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A meniscus transplant or meniscal transplant is a transplant of the meniscus of the knee, which separates the thigh bone (femur) from the lower leg bone (tibia). The worn or damaged meniscus is removed and is replaced with a new one from a donor. The meniscus to be transplanted is taken from a cadaver, and, as such, is known as an allograft. Meniscal transplantation is technically difficult, as it must be sized accurately for each person, positioned properly and secured to the tibial plateau. As of 2012, only a few surgeons have significant volume of experience in meniscus transplantation world wide. ==Background== Each knee has an inside (medial) and an outside (lateral) meniscus. The menisci play several key roles that are vital in maintaining the health of the knee. Specifically, they act as shock absorbers and load sharers, increase the stability of the knee, and provide lubrication and nutrition to the bearing surface (articular cartilage) of the knee. They were once thought of as vestigial structures that served no real purpose. If injured and problematic, they were routinely excised through a procedure called meniscectomy.〔 It is now known that a knee joint without healthy menisci is at significantly increased risk of developing wear and tear arthritis (post-traumatic or osteoarthritis). The arthritis is a result of the increased contact forces and shear that results from loss of shock absorption and stability after meniscectomy. For this reason, current surgical strategies are focused on preserving as much of the meniscus as possible or replacing it if necessary. Certain meniscal tears are repairable with sutures, predominantly those that are freshly torn and involve healthy tissue. The closer tear is to the peripheral blood supply the higher the likelihood of successful repair.〔 Patients with unrepairable meniscal injuries usually have symptoms of pain, catching, swelling or locking in the knee. The surgeon may perform a partial or complete meniscectomy to alleviate the symptoms in the short-term.〔 The more meniscal tissue removed, the higher the likelihood of subsequently developing arthritis.〔 Recognizing the biomechanical importance of the menisci, surgeons in the late 1980s proposed meniscus transplantation and meniscus reconstruction as two new surgical options for the patient with a meniscus deficient knee. Recognizing from experiments performed by R.J. Webber, PhD that meniscus cells have the ability to grow in tissue culture, K.R. Stone, M.D. developed the first meniscus reconstruction device called a collagen regeneration template in 1986.〔 The template or scaffold was composed of glycosaminoglycan (sugar/proteins that make up cartilage tissue) and was designed to have pores into which cells could grow. Its cross-linking preserved the scaffold in the knee joint long enough for new meniscus tissue to grow into it.〔 (Patents 5,158,574, 5,116,374, 5,007,934) This scaffold was tested in animals and subsequently in people and was found to successfully replace lost segments of meniscus tissue〔〔 (Fig 1). It became widely available in Europe and temporarily in the US in 2009. However, in cases where large areas of meniscus are missing, full intact meniscus transplantation has been suggested.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Meniscus transplant」の詳細全文を読む スポンサード リンク
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