Serum and knee synovial fluid matrix metalloproteinase-13 and tumor necrosis factor-alpha levels in patients with late-stage osteoarthritis.

OBJECTIVE: The aim of this study was to compare serum and synovial fluid levels of matrix metalloproteinase-13 (MMP-13) and tumor necrosis factor-alpha (TNF-α) in 2 stages of osteoarthritis, and investigate their correlation with Western Ontario and McMaster Universities Arthritis Index (WOMAC) scores.
METHODS: Forty-two patients (mean age: 64±8.8 years) with grade 3 and grade 4 knee osteoarthritis according to Kellgren-Lawrence criteria were enrolled in the study and underwent total knee arthroplasty. TNF-α and MMP-13 levels were measured preoperatively from venous blood samples and intraoperatively from knee synovial fluid via enzyme-linked immunosorbent assay. Preoperative and 1-month postoperative knee functions were assessed by WOMAC.
RESULTS: Grade 4 synovial fluid MMP-13 (4.76±5.82 pg/ml) was elevated compared to grade 3 (3.95±4.45), whereas grade 3 serum MMP-13 (1.128±0.308 pg/ml) was found elevated compared to grade 4 (1.038±0.204) (p=0.438, p=0.430, respectively). Grade 4 serum TNF-α (0.253±0.277) was elevated compared to grade 3 (0.206±0.219), whereas grade 3 synovial fluid TNF-α (0.129±0.052) was elevated compared to grade 4 (0.118±0.014). Positive correlation was observed between synovial fluid MMP-13 levels and postoperative WOMAC scores. Mean serum TNF-α (0.226±0.246 pg/ml) was elevated compared to synovial levels (0.124±1.59), and synovial MMP-13 (4.31±1.24) was elevated compared to serum levels (1.089±1.519).
CONCLUSION: Despite the systemic increase in TNF-α levels concordant with osteoarthritis grade, MMP-13 levels are elevated via local manner, with a significant correlation with WOMAC scores.