Let’s talk about all the various treatments that we do for the articular cartilage when we are doing a biologic replacement.
When we look into a knee that has damage to the articular cartilage, we decide which of the cartilage procedures that we want to select in order to treat that damaged area -
- If the area is just fibrillated (ragged), but there is no exposed bone, we then do a gentle chondroplasty in order to just remove the fibrillated component, which we believe often breaks off and creates synovitis and inflammation in the joint.
If there is exposed bone, and it is a very small area such as 5 by 8mm or that type of range, then we will often just do a microfracture (photo on right) which will stimulate a healing response to a small area of articular cartilage loss.
- If, on the other hand, there is more exposed bone and the area is larger than let’s say 8 by 8mm, then we will choose to do a paste graft technique where we do a super-microfracture (morselising that exposed bone with a pick), creating a fresh bloody bed and exposing the marrow cells to the surface.
Note that we violate all the principles of microfracture because in this case we want to fracture right through the ‘tide mark’ and create a true fresh fracture in the joint.
We then take articular cartilage and underlying cancellous bone from the intercondylar notch out of the knee, smash it into a paste and then impact that paste into the morselised defect. We do not try to fill the defect because these almost always hypertrophy and will fill on their own.
We are also currently doing a study to determine whether or not patients who had one type of tissue regeneration or another have a different outcome. Meaning, if you have fibrous tissue does that diminish the quality of your outcome over a period of 10-15 years? That study data will be out by the end of this year. Because those biopsies revealed articular cartilage regeneration that was every bit as good as any biopsies we had seen from any other cartilage procedure, such as ACI, we elected not to use ACI for any of the cartilage defects that we see, since ACI required two surgical interventions – one of them being ‘open’ – and required sewing of a periosteum and also a very expensive cartilage growing procedure, we felt that a simple single-stage outpatient procedure where the cartilage was grafted in one step was more cost-effective and at least equally therapeutically-effective as any of the other procedures that we had seen. This is also true when we compared the data to mosaicplasty or OATS-type procedures, all of which we felt created too much of a defect in the bone, and when those procedures failed the patient was left with a very wide trough. And so we use a paste graft technique whenever there is exposed bone that is large enough as part of the biologic knee replacement procedure.
Why is paste grafting not yet a main stream procedure?
Well, in paste grafting there is no product that a company can get behind and sell, and because of that we never had a corporate support for a product of any kind. A surgeon can use any trephine, take the tissue out of the knee, use a simple graft smasher that most of the ENT (ear/nose/throat) sets have, and then return that graft directly back to the patient in the same procedure without incurring any additional charge. And so we were never able to entice a company to get behind paste-grafting even though we now have nice published studies of long term data and this July the Journal of Bone and Joint Surgery (British) will publish our 2-12 year data combining paste graft as well as chondroplasty and microfracture with meniscus transplantation for arthritic knees. So we think we have quite long term solid data that eventually other surgeons may decide to adopt to their armamentarium.