The problem with big heads

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The only thing that John Charnley did in orthopaedics that I don’t like is when he designed those big ugly forceps – I prefer a Lane’s any day. All his other instruments convey the message that he must have been a master surgeon and a gifted engineer. When I started orthopaedics his hip was still THE prosthesis in the UK, although back then the Exeter was already catching up. Now the Exeter and its lookalikes rule supreme and Depuy have incredibly pretty much abandoned the original Charnley, the most studied and successful implant of them all.

Back then the McKee had a 35mm head, the Exeter was 26mm (still a pitfall for today’s revision surgeon who hasn’t checked it properly), the dreaded Ring implant was 32mm, there were quite a few 28mm prostheses about, and the Charnley was 22mm. Why 22?

The simple answer is that with the materials available, Charnley saw it as the best trade off between reducing volumetric wear and the associated creation of polyethylene debris in large amounts, and linear wear eroding the superolateral part of the socket.

Not many people now have Charnley’s landmark book Low Friction Arthroplasty of the Hip, currently trading at upward of £150 on eBay, and fewer have actually read his 1969 paper on head size in a bioengineering journal, but here it is! (The second paper is a very handy review from HSS on the modern thinking on head size issues.)

It’s not a great read in a way, but it contains lots of key thinking. I believe that the main problem with those metal on metal articulations which fail in the present era is lubrication failure. Charnley spotted this as a major issue, hence he wanted inherently low friction materials in contact with each other. As he put it in the paper: “in the absence of a fluid film a good theoretical argument can be made out for using the smallest ball which the load bearing capacity of the plastic will tolerate”. Which was obviously not going to be 32mm.

The paper is based on experiments with polytetrafluoroethylene (PTFE), commonly called Teflon (as in various dodgy politicians), which is not the still useful ultra high molecular weight polyethylene (UHMWPE). This stuff seemed to behave differently in the lab compared to in the human body. It famously failed badly in a large early series of Charnley’s patients which in the current climate would have ended with a visit to the GMC and we would never have enjoyed the amazingness of total hip replacement. Possibly.

But I digress. Remarkably, even as early as 1969, Charnley had intuited that it was the microscopic plastic wear particles that were creating a biological reaction and implant loosening, and it was therefore his mission to reduce the overall volume of wear as much as possible. He ended up with the view that a head diameter half of the outer diameter of the socket was the right balance – see his relatively simple calculations. If the average socket is around 52mm, that makes the Exeter cult about right with 26mm. Which is now virtually abandoned too. As the great man admitted however “little is lost if the diameter lies between 21 and 31mm” 

The old myth that 22mm was chosen for manufacturing reasons is not borne out. It was purely to do with reducing volumetric wear, and Charnley reckoned that going below 22mm meant too high a risk of dislocation, and of ‘boring’ into the socket. The truth is, 22mm worked brilliantly.

The current vogue for large heads of 36 and 40mm is genuinely worrying. There could still be lubrication concerns and idiosyncratic wear problems, however low friction the coupling theoretically is with the latest hard bearing materials.

Finally, all the best orthopods come from the North West of England.

Trauma in the family

If you've ever been a patient, as a doctor you will always find it enlightening, even if it's also unpleasant. If a family member is the patient the same applies, but more unpleasant/scary than if you're the 'victim'.

Here's the experience of  a hardbitten US traumatologist from the Bronx, Paul Levin, when his own daughter was smashed up. Like Steve Krikler's AMUART (see elsewhere), it's fascinating and contains numerous lessons

The wards are not crap

We were happy back then

If you want to get plenty of complaints, or possibly sued, as a consultant, then neglect the wards. If you want to be disliked by the nurses and have ungrateful patients, then neglect the wards. If you want to become the cliche of the 'technical surgeon' obsessed with operating, then neglect the wards. On that last point, the best surgeons also tend to be the most assiduous at ward work and knowing their patients. There are no surgeons who are so good at the cutting stuff that we should ignore their failures in care elsewhere.

If you want to go home content and banish that lingering unease in the back of your mind, then do a ward round.

Here is a very perceptive piece by, God forbid, an anaesthetist on this very topic, one to which I will return.  And note this also:  the best trainees are those who are on top of their inpatient duties

Richard Rothman's lessons learned

If you're fortunate enough to have attended the best arthroplasty meeting in the world, CCJR (Current Concepts in Joint Replacement), either in Las Vegas or Orlando, you may in the past have had the pleasure of hearing Richard Rothman speak.

Rothman is the founder of the Rothman Institute in Philadelphia, a very successful place and in my view, a very high quality one, despite some detractors concerned about "multi-million dollar orthopods". If only.

It's  Rothman's take on a very long career. I draw your attention to the following 5 rules:

1. If in doubt, wait (which fits with Leo Gordon's admonition of 'listen to the surgical gods')
2. Consider what you would do if you were the patient
3. Ask yourself who is best for the job
4. Encourage patients to minimise their risk
5. Avoid jumping from fad to fad. Stick with what works for you

It's worth digesting the whole thing, plenty of it applies to NHS practice.

Joel Matta on being excellent

Many years ago the great Gus Sarmiento (read his excellent memoir) told me how, when he was running the Los Angeles orthopaedic residency programme, he first noticed Joel Matta. He said that whenever they had a postgraduate educational event, Matta who was apparently a fairly self effacing young surgeon, was always the guy who asked the most penetrating and apposite questions, not the usual 'in my experience' guff that you get, which is grandstanding disguised as a question. Sarmiento said that it was most unusual in a resident to have this quality consistently - Matta went on to study with Letournel in Paris and a star of pelvic and acetabular surgery was born.

There are many many pelvic fracture surgeons about now, and much of Matta's more recent published work has been about pelvic osteotomy and the anterior approach to hip replacement. If you've heard him speak then you'll know how good he is.

This is a superb piece on 'how to be good'. It may not turn you into another Joel Matta, but it's great. And yes, speed is not an end in itself, but it's not a bad thing either

AMUART - trauma from the wrong end

A few years ago the much maligned Daily Mail published a fascinating article on three urologists who all had prostate cancer themselves. I've done joint replacements on orthopaedic surgeons and other colleagues and their 'inside stories' are always worth hearing. Steve Krikler is an engaging fellow, and a very energetic educator - at conferences, editing Injury etc. Here he is describing what it's like to be smashed up in an RTA (MVA for any passing Americans). Genuinely enlightening:

Beware the "senior surgeon"

I would hope that if I end up like this - assuming that I haven't already - that someone might find a diplomatic formula of words to point it out to me. Leo Gordon is writing re the US system and general surgery, but these archetypes are global, and in the NHS tend to drift into doing less and less whilst demanding more respect and acclaim. The NHS is probably the softest employer in world healthcare and it's perfectly possible to showboat in the last 10 years before retirement, if you're so inclined. It doesn't take long before a degree of affection is replaced by irritation if they don't tone it down.

They can always hit you harder

In these days of the UK New Deal and the frankly-ridiculous-and-possibly-soon-to-be-abandoned-European Working Time Directive, the young (and sometimes old) surgeon is relatively protected from this concept. Not so when I was a lad - the 24 hours of  Christmas Day 1986 comes to mind. Anyway, LG is 100% correct about this

Understanding knee arthroplasty and the PCL - not as boring as it sounds

Knee arthroplasty is more like hip resurfacing than it is like hip replacement - you really have to understand each stage in a relatively complex sequence, and if you get it wrong, it's not particularly forgiving. Likewise, if you understand each step then you can deal with the unexpected more easily and go off piste with a bit of freehand - if you have to (disclaimer: I am not promoting freehand knee replacement).

There are two keys to this in my view, once you're in the knee. One is understanding the PCL and its role in knee arthritis and knee replacement design. The other is the absolutely fundamental issue of mastering the flexion/extension gap. Wannabe knee surgeons have no excuse for getting the latter wrong.

The first piece is a chapter in a textbook from about 2001, which offers a practical take



As always, you learn more if you get two perspectives on the same topic. I read the second paper here back in the 90's, and I still think it's great, from the excellent AAOS review journal




For the record, I do a PCL sacrificing knee for pretty much ALL primary cases (and most revisions) - it works with almost any deformity and the fully audited long term outcomes are terrific.

The lactate thing and major trauma

Here's a paper which seems pragmatic. Vallier and her colleagues from MetroHealth Medical Center (US spelling) in Cleveland, Ohio - which is a big league level 1 trauma centre - looked at more than 1400 cases from a retrospective database.

My take on their findings is that an absolute figure for lactate and 'safe' operating is not the issue. A range of 2 to 4 mmol/l is OK, and it's the trend that matters. So near patient lactate testing is very handy, and most things can wait till the morning for major surgery, as opposed to essential damage control.

Your anaesthetist  may or may not be aware of this stuff, so you can educate them.

I'll put up a sensible 'lactate protocol' in due course.