Q. Several years ago I injured my knee playing soccer. At that time arthroscopic surgery was performed and some “bone chips” were removed. Recent pain prompted another arthroscopy and I was told that I have damaged areas in the knee “down to bone”. Is my knee doomed? My surgeon is talking about the possibility of trying to re-grow a new joint surface. Is that possible?

A. Joints surface injuries (chondral defects) are potentially serious problems especially in the knee. They can range in severity from minor to severe, usually determined by the depth and size of the defect as well as it’s location on the knee joint surface. If the damage is extensive (i.e. arthritis) there is not much that can be done in terms of re-growing a new joint surface. If, on the other hand you have a focal chondral defect (i.e. “pothole”) in an otherwise healthy stable knee, there are some new alternatives for you.

If the defect is small (under 1cm²) then osteochondral joint surface plugs can be taken from your own joint and transplanted into that area. Other techniques include the “microfracture technique” in which damaged joint surface areas down to bone are treated with an out-patient arthroscopic technique using a specially designed awl to create small holes (vascular channels) and some bleeding at the joint surface which eventually, with the proper post-operative program, will fill in with a repaired tissue that is a type of firm scar tissue but not real joint surface. This can be very effective in certain situations.

The most promising technique that I utilize involves chondrocyte transplantation in which cells from your own knee are taken through a relatively minor arthroscopic surgery procedure. Those cells are then grown in a laboratory in the Boston area (Genzyme) and within several weeks enough cells are grown that can be transplanted into your knee through a more serious, larger, open surgical procedure that eventually allows you to re-grow a new surface on your joint that is remarkably like your original one. The surgery is tedious and the recovery long but if things turn out well, you have a joint surface that hopefully will last a lifetime, rather than one that rapidly deteriorates to an arthritic condition, like so many joint surface injuries are subject to.