What is an antalgic (painful) gait? Let the sensors have their say.

Falsehood flies, and the truth comes limping after it, so that when men come to be undeceived, it is too late; the jest is over, and the tale hath had his effect.

Jonathan Swift

One of the things we are taught as medical students and doctors is how to recognise various types of gait. This is an imperfect art, particularly for the less observant among us! I remember telling someone that his painful, slow gait was due to his hip arthritis only to see that after successful hip surgery his gait was still just as slow. It turned out that he also had early Parkinson’s disease, and I had missed the early signs of his neurological condition. And if you think you are immune to such lapses of judgement, perhaps you – like me – were fooled by Virgil’s limp in the film ‘Usual Suspects‘ (one of my favourite cinematic endings).

One of the most basic gaits to recognise is someone walking with a single painful hip joint. This is commonly called the ‘antalgic’ gait, and is characterised by someone spending less time putting their weight on the painful leg compared to the other leg.

When surgeons replace hip joints they hope to relieve pain – but they also need to restore a normal gait pattern. Although pain relief happens quickly in most patients, restoration of normal function is more gradual. The best way to study this scientifically is to apply movement sensors to the limbs – accelerometers or more sophisticated triple component inertial movement sensors (IMUs). A 1999 paper by Aminian et al examined this question in a group of patients who had hip surgery for arthritis in a single hip. It turned out that simply measuring gait speed didn’t show the improvements as clearly as the ‘assymetry of double stance’ time. This is the difference between the time you spend on the bad leg vs. the good leg – i.e a scientific measure of the ‘antalgic gait’.

Using sensors to detect improvements in gait after hip replacement
Sensor detection of changes in assymetric (antalgic) gait after hip replacement surgery

In the top left (pre-op) picture you can see a big spread from the identical line (diagonal) – and then as we move to the bottom right (9 months post-op) you can see that the difference between double-stance time on either leg has narrowed except in one patient (circled in the image below).

Sensor detects Gait in Hip Osteoarthritis after surgery
Sensor detection of changes in assymetric (antalgic) gait after hip replacement surgery: spot the one exception!

Now, as it happens, this poor chap still had pain in his hip. I guess you could have found that out a lot easier just by asking him, but the point is that we’ve found that out through a very objective test. Looking at the trace from the motion sensors, an analyst miles away with no video footage could ‘diagnose’ that he still had an antalgic gait. The same sort of analytics can pick out differences that are just not obvious even to the practised eye.

This is just a simple example taken from what is a rapidly expanding area of the scientific literature – how to accurately measure and define human movement. In this case, the use of movement sensors provided objective evidence of improvements we could have discerned by observing the patient’s gait or by asking them to complete a questionnaire. However, movement analysis can be used to perform much more complex assessments that should help the therapist understand why our patients haven’t quite returned to full function at work or at home. Physiotherapists, sports scientists and experts in biomechanics/computer analytics are leading the way. Watch this space!

Reference: Arminian K et al Med Biol Eng Comput 1999 37 686-691

Is Guinness good for you if you have arthritis?

Black is most definitely the color of the Irish national drink. Well – black with a creamy head, anyway. Testament to the power of advertising is the number of patients here who still believe the old ad ‘Guinness is good for you’.

Being a reformed teetotaler, I have always tended to err on the side of being rather severe in my warnings about the perils of drink for patients with Rheumatoid or Psoriatic arthritis, particularly if they are taking Methotrexate.   The other poor souls who have had to endure my sermonizing include those who are unfortunate enough to have gout.

As a doctor who purports to practice ‘evidence based medicine’ it is always reassuring when the evidence base backs up the ’eminence based medicine’ I’ve been practicing for 10 or 20 years. On the other hand it is frankly a bit upsetting when I am forced to eat my oft-repeated words of solemn advice. So here are three ‘factoids’ I’m currently pondering – not exactly proof positive, but some interesting observations at least.

  • Factoid #One – Drinking alcohol seems to be protective against Rheumatoid Arthritis.  This idea has been around since a Seattle study by Voigt and colleagues reported in Epidemiology in 1994. This paper suggested that you were about half as likely to get RA if you drank over 14 drinks a week of alcohol – the authors suggested that could be because alcohol raised Estrogen levels;
    More recently (2010), a Sheffield study by Maxwell and colleagues reported in Rheumatology seemed to confirm that observation. So what are we to make of that? Infusions of Guinness in our day ward, anyone? Unfortunately, alcohol does not seem to reverse the disease once started!
  • Factoid #Two – The risk of liver function test abnormalities in patients who take lowish doses of Methotrexate does not seem to be increased in ‘social alcohol’ drinkers. So said Tilling L and colleagues in 2006. Chris Deighton (2008) seemed to agree, and the BSR guidelines have relaxed the advice about alcohol intake in patients taking Methotrexate. However, this idea is being whispered very softly at the moment, and I think it is right to be cautious until we have more studies to confirm this. Whatever we might think and say, it is quite clear that many patients don’t pay a blind bit of notice to the advice they are given on this subject.
  • Factoid #Three – Not all types of alcohol are bad for patients with gout. One of several excellent studies on gout by HK Choi published in the Lancet in 2004 suggests that whilst beer is bad for gout, wine is not. I doubt very much if Guinness featured among his survey’s favorite tipples, so I guess my patients are still existing in an evidence free zone! Nevertheless, I still advise them to cut down on the beer intake. Old habits die hard.


The most important decade for advances in arthritis treatment?

I’m going to vote for 1890-1900 and I’m calling it the decade of the war against pain. Remarkably, three effective analgesic drugs came into being that decade: two were ‘angels’ but one became a monster.

If you had arthritis before 1890 you had nothing to dull the pain other than the ages old treatment of opium and it’s derivatives. It had been more than 200 years since Thomas Sydenham had developed and popularized an alcohol based tincture of opium called Laudanum based on the writings of Paracelsus.  Even though the addictive properties of this drug was well known it was well into the 20th century before its distribution was restricted. The development of other opium derivatives such as morphine and codeine came at the beginning of the nineteenth century. With so few therapeutic options, it was no wonder that Sir William Osler, considered to be the “Father of Modern Medicine,” once said, “When an arthritis patient walks in the front door, I feel like leaving by the back door.”

And then – in the dying embers of the nineteenth century, there was a pharmaceutical revolution. Out of the blue (Bayer was a former dye factory) we had two new drugs that were going to change the world – Aspirin and Heroin.  Remarkably, the development of Heroin in Bayer came only two weeks after Hoffman first synthesised ASA (Acetyl Salicylic acid, Aspirin).

The three key figures in Bayer were Dreser, Hoffman and Eichengruen. The story of these three figures is mired in intrigue with allegations of intellectual property theft, anti-Semitism being discussed and debated in various articles on the internet

Bayer’s states that the work on Aspirin was done by Felix Hoffmann (whose father had arthritis), but the Jewish chemist Arthur Eichengrün later claimed he was the lead investigator and records of his contribution had been expunged under the Nazi regime. They were not the first to recognize the analgesic properties of salicylic acid, nor even the first to develop acetyl salicylic acid – but they were the first to develop and commercially produce a tablet that was well tolerated.

Although Heinrich Dreser was a key figure in the development of Aspirin, he is probably better known for his enthusiastic development and personal use of ‘Heroin’, so named because of the ‘heroic’ feeling it gave the German workers who tried it. But Dresser was also a shrewd business man, and before long Heroin was being advertised in Europe and the US as a cough suppressant and a drug to quieten babies who would not stop crying! Diacetylmorphine had actually been invented in 1874 by an English chemist, C R Wright. It only took two or three years before it became apparent that Heroin was an extremely dangerous drug with serious addictive properties. It took quite a bit longer before Bayer stopped producing it (1913) and in 1919 prescription of Heroin was outlawed in the US. Just in case anyone is confused, please note – Heroin (diacetylmorphine) is definitely NOT a treatment for arthritis and the unregulated use of this drug has caused untold harm worldwide!

Meanwhile, in Halle, Germany, a clinical pharmacologist Dr Joseph von Mering developed and tried paracetamol (acetaminophen or Tylenol) on his patients. Sadly, his paper in 1893 indicated that there was a high risk of methaemoglobinaemia with paracetamol – and so phenacetin was developed instead. Tragically, it would be more than half a century before Acetaminophen was restored to its rightful place in the armory of weapons against pain.

Reference: Physicians, Fads and Pharmaceuticsals: a History of Aspirin by Anne Adina Judith Andermann – the most authoritative and well referenced article on the subject I could find on the Internet.

Evernote and the Rheumatologist

One of my favourite web tools is Evernote. I use it for clipping articles, URLs or pictures from websites and then going back to put them into lectures, teaching materials, blogs or simply for reference later. It works straight from most browsers and the standalone desktop programme allows you to review, tag and generally tidy up the snippets you’ve collected. It also automatically stores the URL of the page so that you can return to the original page and reference your source if you later use it. The fact that I can access this from work, and indeed from any computer I’m using (including Macs and iphones) is the real deal clincher. Sharing via facebook and twitter from within Evernote is possible although I haven’t used those options.

Fifteen years ago when I first created my ‘arthritislink’ website for patients I often used Yahoo and AltaVista search engines to try and find hidden gems on the internet. At that time there was very little reliable information on the web about arthritis – whereas now the depth and quality of information is so mind-boggling that the main problem is information overload. Every patient can now draw up their own online portfolio of useful advice (perhaps using Evernote) – but do they need help in sorting out the good stuff from the bad? And perhaps we as Rheumatologists should be encouraging people with arthritis to help point us to nuggets of information they have discovered.

I understand that Evernote can also be used to scan text or record voice memos  – I’m going to explore the ‘Evernote Trunk’ and see if if I find anything else worth using. So if you have any tips on how to make the most of this software, please share it with the rest of us!


My First Message to the mobile world

A wicked and most unflattering cartoon of cyberPhil
Typical patient's comment: You didn't have that beard the last time I saw you!

Here we are with the first page of my medical blog, hopefully optimised for mobile phones. I am going to experiment with some of the tools to integrate Twitter and/or Facebook into the blog. I’m going to have a separate design for the full-size version and another one for the mobile user. Hopefully the system will automatically detect the device you are using to view the site. There will be a lot of design work to be done, so please keep the comments coming in to help me get it right!

Thank you for your patience!