Effect of posterior fusion surgery on idiopathic scoliosis in Iran.

BACKGROUND: Scoliosis is a sideways curve in the spine. Considering that postoperative complications are common among these patients, the aim of this study is to examine the postoperative complications of posterior fusion surgery with instrumentation among adult patients with idiopathic scoliosis.
METHODS: In this cross-sectional descriptive study, the postoperative complications were examined among 93 patients with idiopathic scoliosis who underwent posterior fusion surgery with instrumentation. The convenience sampling was used by referring to the files of these patients. The patients were classified into four groups according to the type of scoliosis deformity (long C-shaped, thoracic, thoracolumbar/lumbar, and double-curve) and the complications were compared together.
RESULTS: Postoperative respiratory problems were significantly different between the four groups of scoliosis deformity (P = 0.009); 35 cases of postoperative complications occurred and 20 of them were related to postoperative pulmonary complications.
CONCLUSION: Postoperative complications are common among patients with idiopathic scoliosis who underwent posterior fusion surgery with instrumentation; in addition, pulmonary complications are the most common postoperative complication among these patients.

INTRODUCTION

Scoliosis is a deformity or sideways curve of the spine in the coronal plane. The deformity happens due to many reasons; however, in most cases, the cause is unknown or idiopathic. When the deformity is due to developmental disorders, it is called congenital scoliosis. The incidence of this type of congenital scoliosis is 0.5–1/1000 births.[123] The problems caused by this disorder for the person include respiratory, cardiovascular, blood pressure, neurological, decreased activity level, decreased quality of life, increased incidence of back pain, and also appearance problems.[4] Surgical treatments for adults with scoliosis are so difficult that they do not respond to surgical treatments most of the times. There are several surgical procedures available for scoliosis, the use of which depends on the symptoms of the patient, curvature degree of sclerosis, and the type of scoliosis. Removal of pressure or decompression alone can be beneficial for patients with mild-to-moderate scoliosis, although this approach can also be used for iatrogenic instability and progressive deformities.[56] Decompression together with arthrodesis is used in cases where the progressed spine deformity is associated with an imbalance in the coronal and sagittal plane.[7] The posterior segmental instrumentation is also used to enhance deformity correction and increase the level of effusion in cases requiring fusion at the anterior and posterior approach.[8] It should be noted that these arthrodesis surgical procedures for the treatment of degenerative scoliosis were significantly associated with postoperative and intraoperative complications, increased blood loss, and prolonged hospital stay. The most common complications reported for these surgical procedures include neurological complications, infection, thromboembolism, and death, which can occur for >30% of cases.[9] However, in the previous studies, the cause of these postoperative complications was not clear. Furthermore, there is no extensive study in Iran to examine the magnitude of these scoliosis postoperative complications in a large statistical society. Therefore, considering the existing studies and their contradictory results in addition to the fact that the scoliosis postoperative complications such as infections are very common and can compromise the patient's life by causing other complications, it is possible to prevent the occurrence of these complications, improve the quality of life of the patients, and prevent future health-care costs for these patients by implementing proper treatments, and due follow-ups for people with high-risk factor. The purpose of this study is to examine postoperative complications among patients undergoing scoliosis surgery.

METHODS

In this retrospective, descriptive cross-sectional study, which was approved by the Vice President of Research Affairs of Isfahan University of Medical Sciences, 93 adult patients with idiopathic scoliosis were examined, who underwent posterior spinal fusion with posterior instrumentation (including hook or pedicle screw) for correcting scoliosis in the period of 2006–2015. Samples were taken from patients' files. A list of these files was prepared and samples were randomly selected based on the random number table. The inclusion criteria included all patients with scoliosis who had scoliosis surgery indication, consent for participation in the study, and the angle of scoliosis or Cobb >10°. Considering that the data in this study were collected by referring to patients' files, no exclusion criteria was considered. Patients' information, including age, sex, severity of deformity (mild or Cobb <30°, moderate or 30°< Cobb <50°, and severe or Cobb >50°), deformity or curve type (divided into four categories of long C-shaped, thoracic, thoracolumbar/lumbar, and double-curve), and the presence of (preoperative) respiratory problems was extracted from patients files and recorded. Based on the type of deformity, patients were divided into four groups and the results of this study were examined for these four groups. Before surgery, posterior and anterior radiography in standing position were carried out for all patients, in addition to two lateral oblique radiography, to estimate the angle of the original curve, the change in the location of torso or at the coronal axis from the C7 to the sacrum, the amount of kyphosis (using the Cobb angle of T5-T12), the amount of lordosis (using the Cobb angle of T12-S1), and the pelvic bone curve. In this study, we evaluated the early complications of the disease in the first and second weeks after the surgery. We divided these complications into five groups: pulmonary, infectious, neurological, cardiovascular, and other complications. Each of these complications is described separately in the Results section. The required information was extracted from the patient's files and recorded in the data collection forms prepared for each person. The collected data were entered into SPSS version 24 (IBM, Chicago, IL, United state). The Chi-square test was used for the relation between qualitative data, the ANOVA was used for quantitative and qualitative data; moreover, quantitative data were presented as mean ± standard deviation and qualitative data were presented as numbers or percentages.

RESULTS

In this study, patients were divided into five groups according to the type of deformity. Thus, 13 patients were included in the long C group (6 males and 7 females), 20 patients were included in the thoracic group (13 males and 7 females), 50 patients were included in the thoracolumbar and lumbar group (29 males and 21 females), and 10 patients were included in the double-curve group (5 males and 5 females). The mean age of participants in the long C, thoracic, thoracolumbar or lumbar, and double-curve groups were 19.23 ± 3.24, 25.30 ± 2.34, 20.24 ± 4.57, and 23.50 ± 3.62, respectively. It should be noted that there was no significant difference between the groups in terms of sex (P = 0.52); however, there was a significant difference between the groups in terms of gender (P < 0.0001). Due to the high prevalence of preoperative respiratory problems in patients (25.8%), we examined respiratory problems separately in these groups: respiratory problems in the long C, thoracic, thoracolumbar, or lumbar groups, and double-curve were 23.1%, 20%, 20%, 70%, respectively. Furthermore, there was a significant difference between the groups in terms of respiratory problems (P = 0.009), so that the preoperative respiratory problems in the double-curve group were higher compared to the other groups. The severity of deformity in the groups was as follows: in the long C group, 23.1% were mild, 38.5% moderate, and 38.5% severe; in the thoracic group, 20% were mild, 45% moderate, and 35% severe; in the thoracolumbar group, 26% were mild, 42% moderate, and 32% severe; in the double-curve group, 30% were moderate and 70% were severe. There was no significant difference between the groups in terms of the severity of deformity (P = 0.38) [Patient information is summarized in Table 1].

Table 1

Patients information with scoliosis base on scoliosis type

Variables	Long C (n=13), n (%)	Thoracic (n=20), n (%)	Thoracolumbar and lumbric (n=50), n (%)	Double-curve (n=10), n (%)	Total (n=93), n (%)	P
Gender
Male	6 (46.2)	13 (65)	29 (58)	5 (50)	53 (57)	0.71
Female	7 (53.8)	7 (35)	21 (42)	5 (50)	40 (43)
Age (years), mean±SD	19.23±3.24	25.30±2.34	20.24±4.57	23.50±3.62	21.53±4.48	<0.0001
Preoperative respiratory problems
Yes	3 (23.1)	4 (20)	10 (20)	7 (70)	24 (25.8)	0.009
No	10 (76.9)	16 (80)	40 (80)	3 (36.4)	69 (74.2)
Deformity severity
Mild	3 (23.1)	4 (20)	13 (26)	0 (0)	21 (21.5)	0.38
Moderate	5 (38.5)	9 (45)	21 (42)	3 (30)	38 (40.9)
Severe	5 (38.5)	7 (35)	16 (32)	7 (70)	35 (37.6)
Postoperative complications
Pulmonary	2 (15.38)	5 (25)	10 (20)	3 (30)	20 (21.5)	0.84
Infectious	2 (15.38)	2 (10)	2 (4)	1 (10)	7 (7.5)
Neurology	0	1 (5)	2 (4)	1 (10)	4 (4.3)
Others	0	1 (5)	2 (4)	1 (10)	4 (4.3)

SD - Standard deviation

Postoperative complications

We divided postoperative complications into five categories in this study. The first category included pulmonary complications which were observed in 20 patients (21.5%), of which 10 patients had prolonged atelectasis and needed supportive treatment with oxygen therapy, long-term intubation (> 48 h), and hospitalization for >5 days at the intensive care unit (ICU). Six of them had postoperative pneumonia, and one had both atelectasis and pneumonia. It is worth mentioning that these patients responded to oral treatments. Pneumothorax was developed in three patients, which was corrected with chest tube. Two patients needed intubation and readmission in ICU. The second group included infections which were found in seven patients (7.5%): four cases of superficial incisional surgical site infection (SSI), and two cases of deep incisional SSI, and one case of urinary tract infection. There were neurological complications in four patients (4.3%): three cases of sensory weaknesses in the lower torso and one case of lower diplegia. Four cases (4.3%) had other complications: one case of bar failure, one case of proximal junctional kyphosis, two cases of pseudo-arthritis.

Finally, the rate of complications was shown for the groups who underwent surgical operation: in the long C group, there were two cases of pulmonary complications (15.38%) and two cases of infections (15.38%); in the thoracic group, there were five cases of pulmonary complications (25%), two cases of infections (10%), one case of neurological complications (5%), and one case of other complications (5%); in the thoracolumbar group, there were ten cases of pulmonary complications (20%), two cases of infections (4%), two cases of neurological complications (4%), and two cases of other complications (4%); and in the double-curve group, there were three cases of pulmonary complications (30%), one case of infection (10%), one case of neurological complications (10%), and one case of other complications (10%). There was no significant difference between the groups in terms of postoperative complications (P = 0.84) [Table 1].

DISCUSSION

In this study, patients were divided into four groups according to deformity type: long C, thoracic, thoracolumbar, lumbar, and double-curves. Demographic data and other findings were examined for these four groups. Comparing these four groups, we found no significant difference in terms of demographic information except for the age; the age in the thoracic group seems to be higher compared to the other groups. In addition, before the surgery, respiratory problems of patients were examined. There was a significant difference between the four groups in terms of respiratory problems; the respiratory problems in the double-curve group were more than the other groups; about 70% of the patients in the double-curve group had respiratory problems. Therefore, the severity of symptoms in this group was significantly higher compared to other types of deformity. Postoperative complications were evaluated for all types of deformities. In total, 35 cases (37.63%) reported a complication (see the Results section). Among these 35 cases, the most frequent complication was related to respiratory problems, and this may be because one-third of the patients had respiratory problems before the surgery.

There was also no significant difference between the types of scoliosis deformities in this study in terms of postoperative problems. Postoperative complications in scoliosis correction surgery have been examined in several studies; for example, Cho et al.[9] investigated postoperative complications of posterior fusion surgery with instrumentation for degenerative lumbar scoliosis and concluded that the rate of postoperative complications of posterior fusion surgery with instrumentation for degenerative lumbar scoliosis was about 68%. Blood loss was a significant risk factor for initial intraoperative and postoperative complications. The authors also used the Oswestry Disability Index Questionnaire, which showed that the rate of improvement (better scores) was lower in those who had late complications. In another study on degenerative lumbar scoliosis and the risk factors of postoperative complications in patients who underwent spinal fusion surgery, the authors concluded that the incidence of postoperative complications is highly multifactorial and associated with factors such as surgery duration, class or type of the American Society of Anesthesiologists, insulin-dependent diabetes, and steroid therapy for chronic conditions.[10] In a retrospective study by Phillips et al.,[11] the mortality and postoperative complications in patients with the primary type of scoliosis were investigated, and it was concluded that the mortality rate of scoliosis was higher in syndromic children; a high death rate was reported (about 84%). In a study, Mohamad et al.[12] examined the risk factors for postoperative complications in patients with neuromuscular scoliosis. In this study, the authors concluded that patients with neuromuscular scoliosis undergoing deformity correction surgery had a high-risk factor for the incidence of postoperative complications (about 33.1%). In another study, postoperative complications of scoliosis correction surgery were compared among patients who had previously undergone deformity correction surgery and those who were undergoing scoliosis deformity correction surgery for the first time. It was found that there was no significant difference among patients who had previously undergone scoliosis deformity correction surgery and those who were undergoing scoliosis deformity correction surgery for the first time in terms of the rate of postoperative complications.[13] In a study, Isaacs et al.[8] examined the postoperative complications among adult patients undergoing degenerative scoliosis and concluded that the incidence of complications in adults undergoing scoliosis surgery with less invasive techniques was minimized (reported to be about 12.1%).

CONCLUSION

According to the literature and the results of our study, postoperative complications are common in all types of scoliosis. Besides, considering the techniques available for scoliosis surgery, the incidence rate of postoperative complications can be affected by the surgeon's experience. However, in our study, as in the previous studies, the incidence rate of postoperative complications was relatively high and reported to be 35 cases (37.63%). However, in this study, we concluded that the risk factors causing these complications should be examined and measures should be taken to reduce these complications. Further studies are required in this regard.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.