The value of cartilage biomarkers in progressive knee osteoarthritis: cross-sectional and 6-year follow-up study in middle-aged subjects
Rheumatology International, 07/27/2012

Kumm J et al. – This is the first study to demonstrate biochemical differences over the course of knee osteoarthritis (OA), illustrating a phasic nonpersistent character of OA with periods of progression and stabilization.

• Design tibiofemoral (TF) and patellofemoral (PF) radiographs were graded in 128 subjects (mean age at baseline, 45 ± 6.2 years) in 2002, 2005, and 2008.
• Cartilage degradation was assessed by urinary C–telopeptide fragments of type II collagen (uCTx–II), synthesis by serum type II A procollagen N–terminal propeptide (sPIIANP), and articular tissue turnover in general by cartilage oligomeric matrix protein (sCOMP).

• Several diagnostic associations were found between all studied biomarkers and progressive osteophytosis.
• COMP and CTx–II had a predictive value for subsequent progressive osteophytosis in multiple knee compartments and in case of CTx–II—also for progressive JSN. Over the first 3 years (2002–2005), significant associations were observed between COMP and progressive osteophytosis, whereas 3 years later (2005–2008) between CTx–II and progressive JSN.
• Thus, the associations between cartilage markers (COMP, CTx–II) and progression of radiographic OA features—osteophytes and JSN—were different between 2002–2005 and 2005–2008.
• Logistic regression revealed that for every unit increase in COMP level, there was 33 % higher risk for TF osteophyte progression.
• During early–stage OA, the presence and progression of osteophytosis is accompanied by increased level of cartilage biomarkers.