When the lumbar region is over-rotated or the thighs are over-extended and abducted, it is easy to cause a pulling injury to one side of the psoas major muscle, resulting in congestion, swelling and spasm of the psoas major muscle, which can cause lumbago, abdominal pain, inguinal and perineal cramps, and anterior and medial thigh cramps when the nerves are embedded. The clinical diagnosis can be made according to the following points. 1. Medical history: Before the onset of the disease, there are different degrees of history of super-range activities of the waist and lower limbs or history of repeated twisting of the waist. 2. Symptoms: all of them are low back pain on one side accompanied by abdominal pain symptoms and pain in the anterior medial side of the ipsilateral lower limb, and can only bend the knee and hip on the affected side, and the pain in the lumbar abdomen and ipsilateral lower limb increases when the abdominal pressure increases, and the pain increases after lumbar activity or exertion. 3.Signs: painful area with pressure pain between ipsilateral lumbar 2 and 3 transverse processes (+), local muscle tension, increased pain of resisting hip flexion and knee flexion, with pain of supra-knee release, limited hip and knee extension, weak hip flexion muscles, pain can be significantly relieved after knee flexion and hip flexion in the affected side lying down. 4.Auxiliary examination: ultrasound examination can help diagnose lumbar major muscle injury.