavicular uncoverage
          • increased talo-first metatarsal angle (Simmon angle)
            • seen in stages II-IV
        • weight bearing lateral foot
          • increased talo-first metatarsal angle (Meary angle)
            • angles >4° indicate pes planus
            • seen in stages II-IV
          • decreased calcaneal pitch
            • normal angle is between 17-32°
            • indicates loss of arch height
          • decreased medial cuneiform-floor height
            • indicates loss of arch height
          • subtalar arthritis
            • seen in stages III and IV
        • ankle mortise
          • talar tilt due to deltoid insufficiency
            • seen in stage IV
    • MRI
      • findings
        • variable amounts of tendon degeneration and arthritic changes in the talonavicular, subtalar, and tibiotalar joints
    • Ultrasound
      • increasing role in the evaluation of pathology within the PTT
  • Differential
    • Pes planus secondary to
      • midfoot pathology (osteoarthritis or chronic Lisfranc injury)
        • treat with midfoot fusion and a realignment procedure
      • incompetence of the spring ligament (primary static stabilizer of the talonavicular joint) in the absence of PTT pathology
        • treat with adjunctive spring ligament reconstruction in addition to standard flatfoot reconstruction
  • Treatment
    • Nonoperative
      • ankle foot orthosis
        • indications
          • initial treatment for stage II, III, and IV
          • also for patients who are not operative candidates, sedentary/low demand (age > 60-70)
        • technique
          • AFO family of braces (Arizona, molded, articulating)
            • AFO found to be most effective
            • want medial orthotic post to support valgus collapse
            • Arizona brace is a molded leather gauntlet that provides stability to the tibiotalar joint, hindfoot, and longitudinal arch
      • immobilization in walking cast/boot for 3-4 months
        • indications
          • first line of treatment in stage I disease
      • custom-molded in-shoe orthosis
        • indications
          • stage I patients after a period of immobilization
          • stage II patients
        • technique
          • medial heel lift and longitudinal arch support
            • medial forefoot post indicated if fixed forefoot varus is present
            • UCBL with medial posting
    • Operative
      • tenosynovectomy
        • indications
          • indicated in stage I disease if immobilization fails
      • FDL transfer, calcaneal osteotomy, TAL, ± forefoot correction osteotomy ± spring ligament repair ± lateral column lengthening ± medial column arthrodesis ± PTT debridement
        • indications
          • stage II disease
          • lateral column lengthening for talonavicular uncoverage
          • medial column arthrodesis if deformity is at naviculocuneiform joint
        • contraindications
          • hypermobility
          • neuromuscular conditions
          • severe subtalar arthritis
          • obesity (relative)
          • age >60-70 (relative)
      • first TMT joint arthrodesis, calcaneal osteotomy, TAL ± lateral column lengthening ± PTT debridement
        • indications
          • stage II disease with 1st TMT hypermobility, instability or arthritis
      • isolated subtalar arthrodesis
        • indications
          • absence of fixed forefoot deformity
        • contraindications
          • fixed forefoot supination/varus
            • otherwise will overload lateral border of foot
          • joint hypermobility
      • hindfoot arthrodesis
        • indications
          • typically triple arthrodesis
          • stage II disease with severe subtalar arthritis
          • subtalar and talonavicular arthrodesis can be considered
          • risks included lateral plantar nerve irritation and FHL impingement from long interlocking screw 
      • triple arthrodesis and TAL + deltoid ligament reconstruction
        • indications
          • stage IV disease with passively correctable ankle valgus
      • tibiotalocalcaneal arthrodesis
        • indications
          • stage IV disease with a rigid hindfoot, valgus angulation of the talus, and tibiotalar and subtalar arthritis
  • Techniques
    • FDL transfer
      • indications
        • FDL is synergistic with tibialis posterior and therefore transfer can augment function of deficient PT
        • Stage II disease
      • relative contraindications
        • rigidity of subtalar joint (<15 degrees of motion)
        • fixed forefoot varus deformity (>10-12 degrees)
      • technique
        • find FDL and FHL at knot of Henry
        • insert FDL into navicular near insertion of PT
        • vs. FHL transfer
          • FHL is more complicated to mobilize and has not shown improved results
          • in the midfoot, FHL runs under FDL
    • Calcaneal osteotomy
      • indicated to correct hindfoot valgus
      • techniques include
        • medial displacement calcaneal osteotomy (MDCO)
          • used in stage IIA (insignificant forefoot abduction)
        • Evans lateral column lengthening osteotomy
          • used in stage IIB (significant forefoot abduction)
          • may require additional MDCO to correct the deformity
          • overlengthening may be corrected by a first TMT fusion or medial cuneiform osteotomy
          • overcorrection can lead to lateral column overload
      • can be performed open or through a minimally invasive approach
        • minimally invasive techniques associated with fewer wound complications, lower rates of nerve injury, decreased radiation exposure and shorter operative times
    • TAL or gastrocnemius recession
      • indicated for equinus contracture
    • Forefoot correction osteotomy
      • indicated for fixed forefoot supination/varus (stage IIC)
      • techniques
        • plantarflexion (dorsal opening-wedge) medial cuneiform (Cotton) osteotomy
          • used with a stable medial column (navicular is colinear with first MT)
          • corrects residual forefoot varus after hindfoot correction is made surgically
        • medial column fusion (isolated first TMT fusion, isolated navicular fusion, or combined TMT and navicular fusions)
          • used with an unstable medial column (plantar sag at first TMT and/or naviculocuneiform joint)
    • Spring ligament repair
      • indicated with spring ligament rupture in some cases
    • PTT debridement
      • may also be required
    • Triple arthrodesis
      • triple arthrodesis includes calcaneocuboid, talonavicular, subtalar joints
      • additional medial column stabilization may be required
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