Eur Spine J (2014) 23:1237–1243 DOI 10.1007/s00586-014-3270-6
ORIGINAL ARTICLE
Comparison of anterior and posterior vertebral column resection versus anterior release with posterior internal distraction for severe and rigid scoliosis Chunpeng Ren • Limin Liu • Yueming Song Chunguang Zhou • Hao Liu • Tao Li
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Received: 1 October 2013 / Revised: 8 March 2014 / Accepted: 8 March 2014 / Published online: 20 March 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose This study aimed to compare efficacy, safety, and cost between staged vertebral column resection (VCR) and anterior release with internal distraction in treating severe and rigid idiopathic scoliosis. Methods We examined the records of 43 patients with severe and rigid idiopathic scoliosis treated in our hospital. Group A included 26 patients who underwent anterior VCR followed by posterior vertebral column resection and instrumentation from July 2007 to October 2009. Group B included 17 patients who underwent anterior release with temporary posterior internal distraction, followed by posterior fusion and instrumentation from November 2009 to June 2011. The average preoperative main curve for group A was 101.3° (range 90°–130°) and for group B was 104.8° (range 90°–136°). Minimum follow-up was 2 years. Radiographic and clinical outcomes were compared between the groups. Results A t test demonstrated that the differences between the groups in preoperative and postoperative coronal and sagittal imbalance, thoracic kyphosis correction, and lumbar lordosis were not statistically significant. Patients in group B showed better postoperative (P = 0.031) and final (P = 0.030) main thoracic curve correction (76.8 and 75.6 %, respectively) than patients in
C. Ren L. Liu (&) Y. Song C. Zhou H. Liu T. Li Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, 37 Guoxue Rd, Chengdu 610041, People’s Republic of China e-mail: [email protected] C. Ren e-mail: [email protected] Y. Song e-mail: [email protected]
group A (68.3 and 67.7 %, respectively). Patients in group B had better thoracolumbar or lumbar curve correction (85.8 %) than those in group A (76.8 %; P = 0.048). The differences in blood loss and operation time were not statistically significant (P = 0.094 and P = 0.060, respectively). Hospital stay was longer (P = 0.001) and patient cost was higher (P \ 0.001) for patients in group B. One patient in group A required ventilator support for 12 h after anterior surgery. One transient dyspnea occurred in group B. No neurologic deficits occurred in either group. Conclusion Anterior release with posterior internal distraction produces better corrective effects than anterior and posterior VCR, though hospital stay and costs are greater. Keywords Severe and rigid scoliosis Vertebral column resection Anterior release Internal distraction
Introduction The treatment of severe and rigid scoliosis remains very challenging for spine surgeons. Anterior release combined with posterior correction in one stage or two stages can achieve a correction rate of 40–50 % in patients with severe scoliosis [1–5]. Halo traction is relatively safe and can provide significant corrective forces, but its obvious drawbacks include making daily activities difficult, being poorly tolerated, and risks of cranial nerve injuries, cervical spondylosis, and paralysis [6–11]. Some have suggested that circumferential vertebral column resection (VCR) results in a better scoliosis correction rate than halo traction, and remains a viable option for severe and rigid scoliosis [12, 13]. In the last 10 years, posterior-only VCR (PVCR) has been described and popularized as a singleapproach option with similar results to the anterior and
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posterior approach [12–19]. However, PVCR brings a high neurologic risk and results in greater blood loss than staged VCR [12–17]. Temporary internal distraction is a relatively new method to facilitate curve correction through a safe, staged stretching of the spine. Grass et al. [20] first reported the use of an intermittent distracting rod in 1997 for the correction of high neurologic risk congenital scoliosis, with an average correction of 52 %. In 2006, Buchowski et al. [21] described temporary internal distraction to aid in correcting severe scoliosis for situations in which halo traction is contraindicated. Significant correction was achieved with this approach, without neurological deficits or infections. Patients with severe and rigid scoliosis usually have short stature, low body weight, and low tolerance for surgery. It is important to determine the safest and most effective method to treat this population. The purpose of our study was to compare the radiological and clinical outcomes of anterior VCR followed by posterior VCR and fusion and instrumentation versus anterior release and posterior internal distraction followed by posterior fusion and instrumentation for severe and rigid scoliosis.
Materials and methods We retrospectively reviewed the records of 43 patients with severe and rigid idiopathic scoliosis (major curve Cobb angle C90°, flexibility \30 % on bending films) treated in our hospital. Group A included 26 patients who underwent anterior vertebral column resection followed by posterior vertebral column resection and instrumentation from July 2007 to October 2009. Group B included 17 patients who underwent anterior release with temporary posterior internal distraction, followed by posterior fusion and instrumentation from November 2009 to June 2011. The average preoperative main curves for group A were 101.3° (range 90°–130°) and for group B were 104.8° (range 90°–136°). Patients were reviewed after a minimum follow-up of 2 years (range 2.0–4 years). No patients were lost to follow-up. Clinical records were reviewed for demographic data, radiological data, operating time, blood loss, length of hospital stay, patient expenses, and complications. Radiographic analysis included Cobb angle measurements of coronal curves, thoracic kyphosis, lumbar lordosis, apical vertebral translation (AVT), and coronal and sagittal balance on preoperative, early postoperative, and 2-year or later postoperative radiographs (Figs. 1, 2). In the measurement of coronal curves, the proximal thoracic curve, main thoracic curve, and thoracolumbar or lumbar curve were measured. Flexibility was calculated according to the Cobb angle obtained from bending films. AVT for thoracic curves was measured as the distance between the
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C7 plumb line and the center of the apical vertebral body or disk. AVT for thoracolumbar and lumbar curves was measured as the distance between the center sacral line and the center of the apical vertebral body or disk. Coronal balance was measured as the distance between the C7 plumb line and the center sacral line. Sagittal balance was measured as the distance between the C7 plumb line and the posterosuperior corner of S1. Thoracic kyphosis was measured by the Cobb method from the superior end plate of T5 to the lower end plate of T12, and lumbar lordosis from the superior end plate of T12 to the end plate of S1. All radiographic measurements were made by two of the authors not directly involved in the surgeries. The clinical and radiographic records were compared by independent twosample t test, with P \ 0.05 considered statistically significant. Surgical techniques Staged VCR approach All surgeries were performed by one author (L.L.) with monitoring of somatosensory-evoked and motor-evoked potentials. The VCR technique included staged anterior and posterior procedures. The first stage consisted of an approach on the convex side of the area to be resected through a thoracic or thoracoabdominal incision. The intervertebral disks adjacent to the apical vertebrae were fully excised back to the posterior longitudinal ligament. After piece-by-piece removal of apical vertebrae, the convex pedicle and part of the concave pedicle were resected. Additional disks adjacent to the resection levels were removed to provide adequate anterior release. The resected rib or titanium cage filled with morselized bone graft from the resected vertebrae was packed into the resected area (Fig. 1). A chest tube was then placed and the wound closed in a standard fashion. The posterior procedure was performed 1–2 weeks after the initial surgery. Pedicle screws were inserted segmentally, except at the resected levels. With a temporary rod contoured to the shape of the deformity applied on one side, the remaining posterior elements of the previously resected vertebrae were removed. Using persuasion and rod derotation, the deformity was corrected and temporary rods replaced by contoured permanent rods. Decortication was done at all levels of the planned fusion, and bone graft was placed along the spine for posterior fusion. After posterior surgery, a wake-up test was performed in all patients. Internal distraction approach Similar to anterior VCR, 4–5 disks were removed to provide adequate anterior release. In addition, rib heads were removed to increase spinal flexibility.
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Fig. 1 a–d An 18-year-old male with severe and rigid idiopathic thoracic scoliosis type Lenke 4B? and a 105° Cobb angle corrected in bending films to 90°. e, f The patient underwent anterior VCR of T9, a titanium mesh cage implantation and a release (disks at T7–T8, T8–T9, T9–T10 and T10–T11). g, h The patient underwent anterior
and posterior VCR of T9 and instrumentation from T2–L3. Postoperatively, the Cobb angle was corrected from 105°–33° with an acceptable sagittal kyphosis. i, j At the 24-month follow-up a 3° loss of correction in the thoracic curve was observed. k–n Pre- and postoperative photographs show marked clinical correction
Fig. 2 a–d A 17-year-old female with severe idiopathic scoliosis type Lenke 4A? and a 110° Cobb angle corrected in bending films to 108°. e, f The patient underwent an anterior release (disks at T6–T7, T7–T8, T8–T9 and T9–T10). Right eighth and ninth rib heads were removed and initial distraction was performed. The major curve was corrected to 46°, and thoracic kyphosis was corrected from 65° to 27°.
g, h After posterior spinal fusion from T2 to L4, the major curves were corrected to 16°, and thoracic kyphosis was corrected to 26°. i, j At the 24-month follow-up a 2° loss of correction in the thoracic curve was observed. k–n Pre- and postoperative photographs show marked clinical correction
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Table 1 Patient demographics and surgical data Variable
Group A (n = 26)
Group B (n = 17)
P value
Age (years)
15.1 ± 3.7 (10–24)
17.7 ± 2.9 (14–24)
0.019
Follow-up (months)
28.4 ± 4.6 (24–40)
28.1 ± 5.3 (24–38)
0.850
Anterior release length
3.9 ± 0.7 (3–5)
4.1 ± 0.3 (4–5)
0.206
Posterior fusion length
14.0 ± 0.9 (12–15)
14.4 ± 0.8 (13–15)
0.145
Screw number
14.2 ± 1.2 (12–16)
14.5 ± 1.2 (12–16)
0.427
A staged VCR approach, B internal distraction approach
After the anterior release, the patient was placed in the prone position for internal distraction. Two minimally invasive skin incisions (5–10 cm each) were made at the locations of cephalad and caudad screw insertion. Two pedicle screws were inserted at the cephalad end and two at the caudad end of the major coronal curve on the concave side. A longer distraction rod connected to the cephalad fixation points was inserted subcutaneously, and a shorter distraction rod was connected to the caudad fixation points. These two rods were connected with a side-by-side connector (Fig. 2) and were distracted by repeatedly loosening and tightening alternating screw nuts. The distraction maneuver was performed under spinal cord monitoring in all patients, and both somatosensory-evoked potentials and motor-evoked potentials were observed throughout each procedure. If curve correction of approximately 50 % or more than 50° was not achieved with the first distraction procedure, an additional distraction procedure was performed 1–2 weeks after the initial surgery. Seven patients underwent two distraction procedures. 1–4 weeks after the initial surgery or second distraction, definitive posterior spinal fusion was performed. This process was similar to the above VCR fusion steps. The previously implanted pedicle screws were either retained or partially removed, according to the requirements of further correction. The previously implanted rods were replaced with contoured permanent rods on the convex and concave sides.
Results Group A consisted of 26 patients (17 females and 9 males) and Group B consisted of 17 patients (9 females and 8 males). A statistical t test demonstrated that the differences in duration of follow-up (P = 0.850), anterior release length (P = 0.206), posterior fusion length (P = 0.145),
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and implant screw number (P = 0.427) were not statistically significant. The mean age in group B was higher than in group A (P = 0.019; Table 1). Radiological results The differences in preoperative main curve flexibility, coronal and sagittal plane Cobb angles, and imbalance were not statistically significant (Table 2). Patients in group B showed better postoperative (P = 0.031) and final (P = 0.030) main thoracic curve Cobb angle correction (76.8 and 75.6 %, respectively) than patients in group A (68.3 and 67.7 %, respectively; Table 2). Group B patients had greater postoperative thoracic kyphosis than group A patients (P = 0.041), though the differences in postoperative (P = 0.507) and final (P = 0.134) corrections were not statistically significant. The differences in postoperative and final changes in AVT, coronal and sagittal imbalance, and lumbar lordosis between the two groups were not statistically significant (Table 2). The difference in proximal thoracic curve correction was not statistically significant between the two groups (51.1 ± 12.3 % in group A vs. 51.5 ± 14.3 % in group B, P = 0.925). The mean final correction was 48.8 ± 9.8 % in group A vs. 48.1 ± 10.3 % in group B (P = 0.826). Patients in group B had better thoracolumbar or lumbar curve correction (85.8 ± 13.7 %) than those in group A (76.8 ± 14.4 %, P = 0.048). At final follow-up, thoracolumbar or lumbar curve correction in group B remained greater than in group A (72.8 ± 13.9 % in group A vs. 82.1 ± 12.1 % in group B, P = 0.029). A comparison of proximal thoracic flexibility (23.1 ± 17.4 % in group A vs. 22.6 ± 15.7 % in group B, P = 0.924) and thoracolumbar or lumbar flexibility (45.7 ± 16.1 % in group A vs. 48.4 ± 15.3 % in group B, P = 0.589) found no statistically significant differences. Clinical results Group A had an average score of 95 (range 84–107) on the Scoliosis Research Society’s 22-item questionnaire about health-related quality of life (HRQL). The average score of group B was 104 (range 91–108, P \ 0.01). The differences in blood loss and operation time were not statistically significant (P = 0.094 and P = 0.060, respectively). Group B had considerably longer hospital stays (P = 0.001), higher patient cost (P \ 0.001), and higher implant cost (P \ 0.001) than group A (Table 3). Complications Complications were encountered in two patients in group A. One patient required ventilator support for 12 h after
Eur Spine J (2014) 23:1237–1243 Table 2 Group statistics on main thoracic curve and sagittal plane of group A and group B
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Items
Group A (n = 26)
Group B (n = 17)
P value
Magnitude (°)
101.3 ± 10.3 (90–130)
104.8 ± 12.7 (90–136)
0.349
Flexibility (%)
12.2 ± 6.0 (2.7–24.5)
10.7 ± 5.9 (0.9–23)
0.425
Preoperative
AVT (cm)
7.9 ± 1.6 (6.0–11.4)
8.6 ± 1.8 (6.2–13.3)
0.202
Coronal imbalance (cm)
0.6 ± 0.5 (0–1.5)
0.8 ± 0.6 (-3.6 - 2.8)
0.263
Sagittal imbalance (cm)
0.8 ± 2.2 (-3.1 to 4.6)
T5–T12 kyphosis (°)
52.4 ± 26.1 (6–86)
T12–S1 lordosis (°)
-56.8 ± 17.1 (-122 to -85)
0.4 ± 0.7 (-2.5 to 2.7) 62.2 ± 36.2 (10–115) -66.1 ± 22.4 (-102 to -30)
0.395 0.344 0.156
Postoperative Magnitude (°)
33.1 ± 10.8 (15–52)
25.1 ± 13.1 (12–58)
0.077 0.031
IM corr (%)
68.3 ± 12.5 (51.5–83.7)
76.8 ± 11.7 (54.8–86.9)
Final follow-up (°)
32.9 ± 12.7 (18–55)
26.5 ± 12.0 (12–53)
0.107
Final corr (%)
67.7 ± 11.6 (51.4–83.1)
75.6 ± 10.7 (54.1–86.7)
0.030
AVT (cm)
2.1 ± 1.3 (0.3–4.5)
0.100
73.2 ± 12.3 (57.2–92.7) 2.4 ± 1.4 (1.0–5.1)
74.1 ± 13.2 (60.1–91.8) 3.2 ± 1.8 (0.6–7.8)
Final corr (%)
69.6 ± 13.5 (55.8–90.6)
70.7 ± 15.2 (58.4–90.3)
0.810
0.5 ± 0.6 (-1.2-1.8)
1.000
Coronal imbalance (cm)
A staged VCR approach, B internal distraction approach, AVT apical vertebral translation, IM corr immediate postoperative correction rate, Final corr correction rate of final follow-up
3.0 ± 1.9 (0.5–8.9)
IM corr (%) Final follow-up (°)
0.5 ± 0.4 (0–1.3)
0.824 0.132
Final follow-up (cm)
0.5 ± 0.5 (0–1.4)
0.5 ± 0..6 (-1.0-1.6)
1.000
Sagittal imbalance (cm)
0.7 ± 1.2 (-1.3 to 3.0)
0.2 ± 1.0 (-2.3-2.7)
0.162
Final follow-up (cm)
0.8 ± 1.1 (-1.0 to 3.0)
0.2 ± 1.0 (-2.3-2.8)
0.077
T5–T12 kyphosis (°)
26.5 ± 9.4 (17–44)
32.8 ± 9.6 (15–64)
0.041
IM corr (%)
49.5 ± 11.3 (33.2–60.7)
47.1 ± 11.6 (37.4–69.5)
0.507
Final follow-up (°)
28.7 ± 7.7 (18–42)
33.3 ± 9.4 (19–49)
0.134
Final corr (%)
46.1 ± 11.9 (28.2–60.2)
46.3 ± 10.6 (34.7–67.2)
0.956
T12–S1 lordosis (°)
-45.7 ± 8.9 (-60 to -32)
-44.5 ± 9.6 (-65 to -28)
0.712
Final follow-up (°)
-48.6 ± 6.5 (-62 to -40)
-46.2 ± 7.5 (-66 to -34)
0.333
Table 3 Comparison of clinical outcomes Variable
Group A (n = 26)
Group B (n = 17)
P value
Blood loss (mL)
1,712.5 ± 807.0 (800–3,100)
1,319.1 ± 608.2 (650–2,200)
0.094
Operation time (min)
552.2 ± 64.0 (450–680)
590.6 ± 63.1 (515–755)
0.060
Length of stay (days)
23.8 ± 2.7 (20–28)
33.2 ± 9.2 (21–49)
0.001
Implant cost (RMB:¥)
83,447 ± 4,180.3 (77,433–91,238)
97,429 ± 5,636.4 (89,377–109,331)
\0.001
Hospital expenses (RMB:¥)
123,008 ± 6,463.9 (108,935–132,784)
140,035 ± 11,829.2 \0.001 (123,804–160,347)
A staged VCR approach, B internal distraction approach
anterior surgery. Malposition of one pedicle screw was found in another patient. Fortunately, the patient did not have any neurologic compromise. One patient in group B experienced transient dyspnea after the initial surgery, which subsequently resolved without ventilator support. Two patients complained of soft-tissue pain on the concave
side after the first distraction. There were no neurological complications or instrumentation loosening or breakage.
Discussion It is difficult to correct severe scoliosis with one-stage surgery, such as posterior facet resection, transpedicular osteotomy, partial vertebrectomy, or 360° spinal osteotomy followed by instrumentation and fusion. VCR can be a lifesaving procedure for rigid severe deformities that otherwise may not be treated with standard approaches [22]. Furthermore, rapid and excessive correction in a single surgery increases the risk of neurological compromise and injury to internal organs such as the aorta. In addition, twostage procedures prevent instrumentation failure due to extreme corrective forces that may occur in one-stage procedures [23]. Vertebrectomy was first illustrated in 1922 by MacLennan [24], who described posterior apical resection followed by postoperative casting for the treatment of
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severe scoliosis. In 1997, Bradford [25] performed anterior and posterior VCR to treat 24 patients with rigid coronal decompensation. The average preoperative scoliosis of 103° was corrected by 52 %. Although it obviates a circumferential approach and has less impact on pulmonary function, PVCR is a highly technical procedure that may result in considerable blood loss and a high risk of neurological complications [12–17, 26]. In contrast, two-stage VCR may be safer and easier than PVCR for patients with severe and rigid scoliosis, who tend to have short stature and low body weight [5]. As with any surgical procedure, surgeon experience is crucial for a technically successful outcome. The stiff major curve can be turned into two free segments connected only by spinal cord after VCR. VCR may be a good option for patients with angular kyphosis or angular kyphoscoliosis, but most cases of severe and rigid scoliosis are long, 3-dimensional deformities involving many vertebral levels. Temporary internal distraction is an alternative treatment for severe scoliosis for situations in which halo traction is contraindicated. Buchowski et al. [21] reported an average correction of 80 % by posterior or anterior release and internal distraction followed by posterior spinal fusion with definitive dual-rod fixation, although curvatures \90° were included in that series. This is the first comparison of VCR and internal distraction therapy for severe and rigid scoliosis. The differences between the two methods in restoring sagittal and coronal balance were not statistically significant (Table 2). Group B patients had greater postoperative (P = 0.031) and final (P = 0.030) main thoracic curve Cobb angle correction (76.8 and 75.6 %, respectively) than patients in group A (68.3 and 67.7 %, respectively). Though the mean age of patients in group B was higher than in group A (P = 0.019), the difference in spinal flexibility was not statistically significant (P = 0.425). Bending films can be used to assess spinal flexibility, but traction films would have been more appropriate. This is one area for improvement in our future research. Group B patients had greater satisfaction with postoperative recovery. The distraction operation takes advantage of the viscoelastic properties of the spine and allows maximum correction of the deformity with minimal stress on the tissues and implants. Moreover, this approach allows for multiple distractions. Koptan et al. [27] reported that a three-stage procedure of anterior release, 2 weeks of halogravity traction, followed by posterior instrumentation achieved a significantly better correction than the procedures without traction (average 59 vs. 47 %). The thoracolumbar or lumbar curve correction in group B was greater than in group A in our study. This difference is associated with the long distraction distance. Generally, we fixed the distal pedicle screw to neutral or stable
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vertebrae of the lumbar curve. A single-level osteotomy will not affect the flexibility of the spinal segment above or below the osteotomy and cannot accomplish correction of rotation of those vertebral levels. Thus, a single anterior and posterior VCR cannot achieve 3-dimensional correction of spinal deformity. Li et al. [28] reported posterior extrapleural multiple-level intervertebral space release combined with wedge osteotomy for the treatment of severe rigid scoliosis. A mean of 4.2 disks were excised and 1.2 vertebrae removed per patient. The mean preoperative Cobb angle of 108.5° was corrected by 72.4 %, but mean blood loss during the procedure was 3,990 mL (range 2,600–6,100 mL). Tan et al. [29] and Cheng et al. [30] used less invasive posterior internal distraction followed by posterior correction and instrumentation to correct severe scoliosis. The total major coronal curve correction was 62.9 %. However, when a patient’s flexibility index was C10 %, a two-stage strategy and two-small-incision technique was applied. Because anterior release was applied in our study, flexibility was not a limiting factor. For patients with severe pulmonary dysfunction, an approach without anterior release is a good choice. We found that the differences in operation time and intraoperative blood loss between group A (two surgeries) and group B (two to three surgeries) were not statistically significant. Implant cost and hospital expenses were much higher in group B than in group A. Longer hospital stays, higher implant costs, and sometimes more surgeries in group B contributed the most to the difference in hospital expenses. The rib or titanium mesh cage may tilt or malposition in the process of posterior orthopedic procedures. Great care must be taken in anterior and posterior VCR or PVCR, because the manipulation of posterior surgery causes not only translation but also rotation of the spine, which may cause movement of interbody reconstruction materials. In our study, malposition of the titanium mesh cage occurred in four patients. The rate of cage migration was relatively high (15 %). In an effort to avoid such problems, a slightly longer mesh cage was applied to ensure a tight connection between the cage and the spinal column. A clamp was used to secure the cage during manipulation in the region of the apex, to keep the relative position of the cage and the spinal column unchanged with the modest force. No neurological complications occurred in our study. Each group had one complication associated with lung function, with the patient in group A requiring ventilator support for 12 h. Transient soft-tissue pain on the concave side occurred in two patients in group B after the first distraction. The staged surgical procedures may have contributed to a lower complication rate.
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Conclusion Anterior release with posterior internal distraction results in better corrective effects than anterior and posterior VCR, though the length of hospital stay and hospital costs are greater. Anterior release with internal distraction followed by posterior spinal fusion provides an effective and safe treatment alternative for patients with severe and rigid scoliosis. Acknowledgments
The authors did not receive any funding.
Conflict of interest The authors declare that they have no conflicts of interest.
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1243 12. Bridwell KH (2006) Decision making regarding Smith-Petersen vs. pedicle subtraction osteotomy vs. vertebral column resection for spinal deformity. Spine 31:S171–S178 13. Lenke LG, O’ Leary PT, Bridwell KH (2009) Posterior vertebral column resection for severe pediatric deformity: minimum twoyear follow-up of thirty-five consecutive patients. Spine 34:2213–2221 14. Lenke LG, Sides BA, Koester LA, Hensley M, Blanke KM (2010) Vertebral column resection for the treatment of severe spinal deformity. Clin Orthop Relat Res 468:687–699 15. Smith JS, Wang VY, Ames CP (2008) Vertebral column resection for rigid spinal deformity. Neurosurgery 63:177–182 16. Suk SI, Chung ER, Kim JH, Kim SS, Lee JS, Choi WK (2005) Posterior vertebral column resection for severe rigid scoliosis. Spine 30:1682–1687 17. Hamzaoglu A, Alanay A, Ozturk C, Sarier M, Karadereler S, Ganiyusufoglu K (2011) Posterior vertebral column resection in severe spinal deformities: a total of 102 cases. Spine 36:E340– E344 18. Lenke LG, Newton PO, Sucato DJ, Shufflebarger HL, Emans JB, Sponseller PD et al (2013) Complications after 147 consecutive vertebral column resections for severe pediatric spinal deformity. Spine 38:119–132 19. Jeszenszky D, Haschtmann D, Kleinstuck FS, Sutter M, Eggspuhler A, Weiss M et al (2013) Posterior vertebral column resection in early onset spinal deformities. Eur Spine J 23(1):198–208 20. Grass PJ, Soto AV, Araya Hp (1997) Intermittent distracting rod for correction of high neurologic risk congenital scoliosis. Spine (Phila Pa 1976) 22(16):1922–1927 21. Buchowski JM, Bhatnagar R, Skaggs DL, Sponseller PD (2006) Temporary internal distraction asan aid to correction of severe scoliosis. J Bone Joint Surg Am 88:2035–2041 22. Enercan M, Ozturk C, Kahraman S, Sarıer M, Hamzaoglu A, Alanay A (2013) Osteotomies/spinal column resections in adult deformity. Eur Spine J 22(Suppl 2):S254–S264 23. Sponseller PD, Takenaga RK, Newton P, Boachie O, Flynn J, Letko L (2008) The use of traction in the treatment of severe spinal deformity. Spine 33(21):2305 24. MacLennan A (1922) Scoliosis. Br Med J 2:865–866 25. Bradford DS, Tribus CB (1997) Vertebral column resection for the treatment of rigid coronal decompensation. Spine 22:1590–1599 26. Xie JM, Li T, Wang YS, Zhao Z, Zhang Y, Bi N (2012) Change in Cobb angle of each segment of the major curve after posterior vertebral column resection (PVCR): a preliminary discussion of correction mechanisms of PVCR. Eur Spine J 21:705–710 27. Koptan W, EIMiligui Y (2012) Three-staged correction of severe rigid idiopathic scoliosis using limited halo-gravity traction. Eur Spine J 21(6):1091–1098 28. Li C, Fu QS, Zhou Y, Yu HY, Zhao G (2012) Posterior extrapleural intervertebral space release combined with wedge osteotomy for the treatment of severe rigid scoliosis. Spine 37:E647– E654 29. Tan R, Ma HS, Zou DW, Wu JG, Chen ZM, Zhou XF (2012) Surgical treatment of severe scoliosis and kyphoscoliosis by stages. Chin Med J 125(1):81–86 30. Cheng XF, Ma HS, Tan R, Wu JG, Zhou JW, Zou DW (2012) Two-stage posterior-only procedures for correction of severe spinal deformities. Arch Orthop Trauma Surg 132:193–201
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ORIGINAL ARTICLE
Comparison of anterior and posterior vertebral column resection versus anterior release with posterior internal distraction for severe and rigid scoliosis Chunpeng Ren • Limin Liu • Yueming Song Chunguang Zhou • Hao Liu • Tao Li
•
Received: 1 October 2013 / Revised: 8 March 2014 / Accepted: 8 March 2014 / Published online: 20 March 2014 Ó Springer-Verlag Berlin Heidelberg 2014
Abstract Purpose This study aimed to compare efficacy, safety, and cost between staged vertebral column resection (VCR) and anterior release with internal distraction in treating severe and rigid idiopathic scoliosis. Methods We examined the records of 43 patients with severe and rigid idiopathic scoliosis treated in our hospital. Group A included 26 patients who underwent anterior VCR followed by posterior vertebral column resection and instrumentation from July 2007 to October 2009. Group B included 17 patients who underwent anterior release with temporary posterior internal distraction, followed by posterior fusion and instrumentation from November 2009 to June 2011. The average preoperative main curve for group A was 101.3° (range 90°–130°) and for group B was 104.8° (range 90°–136°). Minimum follow-up was 2 years. Radiographic and clinical outcomes were compared between the groups. Results A t test demonstrated that the differences between the groups in preoperative and postoperative coronal and sagittal imbalance, thoracic kyphosis correction, and lumbar lordosis were not statistically significant. Patients in group B showed better postoperative (P = 0.031) and final (P = 0.030) main thoracic curve correction (76.8 and 75.6 %, respectively) than patients in
C. Ren L. Liu (&) Y. Song C. Zhou H. Liu T. Li Department of Orthopedics, West China Hospital, Sichuan University, Chengdu, 37 Guoxue Rd, Chengdu 610041, People’s Republic of China e-mail: [email protected] C. Ren e-mail: [email protected] Y. Song e-mail: [email protected]
group A (68.3 and 67.7 %, respectively). Patients in group B had better thoracolumbar or lumbar curve correction (85.8 %) than those in group A (76.8 %; P = 0.048). The differences in blood loss and operation time were not statistically significant (P = 0.094 and P = 0.060, respectively). Hospital stay was longer (P = 0.001) and patient cost was higher (P \ 0.001) for patients in group B. One patient in group A required ventilator support for 12 h after anterior surgery. One transient dyspnea occurred in group B. No neurologic deficits occurred in either group. Conclusion Anterior release with posterior internal distraction produces better corrective effects than anterior and posterior VCR, though hospital stay and costs are greater. Keywords Severe and rigid scoliosis Vertebral column resection Anterior release Internal distraction
Introduction The treatment of severe and rigid scoliosis remains very challenging for spine surgeons. Anterior release combined with posterior correction in one stage or two stages can achieve a correction rate of 40–50 % in patients with severe scoliosis [1–5]. Halo traction is relatively safe and can provide significant corrective forces, but its obvious drawbacks include making daily activities difficult, being poorly tolerated, and risks of cranial nerve injuries, cervical spondylosis, and paralysis [6–11]. Some have suggested that circumferential vertebral column resection (VCR) results in a better scoliosis correction rate than halo traction, and remains a viable option for severe and rigid scoliosis [12, 13]. In the last 10 years, posterior-only VCR (PVCR) has been described and popularized as a singleapproach option with similar results to the anterior and
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posterior approach [12–19]. However, PVCR brings a high neurologic risk and results in greater blood loss than staged VCR [12–17]. Temporary internal distraction is a relatively new method to facilitate curve correction through a safe, staged stretching of the spine. Grass et al. [20] first reported the use of an intermittent distracting rod in 1997 for the correction of high neurologic risk congenital scoliosis, with an average correction of 52 %. In 2006, Buchowski et al. [21] described temporary internal distraction to aid in correcting severe scoliosis for situations in which halo traction is contraindicated. Significant correction was achieved with this approach, without neurological deficits or infections. Patients with severe and rigid scoliosis usually have short stature, low body weight, and low tolerance for surgery. It is important to determine the safest and most effective method to treat this population. The purpose of our study was to compare the radiological and clinical outcomes of anterior VCR followed by posterior VCR and fusion and instrumentation versus anterior release and posterior internal distraction followed by posterior fusion and instrumentation for severe and rigid scoliosis.
Materials and methods We retrospectively reviewed the records of 43 patients with severe and rigid idiopathic scoliosis (major curve Cobb angle C90°, flexibility \30 % on bending films) treated in our hospital. Group A included 26 patients who underwent anterior vertebral column resection followed by posterior vertebral column resection and instrumentation from July 2007 to October 2009. Group B included 17 patients who underwent anterior release with temporary posterior internal distraction, followed by posterior fusion and instrumentation from November 2009 to June 2011. The average preoperative main curves for group A were 101.3° (range 90°–130°) and for group B were 104.8° (range 90°–136°). Patients were reviewed after a minimum follow-up of 2 years (range 2.0–4 years). No patients were lost to follow-up. Clinical records were reviewed for demographic data, radiological data, operating time, blood loss, length of hospital stay, patient expenses, and complications. Radiographic analysis included Cobb angle measurements of coronal curves, thoracic kyphosis, lumbar lordosis, apical vertebral translation (AVT), and coronal and sagittal balance on preoperative, early postoperative, and 2-year or later postoperative radiographs (Figs. 1, 2). In the measurement of coronal curves, the proximal thoracic curve, main thoracic curve, and thoracolumbar or lumbar curve were measured. Flexibility was calculated according to the Cobb angle obtained from bending films. AVT for thoracic curves was measured as the distance between the
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C7 plumb line and the center of the apical vertebral body or disk. AVT for thoracolumbar and lumbar curves was measured as the distance between the center sacral line and the center of the apical vertebral body or disk. Coronal balance was measured as the distance between the C7 plumb line and the center sacral line. Sagittal balance was measured as the distance between the C7 plumb line and the posterosuperior corner of S1. Thoracic kyphosis was measured by the Cobb method from the superior end plate of T5 to the lower end plate of T12, and lumbar lordosis from the superior end plate of T12 to the end plate of S1. All radiographic measurements were made by two of the authors not directly involved in the surgeries. The clinical and radiographic records were compared by independent twosample t test, with P \ 0.05 considered statistically significant. Surgical techniques Staged VCR approach All surgeries were performed by one author (L.L.) with monitoring of somatosensory-evoked and motor-evoked potentials. The VCR technique included staged anterior and posterior procedures. The first stage consisted of an approach on the convex side of the area to be resected through a thoracic or thoracoabdominal incision. The intervertebral disks adjacent to the apical vertebrae were fully excised back to the posterior longitudinal ligament. After piece-by-piece removal of apical vertebrae, the convex pedicle and part of the concave pedicle were resected. Additional disks adjacent to the resection levels were removed to provide adequate anterior release. The resected rib or titanium cage filled with morselized bone graft from the resected vertebrae was packed into the resected area (Fig. 1). A chest tube was then placed and the wound closed in a standard fashion. The posterior procedure was performed 1–2 weeks after the initial surgery. Pedicle screws were inserted segmentally, except at the resected levels. With a temporary rod contoured to the shape of the deformity applied on one side, the remaining posterior elements of the previously resected vertebrae were removed. Using persuasion and rod derotation, the deformity was corrected and temporary rods replaced by contoured permanent rods. Decortication was done at all levels of the planned fusion, and bone graft was placed along the spine for posterior fusion. After posterior surgery, a wake-up test was performed in all patients. Internal distraction approach Similar to anterior VCR, 4–5 disks were removed to provide adequate anterior release. In addition, rib heads were removed to increase spinal flexibility.
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Fig. 1 a–d An 18-year-old male with severe and rigid idiopathic thoracic scoliosis type Lenke 4B? and a 105° Cobb angle corrected in bending films to 90°. e, f The patient underwent anterior VCR of T9, a titanium mesh cage implantation and a release (disks at T7–T8, T8–T9, T9–T10 and T10–T11). g, h The patient underwent anterior
and posterior VCR of T9 and instrumentation from T2–L3. Postoperatively, the Cobb angle was corrected from 105°–33° with an acceptable sagittal kyphosis. i, j At the 24-month follow-up a 3° loss of correction in the thoracic curve was observed. k–n Pre- and postoperative photographs show marked clinical correction
Fig. 2 a–d A 17-year-old female with severe idiopathic scoliosis type Lenke 4A? and a 110° Cobb angle corrected in bending films to 108°. e, f The patient underwent an anterior release (disks at T6–T7, T7–T8, T8–T9 and T9–T10). Right eighth and ninth rib heads were removed and initial distraction was performed. The major curve was corrected to 46°, and thoracic kyphosis was corrected from 65° to 27°.
g, h After posterior spinal fusion from T2 to L4, the major curves were corrected to 16°, and thoracic kyphosis was corrected to 26°. i, j At the 24-month follow-up a 2° loss of correction in the thoracic curve was observed. k–n Pre- and postoperative photographs show marked clinical correction
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Table 1 Patient demographics and surgical data Variable
Group A (n = 26)
Group B (n = 17)
P value
Age (years)
15.1 ± 3.7 (10–24)
17.7 ± 2.9 (14–24)
0.019
Follow-up (months)
28.4 ± 4.6 (24–40)
28.1 ± 5.3 (24–38)
0.850
Anterior release length
3.9 ± 0.7 (3–5)
4.1 ± 0.3 (4–5)
0.206
Posterior fusion length
14.0 ± 0.9 (12–15)
14.4 ± 0.8 (13–15)
0.145
Screw number
14.2 ± 1.2 (12–16)
14.5 ± 1.2 (12–16)
0.427
A staged VCR approach, B internal distraction approach
After the anterior release, the patient was placed in the prone position for internal distraction. Two minimally invasive skin incisions (5–10 cm each) were made at the locations of cephalad and caudad screw insertion. Two pedicle screws were inserted at the cephalad end and two at the caudad end of the major coronal curve on the concave side. A longer distraction rod connected to the cephalad fixation points was inserted subcutaneously, and a shorter distraction rod was connected to the caudad fixation points. These two rods were connected with a side-by-side connector (Fig. 2) and were distracted by repeatedly loosening and tightening alternating screw nuts. The distraction maneuver was performed under spinal cord monitoring in all patients, and both somatosensory-evoked potentials and motor-evoked potentials were observed throughout each procedure. If curve correction of approximately 50 % or more than 50° was not achieved with the first distraction procedure, an additional distraction procedure was performed 1–2 weeks after the initial surgery. Seven patients underwent two distraction procedures. 1–4 weeks after the initial surgery or second distraction, definitive posterior spinal fusion was performed. This process was similar to the above VCR fusion steps. The previously implanted pedicle screws were either retained or partially removed, according to the requirements of further correction. The previously implanted rods were replaced with contoured permanent rods on the convex and concave sides.
Results Group A consisted of 26 patients (17 females and 9 males) and Group B consisted of 17 patients (9 females and 8 males). A statistical t test demonstrated that the differences in duration of follow-up (P = 0.850), anterior release length (P = 0.206), posterior fusion length (P = 0.145),
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and implant screw number (P = 0.427) were not statistically significant. The mean age in group B was higher than in group A (P = 0.019; Table 1). Radiological results The differences in preoperative main curve flexibility, coronal and sagittal plane Cobb angles, and imbalance were not statistically significant (Table 2). Patients in group B showed better postoperative (P = 0.031) and final (P = 0.030) main thoracic curve Cobb angle correction (76.8 and 75.6 %, respectively) than patients in group A (68.3 and 67.7 %, respectively; Table 2). Group B patients had greater postoperative thoracic kyphosis than group A patients (P = 0.041), though the differences in postoperative (P = 0.507) and final (P = 0.134) corrections were not statistically significant. The differences in postoperative and final changes in AVT, coronal and sagittal imbalance, and lumbar lordosis between the two groups were not statistically significant (Table 2). The difference in proximal thoracic curve correction was not statistically significant between the two groups (51.1 ± 12.3 % in group A vs. 51.5 ± 14.3 % in group B, P = 0.925). The mean final correction was 48.8 ± 9.8 % in group A vs. 48.1 ± 10.3 % in group B (P = 0.826). Patients in group B had better thoracolumbar or lumbar curve correction (85.8 ± 13.7 %) than those in group A (76.8 ± 14.4 %, P = 0.048). At final follow-up, thoracolumbar or lumbar curve correction in group B remained greater than in group A (72.8 ± 13.9 % in group A vs. 82.1 ± 12.1 % in group B, P = 0.029). A comparison of proximal thoracic flexibility (23.1 ± 17.4 % in group A vs. 22.6 ± 15.7 % in group B, P = 0.924) and thoracolumbar or lumbar flexibility (45.7 ± 16.1 % in group A vs. 48.4 ± 15.3 % in group B, P = 0.589) found no statistically significant differences. Clinical results Group A had an average score of 95 (range 84–107) on the Scoliosis Research Society’s 22-item questionnaire about health-related quality of life (HRQL). The average score of group B was 104 (range 91–108, P \ 0.01). The differences in blood loss and operation time were not statistically significant (P = 0.094 and P = 0.060, respectively). Group B had considerably longer hospital stays (P = 0.001), higher patient cost (P \ 0.001), and higher implant cost (P \ 0.001) than group A (Table 3). Complications Complications were encountered in two patients in group A. One patient required ventilator support for 12 h after
Eur Spine J (2014) 23:1237–1243 Table 2 Group statistics on main thoracic curve and sagittal plane of group A and group B
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Items
Group A (n = 26)
Group B (n = 17)
P value
Magnitude (°)
101.3 ± 10.3 (90–130)
104.8 ± 12.7 (90–136)
0.349
Flexibility (%)
12.2 ± 6.0 (2.7–24.5)
10.7 ± 5.9 (0.9–23)
0.425
Preoperative
AVT (cm)
7.9 ± 1.6 (6.0–11.4)
8.6 ± 1.8 (6.2–13.3)
0.202
Coronal imbalance (cm)
0.6 ± 0.5 (0–1.5)
0.8 ± 0.6 (-3.6 - 2.8)
0.263
Sagittal imbalance (cm)
0.8 ± 2.2 (-3.1 to 4.6)
T5–T12 kyphosis (°)
52.4 ± 26.1 (6–86)
T12–S1 lordosis (°)
-56.8 ± 17.1 (-122 to -85)
0.4 ± 0.7 (-2.5 to 2.7) 62.2 ± 36.2 (10–115) -66.1 ± 22.4 (-102 to -30)
0.395 0.344 0.156
Postoperative Magnitude (°)
33.1 ± 10.8 (15–52)
25.1 ± 13.1 (12–58)
0.077 0.031
IM corr (%)
68.3 ± 12.5 (51.5–83.7)
76.8 ± 11.7 (54.8–86.9)
Final follow-up (°)
32.9 ± 12.7 (18–55)
26.5 ± 12.0 (12–53)
0.107
Final corr (%)
67.7 ± 11.6 (51.4–83.1)
75.6 ± 10.7 (54.1–86.7)
0.030
AVT (cm)
2.1 ± 1.3 (0.3–4.5)
0.100
73.2 ± 12.3 (57.2–92.7) 2.4 ± 1.4 (1.0–5.1)
74.1 ± 13.2 (60.1–91.8) 3.2 ± 1.8 (0.6–7.8)
Final corr (%)
69.6 ± 13.5 (55.8–90.6)
70.7 ± 15.2 (58.4–90.3)
0.810
0.5 ± 0.6 (-1.2-1.8)
1.000
Coronal imbalance (cm)
A staged VCR approach, B internal distraction approach, AVT apical vertebral translation, IM corr immediate postoperative correction rate, Final corr correction rate of final follow-up
3.0 ± 1.9 (0.5–8.9)
IM corr (%) Final follow-up (°)
0.5 ± 0.4 (0–1.3)
0.824 0.132
Final follow-up (cm)
0.5 ± 0.5 (0–1.4)
0.5 ± 0..6 (-1.0-1.6)
1.000
Sagittal imbalance (cm)
0.7 ± 1.2 (-1.3 to 3.0)
0.2 ± 1.0 (-2.3-2.7)
0.162
Final follow-up (cm)
0.8 ± 1.1 (-1.0 to 3.0)
0.2 ± 1.0 (-2.3-2.8)
0.077
T5–T12 kyphosis (°)
26.5 ± 9.4 (17–44)
32.8 ± 9.6 (15–64)
0.041
IM corr (%)
49.5 ± 11.3 (33.2–60.7)
47.1 ± 11.6 (37.4–69.5)
0.507
Final follow-up (°)
28.7 ± 7.7 (18–42)
33.3 ± 9.4 (19–49)
0.134
Final corr (%)
46.1 ± 11.9 (28.2–60.2)
46.3 ± 10.6 (34.7–67.2)
0.956
T12–S1 lordosis (°)
-45.7 ± 8.9 (-60 to -32)
-44.5 ± 9.6 (-65 to -28)
0.712
Final follow-up (°)
-48.6 ± 6.5 (-62 to -40)
-46.2 ± 7.5 (-66 to -34)
0.333
Table 3 Comparison of clinical outcomes Variable
Group A (n = 26)
Group B (n = 17)
P value
Blood loss (mL)
1,712.5 ± 807.0 (800–3,100)
1,319.1 ± 608.2 (650–2,200)
0.094
Operation time (min)
552.2 ± 64.0 (450–680)
590.6 ± 63.1 (515–755)
0.060
Length of stay (days)
23.8 ± 2.7 (20–28)
33.2 ± 9.2 (21–49)
0.001
Implant cost (RMB:¥)
83,447 ± 4,180.3 (77,433–91,238)
97,429 ± 5,636.4 (89,377–109,331)
\0.001
Hospital expenses (RMB:¥)
123,008 ± 6,463.9 (108,935–132,784)
140,035 ± 11,829.2 \0.001 (123,804–160,347)
A staged VCR approach, B internal distraction approach
anterior surgery. Malposition of one pedicle screw was found in another patient. Fortunately, the patient did not have any neurologic compromise. One patient in group B experienced transient dyspnea after the initial surgery, which subsequently resolved without ventilator support. Two patients complained of soft-tissue pain on the concave
side after the first distraction. There were no neurological complications or instrumentation loosening or breakage.
Discussion It is difficult to correct severe scoliosis with one-stage surgery, such as posterior facet resection, transpedicular osteotomy, partial vertebrectomy, or 360° spinal osteotomy followed by instrumentation and fusion. VCR can be a lifesaving procedure for rigid severe deformities that otherwise may not be treated with standard approaches [22]. Furthermore, rapid and excessive correction in a single surgery increases the risk of neurological compromise and injury to internal organs such as the aorta. In addition, twostage procedures prevent instrumentation failure due to extreme corrective forces that may occur in one-stage procedures [23]. Vertebrectomy was first illustrated in 1922 by MacLennan [24], who described posterior apical resection followed by postoperative casting for the treatment of
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severe scoliosis. In 1997, Bradford [25] performed anterior and posterior VCR to treat 24 patients with rigid coronal decompensation. The average preoperative scoliosis of 103° was corrected by 52 %. Although it obviates a circumferential approach and has less impact on pulmonary function, PVCR is a highly technical procedure that may result in considerable blood loss and a high risk of neurological complications [12–17, 26]. In contrast, two-stage VCR may be safer and easier than PVCR for patients with severe and rigid scoliosis, who tend to have short stature and low body weight [5]. As with any surgical procedure, surgeon experience is crucial for a technically successful outcome. The stiff major curve can be turned into two free segments connected only by spinal cord after VCR. VCR may be a good option for patients with angular kyphosis or angular kyphoscoliosis, but most cases of severe and rigid scoliosis are long, 3-dimensional deformities involving many vertebral levels. Temporary internal distraction is an alternative treatment for severe scoliosis for situations in which halo traction is contraindicated. Buchowski et al. [21] reported an average correction of 80 % by posterior or anterior release and internal distraction followed by posterior spinal fusion with definitive dual-rod fixation, although curvatures \90° were included in that series. This is the first comparison of VCR and internal distraction therapy for severe and rigid scoliosis. The differences between the two methods in restoring sagittal and coronal balance were not statistically significant (Table 2). Group B patients had greater postoperative (P = 0.031) and final (P = 0.030) main thoracic curve Cobb angle correction (76.8 and 75.6 %, respectively) than patients in group A (68.3 and 67.7 %, respectively). Though the mean age of patients in group B was higher than in group A (P = 0.019), the difference in spinal flexibility was not statistically significant (P = 0.425). Bending films can be used to assess spinal flexibility, but traction films would have been more appropriate. This is one area for improvement in our future research. Group B patients had greater satisfaction with postoperative recovery. The distraction operation takes advantage of the viscoelastic properties of the spine and allows maximum correction of the deformity with minimal stress on the tissues and implants. Moreover, this approach allows for multiple distractions. Koptan et al. [27] reported that a three-stage procedure of anterior release, 2 weeks of halogravity traction, followed by posterior instrumentation achieved a significantly better correction than the procedures without traction (average 59 vs. 47 %). The thoracolumbar or lumbar curve correction in group B was greater than in group A in our study. This difference is associated with the long distraction distance. Generally, we fixed the distal pedicle screw to neutral or stable
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vertebrae of the lumbar curve. A single-level osteotomy will not affect the flexibility of the spinal segment above or below the osteotomy and cannot accomplish correction of rotation of those vertebral levels. Thus, a single anterior and posterior VCR cannot achieve 3-dimensional correction of spinal deformity. Li et al. [28] reported posterior extrapleural multiple-level intervertebral space release combined with wedge osteotomy for the treatment of severe rigid scoliosis. A mean of 4.2 disks were excised and 1.2 vertebrae removed per patient. The mean preoperative Cobb angle of 108.5° was corrected by 72.4 %, but mean blood loss during the procedure was 3,990 mL (range 2,600–6,100 mL). Tan et al. [29] and Cheng et al. [30] used less invasive posterior internal distraction followed by posterior correction and instrumentation to correct severe scoliosis. The total major coronal curve correction was 62.9 %. However, when a patient’s flexibility index was C10 %, a two-stage strategy and two-small-incision technique was applied. Because anterior release was applied in our study, flexibility was not a limiting factor. For patients with severe pulmonary dysfunction, an approach without anterior release is a good choice. We found that the differences in operation time and intraoperative blood loss between group A (two surgeries) and group B (two to three surgeries) were not statistically significant. Implant cost and hospital expenses were much higher in group B than in group A. Longer hospital stays, higher implant costs, and sometimes more surgeries in group B contributed the most to the difference in hospital expenses. The rib or titanium mesh cage may tilt or malposition in the process of posterior orthopedic procedures. Great care must be taken in anterior and posterior VCR or PVCR, because the manipulation of posterior surgery causes not only translation but also rotation of the spine, which may cause movement of interbody reconstruction materials. In our study, malposition of the titanium mesh cage occurred in four patients. The rate of cage migration was relatively high (15 %). In an effort to avoid such problems, a slightly longer mesh cage was applied to ensure a tight connection between the cage and the spinal column. A clamp was used to secure the cage during manipulation in the region of the apex, to keep the relative position of the cage and the spinal column unchanged with the modest force. No neurological complications occurred in our study. Each group had one complication associated with lung function, with the patient in group A requiring ventilator support for 12 h. Transient soft-tissue pain on the concave side occurred in two patients in group B after the first distraction. The staged surgical procedures may have contributed to a lower complication rate.
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Conclusion Anterior release with posterior internal distraction results in better corrective effects than anterior and posterior VCR, though the length of hospital stay and hospital costs are greater. Anterior release with internal distraction followed by posterior spinal fusion provides an effective and safe treatment alternative for patients with severe and rigid scoliosis. Acknowledgments
The authors did not receive any funding.
Conflict of interest The authors declare that they have no conflicts of interest.
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