Flat hip

　　This disease is ischemic necrosis of the femoral head epiphysis, also known as Legg-Calve-Perthes disease, osteochondritis dissecans of the femoral head. Ischemic necrosis of the adult femoral head caused by various reasons is not included in the scope of this disease.

　　The cause of this disease is not yet clear, and most scholars believe that chronic injury is an important factor.

　　1. Chronic injury Most scholars believe that chronic injury is an important factor. Trauma causes occlusion of the vascular vessels of the bone, leading to secondary ischemic necrosis. The blood supply of the femoral head epiphysis changes significantly from neonates to 12 years old, and only one epiphyseal artery supplies the epiphysis from 4 to 9 years old, at which time the blood supply is the worst, even minor trauma can easily cause blood supply disorders. After 9 years old, the round ligament vessels participate in the blood supply of the femoral head epiphysis. When the epiphyseal plate ossifies and fuses, the diaphyseal vessels enter the femoral head, and this disease no longer occurs.

　　2. Increased pressure Any disease that causes increased joint囊 pressure and femoral head upper end bone pressure, such as synovitis, can increase joint囊 pressure, and can also cause osteonecrosis of the epiphysis, and synovitis can also be the primary disease or secondary to this disease, so it is still not possible to determine the causative relationship.

　　Flat hip has no obvious early symptoms, and there may be joint effusion of the hip joint, which is not easy to find; as the condition progresses, patients may experience hip pain, knee reflex pain, and muscle spasm of the adductor muscles, limitation of hip abduction, and protective limping; if not treated in time, it may leave deformity of the femoral head and form hip arthritis, and the affected hip may have long-term effusion. A few people may have hip joint subluxation, and some may develop into osteoarthritis.

　　This disease is ischemic necrosis of the femoral head epiphysis, also known as Legg-Calve-Perthes disease, osteochondritis dissecans of the femoral head. The disease onset is隐匿, the course is long, and the main symptoms are pain and limping in the affected hip.

　　(1) Early stage:There may be no obvious symptoms, or only the affected limb is weak, and painless limping appears after long-distance walking. The location of pain may be the inguinal region, the anterior and medial side of the thigh, and the knee.

　　(2) Necrosis of the femoral head:Hip pain is obvious, accompanied by muscle spasm and shortening of the affected limb, with muscle spasm mainly in the adductor muscles and iliac oblique muscles, while the gluteal and thigh muscles atrophy. The range of hip joint movement is limited to varying degrees, especially the abduction and internal rotation activities are limited.

　　(3) Late stage:Pain and other symptoms alleviate or disappear, joint mobility returns to normal, or there is limited abduction and rotation activity.

　　Osteochondritis dissecans of the femoral head is mainly caused by various factors leading to ischemic necrosis of the femoral head epiphysis, also known as flat hip. To prevent this disease, it is necessary to target the cause, make an early diagnosis, and early treatment to prevent the occurrence of serious complications.

　　1. It is necessary to strengthen the self-protection awareness of the hip.

　　2. When walking, pay attention to your feet and be careful not to fall, especially when walking on snowy and icy ground in winter.

　　3. Before engaging in sports, it is necessary to fully prepare the hip, feel the body warm up, and make the limbs flexible.

　　4. When carrying or carrying heavy objects, try to avoid hip sprains and try not to do too heavy work.

　　5. After an injury to the hip, it should be treated in a timely manner, and it is absolutely not advisable to walk excessively when the injury has not healed, in order to avoid repeated injury to the hip joint.

　　6. Try not to use or use hormones as much as possible in the treatment of certain conditions, especially when they are painful.

　　7. Try not to develop the habit of drinking alcohol in large quantities over a long period of time.

　　This disease is the ischemic necrosis of the femoral head epiphysis, also known as Legg-Calve-Perthes disease and osteochondrosis of the femoral head. The disease has an insidious onset, a long course, and the main symptoms are pain and limp in the affected hip. The diagnosis of this disease generally does not require laboratory tests, and the diagnosis can be made clear through X-ray examinations and other tests. The specific examination methods are as follows:

　　1. X-ray examination

　　It is the main means and basis for the clinical diagnosis of osteonecrosis of the femoral head. Regular X-ray films of the anteroposterior and frog position of both hip joints should be taken.

　　(1) The synovitis period: The main manifestation on X-ray films is swelling of the soft tissues around the joint, with the femoral head slightly displaced laterally.

　　(2) Early stage of involvement of the femoral head epiphysis: The X-ray signs before necrosis, mainly the epiphysis nucleus is smaller than normal, and continuous observation for 6 months shows no increase, indicating a temporary cessation of endochondral ossification. The joint space is widened, and the superior margin of the femoral neck shows a circular prominence (Gage sign). The anteroposterior X-ray film shows a protrusion of 2-5mm. Subsequently, there is an increase in the density of part or the entire epiphysis. The reasons are: ① Disuse osteoporosis and decalcification of the proximal femoral neck adjacent to the epiphysis lead to increased density of the femoral head epiphysis; ② Necrotic trabeculae are compressed; ③ Early necrotic epiphysis is revascularized, with new bone formation on the surface of necrotic trabeculae, resulting in actual density increase. Some authors suggest that the crescent sign may be the first X-ray sign of bone necrosis, where a clear linear hypodense area can be seen under the cartilage of the anterior and lateral aspect of the femoral head on frog position films. Salter believes that the crescent sign is a subchondral fracture of the joint, which has important clinical significance. It is not only the main basis for diagnosis but also helps to predict the extent of femoral head necrosis, judge the severity of the lesion, and estimate the prognosis.

　　(3) The necrosis period: The X-ray feature is necrosis of the anterior and lateral aspect of the femoral head, with unevenly increased density on the frontal X-ray film. If frog position X-ray films are taken, dense areas can be seen on the anterior and lateral aspect of the femoral head. This condition often requires follow-up observation for 1 year to determine whether it is partial or complete necrosis. If it is complete necrosis, the epiphysis often shows flat deformity, but arthrography can show that the epiphysis of the femoral head still retains its circular contour.

　　(4) The fragmentation period: X-ray films show alternating distribution of hard and sparse areas. The hard area is the result of compression of necrotic trabeculae and the formation of new bone.

　　(5) The healing or sequelae period: At this stage, the lesion is stable, and the osteoporotic area is filled with normal trabeculae, so the density of ossification tends to be uniform and consistent. However, the epiphysis of the femoral head is significantly enlarged and deformed. On X-ray films, the femoral head appears ovate, flat, or mushroom-shaped, and it may dislocate or subluxate laterally. The acetabulum also shows compensatory expansion, with increased medial joint space.

　　2. Radionuclide examination

　　It can not only determine the blood supply of bone tissue but also reflect the metabolic state of bone cells. It is of great significance for early diagnosis, early determination of the scope of femoral head necrosis, and differential diagnosis. Clinically, intravenous 99mTc is often used, followed by scintigraphy. Early manifestations include radioactive稀疏 or defects in the necrotic area, and in the regeneration period, local radioactive accumulation can be seen. Crenshaw et al. believe that if the radioisotope sparsity of the necrotic area on the affected side is less than 50% compared to the healthy side, it is an early lesion, equivalent to Catterall's type I or II, or Salter's type A. Otherwise, it is considered late-stage, equivalent to Catterall's type III or IV, or Salter's type B. Compared with X-ray examination, radionuclide examination can determine the scope of necrosis 6 to 9 months earlier and show the regeneration of blood vessels in the necrotic area 3 to 6 months earlier.

　　3. Arthrography

　　It is generally not considered a routine examination. However, some authors believe that arthrography can be used to detect the enlargement of the femoral head early, which is helpful in observing the gross morphological changes of the joint cartilage and can clearly identify the cause of early malcover of the femoral head. Arthrography during the healing stage can more realistically show the degree of joint deformation, which is of reference significance for selecting treatment methods. However, it is an invasive examination, and some children who cannot cooperate with the examination may require anesthesia. Therefore, arthrography should not be included as an essential examination item.

　　In recent years, with the application of magnetic resonance imaging technology, some hospitals have also conducted this examination for Perthes disease. Practice has proven that this examination is of great value for diagnosing bone ischemic changes and can make an early diagnosis. The ischemic area is characterized by a low signal area and can clearly show the cartilage area and thickness around the acetabular margin of the femoral head. The hip joint in magnetic resonance imaging is similar to that seen in arthrography, which can clearly show whether the shape of the femoral head is normal. Magnetic resonance imaging is superior to X-ray examination in determining ischemic lesions and does not cause radioactive damage. However, it is not yet widely applicable.

　　This disease is the most common osteochondrosis, characterized by ischemic necrosis of the epiphysis, mainly affecting the epiphysis of the femoral head and the metaphysis of the femur, and occasionally affecting the acetabulum. Once diagnosed, appropriate treatment should be taken promptly to prevent the condition from worsening. While receiving timely treatment, patients should also pay attention to dietary care, which will help in early recovery.

　　Attention should be paid to a reasonable and balanced diet, and dietary preferences should not be exclusive. Maintain a moderate diet and avoid excessive hunger or overeating. Quit smoking and alcohol. Increase the intake of calcium, consume high-calcium foods such as milk, eggs, soy products, vegetables, and fruits, and supplement calcium as necessary.

　　It is advisable to avoid eating any citrus fruits, especially oranges and tangerines, and to pay attention to the dietary precautions for spurs. Also, avoid sugar, alcohol, and coffee. These substances will hinder the recovery process and disrupt the balance of minerals in the body.

　　The clinical manifestations of flat hip are mainly early limping, pain in the hip, thigh, or knee, limited range of motion of the hip joint, progressive worsening of symptoms, which may cause muscle atrophy of the thigh, and in the late stage, it may cause complications such as osteoarthritis.

　　In terms of treatment, since the hip joint of the child is very sensitive at the onset, skin traction for 1 to 2 weeks can be used first, and further treatment can be considered after the acute symptoms subside.

　　First, non-surgical treatment

　　In the past, long-term hip orthopedic plaster fixation was used, due to its great impact on children's development and joint function, it is now rarely used or not used. Various types of abduction braces are currently commonly used treatment methods, the purpose of which is to:

　　① Place the femoral head deeply in the acetabulum;

　　② Avoid the pressure of the acetabular labrum on the femoral head;

　　③ Make the pressure on the femoral head equal;

　　④ Maintain good range of motion of the hip joint.

　　Second, surgical treatment

　　It was proposed to change the blood supply of the ossification center of the femoral head through surgical methods, so that the blood supply between the femoral head and the femoral neck can be communicated, but the communication between the bone slices or the blood supply was not achieved. Because some people advocate the use of hip synovectomy to treat the disease, which has certain effects, but the mechanism of the surgical action is not clear. Some people also use pedicle (muscle flap or vascular) bone grafting, vascularized bone grafting, etc. In recent years, it is more recognized abroad to perform subtrochanteric or intertrochanteric osteotomy.

　　The advantages of this operation are:

　　① Treatment can be completed within 6 to 8 weeks after surgery;

　　② No further application of braces or other measures to limit activity and weight is required after surgery;

　　③ Osteotomy can cause congestion in the upper segment of the femur;

　　④ Its efficacy is not worse than that of long-term abduction brace fixation.

　　The complications of osteotomy include limb shortening deformity, residual hip bone reversal, non-union at the osteotomy site, and limited joint mobility, etc. It is generally believed that the efficacy is good for those under 7 years old, and the effect will not continue to improve for several years after surgery. The healing process of femoral head epiphysis necrosis can be shortened. On average, the lower limb is shortened by 1.4 cm after surgery.