Synovial fluid concentrations of the C-propeptide of type II collagen correlate with body mass index in primary knee osteoarthritis.
OBJECTIVE
To explore in a cross sectional study in patients with primary knee osteoarthritis (OA) the relations between body mass index (BMI), disease stage, and the concentrations of a putative joint fluid marker of type II collagen synthesis, procollagen II C-propeptide.


METHODS
The study included 142 patients with knee OA (median age 68, median BMI 24.1). OA was staged radiologically. The concentrations in synovial fluid of procollagen II C-propeptide were measured by a sandwich enzyme immunoassay.


RESULTS
Joint fluid concentrations of procollagen II C-propeptide were increased in knees with OA (median 3.7 ng/ml), compared with published reference values for knees in healthy adult volunteers (median 1.3 ng/ml). The concentrations of procollagen II C-propeptide were independently related to both OA stage and BMI (r = 0.343, p < 0.0001 and r, = 0.253, p = 0.002, respectively).


CONCLUSIONS
Joint fluid concentrations of this putative marker of collagen II synthesis are high in early and mid-stage OA, but decrease in end stage disease. In addition and for the first time it was shown that the concentrations in synovial fluid of procollagen II C-propeptide increase with increasing BMI in primary knee OA. The increased joint fluid values of this marker in patients with primary knee OA and a high BMI, may reflect increased rates of collagen synthesis in their joint cartilage and could relate to the previously shown increased risk for disease progression in such patients.
Kobayashi
T
T
Department of Orthopaedic Surgery, National Defence Medical College, Tokorozawa, Japan.
Yoshihara
Y
Y
Samura
A
A
Yamada
H
H
Shinmei
M
M
Roos
H
H
Lohmander
L S
LS
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D015415:Biomarkers / Q000032:analysis; D015992:Body Mass Index; D002135:Calcium-Binding Proteins / Q000032:analysis*; D003094:Collagen / Q000032:analysis*; D024043:Collagen Type II; D003430:Cross-Sectional Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007719:Knee Joint / Q000000981:diagnostic imaging; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000000981:diagnostic imaging / Q000378:metabolism*; D011498:Protein Precursors / Q000032:analysis*; D011859:Radiography; D012044:Regression Analysis; D012307:Risk Factors; D013582:Synovial Fluid / Q000737:chemistry*
D015415:Biomarkers; D002135:Calcium-Binding Proteins; D024043:Collagen Type II; D011498:Protein Precursors; C040072:chondrocalcin; D003094:Collagen