Early-onset scoliosis deformity is defined as a deformity of the spine in the coronal plane of 10° or more with onset before age 10 years. Early-onset scoliosis deformity is a heterogeneous condition that can be idiopathic or nonidiopathic and is associated with neuro-muscular disorders, congenital vertebral abnormalities, and syndromes.1–3 Early-onset scoliosis deformity may reduce life expectancy because deformation of the chest wall can prevent multiplication of the pulmonary alveoli, leading to restrictive lung disease.4 The goal when treating early-onset scoliosis deformity is to maximize possible lung development by maximizing the growth of the spine and thorax. Casting and bracing are commonly used for curves less than 30°, but the results are controversial and less effective in nonidiopathic scoliosis.5
Dimeglio and Canavese6 studied spine growth and demonstrated that the most rapid growing occurs from age 1 to 5 years (2 cm/year). From age 5 to 10 years, the growth is approximately 1 cm/year. The thoracic spine height is approximately 11 cm in newborns, 18 cm at age 5 years, and approximately 22 cm at age 10 years.6–8
Posterior fusion and instrumentation should be avoided until closure of the tri-radiate cartilage to prevent the crankshaft phenomenon, and anterior fusion stops the growth of the thoracic spine, leading itself to restrictive lung disease and cardiac and pulmonary dysfunction.6–9 Because of this, growth-friendly hardware became popular as a tactic to keep the curve in check prior to definitive spine fusion. Good results have been achieved using traditional growing rods (TGRs); however, TGRs require repetitive surgical distraction under anesthesia, and the complication rate can be high, mainly infections.10,11
The recently developed magnetically controlled growing rod (MCGR) system has gained popularity because it does not require additional lengthening surgical procedures and the remotely controlled lengthening can be performed in the out-patient clinic.3
Materials and Methods
This was a retrospective single-center study. From January 2015 to March 2018, 38 consecutive patients with early-onset scoliosis deformity, 15 males and 23 females, were treated using the MCGR system. Ten patients had idiopathic scoliosis (IS), and 28 had nonidiopathic scoliosis (NIS) (4 had congenital scoliosis [CS], 8 had neuromuscular scoliosis [NMS], and 16 had syndromic scoliosis [SS]). Traditional growing rods were removed and replaced with MCGRs in 17 patients.
Patients converted from TGRs were those in whom the surgical program was to change the rod because it was at the end of the elongation space, because of rod breakage, or because of a loss of correction.
Patients were included in this study if they had a curvature greater than 30° at the time of MCGR placement, a minimum follow-up of 12 months, and a minimum of 3 lengthening procedures.
Data extracted from the electronic medical record included age at surgery and last follow-up, follow-up time, length of hospital stay, body mass index (BMI) at surgery, perioperative blood transfusions, intraoperative complications, early complications (within 1 month from surgery), delayed complications (after the first postoperative month), amount of distraction intended for every procedure (displayed on the external remote controller [ERC]), and amount of distraction achieved as measured on the last follow-up radiograph. As indicated by the manufacturer and suggested by Rolton et al,12 the distraction measured was corrected for a magnification factor (9.02/width of the rod on the radiograph) to obtain the actual amount of distraction achieved.
Preoperative, immediate postoperative, and last follow-up radiographs were reviewed for the measurements of Cobb angle, T1-T12 kyphosis angle, T1-T12 distance, and T1-S1 distance. All measurements were made by the same investigator (K.Y.).
All surgical procedures were performed by the senior author (S.L.W.). After administration of antibiotic prophylaxis, general anesthesia, and endotracheal intubation, the patient was positioned prone on the dedicated spinal surgery frame. A single midline incision was made through the skin, subcutaneous tissue, and fascia. The spine was exposed subperiosteally only at the cranial and caudal levels of fixation. Dual rod constructs were used in all patients. All rods were 5.5 mm in diameter. Hooks were used for cranial fixation, and pedicle screws were used caudally.
For those patients converted from TGRs, cranial hooks and caudal screws were maintained if stable during the surgical procedure and were substituted if unstable.
After the MCGR was contoured, inserted, and secured, banked bone chips were used at the cranial and caudal levels to obtain limited posterior fusion to stabilize the construct. A thoracolumbar spine orthosis was applied for 3 months after surgery.
The first lengthening procedure was performed at 3 months after surgery. The amount of distraction per procedure was calculated between 3 and 5 mm.6 Lengthening was performed at 3- to 4-month intervals by the senior author. After a pre-procedure radiograph, the patient was positioned prone with a pillow under the abdomen or sitting in a parent's arms with the patient's back facing the operator. The procedure was stopped when the desired distraction was reached or, in a few instances, when the patient expressed excessive discomfort. After a post-procedure radiograph, the amount of distraction intended and achieved was calculated on the radiographic images obtained and recorded in the medical record.
Sample characteristics and radiographic measures were summarized as mean, standard deviation, and range. A repeated-measures analysis of variance with post hoc Tukey test was conducted to quantify the effect of MCGR placement (change from pre- to postoperative) and of subsequent lengthenings (postoperative to last follow-up) on the Cobb angle, T1-T12 kyphosis, and T1-T12 and T1-S1 distances.
Of 38 patients, 24 met the inclusion criteria. Fourteen patients were excluded because their follow-up was less than 12 months or they underwent fewer than 3 lengthening procedures. Demographic data are summarized in Table 1. Fourteen (58%) patients were female. Six had IS (3 juvenile scoliosis and 3 infantile scoliosis), and 18 had NIS (3 CS, 7 NMS, and 8 SS). Nine patients underwent primary MCGR placement, and 15 had the TGRs removed and replaced with MCGRs (3 were juvenile IS converted from TGRs). One patient had a previously undiagnosed neuromuscular disorder and pelvic imbalance that required caudal fixation to the pelvis.
Demographic and Treatment Data
The mean age at surgery was 6.3±1.8 years (range, 2.8 to 9.3 years). The mean BMI at surgery was 16.3±2.4 kg/m2 (range, 12.6 to 22.1 kg/m2). The mean hospital stay was 4.0±1.4 days (range, 2 to 7 days). Two patients, both with neuromuscular scoliosis and primary implant, received blood transfusions for postoperative anemia. The mean age at last follow-up was 8.8±2.0 years (range, 4.1 to 12 years). The mean follow-up was 29.2±8.6 months (range, 12 to 50 months).
Radiographic results are summarized in Table 2. The mean preoperative Cobb angle of the main curve was 57°±15.5° (range, 35° to 96°). The MCGR placement significantly reduced the Cobb angle (P<.05) by a mean of 21.33°±9.59° (range, 5° to 42°). At last follow-up, the mean Cobb angle was 36.6°±10.5° (range, 5° to 57°), indicating that the subsequent lengthening procedures resulted in essentially no change in correction (mean change, 0.96°; range, −10° to 7°; P>.05).
Analysis of Radiographic Results
The mean preoperative T1-T12 kyphosis angle was 48.4°±11.7° (range, 26° to 70°). The kyphosis decreased by a mean of 10.79°±10.21° (range, −7° to 29°) by MCGR placement (P<.05). At last follow-up, the mean thoracic kyphosis angle was 38.7°±10.8° (range, 5° to 65°), with an average increase related to lengthening of 1.04° (range, −15° to 15°; P>.05).
Prior to rod placement, the mean T1-T12 distance was 17.6±2.4 cm (range, 13.2 to 23.1 cm). The median increase in this distance immediately after surgery was 1.28 cm (range, −0.1 to 4.3 cm, P<.05). At last follow-up, the mean T1-T12 distance was 21.3±3.1 cm (range, 16 to 30 cm), with a median increase of 2.32 cm (range, 0.1 to 6.7 cm; P<.05).
The mean preoperative T1-S1 distance was 28.3±3.4 cm (range, 22.2 to 34.6 cm). The median increase with rod placement was 2.03 cm (range, −0.1 to 6.4 cm; P<.05). The mean final T1-S1 distance was 34±5.3 cm (range, 28 to 44.8 cm); the median increase during follow-up was 3.67 cm (range, 0.2 to 11.1 cm; P<.05). The T1-T12 and T1-S1 distances increased an average of 1.19 and 1.89 cm/year, respectively, during the follow-up period.
A total of 191 outpatient lengthening procedures were performed in 24 patients (mean, 8.0±2.3; range, 3 to 11). Table 3 summarizes the total amount of distraction intended (per the ERC setting) and achieved at last follow-up for each patient. The mean distraction intended was 26.7±7.4 mm (range, 9.8 to 37.5 mm). After correcting for magnification, the mean percentage of achieved-to-intended distraction was 65%±24% (range, 31% to 99%) on the concave side and 68%±22% (range, 11% to 99%) on the convex side at last follow-up. The distraction achieved was similar on the convex and concave sides of the curve (P=.66). Combining the concave and convex sides, the average percentage of achieved-to-intended distraction was significantly smaller in patients who had been previously treated with TGR (61%) compared with those initially treated with MCGR (76%; P=.03)
Summary of Lengthening Procedures by Concave/Convex Side of the Curve
Complications are summarized in Table 4. No intraoperative complications were recorded. There were 9 postoperative complications in 8 patients (33% per patient; 37.5% per occurrence), 6 of whom had NIS. Of 8 patients with complications, 6 were revised from TGR: 5 NIS and 1 IS. Early postoperative complications included 1 wound breakdown (size 1×1 cm) treated with wound care and dressings; 1 wound necrosis and superficial infection treated with debridement and irrigation, antibiotics, and a wound vac; and 1 case of temporary urinary retention managed with a Foley catheter and antibiotics. There were 6 delayed complications in 5 patients. The rods broke in 2 patients, both of whom were mature enough to proceed with posterior spinal fusion. The actuator pin in 1 patient fractured during the lengthening procedure. There were 2 instances of hook pull-out necessitating revision surgery, and 1 patient developed a deep infection of methicillin-resistant Staphylococcus aureus requiring hardware removal, antibiotic therapy, and subsequent posterior spinal fusion.
The aim of early-onset scoliosis deformity treatment is to assist thoracic development through minimizing progression of the deformity during growth. Treatment options include serial casting, bracing, spinal fusion, and growth-friendly instrumentation.3 Traditional growing rods require repeated surgical distractions under anesthesia, and the reported complication rate is high, mainly due to infection.10,11 The recently developed MCGR system has become popular because it does not require additional lengthening surgical procedures; rod lengthening is performed in the outpatient clinic using an external remote-controlled distractor.3 The efficacy and reliability of the MCGR system is still debated, but early reports are encouraging.13–20
In this study, both scoliosis and kyphosis improved (by 40% and 22%, respectively). Most correction occurred at the time of surgery. There is a loss of maximal correction, but it is maintained after subsequent lengthenings. The literature on maintenance of correction is inconsistent; both minor losses and gains have been reported.13–16
The critical issue for patients suffering from early-onset scoliosis deformity is development of chest wall deformity and its influence on lung development, specifically multiplication of the alveoli.4,6–8 In this study, the T1-T12 distance increased an average of 3.7 cm after surgery. The same positive effect was recorded for the T1-S1 distance, which increased by an average of 5.7 cm. These results are comparable to those in the literature.11–20 Distances increased significantly as a result of surgery, and also during the lengthening period between surgery and last follow-up, where an average of 1.19 cm (T1-T12) and 1.89 cm (T1-S1) were gained per year. This is comparable to the annual gains in T1-T12 distance noted by Akbarnia et al.21
The achieved-to-intended distraction percentage was 65% (concave side) to 68% (convex side). This was higher than the 33% reported by Rolton et al12 (N=21 patients) and the 46% reported by Lebon et al13 (N=30 patients). Gilday et al22 studied a series of 31 patients. Increases in rod length were 14% lower than the programmed distraction.22 They found that the distance between the rod and the skin surface negatively affected the amount of distraction. The difference between the expected and actual lengthening achieved should be considered when calculating the distraction desired. In the current series, there was no statistically significant difference in length gained between the convex and concave sides of the curve. This result is in accord with that recently reported by Nnadi et al.14
Rod slippage has been addressed as a cause of failed or reduced distraction due to failure of the rotation mechanism of the actuator. In a recent prospective series of 22 patients with MCGR and at least 6 distraction procedures, Cheung et al23 found that increased height, weight, and BMI; older age; increased T1-12 and T1-S1 lengths; and less distance between magnets were associated with early rod slippage. Sankar et al24 previously described “the law of diminishing returns” as the decreasing of the amount of length achievable with repeated lengthening of TGRs. They postulated that this phenomenon may be due to autofusion of the spine from prolonged immobilization by a rigid device.24 In a prospective review of 35 patients, Ahmad et al25 also reported diminishing returns with MCGR during a 2-year period. This is contrary to the results of Gardner et al26 in a retrospective series of 28 patients. In the current series, patients treated initially with TGR gained 15% less length compared with those with no prior surgery, supporting the hypothesis that prior spine surgery and instrumentation may influence lengthening. Hence, it remains unclear whether prior surgery influences the subsequent results of the MCGR system.
Eight (33%) of the patients in the current study experienced at least 1 complication. There were 5 mechanical complications: 2 cases of rod breakage (both patients went on to posterior spinal fusion), 2 cases of hook pull-out, and 1 case of the actuator pin breaking inside the cylinder. There were 2 (8%) cases of infection. First, a patient with NIS (CS) undergoing primary MCGR developed a superficial wound infection that was successfully treated with oral antibiotics and wound vacuum therapy; second, a patient with NIS (SS), after previous TGR and multiple surgical lengthenings, developed a deep methicillin-resistant S aureus infection necessitating hardware removal and antibiotic therapy. Additionally, 1 patient had a wound breakdown without evidence of infection, and 1 patient had temporary postoperative urinary retention. Both were treated successfully. Only 2 patients, both of whom had primary MCGR for NIS, received a transfusion for postoperative anemia (hemoglobin less than 7 g/dL).
The reported complication rate after implantation of MCGRs is highly variable across different series. To the current authors' knowledge, the largest study focusing on complications included 54 patients (30 primary and 24 TGR-MCGR conversions).27 At least 1 complication was noted in 42% of the sample, with 28% requiring revision surgery. The infection rate was 4%,27 which the authors compare to the 11% prevalence reported for TGR in a study by Kabirian et al.10
The fact that all surgical and elongation procedures were performed by the same surgeon and all patients were treated with the same operative and postoperative program is a strength of this study. Limitations include the retrospective review of a heterogeneous population in terms of diagnosis (various curve stiffness and evolution time) and previous growing rod surgery. The subpopulations were not large enough to allow an accurate and reliable statistical intergroup analysis, precluding a comparison of the prevalence of complications between patients who had previously TGR and who had primary MCGR.
Trends were noted in patients converted from TGR: first, it is possible to observe a little loss of correction or no immediate improvement changing the rod; second, the lengthening procedure can be less effective. These trends can be caused by the stiffness of the spine from previous surgeries or autofusion phenomenon. On the other hand, by changing the lengthening system we avoid other surgical procedures before the final fusion, and there is a reduced risk of infection and use of drugs for anesthesia.
The main scope of MCGRs is to avoid worsening of the curve before final fusion, maximizing lung development. In the authors' experience, the MCGR system, expected to achieve approximately 66% of intended lengthening, is reliable and effective in the treatment of patients affected by early-onset scoliosis, with a low infection complication rate.
- Williams BA, Matsumoto H, McCalla DJ, et al. Development and initial validation of the classification of early-onset scoliosis (C-EOS). J Bone Joint Surg Am. 2014;96(16):1359–1367. doi:10.2106/JBJS.M.00253 [CrossRef] PMID:25143496
- Yang S, Andras LM, Redding GJ, Skaggs DL. Early-onset scoliosis: a review of history, current treatment, and future directions. Pediatrics. 2016;137(1):137–141. doi:10.1542/peds.2015-0709 [CrossRef] PMID:26644484
- Cunin V. Early-onset scoliosis: current treatment. Orthop Traumatol Surg Res. 2015;101(1) (suppl):S109–S118. doi:10.1016/j.otsr.2014.06.032 [CrossRef] PMID:25623270
- Redding GJ. Early onset scoliosis: a pulmonary perspective. Spine Deform. 2014;2(6):425–429. doi:10.1016/j.jspd.2014.04.010 [CrossRef] PMID:27927400
- Thorsness RJ, Faust JR, Behrend CJ, Sanders JO. Nonsurgical management of early-onset scoliosis. J Am Acad Orthop Surg. 2015;23(9):519–528. doi:10.5435/JAAOS-D-14-00019 [CrossRef] PMID:26306805
- Dimeglio A, Canavese F. The growing spine: how spinal deformities influence normal spine and thoracic cage growth. Eur Spine J. 2012;21(1):64–70. doi:10.1007/s00586-011-1983-3 [CrossRef] PMID:21874626
- Dimeglio A. Growth of the spine before age of 5 years. J Pediatr Orthop B. 1992;1(2):102–107. doi:10.1097/01202412-199201020-00003 [CrossRef]
- Canavese F, Dimeglio A. Normal and abnormal spine and thoracic cage development. World J Orthop. 2013;4(4):167–174. doi:10.5312/wjo.v4.i4.167 [CrossRef] PMID:24147251
- Dubousset J, Herring JA, Shufflebarger H. The crankshaft phenomenon. J Pediatr Orthop. 1989;9(5):541–550. doi:10.1097/01241398-198909010-00008 [CrossRef] PMID:2794027
- Kabirian N, Akbarnia BA, Pawelek JB, et al. Growing Spine Study Group. Deep surgical site infection following 2344 growing-rod procedures for early-onset scoliosis: risk factors and clinical consequences. J Bone Joint Surg Am. 2014;96(15):e128. doi:10.2106/JBJS.M.00618 [CrossRef] PMID:25100781
- Teoh KH, Winson DM, James SH, et al. Do magnetic growing rods have lower complication rates compared with conventional growing rods?Spine J. 2016;16(4) (suppl):S40–S44. doi:10.1016/j.spinee.2015.12.099 [CrossRef] PMID:26850175
- Rolton D, Thakar C, Wilson-MacDonald J, Nnadi C. Radiological and clinical assessment of the distraction achieved with remotely expandable growing rods in early onset scoliosis. Eur Spine J. 2016;25(10):3371–3376. doi:10.1007/s00586-015-4223-4 [CrossRef] PMID:26358257
- Lebon J, Batailler C, Wargny M, et al. Magnetically controlled growing rod in early onset scoliosis: a 30-case multicenter study. Eur Spine J. 2017;26(6):1567–1576. doi:10.1007/s00586-016-4929-y [CrossRef] PMID:28040873
- Nnadi C, Thakar C, Wilson-MacDonald J, et al. An NIHR-approved two-year observational study on magnetically controlled growth rods in the treatment of early onset scoliosis. Bone Joint J. 2018;100-B(4):507–515. doi:10.1302/0301-620X.100B4.BJJ-2017-0813.R1 [CrossRef] PMID:29629587
- Thompson W, Thakar C, Rolton DJ, Wilson-MacDonald J, Nnadi C. The use of magnetically-controlled growing rods to treat children with early-onset scoliosis: early radiological results in 19 children. Bone Joint J. 2016;98-B(9):1240–1247. doi:10.1302/0301-620X.98B9.37545 [CrossRef] PMID:27587527
- Yılmaz B, Eksi MS, Isik S, Özcan-Eksi EE, Toktas ZO, Konya D. Magnetically controlled growing rod in early-onset scoliosis: a minimum of 2-year follow-up. Pediatr Neurosurg. 2016;51(6):292–296. doi:10.1159/000448048 [CrossRef] PMID:27497928
- Ridderbusch K, Rupprecht M, Kunkel P, Hagemann C, Stücker R. Preliminary results of magnetically controlled growing rods for early onset scoliosis. J Pediatr Orthop. 2017;37(8):e575–e580. doi:10.1097/BPO.0000000000000752 [CrossRef] PMID:27182837
- Hickey BA, Towriss C, Baxter G, et al. Early experience of MAGEC magnetic growing rods in the treatment of early onset scoliosis. Eur Spine J. 2014;23(S1)(suppl 1):S61–S65. doi:10.1007/s00586-013-3163-0 [CrossRef] PMID:24413746
- Cheung JP, Samartzis D, Cheung KM. A novel approach to gradual correction of severe spinal deformity in a pediatric patient using the magnetically-controlled growing rod. Spine J. 2014;14(7):e7–e13. doi:10.1016/j.spinee.2014.01.046 [CrossRef] PMID:24495992
- Akbarnia BA, Cheung K, Noordeen H, et al. Next generation of growth-sparing techniques: preliminary clinical results of a magnetically controlled growing rod in 14 patients with early-onset scoliosis. Spine. 2013;38(8):665–670. doi:10.1097/BRS.0b013e3182773560 [CrossRef] PMID:23060057
- Akbarnia BA, Pawelek JB, Cheung KM, et al. Growing Spine Study Group. Traditional growing rods versus magnetically controlled growing rods for the surgical treatment of early-onset scoliosis: a case-match 2-year study. Spine Deform. 2014;2(6):493–497. doi:10.1016/j.jspd.2014.09.050 [CrossRef] PMID:27927412
- Gilday SE, Schwartz MS, Bylski-Austrow DI, et al. Observed length increases of magnetically controlled growing rods are lower than programmed. J Pediatr Orthop. 2018;38(3):e133–e137. doi:10.1097/BPO.0000000000001119 [CrossRef] PMID:29319661
- Cheung JPY, Yiu KKL, Samartzis D, Kwan K, Tan BB, Cheung KMC. Rod lengthening with the magnetically controlled growing rod: factors influencing rod slippage and reduced gains during distractions. Spine. 2018;43(7):E399–E405. doi:10.1097/BRS.0000000000002358 [CrossRef] PMID:28767632
- Sankar WN, Skaggs DL, Yazici M, et al. Lengthening of dual growing rods and the law of diminishing returns. Spine. 2011;36(10):806–809. doi:10.1097/BRS.0b013e318214d78f [CrossRef] PMID:21336236
- Ahmad A, Subramanian T, Panteliadis P, Wilson-Macdonald J, Rothenfluh DA, Nnadi C. Quantifying the ‘law of diminishing returns’ in magnetically controlled growing rods. Bone Joint J. 2017;99-B(12):1658–1664. doi:10.1302/0301-620X.99B12.BJJ-2017-0402.R2 [CrossRef] PMID:29212690
- Gardner A, Beaven A, Marks D, Spilsbury J, Mehta J, Newton Ede M. Does the law of diminishing returns apply to the lengthening of the MCGR rod in early onset scoliosis with reference to growth velocity?J Spine Surg.2017;3(4):525–530. doi:10.21037/jss.2017.08.16 [CrossRef] PMID:29354727
- Choi E, Yaszay B, Mundis G, et al. Implant complications after magnetically controlled growing rods for early onset scoliosis: a multicenter retrospective review. J Pediatr Orthop. 2017;37(8):e588–e592.
Demographic and Treatment Data
|Patient No.||Sex||Diagnosis||No. of Previous TGR Lengthening Procedures||Age at Surgery, y||BMI at Surgery, kg/m2||pRBC Transfusion, units||Follow-up, mo|
|1||M||NIS Ehlers-Danlos syndrome||6||6.4||14.63||-||16|
|2||F||NIS SMA II||NA||4.4||14.85||1||34|
|3||F||NIS Marfan syndrome||3||4.8||12.73||-||36|
|4||M||NIS Spastic quadriplegia||1||6.8||18.43||-||25|
|5||F||IS Juvenile scoliosis||3||6.3||17.45||-||32|
|6||F||NIS Undiagnosed neuromuscular disorder||1||5.0||18.74||-||36|
|7||F||NIS Smith-Magenis syndrome||0||7.8||16.87||-||37|
|8||F||NIS Mitochondrial DNA depletion syndrome||2||5.1||14.67||-||21|
|9||F||NIS SMA II||NA||7.4||22||-||18|
|12||F||IS Infantile scoliosis||NA||3.5||15.49||-||12|
|13||M||IS Juvenile scoliosis||6||9.2||14.5||-||34|
|14||F||NIS Hydrocephalus and developmental delay||0||6.7||22.08||-||39|
|15||F||IS Infantile scoliosis||N/A||2.8||16.61||-||15|
|16||F||NIS SMA II||NA||7.1||17.24||-||18|
|18||M||IS Infantile scoliosis||NA||3.2||12.64||-||35|
|19||M||NIS Chromosome 8 and 2 translocation||6||9.3||14.83||-||12|
|22||M||NIS Spastic quadriparesis||NA||6.8||16.54||1||27|
|23||M||IS Juvenile scoliosis||3||6.8||17.86||-||40|
|24||M||NIS Right flaccid hemiparesis||1||5.4||15.87||-||50|
|Total||14 F/10 M||15 yes/9 no||2|
Analysis of Radiographic Results
|Index||Preoperative||Postoperative||Last Follow-up||Postop–Preop||P||Last Follow-up–Postop||P|
|Cobb angle, mean±SD||57.0º±15.5º||35.7°±11.8°||36.6°±10.5°a||−21.33°±9.59°||S||0.96°±3.99°||NS|
|Kyphosis angle T1-T12, mean±SD||48.4°±11.7°||37.6°±12.1°||38.7°±10.8°a||−10.79°±10.21°||S||1.04°±7.86°||NS|
|T1-T12 length, mean±SD, cm||17.6±2.4||18.9±2.3||21.3±3.1a||1.28±1.19||S||2.32±1.71||S|
|T1-S1 length, mean±SD, cm||28.3±3.4||30.4±3.3||34±5.3a||2.03±1.72||S||3.67±2.99||S|
Summary of Lengthening Procedures by Concave/Convex Side of the Curve
|Patient No.||No. of Procedures (n=191)||Concave Side||Convex Side|
|Intended, cm||Achieved, cm||%a||Intended, cm||Achieved, cm||%a|
|Patient No.||Sex||Diagnosis||Previous TGR/No. of Lengthenings||BMI at Surgery, kg/m2||ASA Class||Early Complications||Delayed Complications|
|1||M||Ehlers-Danlos syndrome||Yes/6||15||3||-||Rod breakage|
|4||M||Spastic quadriplegia||Yes/1||18||3||Urinary retention||-|
|6||F||Undiagnosed neuromuscular disorder||Yes/1||19||3||1×1-cm wound break-down||Hook dislodgment|
|13||M||Idiopathic||Yes/6||15||2||-||Pull-out of 3 hooks|
|14||F||Hydrocephalus and developmental delay||Yes/0||22||2||-||Actuator pin fracture|
|19||M||Chromosome 8 and 2 translocation||Yes/6||15||3||-||MRSA wound infection complicating hardware|
|21||F||Congenital||No||17||3||Wound necrosis, superficial infection||-|
|22||M||Spastic quadriparesis||No||17||2||-||Rod breakage|