Mosaicplasty For Articular Cartilage Injuries

Last week we discussed the microfracture technique for articular cartilage injuries. Many of my patients who read the article commented that they did not realize it was such a serious condition. Yes, indeed, having an articular cartilage injury is worse than tearing your anterior cruciate ligament (ACL). The lengthy rehabilitation makes it much worse.

Generally, the microfracture technique works well only for the smaller lesions (less than 3 cm). If the size of the defect is larger, the surgeon would usually perform mosaicplasty or autologous chondrocyte transplantation (ACT). The latter procedure works better if there is a "kissing lesion" (defect on both joint surfaces).

I wrote that the microfracture technique was made popular by Richard Steadman. For mosaicplasty, it is Professor Laszlo Hangody from Hungary who has probably performed the most procedures and published the most articles on the topic.

Harvesting the bone plugs

Mosaicplasty is a technique in which small bone plugs with healthy hyaline cartilage are taken and then transplanted to cover the defect in the damaged area. The bone plugs are usually taken from an area that is non weight bearing to cover the defect in the affected area. The end result ends up looking like mosaic tiles, hence the name mosaicplasty.

Here's a closer look

The hope is that the body will not miss the taken parts and it can be used where it is needed. Over time, the holes in that part of  bone that is taken will fill with bone and scar tissue. The bone plugs can be from the patient or from fresh cadavers.

The above diagram shows the procedure done on a patient's knee, but it can be done on the ankle, hip and other weight bearing articular surfaces too.

A similar technique to mosaicplasty is Osteochondral Autograft Transfer System or (OATS). The bone plugs used in OATS are usually larger and usually only one or two plugs are needed to fill the area of damage.

See the gaps in between the bone plugs?

In the above pictures, you can see that there are still gaps between the cylindrical bone plugs. This is the main problem with this particular technique. The defect is not filled completely and the gaps normally fill up with fibrocartilage. There is then a worry about how this holds up over time, especially if the patient is keen on returning to sports.

Recently, there has been an improvement/ modification to this technique. A group of researchers, inspired by the honey comb structure of a beehive of honey bees decided to use hexagonal shaped bone plugs instead of the cylindrical ones used previously.

No more gaps?

This is to eliminate the gaps while performing the procedure. The authors named it hexagonal osteochondral graft system (HOGS). Early outcomes of HOGS seemed comparable to mosaicplasty and promising at this stage although further follow up needs to be done.

Advantages of mosaicplasty  are that only one operation is needed (compared to two in ACT) and hence lower cost and less down time. There is less risk of disease transmission and there is a high percentage of hyaline cartilage for the damaged surface.

These procedures require the physiotherapist treating the patient to have knowledge of the biology of articular cartilage and the factors that may influence degradation and repair. The physiotherapist needs to know the nature, location, size of lesion and the surgical procedure performed.

Rehabilitation should address the patient's impairments and functional limitations without jeopardizing healing of the lesion.

I remember back in 1999, as a young physiotherapist a patient told me he had mosaicplasty done and I had asked him what it was. That piqued my interest in articular cartilage injuries and especially so when I later had to have a microfracture procedure done on my right knee in 2003. That also was why I did postgraduate work in that area as I desperately wanted to compete again.

My next post will be on the autologous chondrocyte transplantation/ implantation (ACT) procedure.

References

Erol MF and Karakoyun O. (2016). A New Point Of View For Mosaicplasty In The Treatment Of Focal Cartilage Defects Of Knee Joint: Honeycomb Pattern. SpringerPlus. 5(1): 1170. DOI: 10.1186/s40064-016-2796-y.

Gracitelli GC, Moraes VY et al (2016). Surgical Interventions (Microfracture, Drilling, Mosaicplasty And Allograft Transplantation) For Treating Isolated Cartilage Defects Of The Knee In Adults. Cochrane Database of Systematic Reviews. Issue 9. Art. No CD10675. DOI: 10.1002/4651858.CD010675.pub2.

Hangody L and Balo E (2011). Autologous Osteochondral Mosaicplasty. In Sanchis-Alfonso V. (eds). Anterior Knee Pain And Patellar Instability, London.