Document Title: Stone-JBJS-Dec97.shtml
Article Title: Regeneration of Meniscal Cartilage with Use of a Collagen Scaffold. Analysis of Preliminary Data
Authors: Kevin R. Stone, M.D., J. Richard Steadman, M.D., William G. Rodkey, D.V.M., and Shu-Tung Li, Ph.D.
Publication: Journal of Bone and Joint Surgery (American Edition)
Date: December 1997
Volume 79, pages 1770-1777
Keywords: Meniscal repair, meniscal regrowth, collagen scaffolding, tissue engineering, bioengineering.

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Comments (with additional points by Sue Barber-Westin): This very thought-provoking study involves a small group of 10 patients who underwent meniscus transplantation with tissue that had been regenerated using a collagen scaffold. Sue Barber-Westin, a gifted clinical researcher experienced with knee-cartilage issues, notes that these patients all had a good portion of their native meniscus intact, i.e. they had undergone only partial meniscectomies. She notes that someone with a complete or near-complete menisectomy, or with sectors extending from centre to edge of a meniscus missing, would probably not be a good candidate for this operation. The reason for this is that Stone's method apparently depends on the intact outer portions of the meniscus to provide structural-mechanical strength (and thereby provide some protection to the repaired portion, during the initial postoperative period), given the hoop stresses that naturally develop in the meniscus. (To conceptualize hoop stresses, imagine what would happen to a hypothetical meniscus if a small vertical cut were made in the outer edge. When the knee bears weight, the small cut would grow into a split extending towards the centre of the meniscus.) Results of Stone's collagen-scaffolding method showed good progress at 3 years postoperative. The method appears very promising, but the authors note that further research is needed. Also very promising is that this method appears to provide a good way to repair meniscal damage that affects the avascular central portions of the meniscus -- and said portions are exactly those which are most likely to be removed as a result of injury. This study dates from 1997. Regrettably, since then, no further study on this intriguing collagen-scaffolding concept seems to have been done. Stone's method would be especially desirable for people who have undergone partial menisectomy. This is especially the case today, given that partial menisectomy remains the most common way to deal with meniscal tears due to the fact that it makes little demand on the surgeon's time. Meniscal repair via careful inside-out suturing, a method pioneered by Noyes, is time-consuming and requires a skilled surgeon, but the long-term benefits makes it well worthwhile. (Incidentally, this repair method works well for splits that extend to the outer edge of the meniscus.) Stone's method would also be helpful in cases where the meniscal damage occurs in the form of irreparable shredding. So, the repair method of Noyes and the regrowth method of Stone complement each other. If all meniscal-tearing patients were to undergo these meniscal repair and regrowth techniques instead of merely undergoing partial menisectomy, then a lot of osteoarthritic degeneration would be averted. (Funding for this study was provided by California-based ReGen Biologics.)

Abstract

A collagen scaffold was designed for use as a template for the regeneration of meniscal cartilage and was tested in ten patients in an initial, Food and Drug Administration-approved, clinical feasibility trial. The goal of the study was to evaluate the implantability and safety of the scaffold as well as its ability to support tissue ingrowth. The study was based on the findings of in vitro and in vivo investigations in dogs that had demonstrated cellular ingrowth and tissue regeneration through the scaffold. Nine patients remained in the study for at least thirty-six months, and one patient voluntarily withdrew after three months for personal reasons. The collagen scaffold was found to be implantable and to be safe over the three-year period. Histologically, it supported regeneration of tissue in meniscal defects of various sizes. No adverse immunological reactions were noted on sequential serological testing. On second-look arthroscopy, performed either three or six months after implantation, gross and histological evaluation revealed newly formed tissue replacing the implant as it was resorbed. At thirty-six months, the nine patients reported a decrease in the symptoms. According to a scale that assigned 1 point for strenuous activity and 5 points for an inability to perform sports activity, the average score was 1.5 points before the injury, 3.0 points after the injury and before the operation, and 2.4 points at six months postoperatively, 2.2 points at twelve months, 2.0 points at twenty-four months, and 1.9 points at thirty-six months. According to a scale that assigned 0 points for no pain and 3 points for severe pain, the average pain score was 2.2 points preoperatively and 0.6 point thirty-six months postoperatively. One patient, who had had a repair of a bucket-handle tear of the medial meniscus and augmentation with the collagen scaffold, had retearing of the cartilage nineteen months after implantation. Another patient had débridement because of an irregular area of regeneration at the scaffold-meniscus interface twenty-one months after implantation. Magnetic resonance imaging scans demonstrated progressive maturation of the signal within the regenerated meniscus at three, six, twelve, and thirty-six months. These findings suggest that regeneration of meniscal cartilage through a collagen scaffold is possible. Additional studies are needed to determine long-term efficacy.

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