Osteonecrosis of the femoral head (ONFH), also known as ischemic necrosis of the femoral head, is a disease in which the blood supply to the femoral head is interrupted or damaged, causing the death and subsequent repair of bone cells and bone marrow components, which subsequently leads to structural changes in the femoral head, femoral head collapse, and joint dysfunction.
Femoral head necrosis can occur at any age, but it is most common at the age of 31-60 years old, with no gender difference. It starts with vague or dull pain in the hip joint or its surrounding joints, which is aggravated by weight-bearing activities.
A, the etiology of femoral head necrosis
The etiology of femoral head necrosis is diverse and complex. Although the etiology is different, the common pathological manifestation is the ischemia of the femoral head, and the more unanimously accepted theory is that the blood supply is obstructed. The more common causes are as follows.
1, trauma leading to femoral head necrosis
Such as external impact caused by femoral neck fracture, hip dislocation, hip sprain and contusion, trauma is the main factor causing femoral head necrosis, but the occurrence of traumatic ischemic necrosis of the femoral head, the scope of the size, mainly depends on the degree of vascular destruction and the compensatory capacity of the collateral circulation.
2, drugs lead to femoral head necrosis
The occurrence of femoral head necrosis and hormone to make the type of field, the dosage form, the route of administration is directly related to the total amount and time of dressing vegetation is not proportional, hormonal femoral head necrosis bilateral simultaneous onset is common, and more than half of all patients first side onset, after months or years, the other just onset.
3, alcohol stimulation leads to femoral head necrosis
Due to the accumulation of alcohol in the body caused by long-term heavy drinking, resulting in increased blood lipids and liver function damage, resulting in increased blood viscosity, slowing down the blood flow, thus blocking blood vessels, bleeding or fat embolism, resulting in osteonecrosis.
Second, clinical manifestations
1.Pain
Pain can be intermittent or persistent, aggravated by walking activities, sometimes resting pain, pain is mostly pins and needles, dull pain or soreness and discomfort, often radiating to the inguinal region, inner thigh, posterior hip and medial knee, with a sense of numbness in the region.
2.Joint stiffness and limitation of activities
The affected hip joint flexes and extends unfavorably, has difficulty squatting, cannot stand for a long time, walks with a duck walk, and has early symptoms of abduction and limitation of external rotation.
3.Crippling
Progressive shortening limp, due to hip pain and femoral head collapse, or late onset of hip subluxation, intermittent limp often appears in the early stage, more obvious in children.
4.Special physical examination
Local deep pressure pain, pressure pain at the stop of the adductor muscle, positive 4-character test, positive A11is sign, limited abduction, external rotation or internal rotation, shortening of the affected limb, muscle atrophy, even signs of subluxation, sometimes positive axial pain.
5.Radiological manifestations
X-ray shows that the bone texture is small or interrupted, and the femoral head is cystic, sclerotic, flattened or collapsed.
Three, the type of femoral head necrosis
The typology of femoral head necrosis is divided into six categories according to the size and shape of the necrotic area, as follows.
1.All necrosis of the femoral head
Less common, refers to the head of femur from the edge of the joint all necrosis, head under the type of femoral neck fracture can often cause total head necrosis.
2.Cone (wedge)-shaped necrosis of the femoral head
The most common, the normal femoral head is divided into the central weight-bearing area and the internal and external non-pressure area, the head central cone necrosis is the weight-bearing area osteonecrosis.
3.Hemilunar necrosis of the top of the femoral head
The incidence is very high, osteonecrosis occurs in the front and top of the femoral head, the dead bone is half-moon shaped, the hip joint frog external booth X-ray photo shows the most clear.
4.Focal osteonecrosis of the femoral head
It is the lightest, this type generally does not occur the femoral head collapse.
5.Core necrosis of the femoral head
6.Non-vascular osteonecrosis