What is hip resurfacing?
Hip resurfacing is a surgical procedure that involves removing the damaged portion of the bone and cartilage in the hip socket (acetabulum) and replacing it with a metal shell, after which the ball (femoral head) of the existing joint is resurfaced with a smooth metal covering. This procedure can be an effective alternative to total hip replacement surgery in select patients. Its main advantages over total hip replacement are: (1) hip resurfacing preserves more bone, which can be important in younger patients who may require future hip surgery, and (2) lower dislocation risk, which can be important to patients who have higher than average range of motion requirements for work or sports.
Hip resurfacing is a technically challenging procedure. A successful outcome after hip resurfacing depends on selecting the proper patient, the correct implant with an excellent track record, and having an experienced surgeon perform the procedure.
Who is a candidate for hip resurfacing?
Hip resurfacing is an alternative treatment option for patients with end-stage hip arthritis that is causing significant pain and/or functional limitation. Hip resurfacing may be recommended for patients dealing with hip conditions including:
Most patients have a diagnosis of hip osteoarthritis or hip impingement with associated cartilage damage. It is not uncommon for patients who were diagnosed with mild-to-moderate slipped capital femoral epiphysis as an adolescent to developed secondary arthritis at an early age; this patient group often benefits from hip resurfacing. Since the implant resurfaces the natural hip anatomy, it is unable to correct for large bone deformities or significant differences in leg length, unlike a total hip replacement.
Additionally, the experience of many patients who had different implants placed by many different surgeons over the last 15 years has helped define the optimal candidate for hip resurfacing:
- Younger age (<65 years)
- Good bone quality (no osteopenia or osteoporosis; not on chronic steroids)
- Larger bone size (able to accommodate a 48 to 50 mm femoral head)
- Small degree of bone deformity
- Small difference in leg length
- Non-inflammatory arthritis (osteoarthritis, osteonecrosis or AVN, hip impingement, secondary arthritis)
Patients with inflammatory arthritis, like rheumatoid arthritis, are generally not candidates. Women, particularly of childbearing age, are not good candidates for hip resurfacing, since women often have smaller anatomy that men and the implant releases metal ions into the blood which could adversely affect a pregnancy. Women also appear to be at elevated risk for serious soft tissue reactions around the hip after metal-on-metal joint replacement.
How do I decide when I need a hip resurfacing?
Choosing to have a hip resurfacing surgery is a personal decision that is made together with Dr. McLawhorn. Your preference for surgery, your lifestyle demands, and your expectations for outcomes after surgery aid the decision-making process and will guide your choice between nonsurgical care and hip surgery.
In general, when hip pain begins to interfere with your daily life, prevents you from participating in your recreational activities, wakes you from sleep, and/or requires prescription pain medication, hip resurfacing surgery is a consideration.
What are the goals for hip resurfacing surgery?
First and foremost, the purpose of hip resurfacing surgery is to improve pain. Other general goals are:
- Improve hip function
- Provide a stable hip that does not dislocate
- Prevent excessive wear of the implanted components
- Avoid complications
Ideally, patients can return to work and the activities they love to perform without worrying about their hip resurfacing. After complete recovery from surgery, some patients may even forget that they had a hip surgery.
What does hip resurfacing involve?
As with total hip replacement, hip resurfacing involves the joint surgeon removing damaged cartilage and bone in the hip socket (acetabulum) and replacing it with a metal shell that holds the femoral head. But unlike a total hip replacement, hip resurfacing preserves part of the femoral head and femoral neck. The patient’s existing femoral head is reshaped during surgery and capped with a smooth metal covering.
The general steps of the surgery are:
- Regional anesthesia is provided with either a spinal or epidural to numb your body from the waist down; sedation through an IV will allow you to sleep throughout the surgery
- Antibiotics are given prior to surgery to prevent infection
- The hip joint is accessed from back of the joint (posterior approach)
- The incision is typically 6 to 8 inches, permitting full access to the hip joint for precise and accurate placement of the implant components.
- The hip is gently dislocated
- Any damaged cartilage on the surface of the acetabulum is removed, and the socket is reshaped into a perfect hemisphere
- The metal socket is then placed within the reshaped acetabulum
- The damaged femoral head is carefully reshaped
- A metal cap is cemented on the reshaped femoral head
- The new ball moves inside of the socket liner, providing very low-friction motion
- The soft tissues are closed over the hip joint
What materials are hip resurfacings made of?
Dr. McLawhorn uses a hip resurfacing implant that has the best track record of success in the United States, the United Kingdom, and Australia: the Birmingham Hip Resurfacing, or “BHR”. This implant has the lowest risk of complications and revision surgery. In properly selected patients, survivorship of the BHR implant is better than a total hip replacement. The metal shell and metal head are both made of cobalt-chrome. During surgery, the metal shell is press-fit into the reshaped socket (acetabulum). The outer surface of the shell is coated with a material (hydroxyapatite) that allows your bone to grow onto the component for long-term fixation. The metal femoral head is fixed onto the reshaped femoral head using bone cement (polymethyl methacrylate [PMMA]). The metal surfaces are highly polished and machined to achieve very low friction motion and low wear.
What are the advantages of hip resurfacing?
Advantages of hip resurfacing surgery include:
- Compared to a total hip replacement, more bone in the thigh bone is retained, which may be beneficial in young patients who may require hip surgery in the future
- The size of the femoral head following hip resurfacing is larger (and closer to the size of the natural ball of the hip) than it is with an artificial femoral head from total hip replacement. This larger size may lead to better range of motion and reduced risk of hip dislocation
What are the risks of hip resurfacing?
For the properly selected patient, data out to 15 years suggests that the outcomes of hip resurfacing are excellent. However, there are some risks associated with hip resurfacing that patients should be aware of:
- Femoral neck fracture
- Adverse local soft tissue reaction (ALTR), including aseptic lymphocytic vasculitis-associated lesions (ALVAL) and pseudotumor
- Elevated cobalt and chromium ions in the blood
While the risks for each of these outcomes are low, they do occur. Femoral neck fracture (a break in the supporting bone just below the femoral implant or “ball” of the hip) usually happens shortly after surgery, and it requires a second surgery to convert the hip resurfacing to a total hip replacement. ALTR occurs randomly in patients with metal-on-metal hips. At this time, no one can predict who will develop ALTR, but patients fitting the ideal selection criteria for hip resurfacing have less risk than others. Finally, elevated metal ions usually occur in metal-on-metal hip implants that are not functioning in the expected way. It is important to investigate the reason for elevated metal ions. If there are no symptoms or obvious reasons for elevated metal ions, simple monitoring to make sure the levels fall may be a reasonable option.
What can I expect after hip resurfacing?
Immediately after surgery, you will be able to walk on your hip resurfacing. Crutches will be used for several weeks, while your bone adjusts to the resurfacing implant. Dr. McLawhorn recommends following posterior hip precautions (no hip flexion greater than 90-degrees, no crossing of the operated leg over the body, and no internal rotation) for 6 weeks. Depending on the demands of your job, you may return to work within 2 to 3 weeks of surgery. Return to full normal activity, heavy labor and sports can occur at 6 months after surgery.
Dr. McLawhorn recommends close follow-up of all his hip resurfacing patients. In general, patients will be evaluated at 6 weeks, 12 weeks, and 1 year after surgery, then every 1 to 2 years thereafter. A clinical examination and X-rays will be performed at each of these visits. Other tests, such as metal ion levels, ultrasound and/or MRI are not necessary for routine patient visits.
If you are suffering from a debilitating hip condition and exploring hip resurfacing as a treatment option, it is important to seek advice from an orthopedic hip specialist to accurately diagnose and treat your condition. Dr. McLawhorn is a hip and knee specialist at Hospital for Special Surgery serving patients in New York City, and Stamford, Connecticut. To learn more, call 203-705-2113 (CT) / 212-606-1065 (NYC) today or schedule an appointment by using the form on this page.