Effects of intercostal nerve resection on the longitudinal rib growth in the growing rabbit.

Two, three, or four intercostal nerves with their vasoconstrictive sympathetic fibers were resected on the right side of 15 growing rabbits. Animals submitted to sham operations and intact animals formed two control groups. A scintigraphic study with 99mTc-methylene diphosphonate, performed on the test group 2 months after the resection, showed a significantly greater uptake of the isotope on the right than on the left costochondral junctions (p less than 0.05). Three months later the difference was still larger. There was no such significant difference in the rabbits of the two reference groups. In the rabbits of both these groups, the right and left ribs of each pair were almost equal in length. Of the denervated ribs of the rabbits composing the test group, the right ribs increased in length to a greater extent than the corresponding left ribs. The difference was statistically significant (p less than 0.05). As a consequence of this left-right difference in length, mild thoracic scoliosis convex to the left developed 2 months after the resection. The total weight and volume of the denervated right ribs increased significantly more than those of the corresponding control left ribs (p less than 0.05), but their mineral content per unit of weight or volume showed no significant difference.