Ultrasonography and Low-field Magnetic Resonance Imaging of the Common Calcanean Tendon in a Rabbit Model for Tendinopathy Research: a Descriptive Study of Normal Anatomy.

In spite of recent advances in treatment protocols, tendinopathies continue to challenge orthopaedists and surgeons. Due to the complexity of both tendon injuries and the healing processes, animal models are essential for addressing fundamental questions in tendinopathy research. Diagnostic imaging could contribute to the evaluation of animal models, thus providing information, which could be translated to human tendinopathies. The objective of our study was to evaluate in situ appearance of the rabbit common calcanean tendon with ultrasonography and magnetic resonance imaging. Additionally, we sought to assess and compare the feasibility and usefulness of these techniques in a rabbit model while focusing on the imaging of the particular structures involved in calcaneal tendon disorders. Eight California rabbits were used for post-mortem sonographic and low-field magnetic resonance examination. Morphometry was performed on longitudinal sonograms and sagittal MRI scans. The craniocaudal diameter of the tendon was measured at four points of interest. Ultrasonography and magnetic resonance provided good visualisation of the tendon origin, the paratenon and the pre-Achilles fat pad. Magnetic resonance images presented in more detail the structure of the calcaneal insertion. Both modalities failed to visualise the individual components of the common calcanean tendon and the bursa of the calcaneal tendon. Statistical analysis of measurements obtained showed that the craniocaudal diameter of the common calcanean tendon in a rabbit increases significantly with a growing length from the calcaneal tuber. Both magnetic resonance and ultrasonography are feasible, and should be considered complementary, not alternative imaging techniques in a rabbit common calcanean tendon model.

Rabbit common calcanean tendon as an animal model: ultrasonographic anatomy and morphometry.

BACKGROUND: The aim of the present study was to evaluate usefulness of ultrasonography in assessment of rabbit common calcanean tendon, to describe its ultrasonographic anatomy and to perform morphometric analysis of this structure. MATERIALS AND METHODS: Fifteen skeletally-matured New Zealand rabbits were used in the study. Ultrasonographic examinations of common calcanean tendon (CCT) were performed in longitudinal and transverse planes from caudal approach. Sagittal diameters of superficial digital flexor tendon and CCT were measured on longitudinal scans. Sagittal and transverse diameter, cross-sectional area and perimeter of the CCT were assessed on transverse scans. Statistical analysis was performed using StatisticaPL software (StatSoft®, Poland). RESULTS: In longitudinal images structure of CCT was clearly visualised. Its superficial hypoechoic part corresponds to superficial digital flexor tendon and deeper hyperechoic to gastrocnemius tendon. In transverse images cross-sectional area presented varied echotexture. Proximally, CCT was rounded in transverse section and became slightly wider and flattered distally. Statistical analysis showed no differences between results obtained from right and left hindlimb (p > 0.05). Measurements of sagittal diameter of CCT obtained in transverse planes were significantly higher than sagittal diameter measurements obtained in longitudinal plane in corresponding locations (p < 0.001). All performed measurements showed a growing trend with the increasing distance from the calcaneal tuber. CONCLUSIONS: Ultrasonography is suitable technique for assessment of CCT in a rabbit model and provides satisfactory images for morphometrical evaluation.

Comparative analysis of markers of cell proliferation in canine mast cell tumours according to current classifications.

The study aimed at immunohistochemical analysis of various markers of cell proliferation and comparison of the results with canine mast cell tumours grading systems according to the Patnaik and Kiupel. Tissue sections were stained using classical technique with haematoxylin and eosin, and immunohistochemical studies were performed with Ki-67, PCNA and MCM-3 antibodies. Additionally the mitotic index was assessed. Statistical analysis including rank correlation Spearman's and ANOVA Friedman analysis was performed. The significance was set at p<0.05. Expression of all examined antigens was detected. The results obtained allow concluding that there is a strong relationship between all the cell markers. However, due to the very strong response and positive reaction in the majority of tumours PCNA is not recommended as a prognostic indicator. Ki-67 and MCM-3 can be successfully used in the evaluation of canine mast cell tumours.