My orthopedic surgeon is going to patch up a hole in my knee joint. She plans on using some cartilage from another part of my knee that doesn’t get much pressure. Evidently there is a patch that goes over the hole once it’s filled up. I understand that patch can be made of collagen tissue or bone. Which is better? I’m assuming the bone since it’s stronger, but thought I would check it out before my surgery is done.

Defects or lesions of the articular cartilage (lining the surface of the knee joint) can be treated in several different ways. One of those methods that has become quite popular is a technique called autologous chondrocyte implantation or ACI.

The surgeon uses the patient’s own chondrocytes (cartilage cells) harvested from another area of the knee. Usually the donor cells come from an area that has little weight put on it.

Once the donor cells have been harvested, they are taken to a lab where more cells can be produced from the graft. When ready, the cells are placed in the defect (hole) and then covered over with a patch. The patch can be made of bone (the outer layer of bone called the periosteum) or it can be made of collagen. Collagen is the basic protein building block that makes up most soft tissue.

Collagen patches are quickly becoming more popular than periosteal (bone) patches for one reason. Bone patches tend to hypertrophy (grow too much bone). Patients end up having a second (revision) surgery after the first transplantation. The surgeon goes back in and debrides (shaves) away the excess bone. This type of complication is much less likely with the ACI-collagen patches.

The ACI-collagen patch cost about $1000 more (per patient) but there are far fewer cases of second surgeries needed for graft hypertrophy or graft failure with the collagen material.

Studies have reported a rate of graft hypertrophy as being around 25 per cent for patients receiving an ACI-periosteal patch. This compares with a 10 per cent rate linked with the ACI-collagen patch.

That information added to the fact that a second surgery costs about $8300 more suggests the ACI-collagen patch may be worth the added investment up front to avoid future costs associated with failure or hypertrophy. And that $8300 figure is based on current costs for hospital, surgeon, and anesthesiologist. Surgeries that take place several years down the road will likely cost more.

A recent study from the University of Nebraska comparing the use of ACI-collagen patches with ACI-periosteal patches showed that the ACI-collagen patch for significant knee articular cartilage lesions is cost-effective. There is already evidence to show that half of all ACI procedures are already being done with the collagen product instead of the periosteum.