Design of a new 3D‐printed joint plug

This paper introduces a kit of parts as a novel three‐dimensional (3D)–printed joint plug, in which each of the parts function cooperatively to treat cartilage damage in joints of the human body (e.g., hips, wrists, elbow, knee, and ankle). Three required and one optional parts are involved in this plug. The first part is a 3D‐printed hard scaffold (bone portion) to accommodate bone cells, and the second is a 3D‐printed soft scaffold (cartilage portion) overlying the bone portion to accommodate chondrocytes. The third part of joint plug is a permeable membrane, termed film, to cover the entire plug to provide coordinated sliding of the joint during the regeneration of the cartilage. Film is also responsible for retention of the chondrocytes while allowing nutrients to diffuse through the membrane. The plug may further include a fourth part, called barrier, which is a membrane to assist the bone portion in avoiding the loss of chondrocytes from the cartilage portion beyond the barrier. Various engagement means among the parts of the plug are assumed, which are discussed in this paper. Moreover, the detailed design criteria and selection of suitable materials for different parts are elaborated. The 3D‐printing practice allows the plug to be personalized and fabricated to fit the shape/size of the target joint and the injured section. Also discussed are the configuration options of the plug to be surgically implanted in a joint. Although the focus of this paper is on the design, a brief overview of a prototype is presented.