Ask a Vail Sports Doc: Cartilage replacement is the ‘holy grail’ of othopedics
December 4, 2017
I recently saw a young male athlete that injured his knee playing football. He struck the front of his knee and the area around his knee cap (patella) against another player's helmet. He had immediate pain and swelling, and these symptoms did not improve much over the next several months.
When I saw him in the office, I was concerned that he had injured the cartilage surface that lines the underside of the patella. A subsequent MRI demonstrated this to be the case. He had knocked off a quarter sized area of the cartilage under the knee cap. This cartilage is the articular cartilage or coating cartilage that lines the underside of the knee cap, the end of the femur bone and the top of the tibia bone within the knee joint.
Historically, this injury did not have very good treatment options.
If the knee cap had been chronically malaligned, then an osteotomy would have been considered where a bone cut is performed and the knee cap better aligned and centered in the groove where it tracks.
For the cartilage defect, a microfracture may have been considered. Microfracture is a technique that was developed several decades ago. In this, small perforations are made in the bone and a resultant scar cartilage can fill a defect in the cartilage.
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Unfortunately, the results of microfracture, especially for treating cartilage defects on the underside of the patella, are poor. The sheer forces in this area are such that any scar cartilage that results from a microfracture is quickly worn away and the patient is back to having exposed bone with no cartilage surface in typically one or two years after microfracture surgery. Other surgical techniques for this problem such as using cartilage from a donor, implanting morselized cartilage donor tissue or using a technique called mosaicplasty have a fairly high failure rate.
Fortunately, there exists a better option for treating cartilage defects of the knee cap.
This technique is called autologous chondrocyte implantation. In ACI, the surgeon takes a biopsy of the patient's coating cartilage from the periphery of the knee. This biopsy is then sent to a lab where the cartilage cells, or chondrocytes, are isolated. The chondrocytes are then multiplied in culture over a 30-day period of time. The cells are then sent back to the surgeon and the patient is brought back to surgery for implantation of these cartilage cells.
The cells are implanted in a cartilage defect much like an asphalt patch is used to fix a pothole in the road. In my experience of using this technique, most patients are doing well and having minimal or no pain after a few months. Unfortunately, returning to unrestricted sports and activities can be nine to 12 months as it takes this long for the cartilage cells to bond to the bone, harden and mature.
A recent study was published which demonstrated good or excellent long-term results in young patients treated with ACI for cartilage defects of the knee cap. I found this study encouraging, as again, there have not been other good solutions for this difficult problem.
I tell patients who have cartilage loss in the knee that cartilage replacement is the "holy grail" of orthopedics and we are not there yet. However, the results of this surgical technique are encouraging, and my hope is that further development in the field of regenerative medicine and the use of stem cells can improve upon these surgical techniques and results further in the future.
Dr. Rick Cunningham is a knee and shoulder sports medicine specialist with Vail-Summit Orthopaedics. He is a physician for the U.S. Ski Team. For more information, visit http://www.VailKnee.com or to learn more about Vail-Summit Orthopaedics, visit http://www.vsortho.com.
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