Structural and biomechanical characteristics of the diaphragmatic tendon in infancy and childhood: an initial analysis.

Background: Engineered tendon grafts have been shown, experimentally, to be promising alternatives for partial diaphragmatic replacement. This study was aimed at determining the cellularity, extracellular matrix composition, and biomechanical characteristics of the diaphragmatic tendon in infants and children to be used as a reference for proper diaphragmatic graft engineering.

Methods: The left diaphragmatic tendon was procured at autopsy from 13 patients divided into 2 groups. Group I (n = 9) consisted of newborns and infants. Group II (n = 4) consisted of children and adolescents. Samples underwent quantitative assays for total DNA, glycosaminoglycans, collagen, and elastin contents. Biomechanical measurements included modular and ultimate tensile strength analyses. Statistical comparisons were by the 2-sample Student's t test.

Results: Group I showed significantly higher levels of total DNA, glycosaminoglycans, collagen, and elastin than group II. Conversely, group II tended to have higher modular and ultimate tensile strengths.

Conclusions: In neonates and infants, the diaphragmatic tendon has increased cell density and higher levels of major extracellular matrix components than in older children, in whom the diaphragmatic tendon tends to have higher tensile strength. Engineered diaphragmatic constructs should be tailored to the distinct anatomical, functional, and biomechanical characteristics of the diaphragmatic tendon at different age groups.