In this section you will find answers to the most frequently asked questions we receive regarding hip resurfacing at the Joint Replacement Institute.
1.Q. What is hip resurfacing (HR)?
A. Hip resurfacing is a bone-conserving alternative to conventional total hip replacement (THR). Unlike THR, hip resurfacing does not involve the removal of the femoral head and neck nor removal of bone from the femur. Rather, the head, neck and femur bone is preserved in an effort to facilitate future surgery should it be necessary and to enable the patient to take advantage of newer technology or treatments in the future. Refer to the interactive animations on this website for detailed descriptions of both hip resurfacing and total hip replacement.
The current generation of hip resurfacing devices utilize a metal-metal bearing rather than the metal-polyethylene bearings that were utilized in the 1970’s and 1980’s. Metal-metal bearings have demonstrated a much lower wear, minimal bone loss and inflammatory tissue reaction about the hip joint as compared to metal-polyethylene bearings.
Hip resurfacing is anatomically and biomechanically more similar to the natural hip joint, resulting in increased stability and flexibility. Further, dislocation risk is virtually eliminated. Higher activity levels are typically achieved with less risk than with a THR should a revision ever be necessary.These benefits are realized because the head diameter that results from resurfacing is very similar to the patient’s normal head diameter and these larger head sizes are typically much larger than the femoral balls utilized in conventional THR. It should be noted, however, that THR with larger femoral balls is now available and these devices can also result in a high degree of stability with minimized risk of dislocation.
2. Q. Is prolotherapy effective for reducing pain of OA in hips?
A. Prolotherapy targets ligaments and tendons and so would not be effective with osteoarthritis of the hip joint.
3. Q. What chance is there in the coming years that a cartilage repair surgery or repair therapy may be developed and proven effective?
A. Unlikely to be of any benefit for OA of the hip because most are caused by an anatomical abnormality.
4. Q. What is the difference between metal-on-metal hip resurfacing and femoral head or “hemi” resurfacing?
A. Hemi-resurfacing (Femoral head only) is indicated for patients with early stage (i.e., stage II, stage III/early stage IV) avascular necrosis (AVN) in which the articular cartilage is in relatively good condition. In other words, the hip is not yet arthritic. Therefore, the acetabulum is not replaced. There are several hemi-resurfacing devices that are commercially available (i.e., FDA approved). The procedure may be indicated for some patients under ~30 years.
Metal-metal hip resurfacing, on the other hand, is indicated for hip arthritis in which the articular cartilage has deteriorated and, therefore, the acetabulum (socket) must be replaced. See Directors’s message for information on Status of FDA approval.
5. Q. Hip resurfacing is called "bone preserving" but the ball size is larger than that of a typical stemmed–type total hip replacement (THR), so does it require greater bone removal on the pelvic side?
A. No. Resurfacing actually takes less bone on both sides. The same cup can be used for both so if a revision is required due to problems with the femoral cap, the acetabular cup can usually be retained.
6. Q. How do the chances for long-term hip dislocation compare between hip resurfacing, large head metal-on metal, large head ceramic, and typical metal on plastic THR?
A. Provided that the surgery is well done and the components are optimally positioned, the larger the ball size the more stable the joint will be. The ball size will be reduced with any 2-part socket and the risk of instability increased. The risk of dislocation is therefore greater with ceramic bearings, then polyethylene, then metal-on-metal, in descending order. A 40mm or greater ball size provides the best stability.
7. Q. How do I know if I am a candidate for hip resurfacing?
A. A surgeon who is experienced in hip resurfacing can determine if you are an appropriate candidate for the procedure following an examination and a review of x-rays. However Dr. Amstutz has reported improved short to mid-term results even in hips with bone defects1 while other surgeons have been reluctant to resurface unless the bone quality is good2. Initially, hip resurfacing was indicated for active adults in whom additional surgery may be required within their lifetime based upon their age, activity level and other factors. However our up to 11+ year results suggest that life time durability may be possible and therefore our age and other indications are expanding.
8. Q. Should I have my bone density measured? If so, what is the minimum DEXA reading you accept to avoid neck fracture?
A. The role of the DEXA scan, or even CT, is not clear. DEXA does not seem to correlate with the prevalence of femoral neck fracture in HR. Statistically, active older patients do well with resurfacing. Unless there are other obvious contraindications, the final decision must be made by a surgeon who has experience and confidence in performing the procedure.
9. Q. Can hip resurfacing be done in the case of protrusion?
A. Yes, it can work very well and does not present undue difficulty. The Conserve®Plus system has several sockets to use. We have resurfaced many.
10. Q. To what extent can cysts in the femoral head and/or pelvic bone be repaired and are acceptable for HR surgery?
A. While it is true that large cysts did correlate with higher failure rates in the very early HCA series, with improved surgical technique, the failures have virtually been eliminated in the HCA experience, expanding the indications (See resource library).
11. Q. How big can femoral cysts be and HR still be performed?
A. Most surgeons will perform only when the bone quality is good while other accept up to 30% of the femoral head being defective. However HCA has accepted much larger defects in young patients but surgical technique is critical. The size of the bone, the size of the defect, the quality of the bone, the patient's weight and their intended activities all play a role in the decision making process. A surgeon with little hip resurfacing experience would be wise to choose patients without large cysts.
12. Q. When and why does HCA recommend cementing in the stem?
A.Cementing of the metaphyseal stem is useful in cases with known risk factors for early failure (i.e. femoral component size smaller than 48mm and presence of femoral defects greater than 1cm) but is unnecessary in hips of large size with good bone quality. Cementing the metaphyseal stem is an effective way to increase the area of the bone-cement interface and enhance initial fixation of the component.
13. Q.What experience level should I search for in a HR surgeon?
A. There is a substantial learning curve with hip resurfacing. You would want a surgeon who was quite experienced with THR and has had good results with resurfacing. Excellent technique can only be developed by doing the surgery regularly. There is no substitute for experience. I (HCA) continue to fine-tune my technique after several thousand resurfacings.
14. Q. On a surgeon’s stats, how can you find out how many times the surgeon has assisted or performed HR as the lead surgeon?
A. Ask them directly. How many resurfacing they have performed in the past year would also be instructive since volume develops technique.
15. Q. How do you judge whether a new HR surgeon is competent? Especially one that doesn't have a big loyal following?
A. Find out how he learned resurfacing. Did he take a class, observe, scrub in and assist? Did he spend time with an experienced resurfacing surgeon? Has he done at least 50? What are the results?
16. Q. How many HR surgeries does it take to overcome the HR learning curve?
A. This very much depends on the previous experience level of the surgeon, the amount of time spent with an experienced resurfacing surgeon and the rate at which the surgeon is implanting HR devices. For example one HR per month is probably not enough to develop great technique.
17 Q. Do health insurance carriers cover the costs associated with hip resurfacing surgery?
A. Hip resurfacing is considered a “covered service” by Aetna and the Medicare intermediary here in California. The vast majority of all other national and regional insurance carriers are now authorizing. Our office will contact your carrier following your initial consultation The carrier will typically render a coverage decision within a relatively short period of time although the response time varies from carrier to carrier. If you are a Medicare beneficiary from another state and you undergo the surgery then the surgery would be covered by Medicare. The Medicare intermediaries in the other regions of the country make independent determinations of coverage for surgeries performed in those regions but there have been no recent denials.
19 Q. What is the JRI surgeons’ opinion regarding the “mini-incision” surgical approach and is it used in hip resurfacing surgery?
A. There is considerable interest in minimally invasive surgery. However, one must distinguish between the so called “mini-incision” technique and “minimally invasive” surgery. At this time, consensus has not been reached on what constitutes “mini-incision” or how it is defined. Further, there is considerable variability in the length of incision used for the “standard” total hip. Although there is considerable enthusiasm, the efficacy of "mini-incision" techniques has not yet been demonstrated by appropriate scientific trials. Ideally, patients of similar characteristics would be randomized to a “standard” incision or a “mini-incision”. Establishing the efficacy of any new technique would require a favorable operative time (currently the mini takes longer), a lower blood loss, a shorter hospital length-of-stay, a faster return to work and other normal activities, as well as an equal rate of complications (wound healing, dislocation, infection, survivorship, etc.) – in a comparable group of patients with similar attitude and motivation. Therefore, in the “ideal” patient, the standard incision would be small and the patient would recover quickly but not due to the length of the skin incision, but rather because of the good starting material! At the present time neither safety nor efficacy have been established for “mini-incision” techniques. In fact, many centers report higher short-term complication rates and it is extremely unlikely that the long-term stability, wear, fixation and durability of THR using a mini-incision approach will be improved. At the JRI the incision length is adjusted according to the size and bulk of the patient and the type of procedure being performed although “mini-incision techniques” are not currently recommended for hip resurfacing due to the limited access and visualization of the hip joint that characterizes these approaches. Irrespective of the procedure, the most important variable is the quality of surgery being performed. It is unwise under any circumstances to compromise the visibility of the surgeon nor the best available implantation techniques as the primary goal is to optimize long-term durability.
Our advice to prospective hip replacement patients considering the “mini-
incision” is:
1. If your BMI [(weight (in kg) / height (in m)) squared] is less than
25, then the standard incision is so small that any benefit from a "mini
incision" is questionable.
2. If your BMI is 25 or more (getting more obese), and your hip is
stiff, the efficacy of the "mini incision" has not been demonstrated.
Basically, if you want a small incision, you need to be thin.
REMEMBER: A TOTAL HIP REPLACEMENT IS A TOTAL HIP
REPLACEMENT REGARDLESS OF THE SIZE OF THE INCISION. HIP
RESURFACING IS THE ONLY “MINIMALLY BONE INVASIVE”
TECHNIQUE BECAUSE YOUR FEMORAL BONE IS PRESERVED!
20. Q. What are the differences between the posterior and anterior surgical approaches?
A. Recovery is quicker with the posterior approach because no important muscle groups are sectioned. The posterior approach is also well-suited for patients who are large, well muscled or who require special techniques to implant the hip resurfacing socket.
In the past some surgeons changed from the posterior to the anterior approach to improve stability and reduce the incidence of dislocation after THR. This was effective when THR ball size was small (22,28,32mm). However the risk of dislocation is overcome by using larger ball sizes and at the JRI 36mm is generally the minimum so there is no advantage left to the anterior approach. Wear data now available supports the use of larger ball sizes from 36 mm up to 54mm with Metal on Metal technology and up to 40 mm with new cross-linked polyethylene. The largest ball size available for ceramic on ceramic bearings is 36 mm because a two part socket is required and ceramic material must be relatively thick to minimize the risk of fracture. Resurfacing is best performed with a posterior approach. However, even a hip resurfacing procedure can technically be performed in most individuals using an anterior approach but this requires removal of 33% to 50% of the abductor muscles. Even though the muscle group is reattached, the muscles are strong and, therefore, the reattachment may pull loose even if activities are restricted for a prolonged period.
Summary of Advantages - Posterior vs. Anterior Approach:
The posterior approach for hip resurfacing has the following advantages now
that the instrumentation has been redesigned specifically for that approach:
1. No important muscle groups are sectioned.
2. There is no release of the abductor muscles. They are the most important
muscles stabilizing the hip during walking and other activities.
3. The gluteus medius and minimus remain intact. The only muscle groups
that are released are the short rotators that are repaired at the conclusion of
the procedure. However, no important gait or other disturbances results
from a release even if they are not repaired because the rotation is
accomplished by other muscles. One of the two insertions of the gluteus
maximus tendon which extends the hip may be released in large obese or
very muscular individual but there is no resulting muscular weakness.
4. The new instrumentation facilitates a smaller incision especially in thin
individuals. A longer incision is necessary in well muscled or overweight
patients. A slightly longer incision is necessary in resurfacing than
when the head and neck are amputated in conventional THR. In hip
resurfacing the surgeon must work around the head and neck to be able to
prepare the acetabulum and implant the socket accurately. Hip resurfacing
is technically more demanding and takes slightly longer. Since hip
resurfacing is an anatomical replacement, leg length equalization is
facilitated and more precise. Leg length equalization in THR is more
demanding, less certain and requires an intra-operative X-ray.
5. The anterior approach requires removal of some of the abductor muscles
for either hip resurfacing or THR. Even though they are repaired this
reattachment may not be 100% successful.
21.Q.Does the debris generated from metal-metal bearings cause cancer or other systemic organ disease?
A. Metal-metal bearings have advantages for active patients because their wear resistance is much greater than that of polyethylene, they do not fracture and they perform better with larger diameter balls. It has been known for three decades that the serum and urine levels of cobalt and chromium (the main elements in a metal-metal hip bearing) are increased in patients with a metal-metal bearing. The health impact of such ion levels has not been established and continues to be debated. Trace element analysis requires very sensitive equipment since the levels are in parts per billion (ppb). Absent some environmental exposure, serum and urine levels of cobalt and chromium are effectively zero in people with no metallic implants. In patients with a well-functioning total joint with a metal-on-polyethylene bearing, the serum levels are generally less than 1 ppb. In patients with a well-functioning prosthesis with a metal-metal bearing, the ion levels are generally between 1 and 5 ppb. These levels are very low and are 1/10th to 100 times less than posted industrial toxic levels. If there is any increase in overall health risk to patients with a metal-metal bearing prosthesis and none has been proven today , it must be very low, given the thousands of MM implants used since their reintroduction 20 years ago. The JRI continues to closely monitor patients with metal-metal bearing prostheses to better define the benefits and risks of this technology.
22 Q. How long will a hip resurfacing last?
A. We simply cannot predict how long the hip resurfacing implants will last forseveral reasons. Durability is directly related to several factors including the quality of the femoral bone, implant design,
the patient’s unique anatomy patient’s activity level and most importantly the surgeon’s skill in performing the surgery. It is difficult and inappropriate to prognosticate about a device’s performance and longevity without long-term clinical data. In the absence of
speculative. However the comprehensive follow-up the Conserve®Plus procedures have enabled us to carefully follow up patients beyond 11 years and their survivorship data, even with the earliest technique and most seriously affected hip with severe cystic disease, is better than 90.5%. Now with improved techniques we would be disappointed if that figure did not reach 98% We also have identified signs of impending failure and in the absence of any of these signs, very long-term survivorship is possible.
23. Q. What is my first step in having hip resurfacing surgery at the JRI?
A. The first step in the process is to have a consultation with one of our surgeons. As a matter of convenience for out-of-state patients, we offer consultations by telephone. It is JRI policy that consultations by telephone are not billable to insurance plans and, therefore, the patient must pay for this service in advance. To request a telephone consultation, please contact the JRI at jovitaortega@dochs.org and a member of our staff will contact you. For a telephone consultation, we would mail you forms to complete and ask that you return the completed forms with recent hip x-rays (i.e., < 3 months) and the fee payment. The respective surgeon’s patient coordinator would then contact you to schedule the date and time for the consultation.
To schedule an in-office appointment with one of our surgeons, please call the JRI at (213) 484-7600 for both Dr. Amstutz or Dr. Schmalzried.
24. Q. If I have hip resurfacing surgery at the JRI and I am traveling from out of state, how long is my stay in Los Angeles?
A. The time in LA is typically 3-6 nights which includes a 2-3 night hospital stay (3-4 nights for bilateral surgery); and 1-2 days in advance of surgery to undergo a medical examination, pre-op visit with the surgeon, sign paperwork,
register at the hospital, etc... Arrangements may be made to stay pre-op, during hospital stay by family member or post-op at St Vincent’s Guest Facility Seton Hall. See the St Vincent Medical Website or contact our office for additional information.On occasion, the internist will ask you to spend an additional night following hospital discharge for routine monitoring associated with our anti-coagulation protocols. A subcuticular wound closure is generally performed and sealed with dermabond. If staples are used, then they are generally removed 8-10 days following surgery and can be removed by your family physician.
25. Q. Following discharge from the hospital, am I transferred to an extended stay, rehabilitation or skilled nursing care facility?
A. Rarely is a JRI patient transferred to another facility following hospital discharge regardless of the type of joint replacement they received. In other words, our patients are almost always discharged directly to home. Occasionally, a patient is transferred to a transitional care unit at St Vincent’s medical Center or rehabilitation or skilled nursing facility if the surgeon feels that it would be beneficial, such as in the case of elderly patients who are less ambulatory or stable or if they have other medical conditions that require closer post-operative monitoring
26. Q. Do I need to donate blood for my surgery?
A. As with many surgeries, bleeding can occur during hip surgery and you may require a blood transfusion. However, due to advances in operative and anesthesia techniques, the need for blood donation prior to hip resurfacing or THR has been eliminated or significantly reduced. For example, blood donation prior to surgery is typically not required for male patients. Small female patients may donate one unit of blood for unilateral surgery (one hip) because their effective blood volume and hence reserve is less. Two units are suggested for bilateral surgery (both hips) for both men and women. Revision surgery will typically be required to donate blood prior to surgery although the number of units may vary depending upon the anticipated complexity of the patient’s case. Refer to “Planning for Your Surgery” in the Hip Replacement section of the website for detailed information regarding the types of blood donation. If your surgeon recommends that you donate one or more units of blood, then our office will fax an order signed by the surgeon to the blood donation facility that you designate.
References
1. Amstutz H, Le Duff M, Campbell P, Dorey F. The effects of technique changes on aseptic loosening of the femoral component in hip resurfacing. Results of 600 Conserve Plus with a 3-9 year follow-up. J Arthroplasty. 2007;22:481-9.
2. Eastaugh-Waring S, Seenath S, Learmonth D, Learmonth I. The practical limitations of resurfacing hip arthroplasty. J Arthroplasty. 2006;21:18-22.
Copyright 2005 Joint Replacement Institute Los Angeles, CA · (213) 484-7600 · JRIinfo@dochs.org
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