The patient, Liu, had swelling of the metacarpophalangeal joint of the right thumb with severe pain radiating to the distal end of the finger. The right thumb was in a passive extension position, and external assistance was required to flex and extend the finger with severe pain and popping, which seriously affected the function of the right hand. On examination, a hard nodule can be palpated at the metacarpophalangeal joint of the right thumb, with significant pressure pain. This disease is a common form of flexor tendon stenosis, which has been treated conservatively or by surgical incision. We performed a minimally invasive small needle treatment. Local anesthesia was administered at the point of entry, and the small needle was inserted vertically and gently inserted in the direction of the tendon, and the patient’s thumb, which was limited in flexion and extension, moved freely instantly. The entire procedure is bloodless and injury-free, leaving only a 0.8 mm needle knife incision in the skin of the affected finger. The small needle knife is a new medical device that has the characteristics of both a needle and a knife. It is shaped like a “needle”, but the tip of the needle is a flat blade of only 0.8 mm, so it is called a small needle knife because of its small size. It can reach the lesion directly, through clinical twisting, picking, pushing and pulling and other surgical techniques, so that the adhesion of the lesion tissue quickly peeled off, scraping scar, loosening the flesh and bone, spasm and pain, so as to restore function and achieve the purpose of healing. Acupuncture medicine is the fusion of Chinese medicine acupuncture needles and Western medicine surgery knife into one, combining the two therapeutic effects, breaking the traditional internal medicine only control but not cure method, small acupuncture knife in the clinic for more than twenty years to achieve very satisfactory results. Small needle knife treatment can be widely used in various pathologies caused by pain in the neck, shoulder, waist and legs; bursitis; various tendon sheaths; cervical spondylosis; lumbar intervertebral disc herniation; dermatome nerve entrapment syndrome; sacroiliac arthritis, frozen shoulder; third lumbar transverse process syndrome; osteoarthritis; collar ligament injury; sternocleidomastoid tendonitis; supraspinatus muscle injury; infraspinatus muscle injury; scapularis muscle injury; internal epicondylitis of the humerus; skeletal lumbar Ligament injury; chronic lumbar and gluteal muscle injury; sciatica, rheumatism, rheumatoid arthritis, etc. The whole procedure is less painful and less time consuming, generally between a few minutes to ten minutes, and does not require a long rest. The impact on work life is minimal. The treatment process is generally not restricted by the environment and conditions, the treatment incision is small, without sutures, the damage to human tissue is also small, and is not easy to cause infection, less adverse reactions, the patient also has no obvious pain and fear, no need to rest after surgery, short treatment time, short course of treatment, low price, good efficacy, easy for patients to accept, is an effective means of treating pain diseases.