Gait analysis in hallux valgus.

The solar pressure zones were analyzed in the feet of 66 patients suffering from hallux valgus, together with 60 normal subjects. The EMED Gait Analysis System was used. In the hallux valgus group, the maximum pressure was found to be increased significantly in the small toe region and more proximally situated, close to the metatarsophalangeal joint. In the normal subjects, the maximum pressure was increased significantly in the first, second, third, and fourth metatarsal and heel regions. In general, the hallux valgus group had smaller contact areas compared to the control group. The increased pressure in the small toe region, together with the smaller contact areas manifested by the hallux valgus group, were interpreted in this work as being the possible causes of the metatarsalgia seen in patients with the deformity.

Effects of rib elongation on the spine. I. Distortion of the vertebral alignment in the rabbit.

Elongation of one rib on the right side by 1 cm was achieved in two groups of adult rabbits of different age, by osteotomy and application of a metallic expander. The procedure resulted in immediate deviation of the spine in the frontal and sagittal planes, with moderate scoliosis, convex to the left, and a significant decrease in the normal cervicothoracic lordosis and thoracolumbar kyphosis. Moreover, computed tomography (CT) scanning demonstrated rotation of vertebra about the longitudinal axis relative to the anterior midline of the body, and deviation of the spinous process toward the convex, left side, of the scoliotic deformity. Rib hump developed on the right side--that of the elongated rib. These changes, which occurred simultaneously in the three planes, were less pronounced in the group of older animals. Two weeks after the operation, the distorted configuration of the spine remained unchanged. The observed changes in the alignment of the vertebrae--changes that, except for their direction on the horizontal plane, resembled those associated with idiopathic scoliosis in man--support the earlier proposed link between the early stage of development of this condition and asymmetry of rib growth.

Effects of rib elongation on the spine. II. Correction of scoliosis in the rabbit.

Three intercostal nerves on the right side of growing rabbits were resected partially. From 1 to 3 months later, moderate left-convex thoracic scoliosis with rotation of vertebrae had developed, and the sagittal curvatures of the spine had diminished. In one group of these animals, a mechanically produced increase of 1 cm in the length of one rib on the side of the convexity resulted in an immediate correction of the scoliotic deformity, an improvement that was still evident 3 weeks after the operation. In two other groups of rabbits, a further resection of three intercostal nerves, this time on the left convex side, 1 and 2 months after the first operation, resulted in regression of scoliosis or halted its progression. These results further support a new concept in which the precipitating factor in the development of scoliosis is ascribed to asymmetric longitudinal growth of the ribs. They also suggest that regulation of the rib length could be a promising approach to the effective correction of progressive scoliosis at an early stage in man.

Vascular changes in the chest wall after unilateral resection of the intercostal nerves in the growing rabbit.

In young, growing white New Zealand rabbits the third, fourth, and fifth intercostal nerves were resected anteriorly on the right side. Six months later the animals developed structural left convex scoliosis, with a Cobb angle ranging from 15 to 31 degrees. The vascular structure changes of the anterior chest wall were evaluated by measuring surface temperature and fluorescein intensity of the pectoral muscles, and the capillary density of the pectoral and intercostal muscle and periosteal parts of the ribs after angiography. In five normal control rabbits there was neither scoliotic deformity nor significant differences in the examined vascular variables between the right and left sides. In the animals undergoing resection, the temperature of the pectoral muscle on the side of the denervation--the right side--was significantly increased (p less than 0.05), but the difference was not correlated to the degree of scoliosis. The fluorescence index was significantly greater (p less than 0.05) on the right than on the left side, this difference being fairly strongly correlated to the degree of scoliosis. The capillary densities of the costal periosteum and the intercostal and the pectoral muscle were significantly greater (p less than 0.05) on the right than on the left side, and the difference was positively correlated to the degree of scoliosis. The volume density of the periosteum of the ribs was likewise significantly greater on the right. These results demonstrate that unilateral resection of the intercostal nerves significantly increases the vascularity of the structures on the denervated side of the thorax.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Induction of scoliosis in the growing rabbit by unilateral rib-growth stimulation.

Growing rabbits were subjected to surgical resection of the intercostal nerves on the right side, posteriorly or anteriorly. Two other groups of animals were used as sham and as normal controls. Six months after the nerve resection, there was no electromyographic evidence of denervation of the involved muscles. Radiologic examinations revealed progressive development of a curve, convex to the left, in each animal of the two resection groups. Analysis of structural changes by computed tomography showed rotation of the apical vertebra about the longitudinal axis. Rib cage deformity was diagnosed in 82% of the rabbits. The experimental model developed for induction of scoliosis is simple. The surgical procedure involves just one selected and easily recognized anatomic structure, leaving the vertebral structures and their vicinity intact. Reliable analysis of the underlying mechanism of the developing scoliosis is thereby assured.