This is a quick note on a piece of information that Aldo Vezzoni gave at the THR course in Munich last year. The tendency is to template for stem size and cup size based on a standard, extended hip Ventrodorsal projection as is horn above. The problem with this is that the Kyon cementless THR femoral prosthesis is inserted at an angle that aims to mimic the natural ante version of the hip (20 -25 degrees). This projection will not give a good assessment of the femoral width then in the plane that will be used for implantation.

Standard VD view

In fact when we take our post op views we always do the “yoga” view to assess the penetration of the medial cortex by the stem screws and how closely the stem is apposed to the medial cortex:

This is the best view to use in pre operative assessment of the appropriate stem size also. In countries other than the UK this can be done by manually rotating the femur whilst the radiograph is being taken. In the UK we cannot remain within the radiography room and so we use a combination of sand bags and foam supports to rotate the femur as can be seen below.

This gives us a better projection of the femur and reduces the risk of undersized femoral prostheses.

The standard VD projection indicated that this patient would need a small stem, whilst this projection indicates clearly that a medium stem will easily fit. This will guide the surgical opening and reaming of the femur.

It is also an excellent projection for assessing the cranial and caudal lips of the acetabulum which defines cup size.

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Just to let you all know that the  iPhone App “Torrington Orthopaedics” has now been updated and the update is now available on the App store. It permits background activity so that it will update posts better. You can also pull down on the home page to load new posts.

I ma currently working on my next post which is how to diagnose Cranial Cruciate Ligament Rupture. I am drawing on the data from 650 of our cases and using video and animation to help make the subject more interesting, enjoyable and relevant. If I get a move on I may get this up by the end of the day.

If you have been using the App and enjoy it, why not take the time to rate it on the App store.

My plan to migrate the old site at torvet.co.uk to this site is unfolding. I want to preserve some of the features of the old site whilst utilising the blog based features of the new site. Striking the balance between static and dynamic content is the key I think.