Graft-bone healing of a meniscus autograft anchored in bone tunnels.

Abstract

This experiment was designed to histologically study the attachment process between a meniscus autograft and bone when the meniscus autograft is placed within bone at its anterior and posterior horns. In order to provide a time-sequenced histologic picture, a canine model was used. The study group consisted of eleven mature canines that underwent complete medial meniscectomy of the stifle joint followed by immediate replacement using an autogenous tissue meniscal scaffold fashioned from the lateral fascia of the thigh. The graft was fixed in bone tunnels at the anterior and posterior horns. One animal was sacrificed immediately after implantation, one at 10 days, three at 28 days, two at 3 months, two at 6 months, and two at nine months. Photographs were taken and histologic sections through bone tunnels were analyzed. The graft consisted of rolled tensor fascia and exogenous clot. The attachment process begins with the invasion of an interface of well vascularized, primitive mesenchymal cells between the soft-tissue graft and the host bone. Histologic evidence of collagenous attachment to bone is visible at one month after graft implantation. Collagen organization with increasing soft tissue attachment to bone is progressive throughout the nine months time frame of the study. The attachment points become increasingly more continuous from three to six months. By six months, the attachment points are confluent and continuous throughout the depths of the tunnel.