Avascular Necrosis Hip

Avascular necrosis of the hip can also be termed osteonecrosis or ischemic necrosis of the femoral head. The bone structure weakness and the integrity of the structure can be lost. This leads to progressive secondary arthritis and can result in the collapse of the bone. This is caused by abnormal microcirculation and which leads to the death of cells (necrosis).

Avascular hip necrosis is a rare condition that is reported to occur in 2 out of 100 000 people in the UK (Lamb et al, 2019), and up to 6 per 100 000 in the USA (Mujoomdar et al, 2012). It is more common in men, typically occurring between 25 to 44 years, and less common in women occurring at an older age, between 55 to 75. Hip avascular necrosis is one of the common reasons for total hip replacement surgery.

Avascular Necrosis Hip Causes

Risk factors for avascular necrosis of the hip are varied including trauma, lifestyle factors, family history, sex, health, and medication. Men are at higher risk and there is a hereditary link. People who have conditions such as lupus, sickle cell anemia, and Gaucher disease have a higher risk of osteonecrosis.

Trauma is the cause of many cases of avascular necrosis of the hip, usually following a fall onto the hip. Health factors that can contribute include cholesterol levels, blood clotting issues, blood circulation issues, and immunosuppression such as being HIV positive. Some medications such as chemotherapy and steroids can also increase risk. Lifestyle factors such as being overweight or obese, smoking, abuse of alcohol, and living in an urban area all increase the risk of idiopathic or spontaneous avascular hip necrosis.

Avascular Necrosis Hip Symptoms

The most common symptom of avascular necrosis of the hip is pain, often felt in the groin or buttock. This is usually described as an ache or throbbing pain. Movement of the hip joint and weight-bearing through the hip joint will worsen symptoms. Typically pain is low in the early stages of the condition and worsens as it progresses.

As the hip avascular necrosis progresses, stiffness of the hip will become apparent and a loss of range of movement of the hip joint, initially due to pain will occur. In the later stages, a restriction of the range of movement may be caused by a change in the shape of the bone as its structural integrity collapses. It is unusual to see any swelling or bruising.

Avascular Necrosis Hip Radiology and Diagnosis

Diagnosis of avascular necrosis of the hip is done by an experienced medical professional such as a medical doctor or physical therapist. There is no specific or special test for avascular necrosis, a physical examination will look for a pattern of pain that matches this condition as well as any stiffness or reduced range of movement in the joint.

MRI imaging is the best diagnostic tool for the diagnosis of avascular necrosis of the hip. Unfortunately, avascular necrosis of the hip is often wrongly diagnosed as non-specific or mechanical hip pain, such as osteoarthritis. An x-ray can provide a false negative in the early stages of this condition.

Stages of Avascular Necrosis Hip

Stage 1

Typically asymptomatic.
Radiography with x-ray may show a normal hip, while MRI may show minor osteopenia, oedema or dead bone.

Stage 2

Minor symptoms of pain are usually present.
Radiography may still look normal on x-ray, but MRI can show sclerosis, osteopenia, or subchondral cysts.

Stage 3

Symptomatic of pain, joint stiffness and reduced range of motion.
Now x-ray and MRI will show pathology in the form of a crescent sign, a sign of bone collapse.

Stage 4

More painful and worse restriction of joint range of motion.
X-ray and MRI show cartilage damage and osteoarthritis, and further collapse of subchondral bone.

Stage 5

Pain and severe dysfunction of the hip joint.
Both hip surfaces are affected and visible on x-ray and MRI.

Does Hip Replacement Cure Avascular Necrosis?

In the later stages of avascular necrosis, there may be no other options other than surgery. A total hip replacement will remove the affected tissue and replace it with a prosthesis. This will in effect cure the condition of avascular necrosis of the hip and provide a functioning hip joint, although a total hip replacement does have its own restrictions and certain precautions must be taken.

Can avascular necrosis return after hip replacement?

While it is unlikely for avascular necrosis to return after hip replacement surgery, if it has been completed without complications, there is a significantly higher failure rate. Individuals with avascular necrosis of the hip have a higher rate of failure after total hip replacement than those without the condition.

Physiotherapy with James McCormack

This is not medical advice. We recommend a consultation with a medical professional such as James McCormack. He offers Online Physiotherapy Appointments.