Predictability of spontaneous thoracic curve correction after anterior thoracolumbar correction and fusion in adolescent idiopathic scoliosis. A retrospective study on a consecutive series of 29 patients with a minimum follow-up of 2 years.

BACKGROUND CONTEXT: According to the Lenke classification, a Type 5 adolescent idiopathic scoliosis can be surgically treated with selective anterior thoracolumbar or lumbar fusion. PURPOSE: This study aims to predict the spontaneous correction of the unfused thoracic curve after anterior thoracolumbar fusion and to study whether age is of influence on this predictability. STUDY DESIGN: Retrospective study on a consecutive series of patients. PATIENT SAMPLE: Of a consecutive series of 38 patients with idiopathic thoracolumbar scoliosis, Lenke type 5, 29 patients were included in the study. All patients were treated with anterior spinal fusion and instrumentation. A minimum follow-up of 2 years was available for all patients (mean, 4 years; range, 2-17 years). To investigate the influence of age on the outcome, we divided the group into two subgroups: an adolescent (n=13) and an adult age group (n=16). The mean age in the adolescent group was 17 (range, 13-21 years) and 38 years (range, 22-54 years) in the adult group. OUTCOME MEASURES: Physiological measures include coronal Cobb angle, apical vertebral translation (AVT) and apical vertebral rotation (AVR), shoulder tilt, trunk shift, L4 tilt, and pelvic tilt. Relative corrections were computed for the thoracolumbar and thoracic curves in each patient using the following formula: (preoperative curve-postoperative curve)/preoperative curve×100 (%). The correlation coefficient between the relative (%) corrections of the thoracic and thoracolumbar curves was calculated for the whole group as for the two age subgroups. METHODS: For radiographic evaluation, we used standing anteroposterior and lateral projections of the thoracolumbar spine to determine Cobb angle, AVT and AVR, and coronal balance. RESULTS: Both the thoracolumbar and thoracic curves in the whole group improved after surgery (45% and 19%, respectively, p<.01). In the adolescent age group, a significant correlation between the relative (%) correction of the thoracolumbar curve and the relative (%) correction of the thoracic curve was found (R=0.704; p=.01) and between age and relative (%) correction of the thoracic curve (R=-0.805; p<.01). CONCLUSIONS: These results show that the spontaneous correction of the thoracic curve is a reflection of the thoracolumbar curve correction in adolescent thoracolumbar idiopathic scoliosis. Moreover, the predictability of the thoracic curve correction in the individual patient seems to decrease with increasing age of the patient.

Pulmonary function after less invasive anterior instrumentation and fusion for idiopathic thoracic scoliosis.

PURPOSE: Standard thoracotomy for anterior instrumentation and fusion of the thoracic spine in idiopathic scoliosis may have detrimental effects on pulmonary function. In this study we describe a less invasive anterior surgical technique and show the pre- and postoperative pulmonary function with a minimum follow-up of 2 years. METHODS: Twenty patients with Lenke type 1 adolescent thoracic idiopathic scoliosis were treated with anterior spinal fusion and instrumentation. The mean preoperative Cobb angle of the thoracic curve was 53° ± 5.8. Pulmonary function tests (PFT) and radiographic evaluation was performed. RESULTS: The mean postoperative correction in Cobb angle of the thoracic curve was 27° ± 8.2 (49%).The mean preoperative FEV1 was 2.81 ± 0.43 L, which increased to 3.14 ± 0.50 L at 2 years postoperatively (P = 0.000). The mean FEV1% did not change (89.60 ± 7.49% preoperatively, versus 90.53 ± 5.95% at 2 years follow-up, P = 0.467). The TLC increased from 4.62 ± 0.62 L preoperatively to 5.17 ± 0.63 L at 2 years follow-up (P = 0.000). The FEV1% at two years of follow-up improved to 104% of the FEV1% predicted value. The FEV1 improved to 97% of the FEV1 predicted value. CONCLUSION: Anterior spinal fusion for idiopathic scoliosis by means of a minimal open thoracotomy proved to be a safe surgical technique that resulted in an improvement of pulmonary function. Our results are similar to those of thoracoscopic procedures reported in literature.

Predictability of the spontaneous lumbar curve correction after selective thoracic fusion in idiopathic scoliosis.

In this study we tried to achieve a better understanding of the biodynamic mechanism of balance in the scoliotic spine. Therefore we focused on the pre- and postoperative spine of patients with idiopathic scoliosis with a primary thoracic curve and a secondary lumbar curve. Several studies showed that the lumbar curve spontaneously corrects and improves after selective thoracic fusion. We try to understand and describe this spontaneous compensatory lumbar curve correction after selective thoracic correction and fusion. We performed a retrospective examination of pre- and postoperative radiographs of the spine of 38 patients with idiopathic scoliosis King type II and III. Frontal Cobb angles of the thoracic and lumbar curves were assessed on pre- and postoperative antero-posterior and side bending radiographs. We determined the postoperative corrections of the thoracic and lumbar curves. Relative (%) corrections and correlations of the postoperative corrections were calculated. The group was divided in three subgroups, depending on lumbar curve modifier, according to Lenkes classification system. The calculations were done for the whole group as for each subgroup. As expected, significant correlations were present between the relative correction of the main thoracic and the lumbar curve (mean R = 0.590; P = 0.001). The relation between relative thoracic and lumbar correction decreased with the lumbar modifier type. This study shows a highly significant correlation between the relative corrections of the main thoracic curve and the lumbar curve after selective thoracic fusion in idiopathic scoliosis. This correlation depends on lumbar curve modifier type. This new classification system seems to be of great predictable value for the spontaneous correction of the lumbar curve. Depending on the curve-type, a different technique for predicting the outcome should be used. The lumbar curve correction does not occur throughout the whole lumbar curve. Most correction is achieved in the upper part of the curve. The distal lumbar curve seems to be more rigid and less important in the spontaneous curve correction.

Predictable correction of the unfused lumbar lordosis after thoracic correction and fusion in Scheuermann kyphosis.

STUDY DESIGN: A retrospective examination of preoperative and postoperative radiographs of the sagittal spine of 30 patients with Scheuermann kyphosis. OBJECTIVES: To determine significant correlations between kyphosis and lordosis in Scheuermann kyphosis, determine predictability of spontaneous sagittal lordosis correction after thoracic correction and fusion, and understand better the biomechanics of the spine. SUMMARY OF BACKGROUND DATA: Previous studies described relations between kyphosis and lordosis in healthy people. To our knowledge, no relationships, have been described between kyphosis and lordosis in Scheuermann kyphosis. METHODS: On radiographs, maximum kyphosis, maximum lordosis, sacral slope and L5-S1 angle were measured in the preoperative and postoperative standing lateral radiographs of the spine, and correlations were calculated. RESULTS: Preoperative significant correlations were present between kyphosis and lordosis (R = 0.421; P = 0.021), and between lordosis and sacral slope (R = 0.824; P < 0001). Postoperative correlations were stronger (R = 0.591; P = 0.001 and R = 0.844; P < 0.001). The percentage of correction of kyphosis was correlated with the percentage of spontaneous decrease of lordosis (R = 0.593; P < 0.001). A negative correlation between L5-S1 angle and upper lumbar segment of lordosis was found before and after surgery. CONCLUSIONS: This study shows a significant correlation between kyphosis and lordosis before and after surgery. Surgical correction of thoracic hyperkyphosis gives a predictable spontaneous decrease of lumbar lordosis. Correction of lordosis occurs mainly in the upper segment of lumbar lordosis.