Orthopedic Corner: New techniques for cartilage restoration promising
Dr. David Shenton
My doctor told me I was developing knee arthritis from an old injury. Would any of these newer cartilage replacement therapies that I have read about help me? - Kris, area patient
The articular cartilage is a shiny, smooth tissue which covers the ends of the bones in your joints. Along with natural lubricating fluid, this provides very low friction surfaces. However, with damage or trauma, there will be breaks in this surface that eventually wear, leading to a more diffuse joint process referred to as degenerative joint disease, or osteoarthritis. This is a very common and potentially debilitating problem.
Developing a treatment to restore injured articular cartilage has long been the "Holy Grail" in orthopedics. Countless efforts in this field date back decades, and there have been qualified successes. In all of these efforts, a couple of things seem to be true: First, almost all of the different techniques work well with small, discrete areas of damage in the joint cartilage in an otherwise normal, healthy joint; Secondly, the techniques seem to work best when studied in short-term follow up. None of these efforts have had any real success in reversing a more diffuse degenerative process.
The most popular surgical techniques for restoring joint cartilage have included the following:
1. A group of "chondroplasty" techniques going back two decades.
These are efforts to break through the bone into the marrow, thereby encouraging healing including marrow cells that could then form new cartilage. These techniques go by various names including abrasion chondroplasty, or microfracture, and has been done with drilling or repetitive impacting with a small "pick." The "fibrocartilage" which results is not as durable as the original.
2. Osteochondral grafting.
A plug or plugs consisting of cylinders of bone with normal articular cartilage caps are transplanted into the injured area, either from another spot in the same knee (autograft) or from another person (allograft). The allograft has been used in larger defects and shows promise, but there is a limited supply.
3. Autologous chondrocyte implantation (ACI).
This requires two surgeries. In the first, the surgeon harvests cartilage cells from a less critical surface of the knee. These cells are then cultured and grown outside of the body. In the second surgery, the injury site is cleaned down to bone. The defect is covered with a thin layer of tissue and the cultured cartilage cells are injected underneath this patch. The hope is that these will mature into normal cartilage. Early results in some medium-sized knee cartilage defects are promising.
4. Mesenchymal stem cell regeneration.
This newest technique involves using special stem cells (MSCs) found in adult bone marrow. It is hoped that these cells can be taken, placed into a gel and then inserted into a cartilage defect where it could then grow new cartilage. This research is still in early stages.
In most cases, these techniques require lengthy rehab and several weeks on crutches with limited weight bearing on the injured joint. Return to vigorous activities may take many months. There is a great need for reliable techniques for restoring injured articular "joint" cartilage. There is much ongoing research, and some results are encouraging.
Each technique has its pros and cons. Many factors need to be considered, including the patient's age, the size of the cartilage defect and the overall alignment of the limb. The newer techniques should be considered "investigational" rather than tried-and-true therapies. None of the present techniques are appropriate for more diffuse arthritic process or "degenerative joint disease."
The future holds a lot of promise for treatment of this difficult problem.