summary Cavovarus Foot is a common condition that may be caused by a neurologic or traumatic disorder, seen in both the pediatric and adult population, that presents with a cavus arch and hindfoot varus. Diagnosis is made clinically with the presence of a foot deformity characterized by cavus, hindfoot varus, plantarflexion of the 1st ray, and forefoot adduction. A coleman block test is useful to assess for the flexibility of the hindfoot deformity to assist with surgical planning. Treatment ranges from orthotics to operative soft tissue release and operative osteotomies depending on patient age and flexibility of the foot deformity. Epidemiology Demographics seen in both pediatric and adult populations Anatomic location when bilateral often hereditary or congenital Etiology Deformity characterized by cavus (elevated longitudinal arch) plantarflexion of the 1st ray and forefoot pronation hindfoot varus forefoot adduction Pathophysiology neurologic 67% due to a neurologic condition diagnosis of neurologic condition is critical to render appropriate treatment unilateral - rule out tethered spinal cord or spinal cord tumor bilateral - most commonly due to Charcot-Marie-Tooth (CMT) disease muscle imbalances generate deformity weak tibialis anterior and peroneus brevis overpowered by strong peroneus longus and posterior tibialis results in plantarflexed 1st ray and forefoot pronation with compensatory hindfoot varus with the 1st metatarsal plantflexed and forefoot pronated, the medial forefoot strikes ground first the subtalar joint supinates to bring the lateral forefoot to the ground and maintain three-point contact, resulting in hindfoot varus while initially flexible, hindfoot varus can become rigid with time idiopathic usually subtle and bilateral traumatic talus fracture malunion compartment syndrome crush injury Associated conditions conditions which present with cavovarus foot Charcot-Marie-Tooth disease Cerebral palsy Freidreich's ataxia Spinal cord lesions Polio Amnitoic band syndrome (ABS) conditions caused by the presense of cavovarus foot see complications below Presentation History recurrent ankle sprains and lateral ankle pain peroneal tendon pathology lateral foot pain excessive weight bearing by the lateral foot due to deformity can result in 5th metatarsal stress fractures painful plantar calluses under 1st metatarsal head and 5th metatarsal head or base plantar fasciitis elevated medial arch, forefoot pronation and tight gastronemius lead to contracture of the plantar fascia Physical exam Coleman block test evaluates flexibility of hindfoot deformity technique place 1" block under the lateral foot eliminates contribution of the plantarflexed 1st ray and forefoot pronation to the hindfoot deformity findings flexible hindfoot will correct to neutral or valgus when block placed under lateral aspect of foot rigid hindfoot will not correct to neutral guides surgical treatment flexible hindfoot deformities resolve with forefoot corrective procedures rigid hindfoot deformities require corrective hindfoot osteotomy in addition to forefoot procedures peek-a-boo heel anterior standing examination shows varus heel "peeking" around the ankle prominent first metatarsal fat pads Silfverskiold test check dorsiflexion with both knee flexion and knee extension if tight only with knee extension, then gastrocnemius is tight if tight also with knee flexion, then soleus is also tight gastronemius tightness often present with cavovarus foot altered gait unstable base of support increased double limb stance and decreased single limb stance wasting of 1st dorsal interosseous muscle of the hand suggestive of CMT spine exam scoliosis is suggestive of CMT spinal dysraphism Imaging Radiographs recommended views standing anteroposterior (AP), lateral radiographs of the ankle standing AP, lateral and oblique radiographs of the foot findings AP foot talocalcaneal angle < 20° (nl 20-45°) hindfoot varus talonavicular overcoverage talonavicular angle > 7° indicates forefoot adduction metatarsal overlap forefoot pronation lateral foot lateral talo-first metatarsal angle (Meary's angle) > 4° apex dorsal break in Meary's line caused by plantarflexion of the 1st ray calcaneal pitch or inclination angle > 30° sinus tarsi see-through sign and double talar dome sign due to external rotation of the ankle and hindfoot relative to the xray cassette, which is placed along the medial border of the adducted forefoot bell-shaped cuboid increased distance between base of 5th metatarsal and medial cuneiform oblique foot metatarsal stress fractures calcaneonavicular coalitions Studies Electrodiagnostic Studies (EMG/NCS) diagnostic algorithm for CMT generally dictates a neurologic physical exam electrodiagnostic studies genetic testing Genetic studies used to confirm diagnosis after physical exam and electrodiagnostic studies Treatment Nonoperative accomodative shoe wear indications rarely sufficient except in mild deformity full-length semi-rigid insole orthotic with a depression for the first ray and a lateral wedge indications mild cavus foot deformity in adult (not indicated in children) supramalleolar orthosis (SMO) indications more severe cavovarus deformity recalcitrant to shoewear accomodations ankle foot orthosis (AFO) indications may be needed if equinus also present, resulting in equinocavovarus foot deformity works best if equinus is a dynamic defomrity (not rigid) lace-up ankle brace and/or high-top shoe or boots indications may consider in moderate deformities when patient does not tolerate the more rigid bracing with an SMO or AFO Operative soft tissue reconstruction indications failure of nonoperative treatment performed with a combination of the following procedures plantar release indications cavus deformity technique plantar fascia release Steindler stripping (release short flexors off the calcaneus) peroneus longus to brevis transfer indications plantar flexed first ray technique decreases plantarflexion force on first ray without weakening eversion posterior tibial tendon transfer indications muscle imbalance posterior tibialis typically is markedly stronger than evertors and maintains strength for a long time in most cavovarus feet may consider transfer of posterior tibialis to dorsum of foot if severe dorsiflexion weakness of anterior tibialis lengthening of gastrocnemius or tendoachilles (TAL) indication true ankle equinus gastrocnemius recession produces less calf weakness and can be combined with plantar release simultaneously TAL should be staged several weeks after plantar release 1st metatarsal dorsiflexion osteotomy indications flexible hindfoot varus deformities (normal Coleman block test) corrects the forefoot pronation driving the hindfoot deformity lateral ankle ligament reconstruction (e.g. Broström ligament reconstruction) indications chronic ankle instability due to lignamentous incompetence following long-standing cavovarus Jones transfer(s) of EHL to neck of 1st MT and lesser toe extensors to 2nd-5th MT necks indication toe clawing combined with cavus foot performed if the indication is met and time permits the modified Jones transfer for the hallux includes an IP joint fusion lateralizing calcaneal valgus-producing osteotomy indications rigid hindfoot varus deformity (abnormal Coleman block test) triple arthrodesis indication almost never indicated due to very poor long-term results Complications Ankle instability standard lateral ankle ligament reconstruction will fail if cavovarus deformity is not concomitantly addressed untreated can lead to varus ankle arthritis Stress fractures 5th metatarsal base (Jones fracture) 4th metatarsal navicular medial malleolus Hallux sesamoiditis overload from plantarflexed 1st metatarsal head Peroneal tendon pathology tendonitis, tears, subluxation or dislocation peroneus brevis most commonly involved Plantar fasciitis contracture of the plantar fascia results from elevated medial arch, forefoot pronation and tight gastronemius Prognosis Depends on deformity severity etiology patient age