Fig. 1

Construction of 3D-MRI nomograms. The distribution and total point number of predictive variables overlap along the nomogram scales. The box plot shows the categorical variables (e.g., KL grade, race, and gender), with the box size indicating percentage. The density plot shows the distribution of continuous variables (e.g., 3D bone shape of tibia and patella at the baseline, 3D bone shape changes of tibia and femur at 24 months of follow-up, age, and total score). The definite value of each red point corresponds to the scale of the variable’s axis (β(χ-m) term). The observation values overlap at the total score axis. A straight line is drawn through this point and downward extending to the risk axis, and the point of intersection with the risk axis represents the occurrence probability of the radiographic progression of osteoarthritis. A Nomogram for 3D bone shape at the baseline. B Nomogram for 3D bone shape change at 24 months