64 - Freie Mitteilung
16. Mai 2019, 13:45 - 15:15, Szenario 1, 5. OG
Load-induced changes in articular cartilage biomarkers before and after a high tibial osteotomy in patients with medial compartment knee osteoarthritis
A. Mündermann1, A.-M. Liphardt2, 3, G. Pagenstert1, C. Egloff1, C. Nueesch1, Presenter: A. Mündermann1 (1Basel, 2Erlangen/DE, 3Cologne/DE)
High tibial osteotomy (HTO) is a joint preserving surgery in patients with varus knee alignment and knee osteoarthritis. The goal of HTO is achieving a balanced transfer of ambulatory load between the medial and lateral compartments of the knee. We investigated load-induced changes in biomarkers of articular cartilage metabolism before and after opening wedge HTO in patients with medial compartment knee osteoarthritis.
Blood samples of ten patients (6 male; 44.3 ± 8.6 years, 25.8 ± 3.9 kg/m2) were collected 4 weeks before and 6 months after HTO, each time immediately before (t0) and 0, 0.5, 1.5, 3.5, and 5.5 hours (t1-t5) after a 30-minute walking exercise on an instrumented treadmill. Serum levels of cartilage oligomeric matrix protein (COMP), matrix metalloproteinase (MMP)-3, -1, 9, interleukin- (IL)-6, C-propeptide II (CPII), cleavage of type II collagenases (C2C), Proteoglycan 4 (PRG-4) und A disintegrin and metalloproteinase with thrombospondin motifs 4 (ADAMTS-4) were analyzed using commercial ELISA kits. Differences in serum levels were detected using ANOVA for repeated measures with surgery (pre/post) and time after 30-minute walking as within subject factors (P<0.05).
Baseline COMP values were higher and C2C and CPII values were lower after the HTO (P<0.05). Both pre- and postoperatively, COMP, MMP-3, C2C, and CPII increased by 10 to 70% immediately after the walking exercise, and PRG-4 decreased by 43% (P<0.05). Up to 5.5 hours after the walking exercise, COMP and MMP-3 decreased to up to 25% below the baseline levels. IL-6 decreased 3.5 and 5.5 hours after the walking stress test by more than 400 and 500%, respectively. Both pre- and postoperatively, PRG-4 and MMP-9 showed clear maxima 3.5 hours after the walking exercise.
The immediate and delayed load-induced changes in biomarkers of articular cartilage not only suggest diffusion of biomarkers but also (possibly delayed) metabolic processes, respectively. The decrease in PRG-4—or lubricin—immediately after the walking exercise may indicate increased friction of the arthritic joint. The lacking pre- to postoperative differences in load-induced changes in cartilage biomarkers may be caused by individually different load corrections of the HTO, which may result in individually different magnitude of load-induced changes. We will evaluate these possibilities in subsequent analyses.