Meniscus prosthetic devices with anti-migration or radiopaque features

A prosthetic meniscus device for placement in a knee joint, the prosthetic meniscus device having a substantially ellipsoidal shape and comprising:

• a central portion having an upper femur-contacting surface for engagement with a portion of a femur and an opposing lower tibial-contacting surface for engagement with a portion of a tibia, the central portion comprising a resilient material;
• an outer portion surrounding the central portion and having an increased thickness relative to the central portion, the outer portion comprising a resilient material with at least one reinforcing fiber embedded in the resilient material of the outer portion, the at least one reinforcing fiber disposed circumferentially around the central portion;
• and
• a retention structure formed on the outer portion, the retention structure sized and shaped to prevent posterior migration of the prosthetic device in the joint, the retention structure having a posterior channel configured to engage a posterior remnant of a meniscus,
• wherein the posterior channel comprises a pocket formed on a posterior sidewall of the outer portion and configured to receive the posterior remnant of the meniscus,
• wherein the pocket is disposed between first and second posteriorly extending fork portions of the posterior sidewall of the outer portion,
• wherein the first fork portion is disposed inferiorly to the pocket, and the second fork portion is disposed superiorly to the pocket,
• wherein the pocket comprises a concave shape defined at least in part by a superior surface of the first fork portion and an inferior surface of the second fork portion,
• wherein the first fork portion defines a posteriorly-extending inferior plow blade configured to slide under at least a portion of the remnant of the meniscus,
• wherein the first fork portion comprises a first leading edge and the second fork portion comprises a second leading edge, wherein the first leading edge extends further posteriorly than the second leading edge, and
• wherein the retention structure is configured to inhibit extreme movement of the prosthetic meniscus device within the knee joint while permitting free floating of the prosthetic meniscus device over a significant range.