[Identification of the best sites for the histopathological study of tarsitis in patients with spondyloarthropathies].

BACKGROUND: Foot involvement in patients with spondyloarthropathies (SpA) includes a peculiar clinical spectrum ranging from tarsal swelling to bone ankylosis similar to axial disease in patients with ankylosing spondylitis. Hypothetically, the study of these lesions could help to explain phenomena that occur in the vertebral column.

OBJECTIVE: To identify the best site for sampling foot tissues in cadavers with a view to implementing the procedure in patients with SpA.

MATERIAL AND METHODS: Six sites including foot tendons and entheses from the cadavers of individuals<50 years with no musculoskeletal disease were selected by consensus. Tissue samples included>1 cm of endon and synovial sheath and 0.2 mm of periosteum, which were fixed in 5-formaldheid solution, 70% alcohol and paraffin. Paraffin blocks were then cut into 3? slices and stained with hematoxylin, eosin and Masson trichromic.

RESULTS: There were 31 pieces of tendon, 8 pieces of entheses and 5 pieces of periosteum, but no synovial membrane was identified. Tendons were identified in more than a half of the sites biopsied and entheses in 50% of samples from the upper segment of the tendon and synovial sheath of the tibialis posterior and the peroneus brevis insertion on the 5th metatarsal head. Tendon tissues consisted of fusiform cells in an undulated pattern separated by fine bands of loose and dense connective tissue. Entheses included tendon, epitendon and endotendon attachments to bone through a small fragment of non-calcified fibrocartilage.

CONCLUSION: Slightly more than 50% of the sites selected for study contained tendon tissues useful for histologic examination. The same results were obtained for enthuses in only one site. Overall, these sites appear suitable for study in patients with SpA.