Fig. 2.

Nomogram for prediction of a beneficial functional outcome 5 years after rTKA in a given patient. To obtain the predicted probability of a beneficial outcome, (1) Locate the patient’s values for “Preoperative fKSS”, “Gender”, “Age at surgery”, “Femoral bone defect”, and “Severe stiffness” on the corresponding axes, (2) Draw a vertical line from the located value on each axis to the “Points”-axis to determine how many points are attributed for each predictor, (3) Sum the points for all variables, (4) Locate the sum on the “Total Points”-axis, and (5) Draw a vertical line towards the “Predicted probability of a beneficial outcome after rTKA”-axis to determine the probability of a beneficial functional outcome 5 years after rTKA. To illustrate the use of the nomogram, the outcome for a 65-year-old female patient with a preoperative fKSS of 50 who has a type IIb AORI femur bone defect, and severe stiffness as main reason for revision is predicted. After locating the patient’s values for “Preoperative fKSS” (50), “Gender” (female), “Age at surgery” (65), “Femoral bone defect” (type IIb), and “Severe stiffness” (yes) on the corresponding axes, draw a vertical line up from each of these values to the “Points”-axis to determine how many points are attributed for each predictor. “Gender” (female), “Femoral bone defect” (type IIb), and “Severe stiffness” (yes) are attributed 0 points each. “Preoperative fKSS” (50) and “Age at surgery” (65) are attributed 34 and 39 points, respectively. The sum of the attributed points is 73. After locating 73 on the “Total Points”-axis, a vertical line is drawn downwards to the “Predicted probability of a beneficial outcome after rTKA”-axis to determine the probability of a beneficial functional outcome 5 years after rTKA, which is 26% for this particular patient