Diagnosis and treatment of ischemic necrosis of the femoral head
Ischemic osteonecrosis, also known as aseptic osteonecrosis, is a specific disease in which bone cell death and subsequent repair processes occur after interruption of blood flow to the bone. Ischemic osteonecrosis can occur in many bones throughout the body, but ischemic necrosis of the femoral head is the most common. The new definition of ischemic necrosis of the femoral head by the American Academy of Orthopaedic Surgeons is a disease in which the blood supply to the femoral head is interrupted or impaired, causing the death of bone cells and bone marrow components and subsequent repair, followed by structural changes in the femoral head and collapse of the femoral head, causing joint pain and joint dysfunction in patients, which is the most common worldwide problem in the field of orthopaedics. There are no statistics on the incidence of ischemic necrosis of the femoral head in China, but according to statistics from the United States and Japan, the number of patients with ischemic necrosis of the femoral head in China is estimated to be 5 million to 7.5 million, with 75,000 to 150,000 new cases each year, and the actual number may be higher due to the more common abuse of hormones and serious alcoholism in our primary hospitals.
Ischemic necrosis of the femoral head is classified as an unsolved or intractable disease in the United States and Japan. Non-traumatic ischemic necrosis of the femoral head affects mostly young and middle-aged people and often develops bilaterally in the hip joint. According to the study of the natural course of the disease, ischemic necrosis of the femoral head without effective treatment will progress to femoral head collapse within 1-4 years and cause significant pain and claudication, and most patients have to undergo artificial joint replacement, but the long-term outcome of artificial joint replacement for young people is not ideal, mainly because of the complications caused by the prosthesis, some patients may have to face more than 2 replacements in their lifetime, which will bring a heavy financial burden to society and patients. Therefore, it is imperative to seek effective treatment to preserve the patient’s own femoral head. Therefore, early diagnosis and early treatment are very important.
Causes of ischemic necrosis of the femoral head
The etiology of ischemic necrosis of the femoral head can be divided into two categories, namely traumatic and non-traumatic. Traumatic ischemic necrosis of the femoral head has a clear cause, namely hip trauma, such as femoral neck fracture, traumatic hip dislocation, femoral head fracture combined with dislocation, and violent hip sprain and contusion. The most common cause is long-term hormone therapy, followed by excessive alcohol consumption. Other diseases can lead to ischemic necrosis of the femoral head, such as after kidney transplantation, hyperlipidemia, Gaucher disease, sickle cell anemia, decompression sickness, radiation sickness, etc.
The most common cause of ischemic necrosis of the femoral head in young and middle-aged people in China is the long-term use of cortisol hormones (prednisone, dexamethasone, prednisone, etc.) for various reasons, such as systemic lupus erythematosus, kidney disease, rheumatoid arthritis, etc. One study showed that with prednisone 30 mg daily for one month, about 1/3 of patients develop osteonecrosis, with risk factors such as total dose over 2000 mg, duration over 30 days, and high-dose shock therapy. There is no clear time frame from the use of hormones to the detection of abnormal changes on MRI. According to the analysis of the results of the census conducted by Prof. Li Zirong on SAR patients in Beijing, the time of occurrence is 3-9 months. Ischemic necrosis of the femoral head was reported by the Japanese to occur as early as 9 weeks after kidney transplantation and 39 to 100 days in patients with systemic lupus erythematosus.
Long-term excessive alcohol consumption is another common cause of ischemic necrosis of the femoral head in China, mostly occurring after the age of 40 (20 years of alcohol consumption), with the youngest patient being 25 years old and the number of years of alcohol consumption being 7 years. As for the amount and time frame of alcohol consumption there is no definite statistical information.
Pathogenesis of ischemic necrosis of the femoral head
The exact pathogenesis of ischemic necrosis of the femoral head is still not very clear, and the common doctrines are as follows.
1, fat embolism: it has been clinically proven that there is fat embolism in the blood vessels of femoral head necrosis.
2.Interrupted arterial blood flow: Femoral neck fractures via the cervical and inferior head type are intra-articular capsule fractures, and the main blood supply to the femoral head is interrupted after the fracture.
3.Venous blood flow occlusion: blood and fluid accumulation in the hip joint capsule leads to increased intraosseous pressure in the femoral head, resulting in obstruction of venous blood flow in the femoral head.
4, arteriosclerosis occlusion: arteriosclerosis and other vascular diseases lead to occlusion of the nutritive vessels of the femoral head, and the blood supply to the femoral head is reduced or interrupted.
5.Filling of extravascular sinusoidal gap
Clinical manifestations and diagnosis of ischemic necrosis of the femoral head
I. Clinical manifestations
Non-traumatic ischemic necrosis of the femoral head is mostly seen in middle-aged and young people, and bilateral involvement accounts for 50%~80%.
1. Hip pain: Hip pain is the earliest complaint, mainly pain at the front side of the hip joint, radiating to the hip and knee joint. The pain is persistent or intermittent, and is not serious in the early stage, but gradually worsens later. It is aggravated after prolonged standing and walking, and relieved after rest. With the development of the disease, the symptoms may gradually worsen, from intermittent pain to persistent pain, and the pain may increase, and signs such as claudication, local percussion pain, muscle atrophy and limitation of hip joint movement may gradually appear. The early stage of ischemic necrosis of the femoral head can have no obvious symptoms, and often when the patient’s symptoms are obvious, X-ray examination reveals that it is no longer early.
2. Physical examination: pressure pain on the anterior side of the hip joint, limitation of hip joint movement, positive “4” test (the patient flexes the affected hip and knee joint, cross-legged, and places the affected ankle above the opposite knee joint, at which time the affected hip becomes painful and the affected knee joint cannot be flattened).
Second, imaging diagnosis
1.Conventional X-ray film: conventional X-ray film includes bilateral hip orthopantomogram and frog position film, which is the most basic imaging examination means to diagnose ischemic necrosis of femoral head, and is used as the first choice for all patients with hip pain to help determine the diagnosis and carry out staging and exclude other diseases.
2.CT examination: CT examination is more sensitive than X-ray for the diagnosis of ischemic necrosis of the femoral head, and can be used for the early detection of tiny lesions and microfractures of subchondral bone plate, etc. It is important for the staging of ischemic necrosis of the femoral head, and the staging is more accurate than X-ray according to what is seen in CT examination.
3, bone scan: bone scan has great value for early diagnosis of ischemic necrosis of the femoral head, especially in the X-ray examination does not see obvious abnormalities, but the clinical suspicion of ischemic necrosis of the femoral head is more useful. Bone scan can often diagnose ischemic necrosis of the femoral head 3-6 months earlier compared with X-ray examination. In the early stage of ischemic necrosis of the femoral head, a radionuclide concentration zone appears under the cartilage of the femoral head, indicating vascularization and tissue repair around the necrotic area of the femoral head; in the late stage of ischemic necrosis of the femoral head, no radionuclide concentration appears in the femoral head. However, due to the high false positive rate of bone scan, the diagnostic accuracy rate is 91%~95%.
4.MRI: MRI is an effective non-invasive method for early diagnosis. Normal bones show low signal in the bone cortex and high signal in the bone marrow on T1- and T2-weighted images. The change of signal intensity in bone is an early and sensitive sign of osteonecrosis.
Treatment
The choice of treatment for ischemic necrosis of the femoral head should be based on the patient’s age, occupation, etiology, necrosis volume, different stages and technical conditions. Surgical treatment includes medullary decompression, removal of necrotic lesions plus bone grafting (free autologous bone, autologous bone graft with vascular or myotome), osteotomy and artificial total hip replacement. Total hip arthroplasty is the choice for head preservation treatment failure or advanced ischemic necrosis of the femoral head.
I. Conservative treatment
Conservative treatment mainly includes avoiding or reducing weight-bearing, medication and physical therapy. By reducing the pressure on the weight-bearing area of the femoral head, conservative treatment tries to promote local blood supply, reduce inflammation, increase bone tissue density and promote bone and cartilage growth, thus delaying the further progress of femoral head necrosis and avoiding femoral head collapse. However, in terms of available clinical evidence, the efficacy of conservative treatment is also quite “conservative”. Therefore, the current view is that conservative treatment is not only difficult to delay the natural course of femoral head necrosis, but also requires a certain observation period to assess the efficacy after conservative treatment, which delays the early and reasonable treatment of femoral head necrosis.
1, drug treatment
At present, there is no special drug for the treatment of ischemic necrosis of the femoral head. Because of the large number of patients with ischemic necrosis of the femoral head in China, most patients have little knowledge of the disease, once diagnosed with the disease is more nervous, psychological pressure, seeking medical help everywhere, hoping to cure or cure, see what advertising, serving Chinese medicine without surgery can treat ischemic necrosis of the femoral head, went to seek treatment, spent a lot of money, ate a lot of Chinese medicine did not work, the condition worsened. Patients choose Chinese medicine treatment, must go to the government-run large hospital Chinese medicine department or Chinese hospital to see the doctor to take medicine, can not believe in the charlatan, or what the doctor, Chinese medicine ancestral secret recipe, etc..
Diphosphonates are currently proven effective in the treatment of ischemic necrosis of the femoral head through evidence-based medicine. Diphosphonates delay bone resorption and osteoporosis by inhibiting the activity of osteoclasts, and at the same time, increase the activity of osteoblasts to promote osteogenesis.
2.Physical therapy
Electromagnetic therapy for ischemic necrosis of the femoral head was reported in the literature in the last century, but the U.S. Drug and Food Administration has not approved its official clinical application so far.
Hip preservation therapy or head preservation therapy
1.Medullary decompression of the femoral head
Medullary decompression of the femoral head is the most common procedure used to treat early ischemic necrosis of the femoral head. The theoretical basis of medullary decompression for ischemic necrosis of the femoral head is that the pressure inside the necrotic femoral head is increased, and intraosseous venography shows that the contrast agent is retained. After medullary decompression, the pressure inside the femoral head is reduced, which restores blood flow inside the femoral head, improves circulation and reduces pain.
2.Femoral head necrosis lesion removal plus bone grafting
This is the most current surgical method to treat ischemic necrosis of the femoral head. The lesion removal can be minimally invasive, by drilling a tunnel under the greater trochanter to the femoral head, scraping the necrotic lesion through the tunnel with a special scraping spoon, and then implanting bone, with autologous cancellous bone and anastomosed fibula; the lesion removal can also be done by opening a window at the junction of the femoral head and neck, or by opening a window through the cartilage of the femoral head, and then performing support. The bone graft can be made of non-vascularized autologous iliac bone, iliac bone with a vascularized tip, femur bone with a vascularized tip, etc.
4.Medullary decompression with tantalum rod implantation
Porous tantalum metal has enough strength to withstand physiological load, which is a good support for the femoral head that is about to collapse. The pore spacing of the porous tantalum rods is large and completely connected to each other, close to the pore spacing of human bone trabeculae, allowing reliable and rapid bone growth. At the same time, tantalum metal has good biocompatibility, allowing human bone tissue to grow well into the pores of the metal tantalum rods, making the human bone and the metal tantalum rods one and the same. In addition, its elastic modulus is similar to that of bone, which can reduce stress shading. In recent years, domestic and foreign scholars have reported that the use of medullary decompression plus tantalum rod implantation has certain efficacy in treating ischemic necrosis of the femoral head. The use of medullary decompression and porous tantalum rod implantation in the treatment of femoral head necrosis can provide both structural support of subchondral bone, delay the time of femoral head collapse and postpone the time of total hip replacement.
5. Osteotomy of the femoral trochanter
There are two major types of femoral osteotomies used to treat ischemic necrosis of the femoral head: one is intertrochanteric inversion with flexion or extension, or abduction with extension or flexion osteotomy; the other is transtrochanteric rotational osteotomy. The concept and purpose of osteotomy is to change the weight-bearing surface of the femoral head through osteotomy, to move the non-necrotic normal femoral head to the weight-bearing area, to prevent the collapse of the non-collapsed femoral head, and to prevent further collapse of the existing mildly collapsed femoral head, so as to improve clinical symptoms and joint function.
Artificial total hip arthroplasty
Although the efficacy of various surgical treatments to preserve the femoral head is improving, there are still a considerable proportion and number of cases of ischemic necrosis of the femoral head that will progress to the extent of requiring total hip arthroplasty. Total hip arthroplasty is the ultimate treatment for patients with ischemic necrosis of the femoral head, and it is the most widely used, most technically mature, and has very satisfactory surgical results.