Is roentgen stereophotogrammetric analysis (RSA) the new black?

A physician’s job is to avoid “trial and terror” as one of my senior colleagues taught me early on. Preventing bad implants from reaching the market is vital in orthopaedics. This is especially true since the current implants have a > 95 % 10 year survival. It is therefore great to see Göran Selvik’s RSA method (Selvik et al. 1983) generating headlines in both Acta Orthopaedica and JBJS Am.

In JBJS Am. a valuable 10 year follow-up of 41 hip arthroplasties (Nieuwenhuijse et al. 2012) validate the use of RSA. They could see an impressive correlation between micro motion at 2 years and late follow-up. About one fourth of all the cups turned out to be loose at the end of the follow-up. The C-statistic or area under the receiver operating curve statistic was 0.88 which is close to the ideal 1. The C-statistic is a measure of the specificity (that only the right patients are identified) and sensitivity (that all that later show movement actually are discovered). Continue reading

Creating nice flow diagrams

My favorite tool for creating flow diagram is Dia – it’s easy and open source. It’s homepage is not that impressive but the Facebook group seems to be pretty active. There you can also find that downloads increased by 23 % in 2011 to 1.4 million downloads.

In this tutorial I want to show you how easy you can create a great looking flow diagram like the one CONSORT recommends for publication of RCT:s. Continue reading

Finally – 64-bit software is here

For a while I’ve been wondering when we’re going to do the switch to full 64-bit systems… and it’s finally happening!

Flash and Java are finally available in 64-bit version. Without these two the wheels stop turning… well I guess Flash days might be counted with Apples push towards HTML 5.

I’ve also found this new awesome browser Waterfox that loads heavy sites such as CrossValidated in no-time. Regular Firefox is non-responsive for 30 seconds while I barely notice the MathJax script loading with Waterfox. Continue reading

My two favorite IDE’s for R – tips & tricks

The two IDE that I use for R are RStudio and Eclipse with StatET. They complement each other nicely, RStudio works out of the box while I previously shown how to get Eclipse & StatET going, you can find it here, which is slightly challanging.


I use RStudio for all my statistics where I don’t want to create functions or more advanced programming. It’s great since it allows me to get immediate help, code completes the initiated variables. The settings are simple and you hardly need to do anything. Continue reading

Setting up StatET & Eclipse in Windows

A view of the StatET plugin in the Juno Eclipse. The environment is perfect for developing R packages and creating more complex functions.

I wanted to write about creating R-packages in Windows but after trying to get StatET to work seamlessly in Windows I decided that maybe I should start with the very basics. I found Longhow Lam’s excellent PDF about StatET in a Windows environment to be very helpful.

My basic setup:
OS: Windows 7 64-bit
R: 2.15.1 64-bit
Eclipse: Juno (3.8) 64-bit – Eclipse 4.2.0
StatET: 3.1 Continue reading

Swedish orthopaedic surgery gets a bronze

Time for some bragging: In a paper from 2010 The 100 classic papers of orthopaedic surgery you can read that Sweden comes in third when looking at the most cited articles throughout orthopaedic times 🙂

At the top is (of course) USA with 77 articles, then comes England with 10 articles and by beating Canada with 1 article Sweden gets the bronze with 5 articles. For a country with only 9.5 million inhabitants I think that it’s rather impressive. Continue reading