Low vitamin K status is associated with osteoarthritis in the hand and knee.
OBJECTIVE
Poor intake of vitamin K is common. Insufficient vitamin K can result in abnormal cartilage and bone mineralization. Furthermore, osteophyte growth, seen in osteoarthritis (OA), may be a vitamin K-dependent process. We undertook this study to determine whether vitamin K deficiency is associated with radiographic features of OA.


METHODS
We conducted an analysis among 672 participants (mean age 65.6 years, 358 women) in the Framingham Offspring Study, a population-based prospective observational cohort. Levels of plasma phylloquinone (the primary form of vitamin K) had previously been measured in these participants, for whom we also had bilateral hand and knee radiographs. The main outcomes were 1) prevalence ratios (PRs) of OA, osteophytes, and joint space narrowing (JSN) per quartile of plasma phylloquinone level for each joint, adjusting for correlated joints using generalized estimating equations, and 2) adjusted mean number of joints with each feature per quartile of plasma phylloquinone level. Analyses were conducted in hands and knees separately and adjusted for age, sex, body mass index, total energy intake, plasma vitamin D, and femoral neck bone mineral density.


RESULTS
The PRs for OA, osteophytes, and JSN and adjusted mean number of joints with all 3 features in the hand decreased significantly with increasing plasma phylloquinone levels (P<or=0.03 for all). For example, as plasma phylloquinone levels rose, the PR for hand OA decreased from 1.0 to 0.7 (P=0.005). For the knee, only the PR for osteophytes and the adjusted mean number of knee joints with osteophytes decreased significantly with increasing plasma phylloquinone levels (PR decreased from 1.0 to 0.6, P=0.01).


CONCLUSIONS
These observational data support the hypothesis of an association between low plasma levels of vitamin K and increased prevalence of OA manifestations in the hand and knee.
Neogi
Tuhina
T
Boston University School of Medicine, and Brigham and Women's Hospital, Boston, Massachusetts 02118, USA. tneogi@bu.edu
Booth
Sarah L
SL
Zhang
Yu Qing
YQ
Jacques
Paul F
PF
Terkeltaub
Robert
R
Aliabadi
Piran
P
Felson
David T
DT
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D050823:Hand Joints; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000209:etiology; D020370:Osteoarthritis, Knee / Q000209:etiology*; D014813:Vitamin K Deficiency / Q000150:complications*