Unilateral monosegmental fixation (Group I, Fig. 2) was done for 15 children aged from 14 months to 10.5 years (Table 2) with the median age of 28 months. There were 11 females and 4 males. Two eggshell procedures of hemivertebra resection and 13 pedicular excisions were performed. Cobb angle for local scoliosis measured 21.1° to 45.4° preoperatively, 0° to 20.9° postoperatively, was corrected to 74.9% (р˂0.0001) and ranged from 4.1° to 28.7° at a long-term follow-up. Cobb angle for local kyphosis measured 15.1° to 44.1° preoperatively, 0.4° to 10° postoperatively, was corrected to 84.0% (р=0.042) and ranged from 3.2° to 19.0° at a long-term follow-up. Intra-operative blood loss was 50 mL to 600 mL (р=0.002). Operating time ranged from 120 minutes to 250 minutes (р˂0.0001).
Neurologic status was preoperatively classified as Frankel E level in all the patients. No intra- and postoperative neurologic complications were reported. Complications detected in 5 patients of the group (30%) included progression of the curve that required re-operation in three cases at 3-year follow-up with removal of residual hemivertebra (n=1), the crankshaft phenomenon (n=1), adding-on in lumbar spine (n=1) and progression of deformation outside the zone of instrumental fixation in the remaining patients (n=2).
Specific feature with the group included progressive curve extending outside instrumentation segments due to the second hemivertebra in case of multiple vertebral malformations (n=2).
The second surgical intervention comprised either hemivertebra excision or increased length of fixation in these patients.
Bilateral monosegmental fixation (Group II, Fig.3) was performed for 24 patients aged from 14 months to 13.8 years (Table 2) with the median of 35 months. There were 16 female and 8 male patients. An eggshell procedure of hemivertebra resection and 23 pedicular excisions were performed. Cobb angle for local scoliosis measured 14.8° to 51.9° preoperatively, 0° to 25.5° postoperatively, was corrected to 83.7% (р˂0.0001) and ranged from 0° to 27.5° at a long-term follow-up (Table 2). Cobb angle for local kyphosis measured 27.8° to 35.8° preoperatively, -12.8° to 10° postoperatively, was corrected to 100.0% (р=0.077) and ranged from 0.9° to 3.2° at a long-term follow-up (Table 2). Intra-operative blood loss was 48 mL to 750 mL (р˂0.0001). Operating time ranged from 85 minutes to 300 minutes (р˂0.0001).
Neurologic status was preoperatively classified as Frankel E level in all the patients. No intra- and postoperative neurologic complications were reported.
Complications were detected in 7 patients of the group (29%) and included necrosis of the wound edges (n=1), unstable screws (n=2, one with pedicle fracture) followed by revision surgery; broken screw at 2-year follow-up (n=1 with radicular syndrome) that entailed reassembly of metal construct; progressive curve at the site of instrumentation fixation that resulted in PJK (n=3) ; they had intervention which included bracing in one and re-operation in two.
Specific features with the group included progressive curve above instrumented fixation level due to the second hemivertebra in cases of multiple vertebral malformations (n=3) that was treated at the second stage by bracing, hemivertebra excision or increased length of fixation at one-to-three-year follow-up.
A screw appeared to cut through the bone intra-operatively being unstable (n=1) due to evidently dysplastic pedicle with fixation increased to one level and was thereafter stable at the fixation site (n=1).
Bilateral three-segmental fixation (Group III) (Fig.4) was performed for 29 patients aged 18 months to 17 years (Table 2) with the median age of 52 months. There were 15 female and 14 male patients. One eggshell procedure of hemivertebra resection, 19 pedicular excisions, 3 asymmetric PSO and 6 VCR type vertebrectomies were done. Cobb angle for local scoliosis measured 16.7° to 55.1° preoperatively, 0° to 23.6° postoperatively, was corrected to 83.1% (р˂0.0001) and ranged from 0.2° to 28.3° at a long-term follow-up (Table 2). Cobb angle for local kyphosis measured 19.7° to 65.6° preoperatively, 0° to 20.9° postoperatively, was corrected to 86.7% (р˂0.0001) and ranged from 1.1° to 11.4° at a long-term follow-up (Table 2). Intra-operative blood loss was 100 mL to 740 mL (р ˂ 0.0001). Operating time ranged from 125 minutes to 445 minutes (р˂0.0001).
Two patients developed neurological deficit postoperatively:
1. ♂, 4-year-and-5-month-old. Distal paraparesis without progression in postoperative period, Frankel type D.
2. ♂, 4-year-and-4-month-old. Distal paraparesis, hypoesthesia of the skin of the legs. No progression was observed postoperatively, Frankel type D.
Complications observed in 5 cases of the group (17.2%) included mal-position of screws with radicular syndrome (n=1), the patient had re-operation and the mal-positioned screws were reinserted; damage of the dural sac with formation of cerebrospinal fluid cyst and distal paresis on the right leg (n=1) that improved at 6 months after surgery. Progression of deformation that required extension of the construct to one segment below the level of the initial construct at 4 years after previous surgery (n=1), progression of deformity (n=1) due to weight gain of more than 20 kg and non-compliance with recommendations leading to the migration of metal constructs, this required an installation of Dual Growing Rod systems, progressive curve was treated with bracing in one patient (n=1).
Specific features with the group included intra-operative instability with a screw cutting through C6 vertebra and being replaced with a hook.
Progressive curve resulted from a poor quality brace in another patient.
Bilateral polysegmental fixation (Group IV, Fig. 5, 6) was performed for 49 children aged 20 months to 18 years (Table 2) with the median of 108 months. There were 24 female and 25 male patients. Seven eggshell procedure of hemivertebra resections, 22 pedicular excisions, 12 asymmetric PSO and 10 VCR type vertebrectomies were done. Cobb angle for local scoliosis measured 19.2° to 79.0° preoperatively, 0.1° to 34.8° postoperatively, was corrected to 72.5% (р˂0.0001) and ranged from 0.1° to 18.6° at a long-term follow-up. Loss of correction was 12.1%, P=0.21 (Table 2). Cobb angle for local kyphosis measured 25.0° to 161.1° preoperatively, 0° to 43.8° postoperatively, was corrected to 81.6% (р=0.0001) and ranged from 0° to 17.6° at a long-term follow-up (Table 2). Intra-operative blood loss was 50 mL to 1800 mL (р ˂0.0001). Operating time ranged from 115 minutes to 605 minutes (р˂0.0001).
Several patients had pre-operative neurological deficiencies:
1.♀, 6-year-and-3-month-old. Distal paraparesis without progression observed postoperatively (Frankel type С).
2.♂, 8-year-old. Distal flaccid paraplegia. No progression seen postoperatively (Frankel type B).
3.♂, 14-year-old. Distal paraparesis without progression observed postoperatively (Frankel type С).
4.♀, 3-year-and-9-month-old. Distal flaccid paraparesis with underlying myelopathy and paresis aggravated postoperatively. A course of test electric stimulation and neurotropic therapy resulted in some neurological improvement with improved tolerance to physical exertion (Frankel type С).
5.♂, 9-year-old. Distal paraplegia and pelvic organs dysfunction without postoperative improvement (Frankel type A).
Complications revealed in 8 patients of the group (16.3%) comprised progressive curve at the site of instrumentation (n=2) and PJK (n=1) that required re-operation at 2-3 years post-operatively and bracing (n=1). Five patients developed neurologic deficiency including postoperative monoparesis on the left hand without progression (n=1), persistent distal paraplegia (the patient died 5 years post-surgery) (n=1), distal paraparesis after surgery that completely resolved (n=1), left-sided distal paraparesis improved at 3 months (n=1), postoperative pleural effusion and distal paraparesis that resolved (n=1).
Metal construct reassembled at 2-year follow-up due to the fracture of both rods (n=1).
Specific features. One patient died 5 years after surgery, and the cause of death was unknown.
Design of the table is intended as an illustrative tool for comparison between the groups showing the difference in absolute values and statistical significance of the variables.