Ask a Sports Medicine Doc: Treatments and substitutes for a torn meniscus
Ask a Sports Medicine Doc
I tore my meniscus and had to have it removed due to severe knee pain some years ago. Can a meniscus substitute be implanted into my knee?
The meniscus is a tough, rubbery, half-moon-shaped cartilage in the knee. There are two meniscus cartilages with one sandwiched between the femur and the tibia on the inside of the knee (the medial meniscus) and the other one on the outside of the knee (the lateral meniscus). The meniscus is a critical shock absorber cartilage that protects the coating cartilage or articular cartilage on the ends of the femur and the tibia from wearing prematurely. Meniscus tears are one of the most common problems that I see in my office. Patients typically complain of very well localized, intermittent pain over the torn meniscus, and they may also have popping or catching in the knee. The pain is usually worse with squatting or sports that require a lot of knee rotation such as skiing.
If someone comes to surgery for a painful meniscus tear, my goal is to try to repair the meniscus tear with suture and thus save the entire meniscus. Unfortunately, the meniscus has poor blood supply, and they usually tear along the thin inner rim where there is little or no blood supply. Thus, most tears are not candidates for repair due to this lack of blood supply and poor healing potential. Therefore, most meniscus tears must be treated by removing the torn flap that is irritating the knee. It is critical for the knee surgeon to remove only what is torn and unstable and not remove healthy, functioning meniscus tissue.
As for meniscus replacement surgery, the best option currently available is meniscus transplantation in which a donor meniscus is implanted in the knee. The primary indication for this surgery is knee pain localized over the area of the knee where the meniscus has been removed. Moreover, a person must not have any significant arthritis to be a candidate for this procedure. If you have been without your meniscus for many years, it is likely that you have significant arthritis where the coating cartilage has gradually worn away. A transplanted meniscus would fail prematurely if there is already arthritis present in the knee. Another consideration is a patient’s alignment. Special X-rays are obtained to measure leg alignment and determine if a person is knock-kneed or bowlegged. This is done to determine if the meniscus transplant would be overloaded due to malalignment of the leg. If someone were otherwise a candidate for meniscus transplantation but the leg was malaligned, I would also recommend an osteotomy to correct the alignment in addition to doing the meniscus transplantation or else the transplanted meniscus would fail prematurely.
Numerous researchers are working on other possible meniscus substitutes. One group has developed a collagen meniscus implant, which is a bioresorbable collagen matrix designed to serve as a template for one’s own cartilage cells to grow into. Currently, this device is not FDA approved. Hydrogels and polymer scaffolds have also been tried. Stem-cell-based meniscal implants are also being investigated but this work is in the very early stages.
Dr. Rick Cunningham is a knee and shoulder sports medicine specialist with Vail-Summit Orthopaedics. He is a physician for the US Ski Team and chief of surgery at Vail Valley Medical Center. Do you have a sports medicine question you’d like him to answer in this column? Visit his website at http://www.vailknee.com to submit your topic idea. For more information about Vail-Summit Orthopaedics, visit http://www.vsortho.com.
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