Chronological Changes of the Human Allograft Meniscal Transplants: MRI, Arthroscopic and Histologic Study

Kim, Seung Ho; Ha, Kwon Ick; Ahn, Jin Hwan; Chang, Dong Kook

Abstract

Vascular ingrowth is essential for the survial of the graft tissue. The purposes of this study were to evaluate any changes in signal intensity of cqropreserved meniscal allograft with time in the magnetic resonance images(MRI) and to demonstrate the viability of the grafts. Eight patients underwent meniscal transplantation with cryopreserved allcgrafts using the bone block technique. MRIs of the knee were taken at 3 days, 3 weeks, 6 weeks, 3 month, 6 months. And I year after the implantation. A second-look arthroscopy and a small meniscal biopsy(sized 2mm x 2mm1 at the peripheral and central part of the meniscus were conducted at 3 months and 1 year. Three days after the operation, the signal intensity of the implanted meniscus revealed a homogenrous low signaJ intensity that could not be differentiated from that of' a contralateral normal meniscus. At 3 weeks, a high signal intensity appeared at the periphery of the meniscus. This signal, which did not communicate into the joint space, fuither intensified at 6 weeks. The high signal intensity of the meniscus, though still higher than that of the normal meniscus, decrexsed slightly at 3 months and continued to decrease progressively even a year after the implantation. The second-look arthroscopy revealed that the grafts were viable and that there was no tearing or shrinking of the meniscus. Cellular proliferation was also found at the central edge oi' the meniscus at 3 months. This cellular pattern differentiated from that of a nonmal meniscus in that the d stribution of cells was not in an even, but in a clonal pattem. The cellularity after a year, however, was sirnilar to that of normal meniscus except some area with deficiency of cells. It can be concluded that increased signal intensity of' the implanted meniscus with time indicates hypervascularity caused by vascular ingrowth, similar to the high signal intensity ot>tained from normal meniscus in young children. Increasecl signal intensity in the chronological postoperative MRls demonstrates the viability of the implanted cryopreserved meniscal allograft.