Estrogen promotes the onset and development of idiopathic scoliosis via disproportionate endochondral ossification of the anterior and posterior column in a bipedal rat model

Abstract

This study aimed to verify the effects of estrogen on the onset and development of adolescent idiopathic scoliosis and the mechanisms associated with these effects by constructing a pubescent bipedal rat model. Experiments were conducted to investigate whether scoliosis progression was prevented by a Triptorelin treatment. One hundred twenty bipedal rats were divided into female, OVX (ovariectomy), OVX + E2, Triptorelin, sham, and male groups. According to a spinal radiographic analysis, the scoliosis rates and curve severity of the female and OVX + E2 groups were higher than those in the OVX, Triptorelin, and male groups. The measurements obtained from the sagittal plane of thoracic vertebrae CT confirmed a relatively slower growth of the anterior elements and a faster growth of the posterior elements between T11 and T13 in the female and OVX + E2 groups than in the OVX and Triptorelin groups. Histomorphometry and immunohistochemistry revealed a significantly longer hypertrophic zone of the vertebral cartilage growth plates that expressed more type X collagen and less type II collagen in the OVX and Triptorelin groups than in the female and OVX + E2 groups. Ki67 immunostaining confirmed an increase in the proliferation of vertebral growth plate chondrocytes in the OVX group compared with the female and OVX + E2 groups. In conclusion, estrogen obviously increased the incidence of scoliosis and curve severity in pubescent bipedal rats. The underlying mechanism may be a loss of coupling of the endochondral ossification between the anterior and posterior columns. Triptorelin decreased the incidence of scoliosis and curve magnitudes in bipedal female rats.

Low Body Mass Index for Early Screening of Adolescent Idiopathic Scoliosis: A Comparison Based on Standardized Body Mass Index Classifications

“…Although the difference in the prevalence of man and woman adolescents with AIS as per the degree of curvature is unclear, this study shows that the overall prevalence in woman adolescents is higher than that in man adolescents. We can speculate that hormones such as estrogen and estradiol affect the development of scoliosis in woman adolescents [37,38].…”

Current concepts in the diagnosis and management of adolescent idiopathic scoliosis

“…Currently, AIS patients can undergo conservative or surgical management depending on the patient's skeletal maturity and curve severity. The SRS recommends that AIS patients who have not reached skeletal maturity and have curves less than 25°, or patients who have reached skeletal maturity and have curves less than 45°, be observed through radiological means every 6 months until skeletal mature then every 2 years after that in adulthood [3,49].…”

“…Another option is the Rigo Chêneau orthoses (RCOs) developed with the intent to combine biomechanical forces in three dimensions, including curve derotation [53]. The Milwaukee brace (cervico-thoracolumbo-sacral orthosis), on the other hand, is more difficult to hide and less well tolerated and subsequently no longer plays a role in modern AIS bracing techniques [49]. The brace should be applied for 16-20 h a day and success is defined as curve progression less than 5°by the conclusion of treatment [49].…”

“…The Milwaukee brace (cervico-thoracolumbo-sacral orthosis), on the other hand, is more difficult to hide and less well tolerated and subsequently no longer plays a role in modern AIS bracing techniques [49]. The brace should be applied for 16-20 h a day and success is defined as curve progression less than 5°by the conclusion of treatment [49]. Bracing is continued until the peak growth spurt has stopped indicated by Risser 4 or 2 years after menarche in girls or Risser 5 in boys.…”

“…After skeletal maturity, curves less than 30°m ay be discharged as these are not likely to progress. Nighttime braces (Charleston and Providence) are worn for 8 to 10 h a night and may be considered for skeletally immature patients with a single major curve of 25 to 35°and an apex below T8 [49].…”