The Efficacy of Proximal Lumbar Curve Flexibility in Patients with Main Thoracic Adolescent Idiopathic Scoliosis Treated by Selective Thoracic Fusion Surgery

STUDY DESIGN: Retrospective radiographic study. PURPOSE: To evaluate the efficacy of the proximal lumbar curve flexibility compared with the traditional whole lumbar curve flexibility in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS). OVERVIEW OF LITERATURE: Traditionally the flexibility of the whole lumbar curve was measured, and the flexibility of the proximal lumbar curve was not analyzed in any study. METHODS: Twenty-eight MT-AIS patients treated by anterior selective thoracic fusion (STF) were evaluated after mean follow-up of 50.1 months (range, 25 to 116 months). The male : female ratio was in 5 : 23. The man age at surgery was 14 years and 8 months (range, 11.4 to 18.4 years). The lumbar curve was divided into the proximal and distal curves by the lumbar apex. RESULTS: The mean final correction rates (CR)/(flexibilities) of the MT, lumbar, proximal lumbar, and distal lumbar curves were 65.2%/(50.5%), 61.9%/(92.8%), 65.3%/(90.9%), and 36.4%/(134%), respectively. With the final lumbar CR, the lumbar flexibility (r = 0.267, p > 0.05) and the proximal lumbar flexibility (r = 0.327, p > 0.05) was similarly correlated. The mean lumbar CR was similar to the proximal lumbar CR (61.9% vs. 65.3%, p = 0.305). And the correlation between the flexibility and the CR was significant only in the proximal lumbar curve (r = 0.457, p 0.05) or the distal lumbar curve (r = 0.175, p > 0.05). CONCLUSIONS: The proximal lumbar curve flexibility may be an alternative method of measuring the lumbar flexibility in MT-AIS patients treated by STF.

Axial Plane Lumbar Responses after Anterior Selective Thoracic Fusion for Main Thoracic Adolescent Idiopathic Scoliosis

STUDY DESIGN: A retrospective radiographic study. PURPOSE: To evaluate the axial plane lumbar responses after anterior selective thoracic fusion (STF) in patients with main thoracic adolescent idiopathic scoliosis (MT-AIS). OVERVIEW OF LITERATURE: Anterior scoliosis surgery induces more MT derotation through disc preparation than posterior surgery. METHODS: Twenty-eight MT-AIS patients treated with STF were evaluated after a minimum follow-up (FU) of 2 years. The MT and lumbar coronal angles, as well as the MT and lumbar rotational angles at the most rotated vertebrae were measured. RESULTS: At the last FU, the MT coronal correction and derotation rates were 65% and 41%, respectively. The lumbar coronal correction rate was 61% but there was minimal lumbar derotation (2%). Nine cases were decompensated (coronal balance >10 mm). After surgery, the compensated and decompensated groups showed similar MT coronal and axial correction rates. During the FU, the MT and lumbar apecies rotated in the same direction (r=0.443). In addition, significant MT derotation occurred in the decompensated group with increasing lumbar rotational correction loss. At the last FU, while the MT coronal correction was similar between the two groups, there was more MT derotation in the decompensated group. Furthermore, the MT rotational change was strongly associated with the coronal C7 plumb line position (r=0.728). CONCLUSIONS: After anterior STF in patients with MT-AIS, the final MT derotation is strongly associated with the coronal C7 plumb line position. During the FU, the excessive MT derotation in the decompensated group was attributed to excessive lumbar rotational correction loss.

Sagittal Plane Lumbar Responses after Anterior Selective Thoracic Fusion for Main Thoracic Adolescent Idiopathic Scoliosis

STUDY DESIGN: A retrospective radiographic study. PURPOSE: To verify the correlation of sagittal and coronal plane changes after selective thoracic fusion in main thoracic (MT) adolescent idiopathic scoliosis (AIS). OVERVIEW OF LITERATURE: Sagittal plane deformity is known to be essential in the evolution of scoliosis. METHODS: Twenty-eight MT AIS patients treated by anterior selective thoracic fusion were evaluated after minimal follow-up of two years. The unfused lumbar area was divided into proximal and distal parts by the lumbar apex in the coronal plane, and into proximal and distal lumbar lordosis by L2 in the sagittal plane. Surgical motion (the difference between preoperative and postoperative values) and follow-up motion (the difference between postoperative and the last follow-up values) were compared. RESULTS: Immediately after surgery, as thoracic kyphosis increased, lumbar lordosis decreased (r=0.734); proximal lumbar lordosis increased, and distal lumbar lordosis decreased. The proximal lumbar area was mobilized in the sagittal plane, and was straightened in the coronal plane. However, the distal lumbar area was stabilized in the sagittal plane, and showed resistant motion against MT translation in the coronal plane. The surgical motion was correlated to the follow-up motion, i. e., was regulated during follow-up, and the regulatory motion was more precise in the distal than proximal lumbar area in both sagittal and coronal planes. CONCLUSIONS: Sagittal and coronal motions were co-related; optimal sagittal motions were necessary for optimal coronal motions after anterior selective thoracic fusion for MT AIS. Proximal and distal lumbar motions were different for different roles; the proximal lumbar area played a role as a bumper to absorb the MT translatory force, and the distal lumbar area played a role of resistance against MT translation.

Selective Thoracic Fusion with Segmental Pedicle Screw Fixation for the Treatment of Thoracic Idiopathic Scoliosis: More than Five Year's Follow-Up / 대한척추외과학회지

STUDY DESIGN: This is a retrospective study. OBJECTIVES: We wanted to evaluate the outcomes of selective thoracic fusion with segmental pedicle screw fixation for treating thoracic idiopathic scoliosis with a minimum 5-year follow-up. SUMMARY OF THE LITERATURE REVIEW: Segmental pedicle screw fixation has been proven to achieve true segmental control and greater correction of scoliosis in both the coronal and sagittal planes. However, there is no long-term study of selective thoracic fusion with segmental pedicle screw fixation for treating thoracic idiopathic scoliosis. MATERIALS AND METHODS: We analyzed 203 thoracic idiopathic scoliosis patients (236 thoracic curves) who underwent selective thoracic fusion with segmental pedicle screw fixation. The mean patient age at the time of operation was 13.8 years (range: 8.9~18 years). RESULTS: The preoperative thoracic curve of 51+/-12 degrees was corrected to 16+/-7 degrees(69% correction with 3% loss of correction) at the most recent follow-up. The non-instrumented lumbar curve of 30+/-10 degrees was corrected to 10+/-8 degrees(66% correction with 5% loss of correction) at the most recent follow-up. The preoperative thoracic kyphosis of 18+/-11 degrees and the lumbar lordosis of 43+/-10 degrees were improved to 23+/-8 degrees and 46+/-9 degrees, respectively, at the most recent follow-up. There was no junctional kyphosis at the most recent follow-up. Coronal decompensation at the most recent follow-up occurred in 10 patients. Postoperative adding-on occurred in 17 patients who were fused two levels short of the neutral vertebra. Of the 2867 thoracic pedicle screws inserted at the thoracic level, 43 screws were found to be malpositioned (1.5%), but they did not cause neurologic complications or adversely affect the long-term results. CONCLUSIONS: Selective thoracic fusion with segmental pedicle screw fixation for treating thoracic idiopathic scoliosis had satisfactory radiographic and clinical outcomes after surgery, and the outcomes were well-maintained for a minimum of 5 years follow-up. It is a safe and effective method for preserving segments of lumbar motion as well as for the restoration and maintenance of both the coronal and sagittal alignments.

Decompensation in Selective Thoracic Fusion by Segmental Pedicle Screw Fixation in King type II Adolescent Idiopathic Scoliosis (AIS): Causative Factors and its Prevention / 대한척추외과학회지

STUDY DESIGN: A retrospective study. OBJECTIVES: To find the causative factors which induce decompensation after selective thoracic fusion with segmental pedicle screw fixation in King type II AIS. SUMMARY OF LITERATURE REVIEW: Pedicle screw fixation enabling enhanced correction is increasing in use in idiopathic scoliosis. However, there are few reports on the decompensation after selective thoracic fusion with pedicle screw fixation in King type II AIS. MATERIALS AND METHODS: Thirty-nine King type II AIS patients subjected to selective thoracic fusion with pedicle screw fixation were analyzed after a minimum follow up of 1 year. They were reviewed using standing roentgenograms. Deviation of center of T1 from center sacral line greater than 2 cm was considered decompensation. RESULTS: Among 39 patients, compensation was in 35 while decompensation in 4 postoperatively. There was no significant differences between the two groups in preoperative thoracic or lumbar curve characteristics such as curve magnitude, apical deviation or apical rotation. There was a significant difference in thoracic curve correction and postoperative T-curve magnitude divided by preoperative L-curve respectively(p= 0.001). CONCLUSION: Decompensation with selective thoracic fusion with segmental pedicle screw fixation in King type II AIS was not induced by preoperative L-curve characteristics nor derotation maneuver. The factor of decompensation was overcorrection, i.e. if thoracic curve correction was more than 75% or if the magnitude of postoperative T-curve was 30% less than that of preoperative L-curve, there was a high risk of decompensation.

Clinical Results of Selective Thoracic Fusion by Segmental Pedicle Screws in King type II Adolescent Idiopathic Scoliosis ( AIS ) / 대한정형외과학회잡지

STUDY DESIGN: This study analyzes the results of selective thoracic fusion by segmental pedicle screw fixation in King type II adolescent idiopathic scoliosis(AIS). OBJECTIVES: To verify the efficacy of selective thoracic fusion by segmental pedicle screw fixation in King type II adolescent idiopathic scoliosis. SUMMARY OF BACKGROUND DATA: Decompensations following selective thoracic fusion in King type II adolescent idipathic scoliosis have been attributed to relative inability of the lumbar curves to accommodate correction of the thoracic curves. However, with segmental pedicle screw fixation, selective thoracic fusions yielded satisfactory results in most of the patients regardless of the lumbar curve characteristics. MATERIALS AND METHODS: Eighty patients subjected to selective thoracic fusion by segmental pedicle screw fixation were analyzed after a minimum follow-up of 2 years for deformity correction and spinal balance. Deformity correction was performed by derotation of rod contoured to the normal sagittal curve without additional compression or distraction. RESULTS: Mean preoperative thoracic curve of 53.3 was corrected to 20.3 showing a correction of 63.2%. The mean preoperative lumbar curve was 34.4 with a flexibility of 97.2% and mean lumboapical distance(LAD)of 18.0mm, L4 tilt of 8.0, and lumbar apical rotation (LAR) of 10.9. It was corrected to 16.5 showing a correction of 55.5%. All the patients were balanced clinically and radiologically. CONCLUSIONS: Selective thoracic fusion with segmental pedicle screw fixation and rod rotation offers a satisfactory correction of the deformity and maintenance of spinal balance in King type g AIS regardless of lumbar curve magnitude, LAD, L4 tilt or LAR.