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 stage III disease 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 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