I. Anatomical features The plantar tendon membrane is a superficial part of the plantar fascia, similar to the palmar tendon membrane, but more developed and tough, consisting of longitudinal white fibers. It can be divided into middle bundle, lateral bundle and medial bundle. The middle fascicle is the thickest, starting from the medial tuberosity of the heel bone and dividing into five fascicles, which end at the skin of the metatarsal side of each metatarsophalangeal joint, the flexor tendon and the tendon fiber sheath. The intrinsic muscles of the foot that originate from the medial tuberosity of the heel are the bunion, the lesser trochanter and the metatarsophalangeal muscle. The role of the metatarsal tendon membrane is to: 1. protect the plantar tissues of the foot. 2.Provide attachment points for certain intrinsic muscles of the foot. 3, to assist in maintaining the arch of the foot. The exact cause of proximal plantar tenosynovitis is not well understood. Possible causes of pain include: 1. When walking, the metatarsophalangeal joint is dorsally extended, pulling on the metatarsal tendon membrane, which pulls on the heel tuberosity. As the foot muscles and ligaments weaken with age, the force of the metatarsal tendon membrane pulling on the heel tuberosity increases, and the long-term, repeated pulling causes a small tear at the beginning of the metatarsal tendon membrane, secondary to inflammation, causing pain. 2.Osteochondritis at the heel stop of the metatarsal tendon membrane and fatigue fracture of the medial heel tuberosity. 3, Inflammation and edema at the stop of the flexor digitorum teres and its proliferating bone spur leading to entrapment of the first branch of the lateral plantar nerve. Although proximal plantar tenosynovitis is used as a diagnosis, in practice, inflammation of the proximal stop of the plantar tenosynovium and entrapment of the first branch of the lateral plantar nerve may coexist and be clinically indistinguishable. Clinically, it has been found to occur more frequently in obese middle-aged women and in those who enjoy sports, such as professional athletes and dancers who run and jump for long periods of time and in the general population who need to walk long distances. In addition, wearing soft-soled shoes and excessive exercise may also be a cause of metatarsal tendonitis. Other conditions, such as tibial entropion, Achilles tendon contracture, heel exostosis, foot rotation front deformity, and changes in the arch of the foot after degeneration of the tendons and ligaments in middle-aged and elderly people, will subject the metatarsal tendon membrane to greater stress, and the long-term chronic strain can cause small tears in the local tendon membrane and local edema to produce inflammation. Berkowitz compared the thickness of the proximal metatarsal tendon membrane between normal subjects and patients with chronic heel pain by MRI and found that the latter had an increase of 4.4 mm compared to the former. Pathological examination of the proximal metatarsal tendon membrane also revealed collagen necrosis, fibrovascular hyperplasia, chondrogenesis and matrix calcification. This pathological change is similar to the change at the stop of flexor carpi radialis shortis in patients with tennis elbow, and some people have called proximal metatarsal tenosynovitis “tennis heel”. Clinical manifestations Pain on the metatarsal side of the heel. The onset is usually slow. The pain is heavier in the morning when walking the first few steps, and can be partially relieved after further activity. However, the symptoms can be aggravated after prolonged activity. On examination, swelling of the anterior medial aspect of the heel is seen. There is significant pressure pain at the medial heel node and 2-3 cm from the beginning of the metatarsal tendon membrane. Pay attention to whether the patient has abnormal foot force lines, tibial inversion, inversion of the foot, as well as flat feet, high arched feet, etc. The Achilles tendon should also be checked for contracture. X-ray examination: about 50% of patients can see bone spurs on the metatarsal side of the heel node, and ultrasound and MRI examination can show thickening and edema of the metatarsal tendon membrane. The diagnosis is based on local swelling and pain, pressure points, and ultrasound and MRI findings of metatarsal tendon membrane thickening. Treatment 1. Non-surgical treatment is effective in more than 90% of patients, but because it is not possible to determine which treatment has a definite effect when treating, it is often necessary to use a combination of several methods. In some patients, even if they are not treated, the pain can eventually be relieved by itself. However, some patients have pain that can last for years. (1) Reduce activities that expose the heel to percussive impact. Reduce weight in obese patients. (2) Achilles tendon and metatarsal tendon membrane stretching exercises. Since contracture of the Achilles tendon is a common cause of metatarsal tendonitis, moderate stretching of the metatarsal tendon membrane helps the inflammation to subside. Repeated daily Achilles and metatarsal tendon pulling exercises have become one of the most effective ways to reduce pain in patients with metatarsal tendonitis. Metatarsal tendon membrane pulling exercise method: ①Patients sit, bend the knee, put the affected heel on the bed, ankle joint dorsal extension, use the hand to push the 5 toes to the dorsal side, maintain 30 seconds, repeat 5 times. ②Heel lift, sit with the hip on the heel,, maintain for 30 seconds, repeat 5 times. ③Patients sit with the affected heel raised, make the metatarsophalangeal joint extend dorsally as much as possible, push down on the posterior calf with the hand to further increase the metatarsal tendon pulling force, maintain for 30 seconds, repeat 5 times. ④ Place the front part of the affected foot below the wall and plantar flex the ankle joint with force, maintain for 30 seconds, repeat 5 times. Achilles tendon pulling exercise method: ① Flounder muscle pulling exercise, the patient stands toward the wall, the affected side is behind, slowly bend the knee joint to the flexed position, maintain 30 seconds, repeat 5 times. ② gastrocnemius muscle pulling exercise, the patient to the wall standing, the affected side in the back, keep the affected side of the lower limb straight, and the affected foot does not move, the heel can not lift, the upper body moved forward, so that the Achilles tendon is pulled. Maintain 30 seconds, repeat 5 times. ③ Achilles tendon pulling exercise, stand on the inclined plate, body upright, so that the Achilles tendon is pulled. ④Physiotherapy. Such as ultrasound, myoelectric stimulation, hot and cold therapy, etc. But generally the effect is not obvious. ⑤ Correction of poor force line of the foot. Such as the use of foot pads, semi-hard adaptive foot pads for high arched feet, and slightly hard supportive foot pads for flat feet to reduce the tarsal tendon membrane pulling. The use of heel pads can reduce the impact force on the heel, thus reducing pain. (6) Anti-inflammatory and pain-relieving drugs. Local closure. (7) In case of severe pain, use a night splint or plaster rest to fix the ankle joint at 5° to 10° dorsiflexion to avoid contraction of the metatarsal tendon membrane at night, which will cause pain when moving in the morning. (8) Plaster fixation In patients with severe pain, if the above treatment fails, a short leg cast can be used to fix the ankle joint in a neutral position for 1 month. 2.Surgical treatment Very few patients can be treated surgically after more than 6 months of non-surgical treatment. Since the metatarsal tendon membrane plays an important role in maintaining the arch of the foot, complete severance of the metatarsal tendon membrane may have adverse effects on the function of the foot. It has been shown that complete severance of the plantar tendon membrane can cause weakness in walking on the surgical side and 25% less arch stabilization. Currently, the recommended surgical approach is a partial resection of the metatarsal tendon, which is a 35% to 50% cut medially from the metatarsal tendon stop. This can be done with or without removal of the medial heel nodal spur. The procedure can be done incisionally or percutaneously, or arthroscopically if available, with partial metatarsophotomy and spur removal.