- Pain Relief
As with total hip replacement, hip resurfacing offers pain relief for hips damaged by arthritis, avascular necrosis (AVN), femoral articular impingement (FAI), Perthes disease, hip dysplasia, or other disorders leading to destruction of hip articular cartilage.
- Bone Conserving
In hip resurfacing the neck of the femor and a large part of the femoral head are retained. There is no reaming of the femoral canal, eliminating the risk of splitting the femur due to forcible insertion of the stem of the femoral component of the total hip replacement. Should the patient need revision to the femoral side to a total hip, treatment of the femoral bone is identical to primary total hip surgery in that the femoral head and neck are removed. In contrast, revision of a total hip replacement can entail reaming of the femoral canal and risk of splitting the femur either on removal of the original femoral stem or in the insertion of the new femoral component.
- Preserves Natural Geometry
By preserving the femoral neck and most of the femoral head and using a bearing that is the same diameter as the natural joint, hip resurfacing can preserve the mechanics of the natural joint. Preserving the natural mechanics improves the chances of restoring a natural gait. If there are congential deformities, such as hip dysplasia or pistol grip deformity due to Perthes disease, some adjustments can be made by the surgeon to correct these, while large adjustments, to leg lengths differences, for example, may be best left to total hip replacement devices.
- Durable Components
The modern hip resurfacing components are made with a cobalt-chrome alloy that is strong, scratch resistant and durable. Some hip replacement devices that include polyethylene liners that may wear out under heavy, active use. Furthermore the plastic debris particles can cause osteolysis (bone loss) near the devices. Osteolysis may lead to device loosening with complicated revision. The wear of polyethelylene liners and the subsequent cycle of revisions that may follow have been one of the largest challenges in treating the young and active hip patient. Recently there have been improvements to the chemistry of the polyetheylene making it stronger and more durable, but polywthelene wear remains a risk of total hip replacement.
- Surgical Risk
All surgery carries risk. Your physician and surgeon should evalute your health to be sure you are healthy enough to undergo surgery. For young, active patients, this generally should bot be a problem. Specific surgical risks include blood loss (for which transfusions might be required) and risk of infection and deep vein thrombosis (DVT) during and following surgery. Modern surgical materials and techniques can limit blood loss during surgery. Blood thinners and circulation-improving exercises can limit risk of DVT.
- Femoral Neck Fracture
In the process of installing the femoral head a guide hole will be drilled from the top of the femur down to the femoral neck. Also, in the process of preparing the femoral head to accept the cap a shaping tool may contact the neck, notching it. A notch in the neck or a poorly aligned guide bore may weaken the femoral neck creating risk of breakage. Over the years it has been learned to drill the guide bore slightly steeper than the neck angle (not directly down the center of the neck). So proper training, experience and skill of the surgeon will help reduce the likelihood of femoral neck notching and weakening due to inaccurate boring or shaping. The incidence of femeral neck breakage today is much less than in the early days of the modern hip resurfacing devices.
- Metal Allergies
The the metal-on-metal articulation of the modern hip resurfacing device will produce minute amounts of cobalt and chrome debris that will contact tissue in and near the joint. There is a very small percentage (~2-3%) of people who are allergic to this debris and will develop an inflammatory reaction and local swelling as a result. This is a different response than a skin allergy you might have as a reaction to cosmetic jewelry (usually a nickel allergy) as the immune responses internally are different than those of the skin.
- Issues Leading to Excess Wear
In a well-placed joint in a healthy patient the patient's synovial fluid will lubricate the articulating surfaces and there will be minimal wear debris, that is generally well tolerated by the body. An inaccurate placement of the hip resurfacing components can lead to contact along the edge of the acetabular cup leading to higher levels of wear, known as edge wear. Over time it has been learned that avoiding edge wear requires placement of the cup within a set range of installation angles, and this range is more narrow for smaller components. Other situations that can lead to excess wear are failure of acetabular cup to properly seat, dehydration, improper gait or post-surgical body mechanics.
Qualities of the Best Candidates for Hip Resurfacing
- Healthy, Strong Bones
To provide a solid surface to mount the femoral cap and a strong neck to continue to support the patient's weight the bone must be strong. This might be a concern for small patients and post-menopasal women. If you or your surgeon have any concerns about this, a test, known as a DEXA scan, can be performed to quantitatively measure bone density. Another quality of healthy bone is lack of large cysts (holes) in the femoral head. Cysts can develop in response to bone-on-bone rubbing of the femoral head and acetabular bone (hip bone). Spurs can also develop on the acetabulum, but these can be removed during surgery, so they are not considered a risk factor.
- Diagnosis of Osteoarthritis
Surgeons who have long-tern results for modern hip resurfacing (going out to nearly 20 years for a few patients) have noted that the least revisions and subsequent problems come from patients with a diagnosis of osteoarthritis, also known as OA. Osteoarthritis results from overuse (usually in athletes) or due to a mechanical issue or congenital deformation of the femoral head. Diagnoses of dysplazias and some other arthritis types have, statistically, a greater chance of complecations or early revision.
- Patient's Life Expectancy at Least 20 Years
Because one of the primary advantages of hip resurfacing is the preservation of bone to ease future surgeries, or, in other words to avoid the potential complications that are common with multiple total hip replacement surgeries. Thus, the ideal patient will either be quite young, say 60 or younger, or older with a health and genetics that portent a life expectancy more than 20 years.
- Patient Not Prone to Metal Allergies
Susceptibility to internal metal allergies can be difficult to assess; because it is not the same as the skin allergies, the typical skin patch test is not seen as a useful indicator. Metal allergies do tend to be more common in women.
Best Predictors of Success
- Accurate Placement of Device Within Patient
As mentioned above, the hip resurfacing componets should move in such a way that edge loading is avoided. Research has identified a range of angles of placement that show this. A measurement that combines the effects of the angles and the component size is the contact-patch to rim distances. You can read about the details in the files section of the Surfacehippy group or on the
Hip Resurfacing Files
page of this group web site.
- Quality Hospital and Support Staff
Your surgeon is one member of a team that will help to determine the success of your surgery. Check the hospital for their reputation especially regarding infections of surgical patients. Recently some statistics have been compiled for return rates for surgical complications, from for example joint replacement surgery using Medicaid data. While there are some limitiations to using such data (focus on older paitents who are not in the some peer group as most of the best candidates for hip resurfacing), it may help to evaluate the hospital. The stories of other patients from the Surfacehippy group can be helpful, but be aware that there is no single surgeon or hospital that has a 100% sucess or 100% patient satistfacation ratio. Try not to let a single success or failure story sway your decsion.
- Patient Rehab and Recovery
Of course, you, the patient, are a critical member of the surgical team. Orthopedic surgery of any kind is a major trauma to your body and you will be called on to rehabilitate your body, particularly the muscles around your hip joint, to perform exercises to prevent DVT, to follow icing and rest instructions to reduce swelling and inflammation, and to follow instructions about prohibited movements to avoid any chance of dislocation in the period before your muscles and lignments are healded (generally 6 weeks). Once you get beyond the initial recovery stage it is best to focus on restoring a healthy gait rather than going gonzo with intense exercise; slow and steady wins the race.
Finding a Surgeon
- How Much Experience
As described, the success of a hip resurfacing (and to some extent a total hip as well) is dependent on the surgeon accurately placing the device. To help ensure that, experience is necessary, but how much experience is enough? There actually has been a study on this that showed that must problems and complications were found in the first 25 cases, with very small difference in accuracy in cases 100-350. Judging from that study one concludes that 100 cases may be enough, 150 to be sure. Should you go across country, or even overseas, to see a surgeoon who has experience in the thousands? In my opinion that is only necessary if you are a fringe candidate (e.g. small female patient) and you want to be sure your surgeon has seen at least a couple dozen cases like yours.
- Close to Home, If Possible
The surgical procedure in the hospital is just the first step to regaining a pain free active life. There will be follow-up required, that includes physical therapy, staple removal (if used), monitoring of DVT prevention medications and long-term (generally annual or biannual) evaluation. For all those you will have to arrange travel or long-distance referals for physical therapy, x-rays and blood testing. Your physician or a local surgeon may be able to help with some of those things, but generally it is easier if your surgeon is close by.
- Insurance Issues
Health nsurance in the US (and health care in Canada) is mostly regulated by state (or provincial) regulators. For that reason it is usally more convenient and least out-of-pocket cost to arrange coverage for in-network surgeons within the state where you live. Second easiest is out-of-network insurance within your home state. International coverage is the most difficult to arrange -- usually a patient will have to appeal a rejection and try to demonstrate that obtaining care overseas was in the best interest of the insurance company (i.e. cheaper and less likely to have complications). If you are planning to go going out of state, or out-of Province, for your surgery it is best to start by talking to the surgeon's staff above gaining coverage under your policy. You can ask for advice from other patients, but keep in mind that every policy is different even if written in the same state by the same company. Consider also the hospital bill will be the most significant charge and other medical professionals will be involved (and billing for their services); these include anesthesiologist, radiologist, and physical therapists.
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