Congenital vertical talus

　　One, Etiology

　　It is generally believed that this deformity is formed in the first three months of embryonic development. Clinically, there are two types: isolated and associated types. The latter is often part of congenital diseases such as meningomyelocele, multiple joint contractures, neurofibromatosis, trisomy 13-15, 18, etc. The etiology of the isolated type of vertical talus is not clear, and some propose that it is caused by a blockage in the development of the foot embryo. Bitsila conducted experiments on young rabbits, simultaneously cutting the extensor digitorum longus, tibialis anterior, and cruciate ligament of the lower leg, and causing the gastrocnemius to shorten, successfully establishing an animal model of vertical talus. Therefore, he proposed that primary soft tissue lesions are the main factors causing this deformity. Some scholars have found that the incidence rate of certain families and twins is significantly higher than that of the general population, suggesting a genetic factor.

　　Two, Pathological Changes

　　1. Pathological changes can be divided into osseous deformities and soft tissue lesions. The osseous deformity mainly involves the formation of a joint between the navicular bone and the dorsal aspect of the calcaneal neck, locking the talus in a vertical state. The superior aspect of the talus head is flat or ovoid, the calcaneal neck is underdeveloped and shortened, and a joint surface is formed on the dorsal side. The proximal joint surface of the navicular bone tilts plantarward, the calcaneus shifts medially and laterally, the anterior part of the calcaneus deviates laterally and flexes plantarward, the sustentaculum tali is underdeveloped and loses its support for the talus, the lateral column of the foot is concave, and the medial column is relatively longer.

　　2. There are also significant changes in soft tissue, with the tibialis talocalcaneal ligament and the dorsal talocalcaneal ligament showing contracture, which are the main factors affecting reduction. The contracture of the lateral collateral ligament causes the foot to abduct, while the contracture of the interosseous talocalcaneal ligament and the calcaneofibular ligament hinders the reduction of the calcaneus medially and laterally. The plantar and lateral talocalcaneal ligaments, as well as the medial joint capsule, are stretched. The tibialis anterior, extensor digitorum longus, long extensor, short fibular muscle, and gastrocnemius all show increased tension due to contracture. The tendons of the long fibular muscle and the posterior tibial muscle shift forward to the ankle, acting as dorsiflexors.

　　Three, Pathogenesis

　　1. Dislocation of the talocalcaneal joint may form within the uterus as early as the first trimester of pregnancy, while the adjacent subtalocalcaneal joint, tarsal joint, and ankle joint subluxation are secondary. This condition can occur alone or as part of a systemic multiple malformation.

　　2. The talus bone and the neck of the calcaneus form a joint on the dorsal side, making the talus vertical, with the talus head deformed, the talus neck shortened, and the talus shifted medially and laterally, presenting a downward position. The talus appears convex on the sole of the foot. Other tarsal joint changes also occur, with the anterior bundle of the deltoid ligament, the dorsal talocalcaneal ligament, the calcaneocuboid ligament, the talocalcaneal ligament, and the calcaneofibular ligament all showing varying degrees of contracture. At the same time, the posterior joint capsule of the ankle joint and the talocalcaneal joint below the talus also become shorter, the talocalcaneal ligament is stretched and relaxed, and the muscles of the lower leg (tibialis anterior, extensor hallucis longus, extensor digitorum longus, gastrocnemius, etc.) all show contracture; the posterior tibial muscle and the long fibular muscle shift forward, becoming dorsiflexors.

　　1. The age of walking for children with this disease is often not delayed, but the gait is awkward. When standing, the forefoot is obviously abducted, and the talus head and calcaneus bear weight in a varus position, but the posterior part of the calcaneus often cannot touch the ground.

　　2. The disease mainly produces some postoperative complications, including: partial dislocation of the navicular bone, recurrence of deformity after surgery, joint stiffness, navicular bone necrosis, etc. The most serious complication is the ischemic necrosis of the navicular bone. Some scholars believe that if the child's age exceeds 5 years and still undergoes release and reduction, it is one of the causes of talus ischemic necrosis. In addition, it should be avoided to be rough in stripping the talus during surgery. Since the nutrient artery of the talus mainly lies at the neck of the talus, strictly mastering the indications for surgery and avoiding blind stripping during surgery is an important measure to reduce talus ischemic necrosis.

　　Patients often show the disappearance of the arch of the foot or prominence of the sole. The medial and plantar sides of the foot are very prominent due to the prominence of the talus head at this location. The forefoot has a dorsiflexion and abduction deformity. The muscles on the dorsal side of the foot, the tibionavicular ligament, and the talonavicular ligament are often tense and contractile, affecting the plantarflexion and inversion of the forefoot. The calcaneal varus deformity causes the posterior part of the calcaneus to be unable to touch the ground, shortening the muscles, tendons, and ligaments of the posterior part of the foot. Due to the stiffness of the ankle joint, the movement is limited, and the foot deformity is severe. When standing or walking, the heel cannot touch the ground, the gait is unsteady, walking is slow, and the affected foot is prone to fatigue and pain.

　　This disease is congenital and has no effective preventive measures. Early diagnosis and treatment are the key to the prevention and treatment of the disease. Some scholars believe that if the child's age exceeds 5 years and still undergoes release and reduction, it can increase the probability of talus ischemic necrosis as a complication. Therefore, early diagnosis and treatment are extremely important. In addition, it should be avoided to be rough in stripping the talus during surgery. Therefore, strictly mastering the indications for surgery and avoiding blind stripping during surgery is an important measure to reduce talus ischemic necrosis.

　　There are no related laboratory tests. The main examination for this disease is X-ray examination:

　　The talus can be seen in a vertical position in the lateral radiograph, almost parallel to the longitudinal axis of the tibia. The talus is in a plantarflexed position, and the forefoot has a marked dorsiflexion at the midtarsal joint. Since the navicular bone does not have a ossification center before the age of 3, the position of the navicular bone needs to be estimated using the first cuneiform bone's longitudinal axis. If this line extends posteriorly on the dorsal side of the talus head, it indicates that the navicular bone is dislocated posteriorly. In the lateral radiograph with strong dorsiflexion, the axis of the talus in a normal child's foot passes through the lower part of the cuneiform bone, while the axis of the calcaneus passes through the upper part of the cuneiform bone. In congenital vertical talus, the axis of the talus moves to the posterior inferior part of the cuneiform bone, sometimes passing through in front of the calcaneus. The axis of the calcaneus also moves to the plantar side of the cuneiform bone. The anteroposterior radiograph shows a significant increase in the calcaneo-navicular angle (normal value: 20°-40°). After the navicular bone ossifies, its displacement to the dorsal side of the talus neck can be displayed.

　　Congenital vertical talus is a congenital disease with no special dietary taboos. A reasonable diet can be followed, paying attention to nutritional balance and richness, and not eating too much high-salt, spicy, and刺激性 food.

　　One, Treatment Principles

　　The purpose of treatment is to reduce the vertically deformed talus to the normal anatomical position. Treatment should be started as soon as possible after birth. During the child's growth and development, the treatment method can be selected according to the child's age and the degree of deformity. Initially, manual reduction, cast, and Kirschner wire fixation can be used. If manual reduction fails, open reduction can be performed at the age of 3. Some scholars advocate surgical treatment as early as 3 months. For children aged 4-6 years, it is advisable to perform soft tissue surgery first, and then try manual reduction and fixation. For children over 6 years old, generally no surgery is performed, because the talus head is prone to ischemic necrosis, open reduction often fails, and a triple joint fusion surgery should be performed after 10-12 years old, including the excision of the contracted tissue and the corresponding osteotomy, including the excision of the talus head and the navicular bone.

　　Two, Manual Correction

　　Since this deformity is relatively rigid, the earlier the treatment, the better. It is generally believed that the first three weeks after birth are the best time for treatment, and manual reduction may be successful.

　　1. Manual correction with cast fixation:First, actively pull the gastrocnemius muscle and the Achilles ligament. The operator pulls the heel distally and medially with one hand, while pushing the anterior part of the calcaneus with the other hand, which needs to be maintained for 10 seconds. Then, pull the forefoot to the plantar, inversion, and adduction direction, so that the extensor and abductor muscles are stretched; then pull the forefoot distally to stretch the tibialis navicular and talocalcaneal ligaments, and gradually make the forefoot adduct and invert. Each action should be maintained for 10 seconds, and each session should last for 15 minutes. Finally, use a long leg cast to fix the position of the forefoot plantar flexion, inversion, and the hindfoot extension. Generally, change the cast every 2-3 days, and repeat the manual reduction and traction of the contracted soft tissues as described above. Approximately 4-6 weeks later, a closed reduction can be attempted. Start by traction the forefoot and navicular bone in the direction of the foot deformity, so that the navicular bone is above the talus head, and the calcaneus is below the talus. Then, push the talus head from the medial side to the dorsal side, pull the heel to invert, and at the same time, plantar flex and invert the forefoot to restore the normal anatomical relationship of the talocalcaneal joint.

　　2. Manual reduction with Kirschner wire fixation:After the above 6-8 weeks of manual treatment, if reduction is successful, a Kirschner wire can be passed from the first and second toes backward to贯穿the talocalcaneal joint, fixing the foot in plantar flexion and inversion, and using a cast to fix it. Change the cast 2-3 weeks later, increase the dorsal flexion of the foot, and the cast should be fixed for at least 3 months. Even if the manual correction fails, it is necessary to persist in the fixation to relax the soft tissues and prepare for surgical reduction.

　　Three, Open Reduction

　　1. If closed reduction is unsatisfactory, and the child has been three months old, open reduction should be performed. The surgical release of the contracted joint capsule and ligaments mainly includes:

　　(1) The dorsal and lateral parts of the talocalcaneal ligament.

　　(2) The tibialis navicular ligament and the bifurcated ligament.

　　(3) The dorsal and lateral parts of the talocalcaneal joint capsule.

　　(4) Talofibular and talocalcaneal interosseous ligaments. At the same time, extend the contracted tendons, such as the Achilles tendon, tibialis anterior tendon, extensor digitorum longus tendon, and fibular muscles. Then, under direct vision, reduce the talocalcaneal joint, restore the normal force line of the foot, and fix the cuneiform, navicular, and talus with a Kirschner wire. Then, tighten and suture the talonavicular plantar and medial parts, move the posterior tibial tendon to the distal end, and fix it to the plantar side of the first cuneiform. Postoperatively, the affected limb is fixed in a long leg cast for 8 to 12 weeks. Usually, the Kirschner wire is removed after 6 weeks.

　　2. Treatment should not start until after the child is 4 years old, as the medial column of the foot has become significantly longer, hindering the reduction of the talocalcaneal joint. When performing an open reduction, the navicular bone that has slipped to the dorsal side should be excised to allow the first cuneiform to articulate with the talus head. In the future, through growth and shaping, the talus head can occupy the space left by the excised navicular bone. If the child is already older than 8 years and has not been treated, the treatment of open reduction and navicular bone excision is not only difficult to succeed but also prone to talus necrosis. Therefore, it should be postponed until after the age of 10 to perform a triple arthrodesis.

　　3. Open ReductionGenerally, general anesthesia is used. Skin expanders can be placed on the lateral aspect of the foot to relax the skin. First, extend the Achilles tendon, make a transverse incision on the lateral side, cut the posterior joint capsule of the talocalcaneal joint and the talus, and make the talus invertible. Identify the articular surface of the talus and insert a Kirschner wire from the center, and exit from the medial side of the talus body. Use this Kirschner wire and a bone elevator to lift the talus head towards the dorsal side, at the same time making the forefoot invert, so that the talus head can recover the anatomical relationship with the talus articular surface. Insert the Kirschner wire that has been inserted into the talus into the talus, cuneiform, and first metatarsal, maintaining the position obtained during surgery. In older children, the talocalcaneal and talocalcaneal ligaments may interfere with the reduction of the talocalcaneal joint and the talocalcaneal joint, and can be cut. If the tendons of the tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibular muscles are too short to interfere with reduction, they can be extended. A thick Kirschner wire can be transversely crossed in the middle of the calcaneus, and the affected limb is fixed in a long leg cast in a flexed knee of 45°, ankle dorsiflexion of 10° to 15°, foot inversion of 10°, and forefoot plantar flexion inversion position. And pay attention to shaping the arch and heel of the foot. The Kirschner wire is removed after 6 weeks, and the cast fixation needs to be maintained for 3 to 4 months..