SPINE Volume 39, Number 14, pp 1163-1169 ©2014, Lippincott Williams & Wilkins
SURGERY
Surgical Treatment of Lenke 1 Thoracic Adolescent Idiopathic Scoliosis With Maintenance of Kyphosis Using the Simultaneous Double-Rod Rotation Technique Hideki Sudo, MD,* Manabu Ito, MD,* Yuichiro Abe, MD,+ Kuniyoshi Abumi, MD,* MasahikoTakahata, MD,* Ken Nagahama, MD,* Shigeto Hiratsuka, MD,* Kei Kuroki, MD,* and Norimasa Iwasaki, MD*
Study Design. Retrospective analysis of a prospectively collected, consecutive, nonrandomized series of patients. Objective. To assess the surgical outcomes of the simultaneous double-rod rotation technique for treating Lenke 1 thoracic adolescent idiopathic scoliosis (AIS). Summary of Background Data. With the increasing popularity of segmental pedicle screw spinal reconstruction for treating AIS, concerns regarding the limited ability to correct hypokyphosis have also increased. Methods. A consecutive series of 32 patients with Lenke 1 main thoracic AIS treated with the simultaneous double-rod rotation technique at our institution was included. Outcome measures included patient demographics, radiographical measurements, and Scoliosis Research Society questionnaire scores. Results. All 32 patients were followed up for a minimum of 2 years (average, 3.6 yr). The average main thoracic Cobb angle correction rate and the correction loss at the final follow-up were 67.8% and 3.3°, respectively. The average preoperative thoracic kyphosis (T5-T12) was 11.9°, which improved significantly to 20.5° (P < 0.0001) at the final follow-up. An increase in thoracic kyphosis was significantly correlated with an increase in lumbar lordosis at the final follow-up (r = 0.42). The average preoperative vertebral rotation angle was 19.7°, which improved significantly after surgery to 14.9° [P = 0.0001 ). There was no correlation between change in thoracic From the *Department of Orthopaedic Surgery, Hokkaido University Hospital, Sapporo, Japan; and tEniwa Hospital, Eniwa, Japan. Acknowledgment date: February 3, 2014. First revision date: March 23,2014. Acceptance date: March 25, 2014. The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication. No funds were received in support of this work. Relevant financial activities outside the submitted work: board membership, grants/grants pending, payment for development of educational presentations, and travel/accommodations/meeting expenses. Correspondence and reprint requests to Manabu Ito, MD, Department of Advanced Medicine for Spine and Spinal Cord Disorders, Hokkaido University Graduate School of Medicine, North-15, West-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan; F-mail: [email protected] DOI: 10.1097/BRS.0000000000000364 Spine
kyphosis and change in apical vertebral rotation [r - -0.123). The average preoperative total Scoliosis Research Society questionnaire score was 3.0, which significantly improved to 4.4 (P < 0.0001) at the final follow-up. Throughout surgery and even after, there were no instrumentation failures, pseudarthrosis, infection ofthe surgical site, or clinically relevant neurovascular complications. Conclusion. The simultaneous double-rod rotation technique for treating Lenke 1 AIS provides significant sagittal correction of the main thoracic curve while maintaining sagittal profiles and correcting coronal and axial deformities. Key words: adolescent idiopathic scoliosis, main thoracic curve, surgical correction, thoracic kyphosis, patient outcome measures.
Level of Evidence: 4 Spine 2014;39:1163-1169
P
osterior spinal fusion with posterior instrumentation is currently the "gold standard" for the treatment of adolescent idiopathic scoliosis (AIS). The modern segmentai pedicle screw (PS) system is superior to the hook-and-wire or hybrid system for correcting scoliosis.''^ In contrast, open anterior spinal fusion establishes 3-dimensional correction with the fusion of fewer motion segments.-^"'' However, this procedure is reported to decrease pulmonary function in the long term.^ In addition to the satisfactory coronal correction of the main thoracic (MT) and compensatory thoracolumbar and lumbar (TL/L) curves, restoration and maintenance of normal sagittal contour have been receiving increased attention of late.*^" Although Suk et aP reported that all PS constructs result in improved correction of hypokyphosis of the thoracic spine, other authors have reported a postoperative decrease in thoracic kyphosis (TK) using only PSs as instruments.^"-^' Because patients with a Lenke 1 MT AIS curve are typically hypokyphotic, optimal surgical management of AIS requires the maintenance of sagittal balance.'^ We previously reported a new technique called the simultaneous double-rod rotation technique (SDRRT) for correcting AIS while maintaining www.spinejournal.com
1163
Spine
SURCERY
kyphosis.^^ Because this procedure includes upward pushing and lateral translation of the spinal column with simultaneous double-rod rotation maneuvers, it is simple and achieves TK as well as favorable correction of scoliosis.^^ We conducted a retrospective, hospital-based cohort study to evaluate the outcomes of SDRRT in a prospectively collected, consecutive series of patients with Lenke 1 AIS treated at our institution.
MATERIALS AND METHODS After institutional review board approval, data from 32 consecutive patients (3 males, 29 females) with Lenke 1 AIS curves'' who underwent posterior MT curve correction using SDRRT at our institution between 2008 and 2011 were retrospectively reviewed. Exclusion criteria included syndromic, neuromuscular, and congenital scoliosis and the presence of other thoracic scoliosis curves such as Lenke 2 double thoracic curves. No cases were lost to follow-up. Radiographs and Scoliosis Research Society outcome instrument scores (SRS-22) were evaluated for all patients. The average age and Risser sign at surgery were 15.0 (range, 10-20) years and 3.8 (range, 0-5), respectively. The average follow-up period was 3.6 years. Standing long-cassette posteroanterior and lateral radiographs were evaluated for multiple parameters before and after surgery and at the final follow-up. Curve flexibility was evaluated using preoperative supine bending radiographs. Coronal and sagittal Cobb angle measurements of the proximal thoracic (PT), MT, and TL/L curves were obtained. The end vertebral levels were determined on preoperative radiographs and measured on subsequent radiographs to maintain consistency for statistical comparisons. Sagittal measurements included TK (T5-T12), thoracolumbar kyphosis (T10-L2), and lumbar lordosis (LL; Ll-Sl). . Global coronal balance was measured by lateral displacement of the C7 coronal plumb line from the center sacral vertical line. Sagittal balance was evaluated by measuring the absolute displacement of the C7 plumb line relative to the SI posterior-superior corner as the sagittal vertical axis.'"* For regional alignment, MT apical vertebral translation was measured as the distance between the geometric center of the apical vertebrae and the C7 plumb line. TL/L apical vertebral translation was measured as the distance between the geometric center of the apical vertebrae and the center sacral vertical line. The vertebral rotation angle of thoracic apical vertebrae was measured by computed tomography (CT) before and after surgery.'-'•*'^ Image slices at each apical vertebra were selected using scout, sagittal, and/or coronal reconstructions to ensure that the axial images were obtained parallel to the endplates. The selected image of the apical vertebrae included both pedicles and the junction of the inner surface of the laminae. The angle of rotation of the vertebra was measured using the angle between the junction of the laminae, the dorsalcentral aspect of the vertebral foramen and the middle of the vertehral body, and the sagittal plane. "^ Our internal studies of inter-/intrarater reliability have shown excellent K statistics for all continuous measures (0.80-0.99). 1164
www.spinejournal.com
Kyphosis Maintenance for Thoracic Scoliosis • Sudo et al
Fusion was defined according to the criteria of Geek et al": stable coronal and sagittal alignment through the instrumented segments during the follow-up period; no clinical complaints consistent with nonunion; no radiographical evidence of nonunion; and stable instrumentation. All criteria were fulfilled by our patients. The SRS-22 score was used to measure patient outcomes during follow-up. The score was divided into 5 domains on the basis of question type (pain, function, self-image, mental health, and satisfaction). All questions were scored from 1 to 5 (optimal); the average score for each domain was used for analysis.'* Surgical Technique The fusion area is almost similar to the major curve, which is determined using preoperative passive bending radiographs.'^ Surgical procedures were performed as described previously.'^ Briefly, after exposure of the posterior spinal elements, PSs (USS II; DePuy Spine, Raynham, MA) were placed under the guidance of a lateral image intensifier. A side-loading polyaxial screw head was preferred over a top-loading screw head because the former allows a wider range of accessibility to the rod. For pedicles without a cancellous channel, ultrahighmolecular-weight polyethylene cables (NFSPLON Cable System; Alfresa Pharma, Osaka, Japan), and not PSs, were passed under the laminae. If PS placement was difficult at the most cephalad vertebra because of its narrowness, a transverse process hook was used. After the Ponte procedure was used in patients with rigid curves, 2 rods of 6-mm diameter were bent to the anticipated TK. The rod on the concave side was bent more than that on the convex side to control the rotation deformity around the apex. After connecting the 2 rods to all screw heads, the concave-side rod was rotated gently with 2 rod holders. The convex rod automatically rotated in fiexible curves, following the rotation of the concave rod. For rigid curves, however, it is safer for several surgeons to rotate the 2 rods simultaneously. After 90° rod rotation, several screw heads were tightened to lock the rods. Distraction force was first applied on each screw head on the concave side of the thoracic curve so that not only scoliosis but also TK could be corrected more effectively by lengthening the posterior column. Then, compression force was applied segmentally on the convex curve. An in situ rod-bending maneuver was not conducted during the surgery. Local bone grafting followed decortication of the laminae. A brace was not required in any patient.
Statistical Analysis Repeated-measures analysis of variance was performed to compare the differences among preoperative, postoperative, and final follow-up radiographical data. Data were checked for normality and equality of variances, and Bonferroni post hoc analysis was used to set the significance level at 0.005.^-"'^'^ Pearson correlation analysis showed that changes in TK (final follow-up — preoperative measurements) correlated with changes in LL (final follow-up - preoperative measurements) (F < 0.05). Changes in TK (postoperative - preoperative June 2014
SURGERY
Kyphosis Maintenance for Thoracic Scoliosis • Sudo et al
measurements) also correlated with changes in apical vertebral rotation (postoperative - preoperative measurements). A paired i-test was used to compare pre- and postoperative vertebral rotation angles and baseline and final follow-up SRS-22 scores using a P value of 0.05 (2-sided). RESULTS Demographic data are summarized in Table 1. An average of 8.5 segments were instrumented in the 32 patients. The cephalad instrumented vertebrae ranged from T3 to T6, and the caudal instrumented vertebrae ranged from TIO to L2. Radiographical Results The coronal and sagittal radiographical parameters are summarized in Table 2. The average preoperative MT curve was 63.4°. The average preoperative MT curve flexibility on bending radiographs was 59.2% (range, 31%-93%). Postoperative radiographs showed an average MT curve of 17.6°. The average MT curve correction rate was 72.3% (range, 5 5 % 92%). At the final follow-up, the average MT curve was 20.3°, the average correction rate was 67.8% (range, 5 5 % 84%), and the average correction angle loss was 3.3° (range, 0°-14°). No significant differences were observed between postoperative and final follow-up curve measurements (P = 0.3385). The average preoperative PT curve was 28.8°. The average curve on bending radiographs decreased to 16.2° (range, 3°-24°), and the average flexibility was 44.3% (range, 13%-87%). The average PT curve significantly improved to 15.6° after surgery (P < 0.0001). The average final follow-up value was 14.4°, which was not significantly different from the postoperative value (P = 1.0). The average preoperative TL/L curve was 39.1°. The average curve decreased to 5.8° (range, -14° to 18°) on bending radiographs, and the average flexibility was 87.0% (range, 53%-150%). The TL/L curve improved significantly to 12.6° after surgery (P < 0.0001); the final average follow-up value was 13.8°, which was not significantly different from the postoperative value (P = 1.0).
TABLE!.
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^^m^i
.'JnBÜIlfeliün HI èmflm.
1
Sagittal plane analysis revealed that the average preoperative TK was 11.9°, which improved significantly after surgery to an average of 19.1° (P < 0.0001). No significant difference was observed between the postoperative and final follow-up curve measurements (20.5°; P = 1.0). No clinically significant differences were observed between preoperative thoracolumbar kyphosis or LL and those at the final follow-up. Pearson correlation analysis showed a linear relationship between TK and LL. The increase in TK at the final follow-up relative to preoperative TK was significantly correlated with an increase in LL (r = 0.42; Figure 1). With regard to global balance, no significant differences in the C7 plumb lines and the sagittal vertical axis were observed among preoperative, postoperative, and final measurements (P = 0.4225 and 0.5031, respectively). With regard to regional alignment before and after surgery, MT apical vertebral translation significantly improved from an average of 53.2 to 13.4 mm (P < 0.0001). This correction was maintained at the final follow-up (average, 16.7 mm; P = 0.6105). No significant differences were observed in TL/L apical vertebral translation among preoperative, postoperative, and final follow-up measurements (P = 0.9142). Vertebral rotation angles of the thoracic apical vertebrae on CT scans are presented in Table 3. The average preoperative vertebral rotation angle was 19.7° (range, 5°-35°), which improved significantly after surgery to an average of 14.9° (range, 4°-28°; P = 0.0001). There was no correlation between change in TK and change in apical vertebral rotation ( r = -0.123). SRS Data The SRS total and individual domain scores are shown in Table 4. The average preoperative total score was 3.0 (range, 2.0^.0), which significantly improved at the final follow-up to an average of 4.4 (range, 3.6-5.0; P < 0.0001). Surgical Revisions and Complications The implant was observed to be intact at the final followup. All patients demonstrated solid fusion. No surgical site infection or clinically relevant perioperative neurovascular complications were observed.
Mean ± SD (Range) Age at surgery (yr)
15.0 ±2.6 (10-20)
Present age (yr)
18.4 ± 2.6(12-24)
Risser sign
3.8 ± 1.3(0-5)
Cobb length (upper-end to lower-end vertebra)
7.0 ± 1.0 (5-9)
Instrumentation length (segments)
8.5 ± 1.5(6-11)
Operation time (min)
274.3 ± 45.5 (180-380)
Estimated blood loss (mL)
860.3 ±510.8 (250-2780)
Follow-up periods (yr)
3.6 ± 1.3 (2-6)
Spine
Case Presentation An 18-year-old female presented with AIS and a single right convex thoracic curve. The MT curve from T5 to LI was 62°. The TK was 6° (Figure 2A, B). Fier curve pattern was Lenke 1A-. PSs were inserted from T5 to LI. The concave-side rod was first connected to each screw head, followed by the convex-side rod. After connecting the rods, the concave-side rod was rotated 90° with 2 rod holders, which induced the convex-side rod to rotate in accordance with rotation of the concave-side rod. Then, segmentai distraction was performed on the concave side and compression was performed on the convex side. Local bone grafting was performed after decortication of the laminae. Postoperative radiographs showed that the MT curve and TK were 17° and 19°, respectively, and radiographs obtained 4 years after surgery showed them to be 17° and 20°, respectively (Figure 2C, D). www.spinejournal.com
1165
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Kyphosis Maintenance for Thoracic Scoliosis • Sudo et al
•filiilXSKädiographital Pdrameleii^^^H Bonferroni P Preoperative Postoperative
Pre-to Overall P Postoperative
Final
Preoperative to Final
Postoperative to Final
Coronal plane data Proximal thoracic curve (°)
28.8 ± 7.0 (15-45)
15.6 ± 8.0 (0-31)
14.4 ± 6.7 (3-27)
SURGERY
Surgical Treatment of Lenke 1 Thoracic Adolescent Idiopathic Scoliosis With Maintenance of Kyphosis Using the Simultaneous Double-Rod Rotation Technique Hideki Sudo, MD,* Manabu Ito, MD,* Yuichiro Abe, MD,+ Kuniyoshi Abumi, MD,* MasahikoTakahata, MD,* Ken Nagahama, MD,* Shigeto Hiratsuka, MD,* Kei Kuroki, MD,* and Norimasa Iwasaki, MD*
Study Design. Retrospective analysis of a prospectively collected, consecutive, nonrandomized series of patients. Objective. To assess the surgical outcomes of the simultaneous double-rod rotation technique for treating Lenke 1 thoracic adolescent idiopathic scoliosis (AIS). Summary of Background Data. With the increasing popularity of segmental pedicle screw spinal reconstruction for treating AIS, concerns regarding the limited ability to correct hypokyphosis have also increased. Methods. A consecutive series of 32 patients with Lenke 1 main thoracic AIS treated with the simultaneous double-rod rotation technique at our institution was included. Outcome measures included patient demographics, radiographical measurements, and Scoliosis Research Society questionnaire scores. Results. All 32 patients were followed up for a minimum of 2 years (average, 3.6 yr). The average main thoracic Cobb angle correction rate and the correction loss at the final follow-up were 67.8% and 3.3°, respectively. The average preoperative thoracic kyphosis (T5-T12) was 11.9°, which improved significantly to 20.5° (P < 0.0001) at the final follow-up. An increase in thoracic kyphosis was significantly correlated with an increase in lumbar lordosis at the final follow-up (r = 0.42). The average preoperative vertebral rotation angle was 19.7°, which improved significantly after surgery to 14.9° [P = 0.0001 ). There was no correlation between change in thoracic From the *Department of Orthopaedic Surgery, Hokkaido University Hospital, Sapporo, Japan; and tEniwa Hospital, Eniwa, Japan. Acknowledgment date: February 3, 2014. First revision date: March 23,2014. Acceptance date: March 25, 2014. The device(s)/drug(s) is/are FDA-approved or approved by corresponding national agency for this indication. No funds were received in support of this work. Relevant financial activities outside the submitted work: board membership, grants/grants pending, payment for development of educational presentations, and travel/accommodations/meeting expenses. Correspondence and reprint requests to Manabu Ito, MD, Department of Advanced Medicine for Spine and Spinal Cord Disorders, Hokkaido University Graduate School of Medicine, North-15, West-7, Kita-ku, Sapporo, Hokkaido 060-8638, Japan; F-mail: [email protected] DOI: 10.1097/BRS.0000000000000364 Spine
kyphosis and change in apical vertebral rotation [r - -0.123). The average preoperative total Scoliosis Research Society questionnaire score was 3.0, which significantly improved to 4.4 (P < 0.0001) at the final follow-up. Throughout surgery and even after, there were no instrumentation failures, pseudarthrosis, infection ofthe surgical site, or clinically relevant neurovascular complications. Conclusion. The simultaneous double-rod rotation technique for treating Lenke 1 AIS provides significant sagittal correction of the main thoracic curve while maintaining sagittal profiles and correcting coronal and axial deformities. Key words: adolescent idiopathic scoliosis, main thoracic curve, surgical correction, thoracic kyphosis, patient outcome measures.
Level of Evidence: 4 Spine 2014;39:1163-1169
P
osterior spinal fusion with posterior instrumentation is currently the "gold standard" for the treatment of adolescent idiopathic scoliosis (AIS). The modern segmentai pedicle screw (PS) system is superior to the hook-and-wire or hybrid system for correcting scoliosis.''^ In contrast, open anterior spinal fusion establishes 3-dimensional correction with the fusion of fewer motion segments.-^"'' However, this procedure is reported to decrease pulmonary function in the long term.^ In addition to the satisfactory coronal correction of the main thoracic (MT) and compensatory thoracolumbar and lumbar (TL/L) curves, restoration and maintenance of normal sagittal contour have been receiving increased attention of late.*^" Although Suk et aP reported that all PS constructs result in improved correction of hypokyphosis of the thoracic spine, other authors have reported a postoperative decrease in thoracic kyphosis (TK) using only PSs as instruments.^"-^' Because patients with a Lenke 1 MT AIS curve are typically hypokyphotic, optimal surgical management of AIS requires the maintenance of sagittal balance.'^ We previously reported a new technique called the simultaneous double-rod rotation technique (SDRRT) for correcting AIS while maintaining www.spinejournal.com
1163
Spine
SURCERY
kyphosis.^^ Because this procedure includes upward pushing and lateral translation of the spinal column with simultaneous double-rod rotation maneuvers, it is simple and achieves TK as well as favorable correction of scoliosis.^^ We conducted a retrospective, hospital-based cohort study to evaluate the outcomes of SDRRT in a prospectively collected, consecutive series of patients with Lenke 1 AIS treated at our institution.
MATERIALS AND METHODS After institutional review board approval, data from 32 consecutive patients (3 males, 29 females) with Lenke 1 AIS curves'' who underwent posterior MT curve correction using SDRRT at our institution between 2008 and 2011 were retrospectively reviewed. Exclusion criteria included syndromic, neuromuscular, and congenital scoliosis and the presence of other thoracic scoliosis curves such as Lenke 2 double thoracic curves. No cases were lost to follow-up. Radiographs and Scoliosis Research Society outcome instrument scores (SRS-22) were evaluated for all patients. The average age and Risser sign at surgery were 15.0 (range, 10-20) years and 3.8 (range, 0-5), respectively. The average follow-up period was 3.6 years. Standing long-cassette posteroanterior and lateral radiographs were evaluated for multiple parameters before and after surgery and at the final follow-up. Curve flexibility was evaluated using preoperative supine bending radiographs. Coronal and sagittal Cobb angle measurements of the proximal thoracic (PT), MT, and TL/L curves were obtained. The end vertebral levels were determined on preoperative radiographs and measured on subsequent radiographs to maintain consistency for statistical comparisons. Sagittal measurements included TK (T5-T12), thoracolumbar kyphosis (T10-L2), and lumbar lordosis (LL; Ll-Sl). . Global coronal balance was measured by lateral displacement of the C7 coronal plumb line from the center sacral vertical line. Sagittal balance was evaluated by measuring the absolute displacement of the C7 plumb line relative to the SI posterior-superior corner as the sagittal vertical axis.'"* For regional alignment, MT apical vertebral translation was measured as the distance between the geometric center of the apical vertebrae and the C7 plumb line. TL/L apical vertebral translation was measured as the distance between the geometric center of the apical vertebrae and the center sacral vertical line. The vertebral rotation angle of thoracic apical vertebrae was measured by computed tomography (CT) before and after surgery.'-'•*'^ Image slices at each apical vertebra were selected using scout, sagittal, and/or coronal reconstructions to ensure that the axial images were obtained parallel to the endplates. The selected image of the apical vertebrae included both pedicles and the junction of the inner surface of the laminae. The angle of rotation of the vertebra was measured using the angle between the junction of the laminae, the dorsalcentral aspect of the vertebral foramen and the middle of the vertehral body, and the sagittal plane. "^ Our internal studies of inter-/intrarater reliability have shown excellent K statistics for all continuous measures (0.80-0.99). 1164
www.spinejournal.com
Kyphosis Maintenance for Thoracic Scoliosis • Sudo et al
Fusion was defined according to the criteria of Geek et al": stable coronal and sagittal alignment through the instrumented segments during the follow-up period; no clinical complaints consistent with nonunion; no radiographical evidence of nonunion; and stable instrumentation. All criteria were fulfilled by our patients. The SRS-22 score was used to measure patient outcomes during follow-up. The score was divided into 5 domains on the basis of question type (pain, function, self-image, mental health, and satisfaction). All questions were scored from 1 to 5 (optimal); the average score for each domain was used for analysis.'* Surgical Technique The fusion area is almost similar to the major curve, which is determined using preoperative passive bending radiographs.'^ Surgical procedures were performed as described previously.'^ Briefly, after exposure of the posterior spinal elements, PSs (USS II; DePuy Spine, Raynham, MA) were placed under the guidance of a lateral image intensifier. A side-loading polyaxial screw head was preferred over a top-loading screw head because the former allows a wider range of accessibility to the rod. For pedicles without a cancellous channel, ultrahighmolecular-weight polyethylene cables (NFSPLON Cable System; Alfresa Pharma, Osaka, Japan), and not PSs, were passed under the laminae. If PS placement was difficult at the most cephalad vertebra because of its narrowness, a transverse process hook was used. After the Ponte procedure was used in patients with rigid curves, 2 rods of 6-mm diameter were bent to the anticipated TK. The rod on the concave side was bent more than that on the convex side to control the rotation deformity around the apex. After connecting the 2 rods to all screw heads, the concave-side rod was rotated gently with 2 rod holders. The convex rod automatically rotated in fiexible curves, following the rotation of the concave rod. For rigid curves, however, it is safer for several surgeons to rotate the 2 rods simultaneously. After 90° rod rotation, several screw heads were tightened to lock the rods. Distraction force was first applied on each screw head on the concave side of the thoracic curve so that not only scoliosis but also TK could be corrected more effectively by lengthening the posterior column. Then, compression force was applied segmentally on the convex curve. An in situ rod-bending maneuver was not conducted during the surgery. Local bone grafting followed decortication of the laminae. A brace was not required in any patient.
Statistical Analysis Repeated-measures analysis of variance was performed to compare the differences among preoperative, postoperative, and final follow-up radiographical data. Data were checked for normality and equality of variances, and Bonferroni post hoc analysis was used to set the significance level at 0.005.^-"'^'^ Pearson correlation analysis showed that changes in TK (final follow-up — preoperative measurements) correlated with changes in LL (final follow-up - preoperative measurements) (F < 0.05). Changes in TK (postoperative - preoperative June 2014
SURGERY
Kyphosis Maintenance for Thoracic Scoliosis • Sudo et al
measurements) also correlated with changes in apical vertebral rotation (postoperative - preoperative measurements). A paired i-test was used to compare pre- and postoperative vertebral rotation angles and baseline and final follow-up SRS-22 scores using a P value of 0.05 (2-sided). RESULTS Demographic data are summarized in Table 1. An average of 8.5 segments were instrumented in the 32 patients. The cephalad instrumented vertebrae ranged from T3 to T6, and the caudal instrumented vertebrae ranged from TIO to L2. Radiographical Results The coronal and sagittal radiographical parameters are summarized in Table 2. The average preoperative MT curve was 63.4°. The average preoperative MT curve flexibility on bending radiographs was 59.2% (range, 31%-93%). Postoperative radiographs showed an average MT curve of 17.6°. The average MT curve correction rate was 72.3% (range, 5 5 % 92%). At the final follow-up, the average MT curve was 20.3°, the average correction rate was 67.8% (range, 5 5 % 84%), and the average correction angle loss was 3.3° (range, 0°-14°). No significant differences were observed between postoperative and final follow-up curve measurements (P = 0.3385). The average preoperative PT curve was 28.8°. The average curve on bending radiographs decreased to 16.2° (range, 3°-24°), and the average flexibility was 44.3% (range, 13%-87%). The average PT curve significantly improved to 15.6° after surgery (P < 0.0001). The average final follow-up value was 14.4°, which was not significantly different from the postoperative value (P = 1.0). The average preoperative TL/L curve was 39.1°. The average curve decreased to 5.8° (range, -14° to 18°) on bending radiographs, and the average flexibility was 87.0% (range, 53%-150%). The TL/L curve improved significantly to 12.6° after surgery (P < 0.0001); the final average follow-up value was 13.8°, which was not significantly different from the postoperative value (P = 1.0).
TABLE!.
i^^—
.;in¿
^^m^i
.'JnBÜIlfeliün HI èmflm.
1
Sagittal plane analysis revealed that the average preoperative TK was 11.9°, which improved significantly after surgery to an average of 19.1° (P < 0.0001). No significant difference was observed between the postoperative and final follow-up curve measurements (20.5°; P = 1.0). No clinically significant differences were observed between preoperative thoracolumbar kyphosis or LL and those at the final follow-up. Pearson correlation analysis showed a linear relationship between TK and LL. The increase in TK at the final follow-up relative to preoperative TK was significantly correlated with an increase in LL (r = 0.42; Figure 1). With regard to global balance, no significant differences in the C7 plumb lines and the sagittal vertical axis were observed among preoperative, postoperative, and final measurements (P = 0.4225 and 0.5031, respectively). With regard to regional alignment before and after surgery, MT apical vertebral translation significantly improved from an average of 53.2 to 13.4 mm (P < 0.0001). This correction was maintained at the final follow-up (average, 16.7 mm; P = 0.6105). No significant differences were observed in TL/L apical vertebral translation among preoperative, postoperative, and final follow-up measurements (P = 0.9142). Vertebral rotation angles of the thoracic apical vertebrae on CT scans are presented in Table 3. The average preoperative vertebral rotation angle was 19.7° (range, 5°-35°), which improved significantly after surgery to an average of 14.9° (range, 4°-28°; P = 0.0001). There was no correlation between change in TK and change in apical vertebral rotation ( r = -0.123). SRS Data The SRS total and individual domain scores are shown in Table 4. The average preoperative total score was 3.0 (range, 2.0^.0), which significantly improved at the final follow-up to an average of 4.4 (range, 3.6-5.0; P < 0.0001). Surgical Revisions and Complications The implant was observed to be intact at the final followup. All patients demonstrated solid fusion. No surgical site infection or clinically relevant perioperative neurovascular complications were observed.
Mean ± SD (Range) Age at surgery (yr)
15.0 ±2.6 (10-20)
Present age (yr)
18.4 ± 2.6(12-24)
Risser sign
3.8 ± 1.3(0-5)
Cobb length (upper-end to lower-end vertebra)
7.0 ± 1.0 (5-9)
Instrumentation length (segments)
8.5 ± 1.5(6-11)
Operation time (min)
274.3 ± 45.5 (180-380)
Estimated blood loss (mL)
860.3 ±510.8 (250-2780)
Follow-up periods (yr)
3.6 ± 1.3 (2-6)
Spine
Case Presentation An 18-year-old female presented with AIS and a single right convex thoracic curve. The MT curve from T5 to LI was 62°. The TK was 6° (Figure 2A, B). Fier curve pattern was Lenke 1A-. PSs were inserted from T5 to LI. The concave-side rod was first connected to each screw head, followed by the convex-side rod. After connecting the rods, the concave-side rod was rotated 90° with 2 rod holders, which induced the convex-side rod to rotate in accordance with rotation of the concave-side rod. Then, segmentai distraction was performed on the concave side and compression was performed on the convex side. Local bone grafting was performed after decortication of the laminae. Postoperative radiographs showed that the MT curve and TK were 17° and 19°, respectively, and radiographs obtained 4 years after surgery showed them to be 17° and 20°, respectively (Figure 2C, D). www.spinejournal.com
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Kyphosis Maintenance for Thoracic Scoliosis • Sudo et al
•filiilXSKädiographital Pdrameleii^^^H Bonferroni P Preoperative Postoperative
Pre-to Overall P Postoperative
Final
Preoperative to Final
Postoperative to Final
Coronal plane data Proximal thoracic curve (°)
28.8 ± 7.0 (15-45)
15.6 ± 8.0 (0-31)
14.4 ± 6.7 (3-27)
