(1) upright life on land, both feet bear the weight, so the heel bone develops and grows, becoming the largest bone of the foot.
(2) Standing and walking, the foot is required to have flexibility and forward propulsion, so the navicular bone and the medial cuneiform bone rise upward to form the longitudinal arch of the foot.
(3) The original in order to grasp the convenience of the thumb, the thumb is slender and left with the second toe, forming a certain angle, flexible activities similar to the thumb. In order to walk upright requires weight-bearing stability, so the bunion and the second toe are close to parallel, no longer abducted into an angle, and there are ligaments associated with it, the activity is reduced because of it.
(4) Due to the formation of the arch of the foot, the ligaments of the foot develop and grow in order to maintain this arch-shaped structure. Then because the foot is no longer engaged in grasping action, so the foot intrinsic muscle atrophy degeneration.
Our Fang Xianzhi believes that the height of the human foot arch is not uniform, and does not represent the strength of the foot function. For example, in patients with high arches after poliomyelitis, the arches are high but inelastic, and the walking gait is ugly. Another example is the ballerina, who has a flatter arch, but because of the robust development of the intrinsic muscles of the foot, her gait is light, beautiful and elastic. Therefore, Fang believes that the formation of different arch heights, and people’s lives, customs and the environment in which they live. In the past, farmers in southeastern China, more barefoot labor throughout the year, at most, only wear grass tracks in the field, the environment is mostly mud, soft for the arch of the foot has a supporting role. Such a foot, not with shoes and socks, no restraint, can move freely, maintaining the original muscle ligament tension and elasticity, no factors leading to soft tissue contracture, followed by days of field work, the foot inside and outside the muscle have been exercised, muscle development is good, can play a protective role for the arch. These farmers rarely have the occurrence of flatfoot disease.
Modern material civilization is developed, we all wear shoes and socks, there are high-heeled shoes, there is also the so-called “rocket” pointed shoes, the foot horizontal restraint, so that the muscle is often in a state of tension, plus the road is flat and tidy, go out on the bus, or bicycle, rarely activities. In the above circumstances, the foot muscle lack of exercise, not strong enough. If coupled with a rich life, strong and fat, weight gain, the arch can not bear, it is easy to form a flat foot syndrome. Therefore, flat-footedness can be regarded as a degenerative disease in the period of human evolution and advanced material civilization. From the above discussion, it can be seen that the low arch or flat feet, can not be said to be flat feet disease. The arch of the foot can absorb shocks, and a good arch should be elastic. The arch of the foot is too high and the ligaments are too tight; or the arch of the foot is too low and the ligaments are loose and the foot muscles are weak, which will cause pain. Although the arch of the foot is flat, but the ligament is strong, the foot muscle is strong and can play a protective role, with elasticity, can be no symptoms. Therefore, flatfoot syndrome refers to those who have low and flat arches, with the affected foot turned out and inelastic, and have foot pain symptoms when walking and standing.
The clinical anatomy of the foot arch The foot has two arches in different directions, the transverse arch and the longitudinal arch, and the latter is divided into the lateral longitudinal arch and the medial longitudinal arch. The shape of the arch is maintained by the shape of the bones themselves and the strength of the ligaments and muscles. The bones that constitute the arch and the ligaments and muscles that maintain them are closely related to each other and have mutual influence. The longitudinal arch is particularly important, as the longitudinal arch collapses and the transverse arch disappears, but the longitudinal arch can remain intact when the transverse arch collapses.
There are 28 bones in total, except for the seed bone and talus, which are wide at the back and narrow at the bottom, and when they are combined, an arch-shaped structure is naturally formed. In the transverse section of the front part of the foot, the tarsus and five metatarsals can be seen to be arranged in the shape of an arch, with the transverse arch at the base of the metatarsals being more obvious and the head of the metatarsals becoming shallow. The integrity of the transverse arch is dependent on the presence of the longitudinal arch. The posterior arm of the medial longitudinal arch consists of the heel bone and talus, and the anterior arm consists of the first, second, and third cuneiform bones and the metatarsals, which are topped by the navicular bone. The medial longitudinal arch has a high arch, a short posterior arm and a long forearm. The first metatarsal still retains some evolutionary shortcomings, and its connection with the second metatarsal is not strong enough. There is no articular surface between the talonavicular process of the heel bone and the navicular bone, which is connected only by the heel navicular ligament, and the underside of the talonavicular head is pressed against this band, so the medial longitudinal arch is less resistant. In the lateral longitudinal arch, the posterior arm is the heel bone, the top is the dice bone, and the forearm is the fourth and fifth metatarsals. The joint surface of the heel and dice of the lateral longitudinal arch is broad and flat, so it can touch the ground firmly when standing, and the fourth and fifth metatarsals are strongly connected, and the lateral longitudinal arch is also lower, which are its superiority. In short, the posterior arm of the longitudinal arch is short and simple in structure, and the heel bone is the common foundation of the medial and lateral longitudinal arches, so the development of the heel bone is large. The longitudinal arch has a long forearm and a complex structure, especially the first metatarsal bone preserves some evolutionary defects and constitutes a weak point. Therefore, the lateral edge of the foot is stronger than the medial edge. The ligaments are important tissues that maintain the connection between the bones that make up the arch of the foot. The dorsum of the foot is prominent, with little weight bearing and weak ligaments, and the metatarsal side is heavily loaded, which is also particularly important for the maintenance of the foot arch, so the ligaments are thick and strong. The long metatarsal ligament connects the heel bone and the dice bone, and the short metatarsal ligament connects the heel bone and the metatarsal bone. The heel navicular metatarsal ligament, also known as the elastic ligament, starts from the talar process of the heel bone and ends at the bottom of the navicular bone, which is strong and elastic and is an important structure to prevent the talar head from collapsing or tilting inward. The metatarsal tendon membrane starts from the heel tuberosity and divides into five tendon strips, ending at the flexor tendon sheath and the transverse ligament of the metatarsal head, maintaining the longitudinal arch, like a bowstring. The tibiotalar ligament of the medial triangular ligament of the ankle joint connects the medial ankle to the heel bone and prevents its valgus.
The muscles are the third line of defense to maintain the arch of the foot and are also the main line of defense. Foot muscles are divided into two kinds of intrinsic muscles and extrinsic muscles, the former is degenerated and plays little role in human body, and only plays a supplementary role in the maintenance of foot arch. Therefore, the maintenance of the foot arch mainly relies on the role of extrinsic muscles, such muscles are.
(1) Anterior tibial muscle: through the ankle joint in front of the inner side, stopping at the base of the first metatarsal and the first cuneus medially. It can make the ankle joint dorsal extension, lift the foot forward when stepping, also lift the inner edge of the foot, increase the longitudinal arch, and turn the foot inward.
(2) The posterior tibial muscle, along the base of the spring ligament, ends at the navicular tuberosity, the cuneus, the dice bone and the base of the second to fourth metatarsals, but the navicular bone is its main stop. When the posterior tibial muscle contracts, the navicular bone approaches the inner ankle and holds the talar head tightly, strengthening the spring ligament and preventing the talar head from sinking and tilting inward, and the whole foot turns into an inward and inward position around the talar head.
(3) Peroneus longus: through the posterior and lateral side of the outer ankle, dice bone groove to the sole of the foot, on the base of the first metatarsal and the metatarsal side of the first cuneus, and tibialis anterior muscle balance cooperation, such as two strong hanging belt, each foot’s inner and outer side around the sole of the foot, the arch of the foot will be raised upward.
(4) Gastrocnemius muscle: its role makes the front end of the heel plantar flexion, longitudinal arch down, destroying the structure of the arch of the foot. Therefore, gastrocnemius contracture or shortening, prone to flatfoot syndrome.
To sum up, it can be seen that the bone arch, which is composed of many bones of a unique shape with a wide top and a narrow bottom, is properly lowered if it is normal and stable, so that gravity is transmitted to the ligaments, and when the ligaments reach proper tension, the internal and external muscles of the foot begin to contract to assist the ligaments in maintaining the structure of the arch. Therefore, the bones constitute the first line of defense for the arch, the ligaments are the second line of defense, and the muscles are the most important and final third line of defense. Many strong and complex ligaments, longitudinal and transversal, are laid on the plantar side of the foot, no matter how strong they are, they cannot bear excessive load without limitation. If no attention is paid to prevent their overload and chronic strain, the plantar ligaments will gradually be stretched and relaxed, and the normal arch structure cannot be maintained. The contraction of the internal and external muscles of the foot can support the arch and prevent the weight from being directly and fully added to the ligaments. More importantly, the foot muscle can be exercised to become strong and strong, and can actively maintain the arch structure. As for the ligaments, there is no active exercise method to make them stronger. Therefore, the third line of defense, the muscle, is the most important and the only tissue that can be made stronger by taking some measures.
The clinical physiology of the foot arch The foot is the fulcrum of the body, and when walking or standing, it is weight-bearing by the heel bone and the first and fifth metatarsal heads. The weight-bearing line of the lower extremity runs through the central patella down to the first and second metatarsals. The arch of the foot is elastic and absorbs the shock that occurs during walking to protect the joints and internal organs. When walking muscle contraction, the foot bones work together, forming a powerful lever to push the body forward. Walking, the heel first landing, and then moved to the lateral edge of the foot landing, and then moved to the metatarsophalangeal joint of the bunion by the metatarsal head, by the medial edge and back to the heel. So walking activities, 0 is the foot from the back → outside → before → inside → after the repeated circular motion. The completion of these actions rely on muscle contraction, so the strain on the ligaments of the foot is not much. Proper walking is beneficial to the arch of the foot, but not harmful. When people stand upright, the external muscles that maintain the arch of the foot are completely relaxed, and all the weight of the body is borne by the ligaments of the foot, so the long-term accumulative standing work will easily cause strain on the ligaments and contribute to muscle atrophy, as a result of which flatfoot syndrome will occur.
When people run or jump, the heel does not land, both sides of the forefoot is not at the same time on the ground, the contraction of the two foot muscles, one after another, both tension and coordination, ligament strain is less likely, so moderate running and jumping, the arch of the foot is also beneficial. But there must be a good arch as a prerequisite, has lost the elasticity of the arch, or the arch has collapsed, is not suitable for too much running, jumping action. Wearing high-heeled shoes, in standing or walking, the long extensor muscles are in a highly tense state, wearing flat shoes without heel, and make the muscles too relaxed, increasing the burden on the ligaments. Both are detrimental to the maintenance of the arch. Therefore, it is appropriate to wear shoes with a medium height heel.
Etiology and classification
Low arch is not necessarily flatfoot syndrome. However, the arch of a patient with flatfoot syndrome is always low and flat, and there are also symptoms of foot exostosis, loss of elasticity, and pain when standing or walking for a long time. There are many causes of flatfoot syndrome, and there is not yet a unified classification method, today, according to the cause, classified as follows.
1, congenital flatfoot syndrome
Congenital structural flatfoot syndrome: such patients have structural deformities of the foot bones. Some of them have stiff deformities after birth, while others have deformities and symptoms only at the age of about 10, when growth and development are rapid and activities increase; some of them may not show symptoms because of better living and medical conditions and better care. Some of these deformities include tarsal bridge, vertical talus, and paracarpal.
Congenital postural flatfoot syndrome: Congenital postural flatfoot syndrome, without structural deformity, has the following conditions.
(1) In infants who have not yet walked on the ground or just walked, there is a lot of fatty tissue on the bottom of the foot, and in addition, the internal and external muscles of the foot are not developed, so it seems that there is no longitudinal arch in appearance, but in fact there is a longitudinal arch, which is called pseudo-flat foot.
(2) One or both parents of the affected child have mild or severe flatfoot syndrome. After birth, the child has ligament laxity, muscle weakness, sinking arch and valgus when bearing weight, and normal arch when not bearing weight. If the degree of flatfoot of such children is light, living and medical conditions are good, they can get timely medical guidance, wear orthopedic boots, exercise the foot muscle, and the symptoms of flatfoot syndrome do not occur. If the degree of flat feet is heavy, and the lack of medical guidance, it will produce flatfoot syndrome.
(3) Ectropion; the child’s medial deltoid ligament is relaxed, causing the foot to rotate outward from its normal position on the tibia-F side, resulting in the force line of the lower limb shifting medially between the first and second metatarsals, sometimes even to the medial side of the first metatarsal, and the child mostly has a knee valgus deformity. The child has no pain and no discomfort, only the pronounced protrusion of the medial condyle and the outward rotation of the axis of the Achilles and Achilles tendons. If the foot is not weight bearing, the deformity disappears and the longitudinal arch does not collapse. When the child walks, the toes often turn inward so that the load line moves to the central or outer edge of the foot, automatically correcting the deformity unconsciously, and the gait returns to normal when the deformity disappears. Therefore, the child should be encouraged to walk with this gait. If the child’s toes do not turn inward when walking, the sole can be added to the heel of the horse, that is, the inner side of the heel is increased by 0.42cm, the inner edge of the shoe is extended forward by 1.25cm, and the weight is shifted to the outer edge of the foot when standing, so that the foot can turn inward. This heel should continue to apply until the calf and foot to restore the normal relationship.
2.Acquired flatfoot syndrome
Acquired structural flatfoot disease: the affected foot is normal, neither structural deformity, nor functional abnormalities. After the trauma caused by bone and soft tissue deformity, or foot tarsus with septic infection. The deformity occurs when the bone is destroyed, or the foot muscle is paralyzed due to poliomyelitis or cerebral palsy, or the foot muscle is chronically hypoxic due to vascular diseases and atrophy occurs. All of these may lead to the collapse of the foot arch and pain, resulting in acquired structural flatfoot syndrome.
Acquired postural flatfoot syndrome: the child does not have structural deformity, because the ligaments of the foot are not strong enough, the strength of the internal and external muscles that maintain the arch of the foot is not compatible with the weight it carries, resulting in the collapse of the arch of the foot to form flatfoot syndrome. This condition is most likely to occur in two stages of age; ① early childhood: rapid growth and development of the body, increased mobility, foot muscle strength can not adapt to the length, weight and activity capacity of the rapid increase, ② middle and old age, weight increasing, and muscle strength can not be increased. The stability of the foot arch depends on the strong internal and external muscles of the foot to maintain it, and any muscle atrophy and weakness can lead to the occurrence of postural flatfoot syndrome. Such as adolescent development, length and weight rapidly increase, and poor nutrition, sleep deprivation, or usually do not exercise, suddenly long distance or standing for too long; middle-aged and elderly fat, pregnant women, sudden weight gain, prolonged illness bed, once the weight of the ground, unsuitable shoes, resulting in foot muscle atrophy or spasm, etc.. All the above-mentioned reasons can cause the foot muscle strength is not enough to maintain the foot arch, bear the body weight, the longitudinal arch is pressed down, and produce the symptoms of flatfoot syndrome.
Clinical manifestations
Both congenital and acquired structural flatfoot syndrome, which occurs due to structural abnormalities of the foot, are specific flatfoot syndrome and are discussed in a separate topic. The following discussion of clinical symptoms and treatment will focus on acquired postural flatfoot syndrome. Its clinical manifestations can generally be divided into three stages.
Initial stage: After standing and walking for too long, the patient feels foot fatigue, soreness and discomfort, plantar heat, and puffiness in the center and dorsum of the foot. The patient has no obvious foot posture changes except for low arch and foot exostosis. There is mild inversion restriction of foot movement. The rest is not abnormal. There may be mild pressure pain in the navicular spur joint. The above symptoms will disappear completely once rested.
Middle stage; also called spastic stage. If the initial stage is not treated, it will develop into the spastic stage, mainly manifesting as peroneal muscle spasm, with the foot in valgus, abduction and dorsiflexion position, and the activity is significantly restricted. At this time, the pain increases, and walking and standing are not sustainable. Even after a long period of rest, the patient often cannot recover.
Late stage: also called tonic stage. The spastic peroneal muscle is not treated, and the spastic muscle develops into ankylosis, and the long and short ligaments between the foot bones become ankylosed, so that the foot is fixed in valgus, abduction and dorsal extension position. This deformity cannot be restored to normal even after prolonged rest or under anesthesia. However, when the patient has reduced pain or no pain, he can still walk short distances, but it is extremely difficult to run, jump or walk long distances. The walking gait is heavy and inflexible, and cannot absorb the shock force, therefore, traumatic arthritis and pain will occur in the knee, hip, and waist and other weight-bearing joints over time.
Some patients can enter the ankylosing phase directly from the initial stage, and some can stay in the initial stage for a long time. Long-term flatfoot patients can cause secondary changes in the foot, and the more common ones are: ① Bunion: due to the collapse of the longitudinal arch, the transverse arch disappears, the forefoot becomes wider, and the proximal phalanges of the bunions are pulled by the bunion muscles, and the bunion occurs. Traumatic arthritis: mainly occurs in the talonavicular, navicular wedge, heel dice and metatarsophalangeal joints. The joint space is narrowed due to cartilage atrophy, and the edges of the joints produce bony redundancy, and the medial side of the first metatarsal head often has bony redundancy formation, causing bunion swelling.
Human is the only vertebrate that has an arch, and the existence of the arch indicates both human characteristics and a sign of human evolution. The human ancestors lived in the forest and lived an arboreal life, and there was no clear division of labor between the functions of the upper and lower limbs, which were mainly based on climbing and grasping, so the hands and feet were similar, with no arch, well-developed forefoot, long toes and flexible, and the heel was not weight-bearing, and the heel bone was smaller because of it. At this time, the posture of the foot, the forefoot rotated inward, the inner edge of the foot depression, the outer edge of the convex. When human evolution, since the arboreal life moved to the plains, more important and decisive is the development of upright life, hands and feet have a clear division of labor. The hand was mainly engaged in labor production, and the foot was specialized in weight-bearing walking. For this reason, the structure and form of the foot also changed accordingly.