Abstract
The collagen meniscus implant (CMI) is a tissueโengineering technique designed to stimulate regeneration of meniscusโlike tissue in cases of irreparable tears or previous meniscectomy. CMI morphology was investigated before and after implantation by light microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). In a case series biopsy specimens were harvested from four patients who underwent a second arthroscopic look 6 months after placement of the CMI. CMI sections appeared composed of parallel connective laminae of 10โ30 ฮผm, connected by smaller bundles (5โ10 ฮผm). This connective network formed lacunae with diameters between 40 and 60 ฮผm. At greater magnification, the walls of the lacunae demonstrated tightly packed and randomly distributed collagen fibrils, with diameters ranging from 73 to 439 nm. In the biopsy specimens, the lacunae were filled with connective tissue that contained newly formed vessels and fibroblastโlike cells, presenting an abundant rough endoplasmic reticulum and several mitochondria. In the extracellular matrix, the collagen fibrils showed uniform diameters (126 nm ยฑ 32 nm). The original structure of CMI was still recognizable, and no inflammatory cells were detected within the implant. The morphological findings of this case series demonstrate that CMI provides a threeโdimensional scaffold suitable for colonization by precursor cells and vessels and leading to the formation of a fully functional tissue. ยฉ 2005 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2005