Shoes can be one of the problems that affect the foot
2020/10/20 11:23:19
Metatarsophalangeal joint plays an important role in human upright walking. It connects people's toes with other parts of the foot, which can make the feet more stable and fast in walking and running. A study published in 1954 suggested that when the metatarsophalangeal joint bends upward, the plantar aponeurosis, which connects the toe bone and the calcaneus, becomes tighter, creating an upward force that counteracts part of the pressure on the longitudinal arch of the foot, thus making the feet more stable as they move forward.
When people put on a pair of sports shoes with the toe up, the metatarsophalangeal joint will be tilted upward along the curve of the toe, which will produce a similar effect. The more light feeling of walking is due to the reduction of pressure on the longitudinal arch of the foot. From the perspective of evolutionary chemistry, it is still a very short-term phenomenon for humans to wear modern shoes with arch support, cushioning and other supporting functions In the process of evolution, human feet are mainly suitable for walking on the parallel ground. This kind of walking mode with the toes up may be harmful. The most common symptom is plantar fasciitis.
Plantar fasciitis is common in both sports and non exercise groups, especially in runners, accounting for 80% of all heel pain patients. Among them, the prevalence rate of long-distance runners is significantly higher than that of the general population. According to statistics, 10% of long-distance runners or people with long-distance running habits suffer from this disease. It was manifested as pain near the heel when walking, increased pain during jumping and running, obvious tenderness at the proximal attachment of plantar aponeurosis (heel tubercle), and pain in passive traction of metatarsophalangeal joint.
Plantar fascia is a band of connective tissue located in the deep surface of plantar fat layer, which is divided into three parts by two shallow grooves: central zone, lateral zone and medial zone. The medial zone is thinner, the lateral zone is thicker, the middle zone is the thickest, tough and dense, also known as plantar aponeurosis. The plantar fascia is a long triangle, the tip of which adheres to the calcaneal tubercle backward, and the base splits forward into five bundles, ending at the tendon sheath of each toe, but connected with each other by transverse fibers and attached to the metatarsophalangeal joint capsule and toe tendon sheath. The medial plantar nerve and its branches are located in the skin of the plantar medial half and medial three half toes. The lateral plantar nerve is distributed in the lateral half of the sole and the skin of the sole of one half toe. Said for a long time, is to tell you, here the nerve is rich, once the attack, pain!
Why plantar fasciitis can not be cured for a long time? Although it is called plantar fasciitis, it is essentially a general term for a kind of pain. Its core is local degeneration, including muscle strain and loss of heel fat pad. Of course, there are also cases of chronic bursitis at the calcaneal tubercle, which leads to repeated stimulation of the medial and lateral plantar nerves. In recent years, studies at home and abroad have shown that patients with plantar fasciitis do not actually have "inflammation", but have local tissue degenerative changes, such as collagen degeneration, collagen fiber arrangement disorder, mucus matrix disorder, fibroblast proliferation and calcification and other pathological phenomena, rather than the traditional infiltration of inflammatory cells such as white blood cells, lymphocytes and macrophages "Inflammatory response" of the syndrome. Inflammatory cells were also rare in the histological sections of many case studies. You may have guessed that plantar fasciitis has not been cured for a long time. It turns out that the direction of treatment is wrong. Oral or injection of anti-inflammatory drugs is the reason for fish.
The pathogenesis and mechanism of plantar fasciitis are not fully understood, but studies have shown that it may be related to the following factors:
Limited ankle movement
Plantar fascia is an important structure of the plantar, which carries a large biomechanical load. When the foot follows the ground, it bears about 2-3 times the weight. In the normal gait analysis, the plantar fascia changes alternately from pronation force when the foot follows the ground to the supination force at the middle of full foot landing to the supination force when the toe is off the ground. The plantar fascial tension increased in the middle of full foot landing, and reached the peak when the toe dorsiflexion and lifting off the ground.
Biomechanical studies have shown that the ankle joint of normal people can back bend about 10 ° to 15 ° when walking. This kind of back flexion can reduce the traction effect on plantar fascia during walking. If the ankle movement is limited by various factors, the buffering effect will be compensated by the plantar toe joint dorsiflexion. In the process of walking and running, the plantar fascia is lengthened due to the enlargement of the landing area of the sole. When the foot steps out, the plantar fascia is stretched. When the foot steps out, the toe dorsiflexion increases its tension. Such long-term and repeated stretching results in the damage of the plantar fascia microfilaments, which is the pathological basis of plantar fasciitis.
Overuse injury
It is found that the posterior part of plantar fascia is the site of maximum tensile stress, followed by the long plantar ligament. The mechanism of high tension stimulation is the mechanical factor of plantar fasciitis. When the bearing capacity of plantar fascia exceeds its physiological limit, long-term repeated overload will lead to tissue degeneration, fibrosis and plantar fasciitis. Long term, repeated high tension traction is easy to cause micro tissue tear at the starting point of plantar fascia. Under normal circumstances, the micro tissue damage machine will automatically repair, but if the damage degree of the tissue is greater than the repair ability of the body, or new micro damage appears and continues to stack before the recovery of the original micro damage, when this situation accumulates to a certain extent, the tissue will slowly degenerate and eventually lead to plantar fasciitis. In addition, the part connected with plantar fascia is fibrocartilage, which forms a structure similar to "bone tendon junction". Epidemiological investigation shows that, because of the relatively insufficient blood supply, long-term repeated load can easily lead to insufficient tissue repair and long-term accumulation of micro damage, which is very easy to cause degenerative diseases. After degenerative lesions appear, the fascia and fibrocartilage areas are often in a state of tension, which increases the tissue internal pressure and hinders the nutrient dispersion. The secondary tissue edema will further increase the tissue internal pressure, further insufficient nutrition of the main structure and cause a vicious circle.
Musculus propria plantaris
The plantar proper muscle is divided into four layers: the first layer is abductor pollicis, extensor brevis and abductor digitorum minor; the second layer is quadratus plantaris and vermiform muscle; the third layer is flexor pollicis brevis, adductor pollicis brevis and flexor digitorum brevis; the fourth layer is interosseous dorsal muscle and interosseous plantar muscle. The proper plantar muscles are widely connected with plantar fascia, ligaments and tendons. All these tissues form a strong complex of dynamic and static structures. The plantar fascia provides the attachment of flexor digitorum brevis, and also acts as a fascia indicating covering for other muscles such as abductor pollicis; tendons and nerve vessels pass through the plantar fascia to reach the toe; the complex vertical septum and lateral connection structure connect the plantar fascia with deep structure and skin.
Many people have been diagnosed with plantar fasciitis, but there is no heel pain. At this time, we should consider whether there is a problem with the muscles deep in the plantar fascia, and whether the muscle tension is a problem that causes pain, rather than the cause of the fascia itself.
There is nothing wrong with the parts, and there is something wrong with the running shoes (high risk factor)
There are many shoe designs that directly lead to abnormal tension on the plantar fascia and prevent foot muscles from being used.
1. The shoes are warped forward
Many shoes today, including most sports shoes, have an upturned curve in the front area of the toe, which is called "toe spring". This curve will produce a "swing" effect, so that the wearer's weight will be transferred from the heel to the forefoot. When walking with this kind of shoes, most of the time, the toes are lifted up and off the ground, that is, the metatarsophalangeal joint is in the dorsiflexion position. As mentioned above, the plantar fascia will be elongated in this state, and always in a tense state, maintaining an unnatural elongated position. Moreover, the toe forward warping will prevent the toes from grasping the ground, which will hinder the muscles inside the sole to support the arch of the foot to contract, thus affecting the plantar fascia. When you run on the ground under extra stretch, the results can be imagined, it is easy to cause damage.
2. High heel
In addition to the medium and high heels that women often wear, most traditional shoes have heels at least 10 mm higher than their forefeet. A high heel can cause two problems:
1、 The ankle joint is in the plantar flexion position, which leads to the shortening of the adaptability of the posterior leg muscles. Insufficient flexibility of small leg muscles is also one of the risk factors of plantar fasciitis.
2、 It affects the way of weight distribution of human feet.
3. The sole is hard
Too rigid sole will inevitably affect the natural movement of the foot. If the sole is too hard, many movements of the foot will be limited. For example, when the foot lands on the ground, the landing position that rolls from the heel to the sole of the foot will be limited, resulting in the smooth buffering process of the foot.
Considering the small number of experimental research samples, they also said that more research is needed in this direction. The current study is not enough to confirm that toe warping is directly related to plantar fasciitis and other foot problems. In addition, they will further study how toe warping affects the hardness of shoes and the impact of cushions on feet. Of course, for the sake of caution, we may be able to wear shoes with no toe warping or small angle, especially for running, playing basketball and other special activities.