Significant (deep and wide) injury to the cartilage lining the surface of the knee joint can be treated with a transplantation of cartilage cells called chondrocytes. The transplanted chondrocytes usually come from the patient’s own knee — from another area that has little weight put on it. The procedure is called an autologous chondrocyte implantation or ACI.
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 available in the United States and approved for use by the Food and Drug Administration (FDA) but not for knee cartilage repairs. Right now they are only approved for rotator cuff repairs, tendon reconstruction surgery, and dental procedures. When used as a patch for autologous chondrocyte implantation, it is considered an “off-label” use. European surgeons have unlimited approved use of the ACI-collagen patches for chondral repair.
In order to study the use of ACI-collagen patches and compare them to ACI-periosteal patches, surgeons from the University of Nebraska Medical Center conducted this study. They were mainly interested in knowing if there is any cost savings in using the ACI-collagen over the ACI-periosteum.
One way to judge that is by observing how many patients end up having a second (revision) surgery after the first transplantation. The primary reason revision surgery is done after ACI-periosteal grafts is because of hypertrophy (overgrowth of the bone). The surgeon ends up going back in and shaving away the excess bone. This type of complication is much less likely with the ACI-collagen patches.
By following two groups of patients (one group received the ACI-collagen patch, the second group had the ACI-periosteal patch) for 10 years, they made one important discovery. The ACI-collagen patch cost about $1000 more (per patient) but there were far fewer cases of second surgeries needed for graft hypertrophy or graft failure in the collagen group.
Other 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.
The authors conclude 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. Since the collagen patch has not been approved yet by the FDA for this type of problem, this study may help provide the evidence needed to support FDA approval in the near future.