Ischemic necrosis of the femoral head is a pathological process in which the blood supply to the femoral head is impaired or completely interrupted for different reasons, causing necrosis of bone cells and bone marrow hematopoietic cells, followed by structural changes of the femoral head and joint dysfunction. The disease is most commonly seen between the ages of 30 and 50, and about half of them involve the femoral head bilaterally. In the early stage, it is easy to misdiagnose and miss the diagnosis because of the diversity of symptoms and signs.
Etiology
There are more than 40 diseases associated with ischemic necrosis of the femoral head in adults, which are mainly traumatic and non-traumatic in nature. Traumatic ischemic necrosis of the femoral head is the result of trauma that interrupts blood flow to the femoral head, including femoral neck fracture, hip dislocation and intertrochanteric fracture. Non-traumatic ischemic necrosis of the femoral head can be complicated by a variety of medical and surgical conditions and is a progressive chronic process whose common pathology is characterized by impaired blood circulation to the femoral head, leading to osteonecrosis. The following diseases are currently considered to be high-risk factors related to the development of ischemic necrosis of the femoral head in adults.
1. long-term use of hormones
2. long-term heavy alcohol consumption
3. decompression sickness
4. hemoglobinopathies
5. other causes such as gout, pregnancy, Gaucher’s disease, chondrodystrophy, iron toxicity, diabetes, pancreatitis, hemophilia, and pelvic radiation therapy can also cause ischemic necrosis of the femoral head.
Clinical manifestations
Pain is often the earliest clinical symptom of ischemic necrosis of the femoral head, manifested as hip pain or knee pain (ipsilateral hip and knee joints are innervated by the same foraminal nerve, hip lesion can be manifested as ipsilateral knee pain), and the pain can be continuous or intermittent. In case of bilateral lesions, the pain may be alternating.
In the early stage, the hip joint activity is normal, and as the disease progresses, the hip joint activity is mildly restricted, often manifesting as impaired rotational activity. In the advanced stage of the disease, the movement of the medullary joint is obviously limited, and the movements of flexion and extension and retraction are all impaired one after another, and in severe cases, the hip joint is stiff and completely lost.
3. claudication Usually appears at the same time with pain, early painful claudication is intermittent and can be relieved after rest. In late stage, due to femoral head collapse, osteoarthritis and hip subluxation, there may be persistent claudication.
Diagnosis
1. X-ray is the commonly used examination, but the positive rate depends on the physician’s experience. The main manifestations include changes in bone density and the appearance of a 1 to 2 cm wide curved hyaline band in the subchondral bone of the joint, i.e. the “crescent sign”. In advanced stages, the femoral head collapses and osteoarthritis of the hip joint is observed (Figure 1).
2. MRI signal intensity change is currently the most sensitive test for diagnosing ischemic necrosis of the femoral head in adults, and can detect the early signs of necrosis before positive signs appear on X-ray and CT.
X-ray of ischemic necrosis of the right femoral head (Ficat stage III), the femoral head is collapsed, but the joint space remains normal
Bilateral hip MRI, showing early ischemic necrosis of the femoral head bilaterally, with only altered signal intensity and normal femoral head profile
Treatment
Commonly used treatment methods can be divided into the following.
1. non-surgical treatment
Non-surgical treatment is suitable for patients with lesions in Ficat stage I and II. The smaller the lesion, the easier it is to repair. The non-surgical treatment method includes: ① general treatment, including stopping hormones, abstaining from alcohol and other treatments targeting the cause of morbidity, as well as symptomatic treatment such as reducing or prohibiting weight bearing, physical therapy, and non-steroidal anti-inflammatory and analgesic drugs. ②Medication, microvascular dilating drugs are commonly used, mainly for improving local microcirculation. ③ hyperbaric oxygen therapy. It should be noted that non-surgical treatment is only applicable to the early stage of femoral head necrosis, late stage patients should have early surgical treatment, otherwise the condition will be delayed ……
2. Surgical treatment
Currently, surgical treatment is the main treatment for ischemic necrosis of the femoral head in adults, and there are more methods. The specific surgical method chosen depends on the stage of the disease, including early head preservation treatment and late joint reconstruction treatment. The key to head-conserving treatment is to solve three problems: (1) improving the blood supply to the femoral head; (2) removing necrotic bone tissue to avoid collapse of articular cartilage; and (3) promoting new bone formation to support articular cartilage.
Commonly used clinical surgical procedures can be classified as follows.
1.Femoral head marrow core decompression and bone grafting Applicable to the early stage of ischemic necrosis of the femoral head, when the femoral head is intact in shape and without hemimelia sign, mostly seen in Ficat I-II stage. There are various materials for bone grafting, including autologous bone, allogeneic bone, artificial bone and tantalum metal rods, etc.
The femoral head marrow core decompression, necrotic bone removal + DBM artificial bone graft + allogeneic fibula support adopted by West China Hospital has the advantages of minimally invasive, high bone viability and avoiding collapse, and the success rate of early head preservation is 95%. Patients can go to the ground after surgery, and the function of the hip joint is not limited.
2.Arthroplasty is mainly used for Ficat stage III-IV, i.e. large osteonecrosis and severe joint surface collapse. The type of prosthesis and fixation method can be selected according to the patient’s age, bone quality, general condition and activity level.