Varus and valgus alignment and incident and progressive knee osteoarthritis.
OBJECTIVE
Varus and valgus alignment increase medial and lateral tibiofemoral load. Alignment was associated with tibiofemoral osteoarthritis progression in previous studies; an effect on incident osteoarthritis risk is less certain. This study tested whether alignment influences the risk of incident and progressive radiographic tibiofemoral osteoarthritis.


METHODS
In an observational, longitudinal study of the Multicenter Osteoarthritis Study cohort, full-limb x-rays to measure alignment were acquired at baseline and knee x-rays were acquired at baseline and knee x-rays at baseline and 30 months. Varus alignment was defined as ≤178° and valgus ≥182°. Using logistic regression and generalised estimating equations, the associations of baseline alignment and incident osteoarthritis at 30 months (in knees without baseline osteoarthritis) and alignment and osteoarthritis progression (in knees with osteoarthritis) were examined, adjusting. For age, gender, body mass index, injury, laxity and strength, with neutral knees as referent.


RESULTS
2958 knees (1752 participants) were without osteoarthritis at baseline. Varus (adjusted OR 1.49, 95% CI 1.06 to 2.10) but not valgus alignment was associated with incident osteoarthritis. 1307 knees (950 participants) had osteoarthritis at baseline. Varus alignment was associated with a greater risk of medial osteoarthritis progression (adjusted OR 3.59, 95% CI 2.62 to 4.92) and a reduced risk of lateral progression, and valgus with a greater risk of lateral progression (adjusted OR 4.85, 95% CI 3.17 to 7.42) and a reduced risk of medial progression.


CONCLUSIONS
Varus but not valgus alignment increased the risk of incident tibiofemoral osteoarthritis. In knees with osteoarthritis, varus and valgus alignment each increased the risk of progression in the biomechanically stressed compartment.
Northwestern University, Chicago, IL 60611, USA. l-sharma@northwestern.edu
Leena
L
Sharma
Jing
J
Song
Dorothy
D
Dunlop
David
D
Felson
Cora E
CE
Lewis
Neil
N
Segal
James
J
Torner
T Derek V
TD
Cooke
Jean
J
Hietpas
John
J
Lynch
Michael
M
Nevitt
D000368:Aged; D000407:Alabama / Q000453:epidemiology; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D056304:Genu Valgum / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology; D056305:Genu Varum / Q000150:complications* / Q000000981:diagnostic imaging / Q000453:epidemiology; D006801:Humans; D015994:Incidence; D007484:Iowa / Q000453:epidemiology; D007719:Knee Joint / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000209:etiology*; D011859:Radiography