Biochemical and molecular homogeneity in the patellar tendon of the immature pig.

Patellar tendon is widely used for reconstruction of the anterior cruciate ligament. However, few studies have investigated the tendon's homogeneity, a characteristic often assumed of it in experiments. In this study, the assumption that the patellar tendon is homogeneous was tested by dividing the central half of the tendon into six sections along its length and width and comparing commonly measured biochemical parameters and patterns of gene expression among these sections. No significant differences were found between the sections for any of the studied parameters: water content (p > 0.5), DNA content (p > 0.9), total collagen content (p > 0.8), amount of type I collagen (p > 0.7) or type-III collagen (p > 0.7), or expression of mRNA (p > 0.9). For all parameters, the minimum power value for statistical analyses was greater than 0.80. It was concluded that the central half of the tendon is homogeneous in terms of all of the measured parameters. The results provide important information for the many experiments that sample part of the patellar tendon to infer the characteristics of the whole tendon, e.g., biopsy studies.