Fig 1.
Anatomic dissection of the Achilles (A) and plantaris tendons in rabbits (B). (A) Posterior view. (B) Lateral view. The plantaris tendon is located in a superficial and dorsal position in relation to the Achilles tendon.
Fig 2.
Injection performed under direct visualization, in the central region of the substance of the Achilles tendon, using 27 gauge needle coupled in a 100 microliters syringe.
Fig 3.
Distribution of the study groups.
Flowchart for groups distributions, timing of injections and euthanasias.
Fig 4.
Histological Bonar score grading system.
Five different characteristics evaluated, each one graded from zero to three: Line 1: cell morphology (200x magnification, H&E and safranin); Line 2: cellularity (100x magnification, H&E); Line 3: vascularization (400x magnification, H&E); Line 4: accumulation of ground substance (100x magnification, Alcian blue); Line 5: collagen fibers arrangement (polarized light, 100x magnification, picrosirius).
Fig 5.
Specimen (A) attached to the test machine by a cylindrical (B) and a cryogenic clamp (C).
Fig 6.
Histological results after 16 weeks.
(A) Hematoxylin-Eosin, 40x. Control Group: cell morphology slightly altered, well delimited collagen bundles, minimal increase in cellularity, no changes in vascularization or ground substance. (B) HD Group: increased cellularity, altered cellular morphology with greater roundness of the cellular nuclei, loss of the wavy pattern of collagen bundles and areas of neovascularization (black arrows). (C) LD Group: Areas of increased, decreased and acellularity, destruction of collagen bundle architecture, increased number vascular clusters (black arrows) loss of collagen bundle architecture (D) LD Group: diffuse increase of the ground substance, altered cellular morphology, rounding of cell nuclei with halo formation, compatible with chondroid metaplasia (white arrows).
Table 1.
Histological Bonar score: Mean values, standard deviation, Minimum, Median and Maximum values by Group at different euthanasia time-points.
Table 2.
Two-Way ANOVA analysis for histological Bonar score.
Degrees of Freedom, Sum of Squares, Mean Square, F-Value and P-values. Significant influences observed for all variables: Group, Time-point (Weeks) and interaction between Group and Time-point.
Table 3.
Biomechanical parameters at 10 weeks: Mean value and standard deviation for specimens in the Low-Dose (LD) and High-Dose (HD) Groups.
Table 4.
Biomechanical parameters at 12 weeks: Mean value and standard deviation for specimens in the Low-Dose (LD) and High-Dose (HD) Groups.
Table 5.
Biomechanical parameters at 16 weeks: Mean value and standard deviation (SD) for specimens in the Low-Dose (LD), High-Dose (HD) and control Groups.