Interviewed by Vicky Marlow November 7, 2007 (see newer interview below)

The McMinn Centre – website of Derek McMinn - Inventor of the BHR device

Surgical Approach

I started back in 1991 with the antero-lateral approach to the hip for resurfacing. At that time we were worried about blood supply to the femoral head and on theoretical grounds the antero-lateral approach preserved the blood supply well. For many patients the approach was satisfactory but there were some problems. The exposure obtained in large patients was not good. This meant that heavy retraction had to be used, and heavy retraction caused trauma to muscle and other soft tissues which in turn led to heterotopic ossification. The other problem was that some patients had a permanent limp after my surgery as a result of the surgical approach. Please understand that the instruments were crude back then compared to today where newer designs of instruments would cause less tissue trauma and make the antero-lateral approach a better option. The sight of limping patients persuaded me to change my approach to the posterior approach. The theoretical objection to this approach was that it may cause more damage to the femoral head blood supply. It turns out that the problems with femoral head blood supply using the posterior approach are very rare, as you heard at the conference. The big advantage is that an excellent exposure can be obtained, giving the surgeon the best opportunity for perfect component positioning. As you heard, inaccuracy with respect to acetabular

There are two other surgical approaches to be considered by surgeons, but for different reasons these are not reasonable at this time.

The other issue is how well an inexperienced surgeon can be taught to reliably perform an uncomplicated resurfacing operation. It's no use talking about Ronan Treacy's or my own abilities in this regard as we have each performed well over 3,000 resurfacing procedures, and no matter how hard we work, we cannot make any impact on the world demand for this procedure. New surgeons therefore must be trained. As you heard, we tested how good newcomers to the BHR using the posterior approach really were and over 100 new surgeons, as well as Ronan and myself, entered our patients on the Oswestry Outcome Centre database. All those patients have been independently followed up. At 9 years post-op Ronan's and my results are still statistically significantly better, both with regard to failure requiring revision and also with regard to hip function. Never mind statistics, the fact is that the newcomer surgeons achieved very creditable outcomes, which means that the whole package with respect to training, patient selection, surgical technique and implant durability really does work. If anything in that mixture changes then the outcomes achieved may significantly change. To give you one example, during 1996, one year before I started the BHR, I carried out the Corin, double heat treated resurfacing which I designed. All the other ingredients of the package were the same.

Now that time has passed we can see the effect of one factor, implant design, on the outcomes. At 5 years there is no difference between the Corin and the BHR design on my outcomes. At 10 years, however, the Corin series has an 86 % implant survival whereas the BHR series has a 96 % implant survival. In addition, in the patients who have had the Corin resurfacing and have not been revised at 10 years, 20 % have osteolysis or early loosening. These features bode badly for the future. Heat treatment of the metal of the implant is not something that the surgeon can see, and I wasn't aware that the manufacturer had started to use this even though I was the implant designer! The implant looks the same as the historically proven, as-cast alloy and the early results give no cause for concern. The longer term sadly is a different matter. I understand your interest in the surgical approach, but it's the complete package that counts. For a patient, therefore, the key questions for their surgeon are: How long have you done metal on metal resurfacing? Am I a good candidate for hip resurfacing? Is my bone good enough? Do I have avascular necrosis which may increase the failure rate with hip resurfacing? Do I have dysplasia or any other condition which may seriously complicate the procedure and are you confident you can handle any difficulties? What surgical approach do you use and why? How were you trained and what was the resurfacing experience of your trainer? What are your results--- how many have you done and how many failures have you had? What are the hip scores in your resurfacing patients? What complications have you had with hip resurfacing? What type of hip resurfacing do you propose using on me? What are the results of that design used in a) the inventor’s hands and b) what are the results of that design of implant in the hands of independent surgeons e.g. what are that implants results on the Australian national register? If your surgeon is using a device with either no independent results or poor results on the Australian register the question to be answered is: Why are you using it e.g. are you paid to use it or is your hospital paid to use it by the manufacturer of the device?

Bone Recovery and Return To Sport

The evidence from a DEXA study on BHR patients published from Japan is that the bone density in the proximal femur returns to normal 1 year after operation. The at-risk period for femoral neck fracture following the BHR is in the 6 months after surgery. I advise patients not to return to impact sport for 1 year after surgery. For those patients who want to road run, I get them running on a treadmill at 10 months post-op and they resume road running at 12 months post-op. My unit published on activity level after resurfacing some years ago in a group of patients who followed those rules. In young men with a single osteoarthritic hip resurfaced, 92 % played sport and 62 % played impact sport. The ladies were not quite as active, but you can see from the publication that they still had an impressive activity level. In the total group their 10 year implant survival is 99.8 % showing that high activity introduced at a sensible time does not deteriorate the results.

Cementless Components

At the beginning of my experience, all my resurfacings were cementless. The results were not good for cementless femoral components, but cementless acetabular cups were excellent. Of course I have occasional patients with a great result following a cementless femoral component 16+ years post-op. For the total group of patients, however, cementless femoral components were not successful.

In 1994 I started with hybrid fixation using a cemented femoral component and a cementless cup. In my BHR series, i.e. commencing 1997, I continued with hybrid fixation and I have had no loose cups and no loose femoral components. It would be hard to do better than have a zero loosening rate in this large series of BHRs in patients with varying bone quality. Thankfully patients who need resurfacing today need not be the Guinea pigs for a new experiment. Hard information does exist on this subject and should be used by surgeons and patients alike. Those are the short answers to your questions, the long answers are in a multi author book called Modern Hip Resurfacing which I have edited and which will be published by Springer early next year. When it is published, I will send you a signed copy.

Best Regards, Derek

Derek McMinn has written a book that goes into full details regarding his part in developing and designing the BHR device, the book is called Modern Hip Resurfacing.  You can purchase his book here in the U.S.  or here in the U.K, or here.

May 25. 2010

1.  How much does a BHR cost?
For non-insured patients BMI Edgbaston Hospital offers a 'Fixed Price' package of £12,040.00 and this covers everything including hospital, drugs, anaesthesia and surgery during the in-patient stay. Please note that pre-operative and post-operative consultations and x-rays are payable separately.
   
For patients with medical insurance the amounts allowable by each different insurance company vary greatly and patients are encouraged to discuss their particular situation with Mr McMinn's administrative staff.

Photo: Mr. Derek McMinn, taken May 8, 2010 during video interview with Vicky Marlow

2.  How long is the hospital stay following surgery?
Patients are admitted to hospital the day before surgery.  You will be booked into hospital for a total of 7 nights, however, provided you are considered fit enough by the medical staff you may leave hospital a day or two sooner.

3.  When will my skin clips be removed?
Your skin clips will be removed at approximately 12 days post-op.  Prior to discharge from hospital, the nursing staff will liaise with your GP Practice to arrange for a District Nurse to remove your skin clips.

4.  How mobile will I be following surgery?
Following your operation a physiotherapist will visit you every day.  They will enable you to get out of bed and take a few steps the day after the operation.  Following this you will make steady progress under their supervision, walking along the corridor with two elbow crutches.  You will be shown how to get in and out of bed on your own and go up and down stairs safely on your own.  Most patients are instructed to use two elbow crutches for three to four weeks after operation.  You will then be advised to use one walking stick on the unoperated side for a further three to four weeks.  This timetable depends on the extent of reconstruction that was necessary and the quality of bone before operation and may need to be modified to suit each individual.

How will I get home from hospital?
Car - A relative or friend can collect you from hospital and drive you home sitting in the front, passenger side with the seat positioned as far back as possible. A low seat in a small car is not advisable. If it involves a long journey, you will find that stopping for a few minutes every hour to stretch your legs is helpful.

Train - You can travel home by train. You should not travel alone unless you are carrying only a light back-pack.

Plane - International Patients

Short Haul Flights - On discharge from hospital you may, if you wish, travel directly home by plane.

Long Haul Flights - Mr McMinn advises all patients to stay in the UK for a further week after discharge from hospital.  If you choose to take this opportunity to sight-see/reside outside of Birmingham then arrangements can be made for your skin clips to be removed locally.

How soon can I drive following surgery?
You should not drive a manual car for six weeks following surgery because it is considered that the reaction times of your legs do not return to normal before this.  However, if you drive an automatic car and it is your left hip which has been operated on you may drive at three weeks.

How often do I have to attend for follow up?
Mr McMinn will see you for review with a new x-ray at about 6 - 10 weeks after operation.  Some patients will be called for further review a year or two later.  Most others do not need to be reviewed for the next five to ten years.

When can I get back to hobbies and sporting activities?
Gardening - At about 2 months following post-op review.
Golf - Start gently at 4-6 months after operation and gradually increase.
Tennis - Start gentle doubles tennis at around 6 months after operation and gradually increase.
Skiing - 1 year post-op
Running and jogging - 1 year after operation. At around 11 months, you may start jogging on a treadmill with good quality running shoes or trainers. Do this for a couple of months before you start running or jogging outdoors or participating in high-impact sporting activities like squash, cricket, football etc.

Do hip implants set off metal detectors at airports and do I need a letter to confirm implant in situ?
Patients do find that their hip implants set-off metal detectors at airports. A letter from a doctor is no longer given any credence by security officials because of the ease with which they can be ‘created'. They may want to make further physical checks to be sure for themselves. We can however provide you with a letter if you wish.

Is there anything I should do prior to surgery to get into good shape i.e diet, vitamins, exercise etc?
It is important for you to have good quality bone in order for a Birmingham Hip Resurfacing to be successful.  Anti-inflammatory medications and Aspirin tend to damage the bone in the femoral head of an arthritic hip. You should therefore stop taking any anti-inflammatory medication or Aspirin (unless Aspirin is being taken for another medical condition*). For pain relief, Mr McMinn advises Paracetamol or Codeine, or a combination of the two i.e. CoCodamol.

*Providing the prescribing Physician considers it medically safe, Mr McMinn requests ALL patients to stop taking Aspirin 2-3 weeks before surgery as this also causes excess bleeding at surgery which leads to more bruising and a slower recovery.

You will find it beneficial to maintain good muscle strength prior to surgery as this helps with your post-operative recovery. This can be achieved by continuing to exercise within the limits of your own comfort, in particular, cycling and swimming.

Do I need to take antibiotics for dental treatment following hip surgery?
Antibiotic cover is advisable before any dental treatment for the first three months following hip/knee arthroplasty. Thereafter, there is no need for antibiotic cover unless you are being treated for an infection/sepsis (your Dentist will advise you if this is the case). In the presence of infection/sepsis, however, it is important for you to have antibiotic cover for dental treatment at all times.
What is the difference between a Birmingham Hip Resurfacing (BHR) and a total hip replacement (THR)?

The fundamental difference between a BHR and a conventional total hip replacement (THR) is in the femoral (thigh) side. A THR has a long stem inserted into the canal in the thigh bone. Hence the natural femoral head and part of the neck are removed and weight is transmitted through the stem directly into the upper third of the thigh bone. In a resurfacing, the aim is to preserve most of the femoral head and neck. The resurfacing femoral component therefore has a thin (3 to 4 mm) hollow ball surface that directly transmits weight to the femoral head bone underneath it and a very small stem that is not designed to transmit weight. The socket component can be similar in both the THR and a BHR.

There are other differences between a Conventional THR and a BHR. Conventional THR sockets are made of polyethylene (PE). Wear-debris generated from PE wear leads to loosening of the components. This is the primary cause of long-term failure of conventional THRs.  PE wear and loosening are directly related to activity. Hence these THRs do not last well in younger and more active patients. In addition, the minimum thickness needed for a PE socket required that the femoral head had to be smaller in diameter than what a metal-metal joint would permit. A small diameter head has the potential to dislocate more readily than a normal hip and therefore the dislocation rates with conventional THRs are greater than those with BHRs.

However, the beneficial effects of a metal-metal joint have now been transferred from the resurfacing technology to replacements as well. These large diameter metal-metal THRs are showing great promise in reducing wear and dislocation rates. The only difference between a BHR and such large diameter metal-metal joints is the long stem. In a BHR, the absence of a long stem makes a revision, should this ever become necessary in the future, easier.

What is a BHR made of?
The ball (femoral) and socket (acetabular) components of a BHR are made of a tried and tested alloy of cobalt and chromium. This has been in use in orthopaedic surgery for over 70 years. The original alloy is an as-cast high-carbon alloy. The higher carbon content precipitates in the alloy as carbides which have the hardness of ceramics. They give the metal the needed resistance to wear. These carbides can be depleted by heat treatments in the later stages of manufacture - a process that is used in some other brands of resurfacings. They no longer enjoy the same wear resistance as an as-cast device such as the BHR.

Who is a BHR suitable for?
A resurfacing is suitable for the treatment of a hip with severe arthritis when the femoral head bone quality is good. It is used more often in young and active patients than older and less active patients because conventional replacements do not last long in young and active patients. Further, a younger patient is more likely to need a revision of an artificial hip at some stage later in life, and it is easier to successfully revise a BHR than a THR. BHR is likely to fail in patients with poor femoral head bone quality. Therefore, patients with poor femoral head bone quality are not suitable for a resurfacing.

When is the right time to stop waiting and have surgery?
Hip Resurfacing is an operation for pain, discomfort, soreness or stiffness arising from advanced arthritis of the hip, especially if the symptoms are seriously affecting your quality of life. In the absence of severe changes in your hip, other measures should be tried. However, once advanced changes develop, there is no merit in continuing to put up with it, especially if you are being forced to take anti-inflammatory medication regularly to keep the symptoms at bay.

It should also be noted that the typical patient is not in continuous pain or ache from the hip day in and day out. Most patients complain that their discomfort is related to activity. As long as they refrain themselves from being active, they are comfortable. Participating in simple activities, which they had enjoyed all their lives, now seem to flare up their symptoms and make them suffer later that day or the following day.

Taking long-term anti inflammatory medication or aspirin tends to damage bone quality of the femoral head (ball part of the ball and socket hip joint) making it impossible to perform a successful hip resurfacing. In addition, these medications tend to make you bleed more at operation and cause more bruising and internal bleeding after the operation, thereby hampering your recovery and rehabilitation greatly.

What physical restrictions do you have after a BHR?     
The day after your hip resurfacing operation you will be encouraged to stand and start walking. This early resumption of activities is one method of avoiding pooling of blood and unwanted clotting in your leg veins.

The first six weeks after the operation you are in the phase of soft tissue healing. Therefore you will be advised not to put your hip through extreme ranges of movement in order to avoid a dislocation.

After this period, the degree of soft tissue healing is adequate to protect your hip during any voluntary movement. As a matter of fact, the tendency of the healing scar is now to contract in order to gain strength. Contracting scar has the potential to create a stiff and sore hip unless the hip is subjected to regular exercise during this period. Hence you will be encouraged to progressively increase your range of hip movements and increase the strength in the muscles around the hip by resorting to activities like swimming and non-impact exercises in the gym (such as using the bicycle, rowing machine, cross-trainers etc). Any exercise that does not result in excessive loading of the hip is good at this stage. You should try and avoid high impact-loading exercises like running, jogging, football, squash etc for at least a year after the operation.

As your hip improves in flexibility and stability, you may gradually resume your hobbies over the next few months. You may start playing a gentle game of golf after around 4 months and doubles tennis around 6 months. During the next few months, as you find improvement in the strength of your hip, you will be able to play more rigorously. If you are very keen on resuming impact loading sports then please start jogging on the treadmill with good footwear for a few months starting around the eleventh month before moving on to outdoor jogging or high-impact sports.

How long will the implant last?
The development of modern hip resurfacings was based on the secrets of success gleaned from successful historic metal-metal hip replacements which proved their wear resistance, durability and biocompatibility over several decades. The era of modern metal-metal hip resurfacings started in 1991 when Mr McMinn pioneered them. The early models were prototypes that gave precious further information on the best design and material combinations that would make resurfacing successful. Review of the surviving hips amongst these early prototype models show that some of them are still functioning well, in spite of heavy usage over the past 18 years. The hybrid fixed model turned out to be better than the others. Hybrid fixation was therefore adopted in all later models. In 1997, the fixation was made even more reliable using an advanced porous fixation surface and the Birmingham Hip Resurfacing (BHR) was introduced. Mr McMinn has performed over 3000 BHRs since 1997 and nearly 100,000 BHRs have been performed worldwide.

Orthopaedic surgeons consider that an implant has failed if following the original surgery, the patient goes on to have another operation for revision of one or more of the components of the implant. Failure of the component could be either due to a fracture, loosening or any other cause leading to pain and loss of hip function. Nearly 12 years on following the introduction of the BHR, the failure rate in our group of over 3000 patients is 1.6%. Fracture of the femoral neck or a collapse of the femoral head due to pre-existing inherent weakness in the bone or due to premature excess activity early after the operation led to failure in 1.1%. Infection and some other very rare causes such as dislocation or metal allergy led to failure in 0.5%. All of these have then been converted to a total hip replacement and the patients are back to a normal lifestyle following their revision surgery.

Based on the trend of time to failure of an implant, statisticians calculate implant survival to denote what percentage in a given group of patients are likely to reach a certain time point, such as 10, 15 or 20 years after an operation, without the need for a revision. In the younger age group (under 55 years) with osteoarthritis, the implant survival in Mr McMinn's series of BHRs is 99.5% at 11 to 12-years follow-up. The comparative figures for implant survival with the conventional cemented Total Hip Replacement in this age group and diagnosis are 81% at 10 years and 33% at 16 years, according to the Swedish Hip Arthroplasty Register.

What are pseudotumors and what causes them?
A few centres have reported a phenomenon, which has been named ‘pseudotumors’ by a renowned orthopaedic hospital in Oxford. The term pseudotumor refers to a problem, whereby a hip resurfacing or a metal-on-metal hip replacement fails with a painful swelling or with collection of fluid around the hip joint. The word ‘pseudotumor’ has caused consternation among patients who were worried if this is some kind of a hidden cancer or a pre-cancerous condition. These need to be put into perspective.

First, let us be clear that these reactions have nothing to do with cancer. Second, there isn’t a single artificial hip system metal, ceramic or plastic, that does not generate wear debris and all types of wear debris have been associated with these pseudotumor-type adverse reactions. Third, it is now becoming apparent that in a majority of cases of pseudotumors, the primary reason for the development of these reactions is excessive material being worn out from the device because they had been fixed in a skewed fashion in the first place. No artificial hip device lasts long unless it is placed in an optimal position. The components that had been removed in Oxford were tested in a highly sophisticated laboratory. It was found that in every case with a pseudotumor, the wear pattern in the components suggested edge-loading i.e. the components had worn excessively in an unnatural manner because of their placement in an unfavourable position. In components which did not show edge-loading i.e. those components which had been placed in the correct position to start with, no one had developed a pseudotumor.

Most modern artificial devices whether metal, plastic or ceramic, do not tolerate surgical error in component positioning. They wear excessively if they are fixed incorrectly and in the case of ceramics or modern plastics they can also break. Excess wear leads to pain and failure. Hip resurfacing is a technically challenging operation and minor surgical error may occur, especially when performed by surgeons who are not highly experienced. The degree of difficulty is further increased if the patient is a woman because hips in some women may be shallow or the upper end of the thigh bone directed differently. Their bones are petite, leaving no margin for error. The design of some types of resurfacings has been shown to be even less tolerant to minor malpositioning. One Centre reported pseudotumors only with ASR resurfacings, while they did not see any with Birmingham Hip Resurfacings. Therefore an experienced surgeon and a well-proven device are the key to success with a resurfacing.

Furthermore some women are constantly exposed to metals like nickel in costume jewellery which may pre-sensitize them to the tiny amounts of nickel found in the resurfacing or replacement components. It is not yet clear if there is a very tiny group of patients who would react badly in the face of expected and regular amounts of wear. The percentage of patients who may react like that is believed to be very rare, of the order of 1 in a 1000 or less. 

What symptoms do these patients develop?
Out of over 3000 resurfacings over the past 12 years, we had 10 patients who were treated for a local adverse reaction like this. In a majority of these there was only a collection of fluid around the hip joint nearly 10 years or more after their original operation. They complained of groin pain or discomfort. A few developed swelling of the foot or ankle because of the collection of fluid above. In many cases there were subtle X-ray changes, although not in all.

What is the solution if a person develops a pseudotumor several years after a hip resurfacing?
If a person presents with a history suggestive of a pseudotumor, he/she needs to be examined by an orthopaedic surgeon and undergo Xrays, a special multi-slice CT scan and some blood tests in order to establish the diagnosis. The CT scan must be able to reduce artefact from the metal in order to provide any useful information. In some cases it may be necessary to exclude infection by aspiration of the hip joint. If it is indeed a pseudotumor then a revision operation to convert the resurfacing into a total hip replacement with a non-metal-metal bearing will have to be performed.

How do patients recover after revision of a resurfacing to a hip replacement for a pseudotumor?
The ten patients described above have recovered as if they were recovering from any first hip replacement. Their hips are functioning well. The worst affected of these patients underwent the revision operation in January 2010 and needed bone grafting of the socket.  She has seen the sensational reports in the newspaper and questions “What is all the fuss about? I have had 10 good years of my life restored to me. I had then been in my early 50s and now I am in my 60s. I noticed hip discomfort a few months before the 10th anniversary of my operation and I had to undergo a revision operation to convert my hip resurfacing into a hip replacement and I am now getting back to normal again.” She adds, “Ten years ago, had I known that I would need a revision at this stage I would not have changed one thing. I would have gone ahead with the resurfacing operation”. Two months after her revision operation, she kindly agreed to be filmed and you can follow her account on our website, www.mcminncentre.com/flash under the section Case Studies – Other – Joan Lindh.

Questions specific to going to Mr. McMinn for surgery

How do I make an appointment to see Mr McMinn?
Call The McMinn Centre on 0121 455 0411 and we will be happy to arrange a consultation for you. Please note that in order to see Mr McMinn you will need a letter of referral from your General Practitioner which should be received by our office prior to the date of your appointment.

How long do I have to wait for an appointment?
An appointment for consultation can usually be arranged within 2-3 weeks, sometimes sooner.

Where will I be seen for consultation?
Consultations take place at the Consulting Rooms, 7 Chad Road, Edgbaston, Birmingham B15 3EN.

What is the waiting time between consultation and surgery?
A date for surgery can usually be arranged within 3-4 weeks following your consultation, on occasion a date can be arranged earlier. However, if you have specific dates when you would like your surgery carried out then every effort will be made to accommodate you.

At which hospital does Mr McMinn work? 
Mr McMinn carries out all hip surgery plus arthroplasty and arthroscopy of the knee at BMI Edgbaston Hospital.           
Mr McMinn also has a part-time post at The Royal Orthopaedic Hospital where he carries out total knee replacement.

Click here for various Publications by Derek McMinn