Hip resurfacing

Hip resurfacing

Hip resurfacing is an alternative to standard hip replacement surgery used for the treatment of severe hip arthritis. Hip resurfacing is not a new surgery. Hip resurfacing surgery has been performed since the early 1970s. However, recent changes in hip resurfacing implant design has led to a new interest in this procedure.

Resurfacing Surgery
Implant properties

Your hip joint is made up of two major parts. One or both parts may be replaced during surgery:

  • The hip socket (a part of the pelvic bone called the acetabulum)
  • The upper end of the thighbone (called the femoral head)

The new hip that replaces the old one is made up of these parts:

  • A socket, which is usually made of strong metal
  • A liner, which fits inside the socket. It is usually plastic, but some surgeons are now trying other materials, like ceramic and metal. The liner allows the hip to move smoothly.
  • A metal or ceramic ball that will replace the round head (top) of your thigh bone.
  • A metal stem that is attached to the thigh bone to make the joint more stable.
The Procedure

This surgery replaces the diseased and damaged bone in the hip joint with specially designed and manufactured “ball and socket” all-metal implants.
After you receive anesthesia, a surgical cut would be made to open up your hip joint. Often this cut is over the buttocks. Then:

  • The thigh bone is separated from the hip socket,
  • The damaged area is removed. Damaged cartilage and bone are removed from the hip socket (acetabulum).
  • The hip ball is reshaped to fit the femur and just 10mm of bone is removed from the hip.
  • A specially-machined, metal shell implant is firmy pressed into the socket of the pelvis in the anatomic position.
  • Now the surgeon focuses on the thigh bone implant. The end of the thigh is drilled to accept the stem of the implant and dried.
  • Bone cement is placed inside the metal ball component and around the dried bone of the thigh.
  • The metal ball implant is securely inserted on top of the thigh bone.
  • The muscles and tendons around the new joint are repired
  • The surgical cut is closed

The advantages:

Some surgeons have advocated hip resurfacing implants because of several potential advantages. These advantages include:

Maintenance of normal bone

Hip resurfacing surgery removes less bone than a standard hip replacement. In a standard hip replacement, the entire ball of the ball-and-socket hip joint is removed. In a hip resurfacing surgery, instead of removing the ball, a metal cap is placed around where the cartilage has worn off.
Furthermore, because the bone around the implant is supporting the metal cap, this bone tends to remain healthy and strong. The bone around a standard hip replacement can become thin and weak if the hip replacement implant supports the entire load. This problem is called “stress shielding,” and is seen less commonly in hip resurfacing.

Less risk of dislocation

Hip resurfacing implants better replicate the normal anatomy of the hip joint, and therefore have a lower risk of dislocation following surgery. Especially in younger, more active patients, dislocation can be a significant risk of hip replacement surgery.

Easier revision

In the event that the hip resurfacing surgery does not last the entire life of the patient, the revision (repeat) replacement is not as difficult. Every time a revision procedure is performed, a larger surgery and larger implant must be used. By minimizing the bone removed, and using a smaller implant, the revision surgery following hip resurfacing surgery can be more like performing a standard hip replacement.

Who is the “best patient” for a hip resurfacing procedure?

The ideal patient for a hip resurfacing procedure is a young (less than 60 years old) patient with strong bone around the hip joint. Young patients are of particular concern to joint replacement surgeons because of the chance they will need additional replacements (revision hip replacement) at some point later in life. The hip resurfacing procedure is thought to preserve more bone, and prevent possible complications associated with revision hip replacement surgery.

Who is not a good patient for a hip resurfacing surgery?

Patients with problems in the bone around the hip joint should not undergo a hip resurfacing surgery. These include

  • Patients who have bone loss as a result of their arthritis,
  • Patients with osteoporosis
  • Patients with cysts within the bone.

Other factors may sway patients away from considering a hip resurfacing procedure. These factors include:

  • Age higher than 60
  • Gender: Women
  • Obesity, Kidney problems, Diabetis
  • Allergy or oversensitivity to metal implants
  • Inflammatory Arthritis & Osteonecrosis

What are the possible complications of hip resurfacing surgery?

There are a few major concerns with hip resurfacing surgery, and unfortunately, no one knows the long-term results of the implants that are currently being used. Therefore, no one can definitavely say that this surgery is better or wosre than a standard hip replacement.
Possible complications include:

Fracture

The risk of fracture of the bone supporting the hip resurfacing implant has led some doctors to question if this surgery should be done on any patients. While studies have varied, the risk of fracture of the bone seems to be between 1% and 20% of patients. Fractures are more common in pateints who have poor bone quality, obese patients, and women. In addition, fractures are more common for surgeons who have done this surgery less frequently.

Loosening

Similar to standard hip replacements, hip resurfacing implants can become loose over time. If the implant loosens, a standard hip replacement usually needs to be performed.

Metal Ions

All implants inserted into the body slowly wear out over time. Metal implants used in hip resurfacing surgery have been shown to wear less than plastic implants, but the metal implants do release metal ions into the body as they wear. These metal ions can be detected throughout the body in patients who have had metal-on-metal hip replacements or hip resurfacing surgery. The effect of these metal ions in the body is not known. There are concerns about causing hypersensitivity reactions and possible carcinogenic (cancer causing) effects. Fortunatley, there is little data to show this is a problem, but it is a theoretic concern.

What is the recovery from hip resurfacing surgery?

The recovery following hip resurfacing surgery is similar to that following hip replacement surgery. Patient have a lower risk of dislocation of the implants, so the precautions placed on the patient may be less significant.
During the first year after surgery, all impact activities and heavy lifting must be avoided. This is the time frame when the bone holding the implant is most susciptible to fracture. Therefore, current recommendations are to avoid running, jumping, and lifting for the first 12 months after surgery.

Will I need more surgery at a later date?

It is not known how long on average hip resurfacing implants will last. With better designed implants, they seem to be functioning well at the 10 year mark. However, that is still not as good as what is known about standard hip replacements.
If the hip resurfacing implant does develop problems, or if it does wear out, additional surgery may be recommended. Because the initial hip resurfacing surgery removed less bone than a standard hip replacement, the revision (repeat) surgery is usually less complicated following a hip resurfacing procedure. The usual procedure is to convert the worn out hip resurfacing implant to a standard hip replacement.

References

http://orthopedics.about.com/od/hipkneereplacement/a/resurfacing.htm
http://www.salemorthopedic.com/resurfacing.php
http://www.bupa.co.uk/individuals/health-information/directory/h/hip-resurfacing

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