Wu et al reported a nomogram for predicting the likelihood of knee replacement for a patient with osteoarthritis of the knee. The authors are from Guandong Academy of Medical Sciences and Shamtou University.
Patient selection: knee osteoarthritis
Parameters:
(1) cartilage loss area, from 0 to 20 (no units given)
(2) cartilage loss thickness, from 0 to 12 (no units given)
(3) meniscus extrusion, from 0 to 6
(4) knee extension force in Newtons
(5) bone marrow lesion (BML) size from 0 to 16 (no units given)
(6) bone marrow lesion (BML) edema from 0 to 20 (no units given)
(7) history of glucocorticoid injection in past 6 months
(8) contralateral osteoarthritis with Kellegren and Lawrence Grade > 2
points for cartilage loss area =
= 4.275 * (area)
points for cartilage loss thickness =
= 4.875 * (thickness)
points for meniscus extrusion =
= 12.82 * (extrusion)
points for extension force =
= 66.8 - (0.0741 * (extrusion))
points for BML size =
= (6.25 * (size))
points for BML edema =
= 72 - (3.6 * (edema))
|
Parameter
|
Finding
|
Points
|
|
glucocorticoid injection
|
no
|
0
|
|
|
yes
|
100
|
|
contralateral osteoarthritis
|
no
|
0
|
|
|
yes
|
24.6
|
total score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: 0
• maximum score: 584.1
value of X =
= (0.02667 * (score)) - 6.968
probability of knee replacement =
= 1 / (1 + EXP((-1) * X))
Performance:
• The arae under the ROC curve is 0.82.
