Ruptured Achilles tendons show increased lectin stainability

PURPOSE: To ascertain whether lectins could be a useful tool for investigation of the extracellular matrix of degenerated and normal tendons. METHODS: Hematoxylin-eosin-stained slides were assessed blindly using a semiquantitative grading scale for fiber structure, fiber arrangement, rounding of the nuclei, regional variations in cellularity, increased vascularity, decreased collagen stainability, hyalinization, and glycosaminoglycan, with a pathology score giving up to three marks per each of the above variables, with 0 being normal and 3 being maximally abnormal. For lectin staining with Aleuria aurantia, Canavalia ensiformis, Galanthus nivalis, Phaseolus vulgaris, Arachis hypogea, Sambucus nigra, and Triticum vulgaris, assessment of staining on a scale from 0 (no staining) to 5 (strong staining) was performed blindly. RESULTS: The mean pathology sum score of ruptured tendons (N = 14; average age 46.5 yr, range 29-61) was significantly greater than the mean pathology score of the control tendons of Achilles tendons from individuals with no known tendon pathology (N = 16; average age 62.5 yr, range 49-73) (pathology score: 18.5 +/- 3.2 vs 6.1 +/- 2.3). Four of the seven lectins used exhibited significantly positive results. CONCLUSIONS: Ruptured tendons were histologically significantly more degenerated than control tendons. Ruptured tendons showed different lectin staining properties than nonruptured ones. This difference may have resulted from posttranslational changes in the extracellular matrix producing alterations in the biochemistry of the tendon, which might interfere with the interaction with the lateral sugar residues of the collagen molecules or cause steric blockade.