Plantar fasciitis (PF) is a common musculoskeletal injury characterized by inflammation and degeneration at the origin of the fascia and causing heel pain. The disease affects individuals of different ages and activity levels and is the main cause of plantar pain and ankle dysfunction in patients, accounting for 15% of all foot diseases. A previous study showed that PF is more common in middle-aged and elderly people and those who love sports. One in 10 people has their daily quality of life seriously affected by PF. In clinical work, it was found that there was a large difference in the degree of ankle function of PF patients at the time of consultation. The clinical symptoms of plantar fasciitis are mainly heel pain when landing in the morning or after a long rest. The symptoms are aggravated after standing or walking for a long time, and sometimes patients will show a pain-reducing gait. The diagnosis is mainly based on the patient\'s symptoms and signs. There are often local tenderness points when palpating along the plantar fascia and the medial tubercle of the calcaneus. The patient\'s ankle dorsiflexion range of motion may be limited. Ultrasound examination shows increased thickness of the plantar fascia. The patient may also show bone spurs growing into the fascia on X-rays . The cause of plantar fasciitis is still unclear. Its risk factors include age, obesity, foot deformity, limited ankle dorsiflexion, decreased foot proprioception, long-term weight-bearing and walking activities . These factors are interrelated and interact with each other, and the abnormal biomechanical mechanism of the foot is the key to the internal connection between these factors . Poor foot-ankle force line and biomechanics will increase abnormal stress on the plantar fascia during joint movement, leading to micro-tears of the fascia, and then thickening and tightening of the plantar fascia, resulting in inflammation. At present, the intervention treatment methods for plantar fasciitis are divided into two categories: surgery and conservative treatment. Most patients are treated with conservative treatment, which mainly includes insole adjustment, physical therapy and weight loss. Physical therapy programs generally include stretching the plantar fascia and calf muscles, muscle strength training, taping, the use of orthotics and night splints, etc.. Currently, the short-term effect is acceptable, but the long-term effect is poor, and it is easy to relapse, which affects the overall motor function and sports performance.

People have higher and higher requirements for health. In addition to paying attention to local pain relief, patients with plantar fasciitis also have higher demands for improving sports performance. Conventional physical therapy methods can effectively relieve the temporary pain of patients with plantar fasciitis, but the recovery of patients\' motor function is still poor. Only relieving short-term pain symptoms can no longer fully meet people\'s daily life and sports needs. For the long-term rehabilitation of plantar fasciitis, the correction of poor foot biomechanics and the improvement of foot and ankle function are the key to preventing and improving physical function and improving sports performance. Ankle dorsiflexion dysfunction will reduce various sports performances and increase the compensation of other joint functions in the body, thereby increasing the risk and probability of sports injuries. Relevant studies have shown that limited ankle dorsiflexion is one of the causes of plantar fasciitis. A study showed that 211 out of 254 patients had limited ankle dorsiflexion . Individuals with insufficient ankle dorsiflexion during walking may roll their feet forward by dropping the talus and flattening the medial longitudinal arch. The flattening of the arch may stretch the plantar fascia, which may lead to inflammation of the plantar fascia over time . However, the current treatment methods for plantar fasciitis have failed to systematically improve the limited ankle dorsiflexion function of patients, and limited ankle joint function may directly affect the long-term treatment effect of plantar fasciitis.

In summary, since the correction of poor foot force line and the recovery of ankle dorsiflexion function play an important role in the long-term treatment effect of plantar fasciitis, this study aims to design a randomized controlled trial to treat plantar fasciitis in combination with conventional rehabilitation and improvement of limited ankle dorsiflexion function, and to explore its clinical efficacy in combination with various evaluation indicators.