Paxton et al evaluated patients following a primary total knee replacement. They identified risk factors for revision of the arthroplasty. The authors are from Kaiser Permanente in San Diego and West Los Angeles.
Patient selection: primary total knee replacement
Outcome: revision within 5 years
Parameters:
(1) age in years
(2) sex
(3) osteoarthritis
(4) body mass index (BMI) in kilograms per square meter
(5) diabetes mellitus
(6) osteonecrosis
(7) post-traumatic arthritis (PTA)
Parameters
Finding
Points
age in years
-0.04121 * (age)
sex
male
0
female
-0.17099
osteoarthritis
no
0
yes
0.152503
body mass index
0.044426 * SQRT(BMI)
diabetes mellitus
no
0
yes
0.27649
osteonecrosis
no
0
yes
0.930812
PTA
no
0
yes
0.505203
X =
= SUM(points for the 7 parameters) - 1.08118
probability of knee revision within 5 years =
= 1 / (1 + EXP((-1) * X))
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