Generalized low areal and volumetric bone mineral density in adolescent idiopathic scoliosis.

Adolescent idiopathic scoliosis (AIS) may be associated with generalized low bone mineral status. The bone mineral density (BMD) of 75 girls of 12-14 years of age and diagnosed as having AIS were compared with 94 age-matched female control subjects. Areal BMD (aBMD) of the lumbar spine (L2-L4) and the bilateral proximal femur were measured using-energy X-ray absorptiometry (DEXA), and volumetric BMD (vBMD) of the nondominant distal radius and bilateral distal tibias was measured with peripheral quantitative computer tomography (pQCT). Relevant anthropometric parameters and the severity of the spinal deformity (Cobb's angle) also were evaluated and correlated with the BMD measurements. Results revealed the presence of a generalized lower bone mineral status in AIS patients. Detailed analysis showed that the aBMD and vBMD measured at the bilateral lower extremities were significantly lower in AIS patients when compared with the same in the normal controls. The most significant effect was seen in the trabecular BMD (tBMD) of the distal tibias. Of all the AIS girls, 38% of the aBMD and 36% of the vBMD were below -1 SD of the normal. BMD was found to correlate better with "years since menarche" (YSM) than with chronological age. When the BMD was evaluated for the 3 YSM groups, aBMD of the proximal femur and tBMD of distal tibias were found to be significantly lower in the AIS patients. Neither the aBMD nor the vBMD of AIS patients was found to be associated with the severity of spinal deformity. In addition, anthropometric measurements showed significantly longer arm span and lower extremities in the AIS girls. We concluded that the AIS girls had generalized lower aBMDs and vBMDs.

Correlation between curve severity, somatosensory evoked potentials, and magnetic resonance imaging in adolescent idiopathic scoliosis.

STUDY DESIGN: A prospective study in patients with adolescent idiopathic scoliosis of different clinical severity using whole-spine magnetic resonance imaging and somatosensory evoked potentials. OBJECTIVES: To correlate the presence of magnetic resonance imaging structural abnormalities with somatosensory evoked potential-detected functional disorders in the hind brain and spinal cord and the Cobb's angle in patients with adolescent idiopathic scoliosis and to compare the result with those in healthy matched control subjects. SUMMARY OF BACKGROUND DATA: Many different types of neurologic dysfunction have been reported in scoliosis. With the advent of magnetic resonance imaging, there are increased reports on the association of idiopathic scoliosis and syringomyelia, Chiari I malformation, or tonsillar ectopia. The actual link between structural and functional disorder in idiopathic scoliosis is, however, unclear. METHODS: Posterior tibial nerve evoked potentials and whole-spine magnetic resonance imaging were performed in 36 healthy control subjects, 135 patients with adolescent idiopathic scoliosis with Cobb's angle less than 45 degrees, and 29 patients with Cobb's angle more than 45 degrees. RESULTS: Tonsillar ectopia or syringomyelia, detected by magnetic resonance imaging, or functional disturbance in the somatosensory pathway, detected by somatosensory evoked potentials, was found to be significantly more frequent in the group of patients with severe scoliosis curvature, with an incidence of 31% and 27.6%, respectively. Incidence of tonsillar ectopia was 33.3% in patients with abnormal somatosensory evoked potentials in contrast to the much lower incidence of 2.9% in patients with normal somatosensory evoked potentials. There was a significant structural and functional link. The incidence of syringomyelia in patients with and without tonsillar ectopia was 33.3% and 0.7%, respectively. CONCLUSIONS: In patients with adolescent idiopathic scoliosis with severe curve, the significant association with tonsillar ectopia and abnormal somatosensory function points to a neural origin. Disorders in the somatosensory function may be one of the mechanisms linking tonsillar ectopia to scoliosis. Somatosensory evoked potentials and magnetic resonance imaging may have important diagnostic and predictive value and may help in the management of adolescent idiopathic scoliosis.

Persistent osteopenia in adolescent idiopathic scoliosis. A longitudinal follow up study.

STUDY DESIGN: A follow-up study assessing the bone mineral dynamics in adolescent patients with idiopathic scoliosis and associated osteopenia. OBJECTIVES: To investigate whether osteopenia in patients with adolescent idiopathic scoliosis is a transient phenomenon or a persistent problem. SUMMARY OF BACKGROUND DATA: Investigators have suggested a significant correlation of osteopenia with adolescent idiopathic scoliosis. Because one half of the skeletal mass is acquired during the adolescent years, it is of importance to know whether the osteopenia is transient or persistent. METHODS: Using dual-energy x-ray absorptiometry, bone mineral density of bilateral proximal femurs was studied longitudinally in 70 healthy control subjects and 14 patients with adolescent idiopathic scoliosis with significant osteopenia more than 2 standard deviations below the mean normal value. RESULTS: The 14 girls with osteopenic adolescent idiopathic scoliosis who were followed up longitudinally for up to 3 years showed persistent and significantly lower bone mineral density when compared with normal age-, sex- and maturity-matched control subjects. CONCLUSIONS: Patients with adolescent idiopathic scoliosis are at increased risk of osteoporosis than are healthy adolescents. The lower rate of increase of bone mineral density in patients with adolescent idiopathic scoliosis who have low bone mineral density could predict a significantly lower peak bone mass in adulthood, with all the associated problems of osteoporosis. Further investigation is needed to define whether osteopenia-associated scoliosis has the same cause, pathogenetic mechanism, and risk of progression when compared with adolescent scoliosis without osteopenia.

Posterior tibial nerve somatosensory cortical evoked potentials in adolescent idiopathic scoliosis.

STUDY DESIGN: Somatosensory-evoked potentials were used to evaluate neurologic function in patients with adolescent idiopathic scoliosis. OBJECTIVES: To compare the somatosensory-evoked potentials between patients with adolescent idiopathic scoliosis and healthy control individuals, and to determine the incidence of abnormal somatosensory function in patients with adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Somatosensory-evoked potentials are sensitive in detecting structural lesions in the somatosensory pathway. Previous studies on somatosensory function in patients with idiopathic scoliosis have demonstrated statistical differences in somatosensory-evoked potential latency between scoliotic and normal groups. However, no documentation of the actual incidence of abnormal somatosensory-evoked potentials is available. SUBJECTS AND METHODS: Posterior tibial nerve somatosensory cortical evoked potentials were evaluated on 147 young patients with adolescent idiopathic scoliosis and 31 healthy control individuals. RESULTS: Seventeen patients with idiopathic scoliosis showed pathologic evoked potentials. Among them were seven with absent somatosensory-evoked potential waveform and 10 with delayed latency. The results were reproducible on repeated measurement. CONCLUSIONS: Adolescent idiopathic scoliosis could be subdivided according to the somatosensory-evoked potential findings into two subgroups, those with and those without a somatosensory pathologic process. Potential clinical significance in predicting curve progression in idiopathic scoliosis could be pursued further.

Plasma bone-specific alkaline phosphatase as an indicator of osteoblastic activity.

The total plasma alkaline phosphatase level has long been recognised as an indicator of osteoblastic activity, but lack of specificity makes it an insensitive index of the progress of disease and the response to treatment. Selective precipitation by wheatgerm lectin allows measurement of the plasma bone-specific alkaline phosphatase. We measured the plasma levels of this isoenzyme in 170 normal Chinese adolescents and adults, in 49 adults with fractures of a long bone, in 15 patients with osteosarcoma and in 38 patients with osteolytic metastases. The enzyme activity was also determined in 39 patients with liver disease. Of the patients with fractures, 94% had increased plasma activity during the healing process. The level was also increased in those with osteosarcoma but not in those with osteolytic bone metastases. There was no significant increase in activity in the patients with liver disease. We conclude that the plasma bone-specific alkaline phosphatase activity is a sensitive and reliable measure of osteoblastic activity.

Energy metabolism in fracture healing. Measurement of adenosine triphosphate in callus to monitor progress.

We measured the adenosine triphosphate (ATP) content of callus at various intervals during healing in 78 fractured tibiae in 10- to 12-week-old rabbits. The results, compared with the level in normal tissues, showed a high rate of energy metabolism in the early phase of fracture healing, which persisted until the callus was corticalised and remodelling had started. The ATP content could provide a more sensitive index to monitor fracture healing in animal studies. Our findings lend support to the need for nutritional supplements for patients with multiple fractures.