Morphological analysis of the human knee joint for creating custom-made implant models

Restoration of normal knee joint function is the goal of total knee replacement (TKR) surgery. However, due to the various size and shapes of human knee joint of every individual, a ready-made commercial implant may not conform to a patient anatomy for meeting specific patient needs. Since mismatched implants often cause a severe balancing problem and a short-term durability, customizing an implant is a unique solution for patients with a deformity or an abnormal anatomy. This paper presents a methodology that creates a customized knee implant model by extracting typical 3-dimensional (3D) geometrical parameters of the knee. All of the derived parameters are directly used to define the geometry of implant. Software system was developed to extract knee parameters and determine implants for individual. Surgeons are also able to simulate the whole process of surgery with the system, so that they know what the custom-made implant should be for the patient prior to surgery. The feasibility and verification of a custom-made knee implant is described with case study. It indicates that the proposed system is applicable in the early stage of implant design process.