Dr. Mont Interview

1. How did you get started with Hip Resurfacing and tell us about your background and experience as a surgeon.  Where did you train for hip resurfacing?  Who trained you?  Did you continue your training after starting resurfacing?

I began doing hemi-resurfacing for a disease called avascular necrosis or osteonecrosis and sometimes called AVN for short.  As some of you may know, this is a disease that involves only the femoral head and is often associated with alcohol abuse or corticosteroid use.  Some of you may know that Bo Jackson’s hip problems after getting a dislocation may have led to avascular necrosis which was in the news.  So, a traumatic insult such as a fracture or dislocation can also lead to the disease.  It’s notable that this affects a lot of young people and eventually leads to arthritis.  At one point we were doing hemi-resurfacing which is only the femoral head part of the resurfacing procedure and I originally started doing these because two of my mentors, Dr. David Hungerford and Dr. Kenneth Krackow, had taught me this procedure.  Some of the earlier devices we used, for example, did not even have stems.  They simply capped the femoral head and I still believe today that the stemmed part of the device is not that important for stability, it is more for teaching and for alignment issues when you first begin performing these procedures. 

 I began doing the hemi-resurfacings in 1989 and continued doing these and it only became possible to do full resurfacing when there was approval for the Wright Medical trials which began in November of 2000.  I did training with Harlan Amstutz for a week and on other occasions with him before I did the full resurfacing.  I would also say that I continue my training after starting resurfacing as does every good surgeon to the present day.  We all should continue to learn from the results and what we perform and I continuously train surgeons in the most appropriate techniques for performing these procedures.

We keep track of all of our resurfacings in a database which also allows us to analyze successes and failures and appropriate uses of the device. 

2.  Do you preserve neck capsule in your surgeries, can you tell us a little about the reason for doing this and explain to us more in detail exactly what it is?

I preserve some of the neck capsule in the procedures that I do that is along the femoral neck and maybe involved in the femoral blood supply.  I don’t typically preserve as much as is needed in a posterior approach because I do an anterolateral approach and lately I have been doing an anterior approach which doesn’t go through any muscles.  The anterior or anterolateral approaches have much lower dislocation rates and do not need as much capsular preservation to maintain stability.  

In addition, I did find when doing both approaches that when the capsule is repaired, it will often hypertrophy or get larger and this can lead to decreased range of motion in some patients.  The hypertrophy can be compared to an adhesive capsulitis of the shoulder where there is restricted motion after the repair when the body is trying to further repair the capsule.  Since dislocations are not a problem after anterolateral or anterior approaches, this type of capsular repair is not as necessary as in a posterior approach where this can be a problem. 

3.   What is the normal hospital stay barring any complications?

Patients typically stay for two to three days.  I perform the surgeries on Mondays and Thursdays.  If a patient comes in on a Monday, they typically will go home Thursday morning.  If they come in on a Thursday for surgery, they’ll go home Sunday morning.  Many patients will leave a day early in the afternoon.  There are some patients that can do this as an outpatient procedure or leave on post-op day one, but I don’t prefer this approach.

4. What is your typical recovery time after resurfacing? What is your typical rehab protocol?  90 degree restriction?  Walker, Crutches or Cane? Length of time used?  Blood thinners?  TED stockings?  Ice?  PT?

Patients are restricted only in the first five weeks to 50% weight bearing and a 90º rule and no crossing their legs.  After five weeks, they advance to full weight bearing with absolutely no restrictions on position and they start strengthening.  In summary, they use a cane or crutch for the first five weeks with some restrictions of motion and these are lifted at five weeks.   

We are presently working on some advanced rehabilitation protocols that should be used for young patients.  I believe that many of the rehabilitation protocols that have been used in the past were developed for typical patients that are getting standard total hip replacements who might have an average age of approximately 72 years.  In my patient population, the average for resurfacing is 48 years and patients want to return to higher level activities and may need different protocols.  We are presently prospectively analyzing these protocols. 

Blood thinners, if patients have any history of any problems, are used for 42 days, but typically I will use aspirin for five to six weeks with mechanical compression stockings.  We often use ice for post-operative pain.  

5. What approach do you use, posterior lateral or anterior lateral? and why? What muscles/tendons are cut and do you sew them back up or re-attach them?

The choice of approach to use for resurfacing has received much attention and I believe extra “hype.”  In multiple studies now published, there are no reported clinical differences in the short term and up to ten years of follow-up between anterior and posterior approaches.   I believe that any approach can be used and the surgeon should use what they feel most comfortable. 

Short-term differences that patients may report with either approach have to do with other factors in my opinion.  I use the antero-lateral approach because it affords me easy exposure, lower dislocation risk, less chance to disrupt the blood supply of the femoral head---among other reasons.  However, I have no problem with posterior approaches and am currently working on and performing an even more minimally invasive anterior approach in selected patients. Again, I would repeat that a recent prospective randomized study showed no differences in all three approaches.

In summary, the reasons I use the anterolateral approach are as follows:  1) easier to perform; 2) less chance for dislocation; 3) no difference in posterior approach at six months to one year or in long-term studies; 4) increased range of motion from not having to repair the capsule; and 5) multiple studies showing decreased effect on femoral head blood supply.  

Presently, I’m performing an anterior approach which does not go through any muscles. 

6. What is the recommended time you tell your patients before they can start to run again/do impact sports?  Are there any sports you don't want your patients to participate in after surgery?  What are some of the sports your hip resurfacing patients have returned to?

Patients have returned to almost every sport one can conceive, including marathon running and bungee jumping.  I have professional athletes that want to continue to play baseball, basketball and football at a high level.  Whereas, I don’t condone these activities, I like these patients to make sure that their hip muscle strength is appropriate which is the best chance they have.  

Typically, patients can run again at approximately three to four and a half months after surgery, but this is a patient to patient variability and it really depends on how strong their hips are and before they can do these activities, I like a certain baseline level of strength approximately ten pounds of 30 reps on each hip of the major muscle groups and that both hips are symmetrical.   

We don't yet know the long term effects of these sports (past 7 years) but I encourage patients to regularly exercise their hip muscles to unload the joint if they are going to participate

The best sports in my opinion are less impact - swimming, bicycling, elliptical - these are probably fine - the higher impact sports are more likely to lower the lifespan of any implant

I don't encourage running but the patients do it anyway--in one of our studies we found that 30% of patients returned to high impact sports--tennis, running, etc. after any hip arthroplasty

Many patients resume skiing and hunting after resurfacing. I’m not a fan of skiing because of the problems with a potential fall but I have many patients that ski anyway - for more personal answer would have to contact me

Hockey is always pretty contact so hard to gauge - would have to see x-rays but probably waiting 6 months does not change cysts appreciably but again one needs to know what x-rays look like today--if cysts already well formed this could decrease chance--most cysts are miniscule and this would be an irrelevant factor.   

7. What is your opinion about cementless (femoral) devices for resurfacing?

Cementless femoral devices are being used by a few centers.  Some previous generations of designs had high failure rates (over 20%) and at this point, these have to be viewed as experimental.  In addition, many patients could not get cementless devices because the bone of their femoral head is already degenerated and has cysts and the bone wouldn’t grown into these devices in my opinion and, therefore, cement is appropriate.   

I don’t think there’s a tremendous downside of using the cement in this application as was for cemented devices for previous generations cemented hips and do not believe this is a major issue.  At this point, I would question the use of this type of unproven technology that has also had higher failure rates in the past.  

8.  Do you have a cut off age for resurfacing patients or do you go on a case by case basis?

We look at patients on a case by case basis.  We have recently published a study of patients over 60 years of age compared to patients less than 60 years of age and found no difference in the results.  Certainly, there are very active 60 to 70 year old patients that have much better bone stock than some inactive 40 year old patients.  They do not to be considered on a case by case basis and we have actually done resurfacing in patients in their 70’s.  One still has to view this as cautionary because we do not know the long term results past 6 to 7 years of resurfacing in these patients.  

9.  What type of anesthesia do you use,  general or epidural ?

 The type of anesthesia used is on a case by case basis.  We typically like to do a spinal or epidural versus a general, since the cases typically take an hour or less, the results of both are not very different in my hands.  

10.  Are there any cases that you will not take in particular, AVN, dysplasia, small cysts.  Maybe touch on some of the very difficult cases you have been able to resurface.

We have typically taken on very difficult cases which are sometimes considered relative contraindications.  For example, patients with avascular necrosis were initially felt not to be appropriate candidates, but we have now done over 150 of them and our first report at close to 7 year follow-up showed success in 41 out of 42 patients.  We have done resurfacing in patients with inflammatory arthritis, like rheumatoid arthritis, in a small limited number of patients, although I would not recommend this at the present time.   

Again, each patient should be reviewed on a case by case basis and the risks and benefits of doing a resurfacing versus a standard hip replacement should be clearly laid out.  Some patients may accept a two- to three-fold increased risk for resurfacing and that might be worth it, whereas it may not be worth it for other patients. 

11.  Do you do bilateral surgeries the same day, if not how far apart do you recommend?

I do bilateral surgeries, typically a week apart, if a patient would like that.  I don’t believe that the risks of doing unilateral surgery is way under 1% and I personally do not believe that that risk stays under 1% if you do both at the same time.  There is time for turning the patient to their other side, putting the dressing on, and doing a procedure.  Two one hour procedures are much less risky than one two to three hour procedure.  In addition, other surgeons that spend more time doing a single case, in my opinion would even be putting the patient more at risk.  Let’s keep the risk to the patient at the most minimal by doing one hip at a time and doing it a week apart is not waiting too long.  

12.   If you can't perform a hip resurfacing, what THR device do you prefer and why?

I use different hip replacement devices depending on what the patient wants.  Some patients would like an extremely large femoral head and they can get a metal-on-metal head that’s exactly like a resurfacing.  Other patients, if they can’t get a resurfacing, would like an interface that doesn’t involve metal-on-metal interfaces and in that situation, I would do ceramic-on-polyethylene because I think it has the lowest wear rate.

13.  What do you consider an adequate number of surgeries for a doctor to be proficient at hip resurfacing?

Some orthopaedic surgeons can do the procedure well after less than twenty cases - others need more.  This is a hard question to answer.  It may have to do with the type of cases they are performing; are they gaining experience with straightforward hips first and then advancing as they gain experience?  This is the correct way which is better than tackling hard cases too early. 

14. How long do you feel it takes for the bone to be fully healed, grow into the prosthesis?

Bone starts growing into the prosthetic shell immediately, but starts getting fairly sticky by two weeks and then very strong at six weeks, but is not completely healed probably until three to six months. 

Questions and Answers from Dr. Mont Chats

1. What approach do you use?  

The choice of approach to use for resurfacing has received much attention and I believe extra "hype."  In multiple studies now published, there are no reported clinical differences in the short term and up to ten years of follow-up between anterior and posterior approaches.   I believe that any approach can be used and the surgeon should use what they feel most comfortable. 

 Short-term differences that patients may report with either approach have to do with other factors in my opinion.  I use the antero-lateral approach because it affords me easy exposure, lower dislocation risk, less chance to disrupt the blood supply of the femoral head - among other reasons.  However, I have no problem with posterior approaches and am currently working on an even more minimally invasive anterior approach. Again, I would repeat that  a recent prospective randomized study showed no differences in all three approaches.

 2. How heavy is the equipment that you can lift when you are fully recovered?

It is difficult to give you an exact answer. Obviously, this varies from person to person.  Typically, surgeons do not recommend lifting greater than 20-30 pounds on a regular basis after any hip replacement.  This is because the extra force on the hip is believed to accelerate wear of the prostheses which could lead to premature failure of the device.  However, no one really knows the answers to the question of what is too much weight that leads to accelerated wear.  We don’t know if there is a threshold for which staying underneath a level of weight doesn’t lead to appreciable wear or are there other factors—immunological, activity levels, etc. that are more important. 

I usually tell patients that completely sedentary activities will probably afford the best chances of devices lasting 20 years or longer and that patients that do heavy lifting or other high impact activities may lead to prosthetic survival of less than ten years—I have two patients that run marathons yearly.  There is a difference in what patients are capable of doing and what they should do. 

I do believe that if one wants to regularly lift greater than 30 pounds or participate in high impact activities, then they should regularly keep their hip muscles strong.  I know from a study we did that at least 30% of patients will participate in these activities despite surgeon advice to the contrary.  Therefore, keep your hip muscles strong to protect your prosthesis!!

The exercises I advocate encompass 20 minutes every other day—about an hour per week to specifically strengthen your hip abductors, flexors, and extensors.  You can get a copy of these exercise sheets from me - call the office at (410) 601-8500 

3. How soon can you start lifting?  

If one is going to lift, it should be done when the hip muscles are  back to close to normal in strength.  I advocate getting ankle weights and achieving a certain level of hip strength before lifting.

Also remember that there is a difference between simply lifting something without walking in which case the 50 pound weight is distributed to both hips and effectively is 25 pounds of force on each hip.  Not so bad.     If you lift and then walk with the object then the 50 pounds that one is carrying gets multiplied by 3 every time one takes a step on that side, so for each step its 150 pounds of weight.

The same analogy hold for weight loss—if you lose 33 pounds your saving 100 pounds of wear and tear on your hip with each step.  So, the average person takes about 2000 steps or more in a typical day  - so losing 33 pounds saves 100 tons per day on your hip.  Imagine how that might save certain people from even needing joint replacements if they lost the weight.  Weight loss can probably help prolong survival of the prosthesis, among the other benefits.

4.   Since I hunt, after a hip resurfacing, are there limits to how much extra weight (backpack) one should carry?

There is a difference in what a patient might be able to do, what they can do, and what they should do. If one exercises appropriately post-operatively almost every patient could get to close to normal function and be able to lift weights, backpacks, etc. This is not something I would necessarily encourage but the patient has to decide whether the risks of possible premature wear of their components are worth the benefits of the activity they love.

5.  When do you consider arthroscopy of the hip ?

 Arthroscopies work if minimal to no arthritis, otherwise they are not too useful.  Most candidates for resurfacing would not be candidates for arthroscopy. 

6. How do you deal with metal allergies if you are considering resurfacing?

First of all, one has to know what you are allergic to. Nickel allergies are probably ok since resurfacings have minimal to no nickel, but you should  be tested for cobalt and chromium before a metal-on-metal device if one has a metal allergy.

Traditional skin testing for allergies are not great--there are blood tests at specialized labs that do better tests though this is a field that still needs more research.  Four to five labs will do the blood tests from around the country.
The blood tests show antigenic-antibody reactions to the metals tested from the patients blood--if positive one should not get metal on metal devices in my opinion

7.  What Device do you use?

I use multiple devices; Conserve Plus, BHR, and Cormet.  I use all of the devices--they are similar but each has subtle differences in fixation surfaces, etc. 

8. Can metal allergies cause hip bursitis?

Hip bursitis typically does not occur from metal allergies.

9. Is hip bursitis common in the operated hip after resurfacing?

Hip bursitis can be common after any hip surgery - most of the time >99% it is self-limited and will go away by itself or with minimal non-operative treatment.

10. Have you ever performed the surgical removal of the bursa as a last resort of hip bursitis?

I have performed about 5 surgical bursectomies in my career of over 7000 procedures - but most have been after revision surgeries - often when there was a wire-ing of the trochanter which was an older way to approach hip which is rarely used today - most bursitis will respond to non-operative treatment--therapy, occasional injections, etc.

11. Are bone spurs on the femoral neck a contraindication for hip resurfacing?

Bone spurs on femoral neck are not a contraindication for resurfacing--but obviously each x-ray would have to be looked at individually--almost all arthritis is associated with spurs on neck by the way

12. Are their Age Limits for resurfacing?

Most people use about 55 - 60 years as an age limit for surgery - however we just had a paper accepted for resurfacings on patients greater than 60 years and they did just as well as their younger counterparts.

Age is a relative thing and this is a controversial topic

13. Training-How many does a Surgeon Needs to do for competence?

 Some orthopaedic surgeons can do the procedure well after less than twenty cases - others need more - This is a hard question to answer - It may have to do with the type of cases they are performing--are they gaining experience with straightforward hips first and then advancing as they gain experience? -- which is correct way which is better than tackling hard cases too early

14. Exercise: Is it needed Pre-Surgery?

Two studies in the literature have not found any benefit of pre-operative exercise on eventual results of resurfacing or any hip replacement - so don't mind if you exercise ahead of time but don't feel obligated

15. When can’t you do a Resurfacing on Socket Side?

All arthritis generally involves socket changes - it is the extremes of bone loss that may not allow resurfacing since screw fixation is not optimal with resurfacing devices at present. Many companies working on this though at present.

16. I understand that cysts can render the bone unsuitable for resurfacing. What are the risk factors for developing cysts?

Almost all arthritis leads to cysts - it's just a matter of degree--the longer you wait or tolerate arthritis in general the larger the cysts will become - sometimes patients may wait too long to get a resurfacing because the cysts erode away the bone stock on the femoral head - but these are typically very late stage arthritis

17. Why are metal ions are a concern when the concentrations are low (parts per billion?) and we have iron in the blood anyway? Sometimes we take iron supplements to increase iron in the blood to prevent anemia.

We do not know a lot about these low concentrations of metal ions at the present time

18. Can we perform Sports after resurfacing?

Concerning sports - many patients with standard total hip replacements as well as resurfacing participate in all sports.

We don't yet know the long term effects of these sports (past 7 years) but I encourage patients to regularly exercise their hip muscles to unload the joint if they are going to participate.

The best sports in my opinion are less impact - swimming, bicycling, elliptical - these are probably fine - the higher impact sports are more likely to lower the lifespan of any implant.

I don't encourage running but the patients do it anyway - in one of our studies we found that 30% of patients returned to high impact sports--tennis, running, etc. after any hip arthroplasty.

19. Should I lose weight before surgery?  Will I lose afterwards?

I am sure if one has a successful result of any arthroplasty it may help patients be more active and lose weight - this makes sense. Unfortunately, in a few published studies patients still have average weight gains after joint replacements.

We just finished a study of over 200 patients after hip replacement and found an average weight loss for the group of 4%. The highest predictor of patients who lost weight were those who have active pre-operative lifestyles.

20. Can you Ski after resurfacing?

Many patients resume skiing and hunting after resurfacing. I'm not a fan of skiing because of the problems with a potential fall but I have many patients that ski anyway - for more personal answer would have to contact me

Hockey is always pretty contact so hard to gauge - would have to see x-rays but probably waiting 6 months does not change cysts appreciably but again one needs to know what x-rays look like today - if cysts already well formed this could decrease chance--most cysts are miniscule and this would be an irrelevant factor

21. When do you take antibiotics before resurfacing?

 All patients in every hospital in the country get pre-operative antibiotics within 1 hour of surgery - mandated hospital rules which is a good thing

22. Do you suggest antibiotics before dental work after resurfacing and for how long?

I like antibiotics for up to two years after any joint replacement. After two years only for procedures that lead to blood like endodontic surgery. This is also a controversial topic. We wrote two papers on this topic and only found possible dental related infections in patients that had oral procedures that were greater than 1 hour with blood loss that did not get antibiotics. The problem is that sometimes patients don't know what they are getting from their dentist

23. Delay hip resurfacing or Proceed with hip resurfacing...what are the criteria to help make this decision?

Hip resurfacing or any hip replacement should be performed when there is hip arthritis that is not responsive to non-operative treatment modalities typically tried for a period of 6 months or more. Would you like me to elaborate further?

Many patients feel they need a hip replacement because they are told they have a limp and find out that they have arthritis of their hip. Many of these patients have minimal pain or it can be controlled by medications, activity modifications, hip strengthening exercises, and weight loss. A resurfacing or any joint replacement should be a court of last resort.

24. Which is better, resurfacing or standard total hip replacement?

I try not to say one is better than the other but rather list out possible advantages and disadvantages of a resurfacing vs. a THR.

25. What are Advantages and Disadvantages of Resurfacing?

Advantages of a resurfacing in my hands are:

1. More range-of-motion

2. Less risk of dislocation

3. More normal "feeling"

4. Leaves options open for later conversion to standard THR

5. Easy revision if necessary

6. Useful for certain deformities

7. Preservation of femoral bone stock

Disadvantages are:

1. Harder to do

2. Less follow-up -  up to 10 years max

3. Risk of femoral neck fracture

4. Possible elevated metal ion in blood issues

26. I am looking at a steroid shot as the first step is this correct?

Start with meds, activity restrictions, exercise, weight loss, typically even before steroid injections.

 27. Some surgeons  prefers the THR approach because there is evidence for a 1%/year failure rate for the femoral cap on resurfaced hips vs. a 1%/10 year failure rate for THRs? Is this true?

Failure rates early in learning curve were high for resurfacing but now approach and are even superior to standard total hip replacements in some patient populations such as young, active males.

28. How often do you switch to a hip replacement if defects are found during the resurfacing operation?

Less than 1% though this should be continued off-line - I've switched to a total hip replacement about 20 times out of 1650 though more than half I knew were difficult going in.

29. Many people ask doctors if the preserve the neck capsule. Do you and why or why not?

 I don't preserve the capsule as the anterior-lateral approach that I use doesn't lead to dislocations. If you preserve the capsule it can grow larger and lead to stiffness and decrease range-of motion. For posterior approaches where there is a higher dislocation rate many surgeons repair the capsule to keep hip stiffer.

30. Can you have a hip resurfacing if you have psoriatic arthritis?

Patients with inflammatory arthritis which you have are not always the best candidates for resurfacing. That's because the bone is generally weaker.  Psoriatic arthritis though needs to be evaluated on a case by case basis.

Any surgery or trauma can lead to a flare up though this can be controlled so typically patients just need to be monitored if they are getting any surgery.

31. My health insurance will pay for a hip resurfacing device approved for marketing by the FDA. Only Birmingham and Cormet qualify. If I selected Birmingham, will you install it or and how do you decide which device to use?

I would install a Birmingham or Cormet depending on patient preference. Sometimes the choice of device is limited by patient size as Cormet doesn't have smaller sizes.

32. Could you explain what osteopenia is?

If one has true osteopenia one should not be getting a resurfacing. There is a higher risk of femoral neck fracture.

Osteopenia is a term for bone loss that can arise from many conditions: osteoporosis (what you get as you age), disuse osteopenia (if you don't walk on you hip), osteomalacia--Vitamin D disorder--get your sunshine--all have varying degrees of bone loss.

33. What risks are involved with smaller boned women?

Small boned women have thinner necks and could be more susceptible to femoral neck fractures. For example a women with bone half the diameter of a man which is common will have one eighth of the bending strength or only 12.5% of that man.

34. Does the size of the pin on the cap device cause a problem in small boned women?

Probably irrelevant

35.  Is the pin size for all BHR devices the same? I heard that?

Not sure what you mean by pin size--in case yes--they are similar and not really relevant in my opinion

36. I mean the size of the post with cap. I heard some doctors use the some devices for really small women since their neck is smaller?