Method for designing a joint prosthesis

A method for designing a two-part knee prosthesis, the method comprising:

• obtaining kinematic data of a subject's knee using non-invasive measurement of an alignment of the subject's knee in the coronal plane, comprising:
• measuring the alignment of the subject's knee in the coronal plane without load at multiple degrees of flexion of the knee that are each between at least about 0° and about 45° of joint flexion;
• and
• measuring the alignment of the subject's knee in the coronal plane under application of an external force on the subject's knee so as to reduce or correct a varus or a valgus deformity, at each of the multiple degrees of flexion of the knee that are each between at least about 0° and about 45° of joint flexion;
• calculating a difference between the alignment of the subject's knee without load at a respective degree of flexion of the multiple degrees of flexion of the knee and under application of the external force at the respective degree of flexion of the multiple degrees of flexion of the knee for each of the multiple degrees of flexion of the knee thereby obtaining a number of values for the difference;
• calculating an average of the difference values;
• and
• designing the two-part knee prosthesis using the kinematic data by applying the average difference as a target correction in a pre-operative modelling and design of the subject's two-part knee prosthesis,
• wherein the two-part knee prosthesis comprises working surfaces and wherein the working surfaces of the two-part knee prosthesis comprise, consist essentially of or consist of cellular material.