Treatment Of Thoracic Adolescent Idiopathic Scoliosis Research Articles

Long-term Outcome of Selective Thoracic Fusion Using Rod Derotation and Direct Vertebral Rotation in the Treatment of Thoracic Adolescent Idiopathic Scoliosis: More Than 10-Year Follow-up Data.

This was a retrospective comparative study. To evaluate long-term outcomes of selective thoracic fusion (STF) using both rod derotation (RD) and direct vertebral rotation (DVR) with pedicle screw instrumentation (PSI) in the treatment of thoracic adolescent idiopathic scoliosis (AIS) with a minimum 10-year follow-up. Postoperative compensation and maintenance of the unfused lumbar curve after STF is very important factor for the satisfactory results in the treatment of thoracic AIS. Sixty-five patients with thoracic AIS treated with STF from the neutral vertebra (NV) to NV or NV-1 with RD and DVR were retrospectively analyzed with a minimum 10-year follow-up. Patients were divided into 2 groups: satisfactory (n=52) and unsatisfactory groups (n=13). Unsatisfactory results were defined as an adding-on, a lowest instrumented vertebra (LIV) tilt of >10 degrees, or coronal balance >15 mm. No significant differences were observed in the main thoracic curve between the satisfactory and unsatisfactory groups postoperatively (P=0.218) and at the last follow-up (P=0.636). Significant improvements of LIV tilt and disk angle were observed in both groups, but these improvements deteriorated during the follow-up period in the unsatisfactory group. Significant differences of apical vertebra (AV) and end vertebra (EV) were observed postoperatively (AV: P=0.001, EV: P=0.001) and at the last follow-up (AV: P<0.000, EV: P<0.000) between the 2 groups. STF using RD and DVR can achieve satisfactory deformity correction for thoracic AIS with satisfactory compensatory lumbar curve that was maintained over long-term follow-up. Progression of unfused lumbar curve closely related with LIV tilt and disk angle showing insufficient DVR. Therefore, STF with sufficient DVR required to achieve satisfactory deformity correction and prevent a distal adding-on phenomenon in the treatment of thoracic AIS.

The “X-Factor” Index: a new parameter for the assessment of adolescent idiopathic scoliosis correction

The correction rate (CR) and fulcrum bending correction index (FBCI) based on the fulcrum bending radiograph (FBR) were parameters introduced to measure the curve correcting ability; however, such parameters do not account for contributions by various, potential extraneous "X-Factors" (e.g. surgical technique, type and power of the instrumentation, anesthetic technique, etc.) involved in curve correction. As such, the purpose of the following study was to propose the concept of the "X-Factor Index" (XFI) as a new parameter for the assessment of the correcting ability of adolescent idiopathic scoliosis (AIS). A historical cohort radiographic analysis of the FBR in the setting of hook systems in AIS patients (Luk et al. in Spine 23:2303-2307, 1998) was performed to illustrate the concept of XFI. Thirty-five patients with AIS of the thoracic spine undergoing surgical correction were involved in the analysis. Plain posteroanterior (PA) plain radiographs were utilized and Cobb angles were obtained for each patient. Pre- and postoperative PA angles on standing radiograph and preoperative fulcrum bending angles were obtained for each patient. The fulcrum flexibility, curve CR, and FBCI were determined for all patients. The difference between the preoperative fulcrum bending angle and postoperative PA angle was defined as Angle(XF), which accounted for the correction contributed by "X-Factors". The XFI, designed to measure the curve correcting ability, was calculated by dividing Angle(XF) by the fulcrum flexibility. The XFI was compared with the curve CR and FBCI by re-evaluating the original data in the original paper (Luk et al. in Spine 23:2303-2307, 1998). The mean standing PA and FBR alignments of the main thoracic curve were 58.3° and 24.5°, respectively. The mean fulcrum flexibility was 58.8%. The mean postoperative standing PA alignment was 24.7°. The mean curve CR was 58.0% and the mean FBCI was 101.1%. The mean XFI was noted as 1.03%. The CR was significantly positively correlated to curve flexibility (r=0.66; p<0.01).The FBCI (r=-0.47; p=0.005) and the XFI (r=-0.45; p=0.007) were significantly negatively correlated to curve flexibility. The CR was not correlated to Angle(XF) (r=0.29; p=0.089).The FBCI (r=0.97; p<0.01) and the XFI (r=0.961; p<0.01) were significantly positively correlated to Angle(XF). Variation in XFI was noted in some cases originally presenting with same FBCI values. The XFI attempts to quantify the curve correcting ability as contributed by "X-Factors" in the treatment of thoracic AIS. This index may be a valued added parameter to accompany the FBCI for comparing curve correction ability among different series of patients, instrumentation, and surgeons. It is recommended that the XFI should be used to document curve correction, compare between different techniques, and used to improve curve correction for the patient.

Thoracoplasty in Thoracic Adolescent Idiopathic Scoliosis

Retrospective study. To evaluate the effect and outcome of thoracoplasty in conjunction with pedicle screw instrumentation in the treatment of thoracic adolescent idiopathic scoliosis (AIS). Some spine surgeons recently think more correction of hump deformity using pedicle screws without thoracoplasty. Although thoracoplasty has been conventional treatment of rib hump, there are few papers about the results of pedicle screw instrumentation and concomitant thoracoplasty. Eighty-seven patients with thoracic AIS (mean age, 14.4 years) treated by pedicle screw instrumentation were retrospectively analyzed after a minimum follow-up of 2 years. Patients were divided into 3 groups; N-T group (no thoracoplasty with iliac bone graft, n = 37), T+N-DVR [thoracoplasty without direct vertebral rotation (DVR), n = 20] and T+DVR group (thoracoplasty with DVR, n = 30). In the T (T+N-DVR and T+DVR) group, 4 to 8 ribs were resected and used for bone graft. Patients were evaluated for deformity correction, balance, pulmonary function, height and angle of rib hump, clinical outcomes (SRS-30), and complications. In the N-T group, the thoracic curve was corrected from 53 degrees to 16 degrees (69% correction), in the T+N-DVR group from 55 degrees to 18 degrees (69%) and in the T+DVR group from 54 degrees to 10 degrees (81%). There was no difference in postoperative spinal balance and pulmonary function among the 3 groups. The correction rates of hump height and angle were 35% and 38% in the N-T group, respectively, 57% and 58% in the T+N-DVR, and 70% and 72% in the T+DVR. The T group showed significantly better correction of rib hump and self-image score in the SRS-30 questionnaire than the N-T group. There were 8 iliac donor site problems in the N-T group and 3 hemothorax in the T group, which had no adverse effect in the final result. Thoracoplasty showed significantly better rib hump correction, satisfactory clinical outcomes without pulmonary function compromise, or iliac bone graft site morbidity in the treatment of thoracic AIS with pedicle screw instrumentation.

Pedicle morphology in thoracic adolescent idiopathic scoliosis: is pedicle fixation an anatomically viable technique?

A radiographic study of thoracic pedicle anatomy in a group of adolescent idiopathic scoliosis (AIS) patients. To investigate the anatomic constraints of the thoracic pedicles and determine whether the local anatomy would routinely allow pedicle screw insertion at every level. In spite of the clinical successes reported with limited thoracic pedicle screw-rod constructs for thoracic AIS, controversy exists as to the safety of this technique. Twenty-nine patients with right thoracic AIS underwent preoperative thoracic CT scans and plain radiographs. Anatomic parameters were measured from T1 to T12. Information on 512 pedicles was obtained. The transverse width of the pedicles from T1 through T12 ranged from 4.6-8.25 mm. The medial pedicle to lateral rib wall transverse width from T1 through T2 ranged from 12.6 to 17.9 mm. Measured dimensions from the CT scans showed the actual pedicle width to be 1-2 mm larger than would have been predicted from the plain radiographs. Age, Risser grade, curve magnitude, and the amount of segmental axial rotation did not correlate with the morphology or size of the thoracic pedicles investigated. In no case would pedicle morphology have precluded the passage of a pedicle screw. Based on the data identified in this group of adolescent patients, it is reasonable to consider pedicle screw insertion at most levels and pedicle-rib fixation at all levels of the thoracic spine during the treatment of thoracic AIS.