Young people who participate in sports are at risk of injuring their weight bearing joints like the knee. We have very good solutions for patients with damaged knee ligaments & menisci, but till date we did not have any good solution for damaged knee cartilage. The cartilage is the smooth white covering that gives us near frictionless movements in our joints. Once even a small portion of this layer is damaged, the knee is at an increased risk of osteoarthritis, a debilitating illness for a young person.
The cartilage is unique in that once formed (in childhood), it does not have capacity for repair or regeneration. This is mainly because, human cartilage does not have a blood supply of its own, it depends upon the joint fluid for its nourishment.
Till date we surgeons used to rely on three broad types of cartilage treatment
- Abrasion chondroplasty: Simply put it means the removal of loose pieces of cartilage, so that they do not Mechanically lock the joint & thereby relieve pain. The problem of the cartilage defect still remains & this can progress on to osteoarthritis.
- Microfracture: This involves creating small 1-2 mm holes in the bed of the defect, in the hope that the blood clot that forms at the site will convert into cartilage. This conversion is very inconsistent & whatever cartilage does form is of an inferior variety called fibrocartilage. Fibrocartilage, unlike the normal hyaline cartilage, has limited ability to withstand load especially shear forces that are a part of day to day life. It also cannot address large cartilage defects.
- Mosaicplasty: This involves transferring small cylinders of cartilage from a less important portion of the knee, to the cartilage defect. One advantage of doing this procedure is that good, hyaline cartilage is being transferred that will have normal load bearing characteristics. There are several disadvantages, this operation is very technically demanding, even a slight error of a millimeter can result in misplacement of the cartilage plug & failure of the surgery. It cannot be used to fill big defects, as enough donor cartilage is in short supply.
With the availability of this new technique, Autologous Chondrocyte Implantation (ACI), most of the unpredictability & drawbacks of a cartilage restoration surgery have been addressed. ACI is done in two stages:
- First stage: A small 8mm cylinder of cartilage biopsy is taken from the knee, from a less important portion. This is done in a minimally invasive manner through an arthroscopy & is sent to a specialised lab for a cartilage culture.The lab grows to cells to match the size of the defect & sends it back to us. This whole process takes 4-6 weeks.
- Second stage: The cultured cartilage cells are re-implanted into the defect. This is usually done through a small incision. A standard rehabilitation program is followed & the patient can resume day to day life activities within 2 months & active sports within 8 months.
The biggest advantage of ACI is that normal load bearing hyaline cartilage can be re-created at the defect. Simply put, it brings back the knee to its pre-injury status which is a boon for young active patients with this injury.
Frequently asked questions?
Is the surgery done in a single stage?
No, ACI is a two stage surgery, first involving the biopsy & the second involving the implantation.
How many days hospitalisation is required after the first stage?
First stage is a daycare procedure. At the most a single day admission is required.
How fast is the recovery after the first stage?
We allow our patients to put full weight immediately after the first stage. Also full knee movements are started immediately. One can join work & drive a vehicle within a week.
How many days hospitalisation is required after the second stage?
We can do the second stage as well as a daycare procedure, still we advice one day’s admission.
How fast is the recovery after the second stage?
We will not allow weight bearing for 6 weeks after the second stage. The patient is required to use a walker. This is to allow the cultured cartilage cells to incorporate firmly into the defect. Knee motion is also started in a gradual manner. Driving a vehicle is allowed after 6 weeks. One may join work within 3 weeks depending on the nature of the job.
Are there any complications?
There are no complications specific to this procedure. The cells used are from one’s own body, so there are no chances of rejection of the graft. Patient specific complications are best discussed in person with the treating surgeon.