Stage 3
The next step is fragmentation. This is classically referred to as fragmentation when ball joints such as the femoral head are affected, since this ball disintegrates in the X-ray image, leaving small fragments behind. The first detachments of the cartilage-bone structure also occur in other affected joints.
For the time being, however, the detached fragment (dissection) remains in contact with its support. During arthroscopy, the examiner can reach under the cartilage piece with a small hook and lift it, but it is not yet detached. Both the X-ray image, but especially the MRI, shows an interruption of the normally smooth joint space.
The MRI shows that the interruption has occurred in the area of the cartilage. Sclerosis and edema (fluid seam) are still visible. The pain symptomatology increases significantly.
In some cases, acute pain can occur during movement if the damaged cartilage becomes trapped. During knee arthroscopy, the cartilage can be reattached. Particularly in young patients and rather superficial defects, there is a good chance that the cartilage will grow firmly again.
Stage 4
The dissectate can become detached and then lies as a free body in the joint cavity. On the side from which the dissectate has detached, an empty “dissectate bed” can be seen. The free dissectate can shift during movement and thus cause considerable pain due to entrapment.
Also in this case, an arthroscopy is performed. If the cartilage still appears vital despite detachment, it can be reattached with small pins as in stage 3. If the defect is very deep or the piece of cartilage is obviously avital, the joint mouse is removed and the dissectate bed is filled.Either a cylinder of cartilage bone is removed from a low stress area of the joint and transplanted into the defect zone or a cartilage cell transplantation is performed. In this case, either new cartilage is cultivated from the body’s own cells, which takes a long time, or alternatively a prepared collagen fleece is placed in the defect. However, in contrast to the cartilage-bone cylinder, these procedures only have a good result in superficial defects.
