Tibial plateau levelling osteotomy: significance of matrix metalloproteinases in long-term monitoring of canine stifle stabilization after cranial cruciate ligament rupture.

Cranial cruciate ligament rupture is one of the most common causes of osteoarthritis in dogs. Surgical stabilization is obligatory and tibial plateau levelling osteotomy (TPLO) is the most commonly used surgical technique. Studies on the long-term monitoring of matrix metallo-proteinases (MMPs) and acute-phase proteins are limited, especially those with parallel monitoring of changes in the serum, synovial fluid (SF) and urine. We aimed to describe long-term changes in 1) MMPs: gelatinases and caseinases, 2) APPs: ceruloplasmin, haptoglobin and paraoxonase-1, and 3) the correlation of MMPs in the serum, SF and urine with lameness in dogs 2 and 6 months undergoing TPLO. From 17 dogs diagnosed with cranial cruciate ligament rupture, sera, SF and urine samples were collected preoperative 2 and 6 months after the surgery. Relative activity (RA) of MMPs was measured in all samples using zymography. Acute-phase proteins were measured in the serum and SF using spectrophotometry and agarose gel electrophoresis. Relative activity of MMPs in serum was not change at different sampling points. In SF, a marked decrease in MMPs RA was evident, however, only RA of caseinases was significantly reduced during the recovery period. In urine, RA of caseinases was positively correlated with the lameness score with decreasing activity trend during time. Serum and synovial acute-phase proteins were not changed after surgery, which was consistent with the agarose gel analyses. Decreased activity of caseinases pointed to reduced degradation of extracellular matrix after TPLO. Synovial and urine caseinases are potential biomarkers in predicting the recovery outcome following stifle stabilization.