Osteonecrosis of the Hip
Other popular names
- Avascular Necrosis
Who does it affect?
Although osteonecrosis affects people of all ages, it most commonly occurs between the ages of 40 and 65. Men develop osteonecrosis more often than women.
Why does it happen?
Osteonecrosis of the hip is a painful condition that occurs when the blood supply to the bone is disrupted. Because bone cells die without a blood supply, osteonecrosis can ultimately lead to destruction of the hip joint and arthritis.
Although it can occur in any bone, osteonecrosis most often affects the hip.
The hip is a ball-and-socket joint. The socket is formed by the acetabulum, which is part of the large pelvis bone. The ball is the femoral head, which is the upper end of the femur (thighbone). A slippery tissue called articular cartilage covers the surface of the ball and the socket. It creates a smooth, low friction surface that helps the bones glide easily across each other.
Osteonecrosis of the hip develops when the blood supply to the femoral head is disrupted. Without adequate nourishment, the bone in the head of the femur dies and gradually collapses. As a result, the articular cartilage covering the hip bones also collapses, leading to disabling arthritis.
With osteonecrosis, the bone in the head of the femur slowly dies.
Although it is not always known what causes the lack of blood supply, there are a number of risk factors that can make it more likely for someone to develop the disease:
- Injury — Hip dislocations, hip fractures, and other injuries can damage the blood vessels and impair circulation to the femoral head
- Corticosteroid medicines — Many diseases, such as asthma, rheumatoid arthritis, and systemic lupus erythematosus, are treated with steroid medications. Although it is not known exactly why these medications can lead to osteonecrosis, research shows that there is a connection between the disease and long-term steroid use.
- Other medical conditions — Osteonecrosis is associated with other diseases, including Caisson disease (diver's disease or "the bends"), sickle cell disease, myeloproliferative disorders, Gaucher's disease, systemic lupus erythematosus, Crohn's disease, arterial embolism, thombosis, and vasculitis
Osteonecrosis develops in stages and hip pain is typically the first symptom. This may lead to a dull ache or throbbing pain in the groin or buttock area. As the disease progresses, it will become more difficult to stand and put weight on the affected hip, and moving the hip joint will be painful.
How long it takes for the disease to progress through these stages varies from several months to over a year. It is important to diagnose this disease early, because some studies show that early treatment is associated with better outcomes.
Osteonecrosis can progress from a normal, healthy hip (Stage I) to the collapse of the femoral head (Stage IV).
After discussing your symptoms and medical history, you will undergo a detailed physical examination, with your hip and leg manoeuvred into various positions. Increased pain during certain movements may be a sign of osteonecrosis.
An x-ray will be taken to examine degradation to the femoral head.
Occasionally you may be asked to undertake an MRI scan. This is useful to show early changes in the bone that may not show up in an x-ray.
Unfortunately there are no non-surgical treatments that will reverse osteocronosis. Medication or the use of crutches can relieve pain, however the only corrective approach is through surgical means. The type of surgery will depend on your age and the progression stage. If this can be caught prior to femoral head collapse, you may be a candidate for hip preserving procedures.
A common surgical treatment is Core Decompression. This procedure involves drilling one larger hole or several smaller holes into the femoral head to relieve pressure in the bone and create channels for new blood vessels to nourish the affected areas of the hip.
When osteonecrosis of the hip is diagnosed early, core decompression is often successful in preventing collapse of the femoral head and the development of arthritis.
Core decompression may be combined with bone grafting to help regenerate healthy bone and support cartilage at the hip joint. A bone graft is healthy bone tissue that is transplanted to an area of the body where it is needed. I use a number of techniques from a standard autograft, where I take extra bone from one part of your body (harvest) and move (graft) it to another part of your body. You may also be suitable for a bone graft from a donor which would be acquired through a bone bank.
There are also several synthetic bone grafts available today.
In certain circumstances I may suggest a Vascularized Fibula Graft. This is a more complex procedure in which a segment of bone is taken from the small bone in your leg (fibula) along with its blood supply (an artery and vein). This graft is transplanted into a hole created in the femoral neck and head, and the artery and vein are reattached to help heal the area of osteonecrosis.
If osteonecrosis has advanced to femoral head collapse, the most successful treatment is a total hip replacement. This procedure involves replacing the damaged cartilage and bone with artificial implants.
Total hip replacement is successful in relieving pain and restoring function in 90 – 95% of patients and considered to be one of the most successful operations in orthopaedic surgery.
The aim is to mobilise patients as soon as possible after surgery - on the same day or the next day as this helps speed up recovery.
Most patients remain in hospital for three to four days but there is no fixed limit and patients can go home as soon as they can walk safely with elbow crutches non-weight bearing and manage whatever tasks they need to perform at home.
Physiotherapy is an integral part of the recovery process and we have physiotherapists who are specifically trained in the rehabilitation of hip patients. They will guide you through the recovery process and assess that you are safe for discharge.
Recovering from a major hip operation is hard work in the first few weeks. The hip will feel stiff and sore. This is normal and nothing to worry about and it is important to recognise this and the need to get the hip bending despite the discomfort.
Patients should aim to increase the range of movement they can achieve on a daily basis and that the only way to increase the range of movement is to push the hip in to the uncomfortable zone as in general whatever movement is achieved in the first few weeks is kept for life and it is extremely difficult to increase the range of movement after his time.
Most patients do not require out-patient physiotherapy but for patients who are finding the recovery process more difficult then further physiotherapy can be of great assistance and will be arranged if necessary.
Key rehabilitation points:
- Most times, you will be kept non or touch weight bearing for 4 to 6 weeks
- Remember that walking will come back naturally and does not need to be pushed.
- The range of movement will not and this needs to be worked at.
- Patients who try and do too much walking in the weeks after a hip replacement tend to find that this irritates the hip and it becomes more swollen - this swelling can then restrict the range of movement of the hip in the vital few weeks after surgery when the window of opportunity to regain range of movement is still open.
- 3 to 5 days in hospital
- most patients are able to drive 4 to 6 weeks after surgery and discard their elbow crutches during this period.
- most patients feel better than they did prior to surgery within 6 weeks
- It takes a year to get the best out of a hip replacement
Return to normal routine
Bathing and showering
The wounds should be kept clean and dry until the wound has sealed. Showering is fine and the waterproof dressings can be changed afterwards. Bathing is best avoided until the wounds are sealed, typically 10 days after surgery.
In summary, whilst the wounds are wet - keep them dry and when the wounds are dry, you can get them wet!
Surgery is followed by a prolonged course of physiotherapy. This requires a commitment to undertake this rehabilitation in order to achieve the best possible result (at least half an hour per day for 6 months). It is vitally important to stay within the post-operative activity restrictions and physiotherapy guidelines to avoid damaging stretching your hip.
Return to work
The timing of your return to work depends on the type of work and your access, however, the following is a general guide:
- Desk work: as soon as pain allows and you can travel easily to and from work (2 weeks)
- Light duties: if the job allows partial use of crutches or limited walking (2-5 weeks). If the job involves standing for prolonged walking, bending, lifting, stairs but no squatting (7-8 weeks)
- Heavy duties: full squatting, heavy lifting, digging, in and out of heavy machinery, ladder work etc (3-4 months)
When you can walk without crutches or a limp and be in control of your vehicle (about 4-6 weeks).
The surgical techniques described are very successful in relieving all or most or the pain in about 90-95% of cases.
A small percentage of patients sustain a complication that can potentially leave them worse off. In general the level of this risk is approximately 2%.
Some of the specific risks to be considered are:
- Infection; at or less than 1%
- Neurovascular Injury; less than 1 in 1000
- Stiffness; more common but less of a problem. Occasionally requires a manipulation and can persist in some patients
- Risk to life; about 1 in 1000 mainly- from Deep Vein Thrombosis / Pulmonary embolus (DVT/PE) and anaesthetic risks