It is not uncommon to see patients who are nervous and suspect that they have ischemic necrosis of the femoral head when they have hip pain in their lives. The anatomical structure of the hip joint is complex, and the causes of hip pain are also complex and varied. In addition to the familiar diseases such as ischemic necrosis of the femoral head, osteoarthritis of the hip joint, sacroiliac joint lesions and lumbar spine lesions may all cause pain around the hip. The following is a brief introduction to several diseases that may cause hip pain. Osteoarthritis of the hip joint: caused by degenerative changes and damage to the hip cartilage, the clinical manifestation is joint pain and inflexibility. The primary cause is ageing, and the secondary causes are long-term unreasonable posture and movement, congenital abnormal joint development, trauma and drugs. The primary cause is aging, while the secondary causes include long-term unreasonable posture and movement, congenital abnormalities in joint development, trauma and drugs. Hip impingement syndrome: It is mainly due to the abnormal development of the femoral neck or acetabulum, which leads to the impingement of the femoral neck and acetabulum within the normal range of activities, resulting in hip pain. Over time, as the impingement intensifies, the cartilage at the edge of the acetabulum or femoral head becomes damaged and the pain gradually increases. Since the impingement mostly occurs when the hip joint is flexed and the impingement site is mainly located in front of the hip joint, pain in the groin area often occurs, especially when the legs are squatting together. In addition, because the patient’s age is young, the onset of the disease is not long, the location of the lesion is special, and the lesion mainly involves cartilage tissue, so it is difficult to detect the existence of the lesion in the early stage of ordinary X-ray examination. Detailed physical examination and X-ray examination of special positions are required. Adult hip dysplasia: Developmental hip dysplasia was traditionally diagnosed as congenital hip dislocation, but in 1991 the American Academy of Orthopaedic Surgery (AAOS) and the Pediatric Orthopaedic Society of North America (POSNA) unified the term as developmental hip dysplasia or developmental hip dislocation. It is a developmental defect of the acetabulum that results in poor coverage of the femoral head and can vary from mild to severe shallow flattening of the acetabulum to varying degrees of subluxation of the hip joint with a deformity of the proximal femur. Adult acetabular dysplasia is an important causative factor of adult hip osteoarthritis, accounting for 20% to 50% of the total causes of hip osteoarthritis, and is also a common cause of long-term hip pain in middle-aged adults. There are no obvious symptoms in the early stage, so it is not easy to diagnose early. Depending on the severity of the deformity, the age of symptoms can range from teenage to 40 years old. The initial manifestation is hip soreness and discomfort after exercise, aggravated after long standing and prolonged walking, and reduced after rest, then pain gradually appears, mainly in the root of the thigh and groin area, sometimes accompanied by knee pain. It is important to note that the presence of pain means that there is damage to the hip cartilage. An ordinary pelvic X-ray can detect abnormalities. Ischemic necrosis of the femoral head: It is a common and difficult to treat disease in orthopedics. It is caused by damage or interruption of blood supply to the femoral head, resulting in death of bone cells and bone marrow components, followed by bone collapse, hip pain and dysfunction. The causes can be divided into two categories: traumatic and non-traumatic. Traumatic is mainly caused by hip trauma such as hip fracture and dislocation, while non-traumatic is mainly caused by unreasonable application of glucocorticoids and long-term alcohol abuse. The clinical manifestations are pain in the hip joint and the posterior side of the hip, and limitation of hip joint movement. In the early stage, there is no obvious change on X-ray, and MRI often helps to confirm the early lesion. In the late stage, patients will show significant collapse of the femoral head, hyperplasia of the hip joint edge, and fusion or disappearance of the joint space on imaging. Some patients have neither a history of hip trauma nor a history of alcoholism or glucocorticoid medication application for idiopathic ischemic necrosis of the femoral head. Ankylosing spondylitis: its early symptoms are often manifested as lower back, hip and hip pain and joint stiffness, the pain is often aggravated at rest and during inactivity, accompanied by stiffness of the hip and sacroiliac joints in the morning, commonly in young and middle-aged men, mostly bilateral sacroiliac and hip joints at the same time, X-ray examination of the femoral head remains round without collapse, but the joint gap narrows, disappears or even fuses. In addition, there is a laboratory-specific test for the diagnosis of this disease, namely HLA-B27 positivity, so it is easy to differentiate from osteoarthritis of the hip and ischemic necrosis of the femoral head. Rheumatoid arthritis: It can also cause hip pain, which is characterized by pain and stiffness of the hip, often obvious in the morning when the weight is put on the ground and prolonged stiffness (more than 10 minutes), and is commonly seen in female patients in clinical practice. change. Lumbar disc herniation: Lumbar disc herniation is one of the most common orthopedic clinical disorders, which is common among young adults, heavy manual laborers and long-time sitting workers. Lumbar 2-3 and lumbar 3-4 disc herniation can cause pain around the lumbar hip and hip joint, and the posterior lateral hip pain caused by lumbar 4-5 and lumbar 5-sacral 1 disc herniation is often described by patients as “hip pain” and mistaken for hip joint disease. In addition, diseases such as septic arthritis, acetabular glenoid labral injury, hip synovitis, pigmented villous nodular synovitis, temporary osteoporosis (ITOH), femoral head contusion, and synovial hernia (benign lesion in which synovial tissue proliferates and invades the cortex of the femoral neck) can also cause hip pain and limited motion. Therefore, when hip pain occurs, you should go to the hospital for detailed examination and differential diagnosis in a timely manner.