Articular cartilage repair - who gets what technique?

If you read through the reference given in the previous chapter, you will know by now that there are a number of possible surgical techniques that may benefit someone with joint cartilage damage in the knee. To help surgeons decide which procedure to do, a number of flowcharts (or 'algorithms') have been developed. The surgeon can estimate the depth of the damage and the width of the damaged area, and ask the patient questions about their lifestyle and age. Then by referring to the flowchart, the surgeon will have a fairly good idea of what surgery is likely to benefit the patient.

This link outlines the decision criteria for people with 'full thickness' cartilage damage (someone with full thickness cartilage damage will probably have had a hard knock on the bent knee, and a bit of cartilage has been banged right off, leaving the bone exposed below it). Have a read of the article then check out the two powerpoint downloads at the bottom which lead you to the real detail. Because it is quite technical we will try and summarise it here. Clicking the link will open the article in a new window. 

The author of this article about full thickness cartilage lesions (the damaged bit is called a lesion) explains :

1. If the bit of bone which has been knocked off is less than a centimetre by a centimetre it probably won't get any worse and probably does not need surgery. However, if the edges seem unstable, then the surgeon is justified in smoothing off the edges of the lesion using either a 'shaver' that shaves the sharp edges down, or a 'wand' which uses radiofrequency to 'melt' the edges down. The author cautions that the wand needs to be used with care.
2. Lesions larger than this are likely to progress and get bigger. If the lesion is a little over one centimetre by one centimetre and is discovered during arthroscopy, and the edges of the lesion are not a problem, then a marrow stimulation technique such as microfracture are relevant. Such techniques are less effective, however, if the patient is over 40 years of age, so age needs to be taken into consideration particularly if the patient is still very active. The rehabilitation also has its demands so the patient must accept a prolonged rehabilitation before being accepted for microfracture.
3.  If the patient is over 40 and still very active, and/or the lesion is 1-2 cm squared, then a cartilage transfer technique like OATS or mosaicplasty should be preferred. These larger lesions are too big for the fibrocartilage cells to form a strong cover. In OATS and mosaicplasty, as you will have learned in the previous section, use full-thickness 'pegs' of bone and healthy cartilage harvested from a non-weight-bearing part of the knee to implant into the damaged area.
4. Any bigger than 2 cm squared, then a different technique is needed as so many cartilage plugs would need to be harvested that it would cause problems at the donor sites. These larger lesions will need ACI or an allograft (graft from a donor), but the author warns that allograft may not be a very good procedure and states that the ACI would be the treatment of choice.

You will find all that nicely laid out in the first powerpoint presentation, and it is worth printing it out to refer to it as you read on.