Muscle and tendon size relationships in a paralyzed chick embryo model of clubfoot

Clubfoot is a birth defect that may be related to muscle weakness or imbala nce. The purpose of this study was to examine the relationships among muscl e and tendon size and embryonic motility in a paralyzed chick embryo model of clubfoot and arthrogryposis. Decamethonium bromide, a neuromuscular bloc king agent, was administered to a series of embryos in five dosage groups, producing a cohort of embryos with various degrees of paralysis and atrophy of tendons and muscle. Embryonic movement frequency was monitored, and aft er death in late gestation. the cross-sectional areas of the calf musculatu re and the gastrocnemius tendon proximal to the ankle were measured histolo gically. Significant correlations were found between embryonic motility and both muscle(r(2) = 0.52) and tendon (r(2) = 0.77) areas. In addition, a si gnificant correlation (r(2) = 0.74) was found between muscle and tendon are as, suggesting that a measurement of one may be used to predict the other.