Research Article, J Spine Neurosurg Vol: 14 Issue: 1

The Effect of Fusion End-Levels on Sagittal Parameters and Quality of Life in Thoracic and Lumbar Adolescent Idiopathic Scoliosis Patients

Ozgur Ismail Turk^1*, Mustafa Alper Incesoy², Abdulhamit Misir², Suleyman Kasım Tas², Emre Turgut², Suayip Akıncı² and Akif Albayrak²

¹Department of Orthopedics, Istanbul Cevre Hospital, Istanbul, Turkey

²Department of Orthopaedics and Traumatology, Baltalimani Bone and Joint Diseases Training and Research Hospital, Istanbul, Turkey

*Corresponding Author:Ozgur Ismail Turk
Department of Orthopedics, Istanbul Cevre Hospital, Istanbul, Turkey
E-mail: ozgurismailturk@gmail.com

Received date: 03 November, 2023, Manuscript No. JSNS-23-119126;
Editor assigned date: 07 November, 2023, PreQC No. JSNS-23-119126 (PQ);
Reviewed date: 21 November, 2023, QC No. JSNS-23-119126;
Revised date: 22 January, 2025, Manuscript No. JSNS-23-119126 (R);
Published date: 29 January, 2025, DOI: 10.4172/2325-9701.1000202

Citation:Turk OI, Incesoy MA, Misir A, Tas SK, Turgut E, et al. (2025) The Effect of Fusion End-Levels on Sagittal Parameters and Quality of Life in Thoracic and Lumbar Adolescent Idiopathic Scoliosis Patients. J Spine Neurosurg 14:1.

Abstract

Keywords: Scoliosis; Sagittal balance; Spinal fusion; Lenke; Selective; cervical lordosis; Thoracic kyphosis; Lumbar lordosis; Spinopelvic parameters

Abbreviations

PSF: Posterior Spinal Fusion; AIS: Adolescent Idiopathic Scoliosis; UEV: Upper End Vertebra; LEV: Lower End Vertebra; CC: Cobb-to-Cobb; Non-CC: Non Cobb-to-Cobb; G1: Group1/Lenke1; G2: Group2 /Lenke5; LIV: Lower Instrumented Vertebrae; UIV: Upper Instrumented Vertebrae; CL/C2-C7: Cervical Lordosis; TK/T1-T12: Thoracic Kyphosis; LL/L1-L5: Lumbar Lordosis; SS: Sacral Slope; PT: Pelvic Tilt; PI: Pelvic Incidence

Introduction

The current approach in Adolescent Idiopathic Scoliosis (AIS) surgery is to provide both coronal and sagittal balance while correcting the curvature and preserving spinal movements as much as possible [1]. This allowed the formation of the concept of selective fusion, in which only the structural curve is instrumented. The selection of the most proximal and most distal vertebrae to be instrumented in patients undergoing selective fusion is a current question [2-4]. Many recent studies have examined the relationship between Upper and Lower End Vertebra (UEV and LEV) selection and sagittal balance in lumbar and thoracic curvatures and the results of preserving the mobile segments of the spine [5-9]. However, the specific structural features of curves and the incompatibility of patients' clinical expectations with radiograph lead to significant differences between surgeons in the selection of levels [10]. In the literature, no study has evaluated the effect of fusion end levels on the sagittal parameters and quality of life of patients. The aim of this study was to evaluate the impact of fusion end levels on sagittal parameters and patients’ quality of life. We hypothesized that both Cobb-to-Cobb (CC) and non-Cobb-to-Cobb (non-CC) fusion would provide similar sagittal parameters and quality of life improvement in both thoracic and lumbar curve patients.

Materials and Methods

Patients

Patients who underwent surgery at our clinic between 2006 and 2016 with a diagnosis of AIS were examined retrospectively. In order to minimize the number of variables while evaluating level selection differences, Lenke-1 (proximal thoracic) and Lenke-5 (thoracolumbar/ lumbar) patients with a single structural curve were evaluated, and the effects of non-structural curves on parameters were excluded. Among the AIS patients who were screened, 208 patients with Lenke-1 (Group 1, G1) and Lenke-5 (Group 2, G2) curves, technically treated with Posterior Spinal Fusion (PSF) and Segmental Spinal Instrumentation (SSI), were found in archive records. AIS patients with at least 18-month follow-up, those with AP and lateral whole spine roentgenograms in pre-operative, post-operative 6^th month, and the last follow-up visits, and those with SF-36 and SRS-22 forms in pre-operative and the last follow-up visit were included in the study. A total of 162 patients, 72 patients with Lenke-1 (G1) and 90 patients with Lenke-5 (G2) curves treated with PSF and SSI were included. Of these, 57 patients underwent CC fusion (18 patients in G1 and 39 patients in G2), and 105 patients underwent non-CC fusion (54 patients in G1 and 51 patients in G2). In our current clinical approach, we used the Lenke criteria for defining the type of curvature and deciding on selective fusion in AIS patients, and the Scoliosis Research Society (SRS) criteria for selecting Upper Instrumented Vertebrae (UIV) and Lower Instrumented Vertebrae (LIV) for patients who will undergo selective fusion [11,12]. Patients with UEV=UIV and LEV=LIV were referred to as CC, and the others as non-CC [13,14]. Patients with a history of revision surgery, MRI with signs of intraspinal pathology, and patients with non-AIS etiology were excluded from the study. Parameters were compared within the populations as CC and non-CC by time and between groups at all three time points. Lenke-1 and Lenke-5 populations were considered as a statistically whole patient population, and no parameter comparison was made between the populations Standing AP and lateral whole spine roentgenograms taken preoperatively, postoperatively at 6^th months and at the last follow-up visit were evaluated, and sagittal and regional measurements were made using a single monitor. The measurement results were statistically compared, and the SF-36 and SRS-22 measurements were applied preoperatively and at the last follow-up visit.

Imaging

As a standard radiological evaluation, graphs were taken with the same device (Ecoray, HF 525 Plus) with 90 × 35 cassettes. Sagittal plane radiographs were obtained while the patient was standing, with the shoulders flexed forward and the elbows fully flexed. Measurements were performed using a single monitor with INFINITT PACS (INFINITT Healthcare Co.) software. In the sagittal plane and balance assessment, Cervical Lordosis (CL) (C2-C7), Thoracic Kyphosis (TK) (T1-T12), T2-T5 kyphosis, T5-T12 kyphosis, T10-L2 kyphosis, Lumbar Lordosis (LL) (L1-L5), spinopelvic parameters (Sacral Slope (SS), Pelvic Tilt (PT), and Pelvic Incidence (PI)) levels were measured using the Cobb angle method. Data on age, sex, operation surgery time, instrumentation levels, and post-operative follow-up period of the patients included in the study were recorded.

Surgical technique

All cases included in the study received PSF. Transpedicular screws were used for fixation of the spine, and they were connected to each other with titanium rods. In the fusion level determination, fusion level selection rules were applied according to the SRS criteria mentioned in the above sections. Compression was applied to the convex side of the curve, and distraction was applied on the concave side. Scoliotic curve correction maneuvers were performed by applying derotation forces to the apical region. The technique of “freehand” technique was used during screwing. Before installing the rods, a suitable slope was provided for physiological kyphosis and lordosis in the sagittal plane. The neuromonitoring system has been used since 2009. The patients were mobilized on the 1st day after surgery.

Statistical analysis

Mean, standard deviation, median lowest, highest, frequency, and ratio values were used in the descriptive statistics of the data. The distribution of variables was measured using the Kolmogorov– Smirnov test. The Mann–Whitney U test was used to analyze quantitative independent data. The Wilcoxon test was used to analyze dependent quantitative data. The chi-square test was used for the analysis of qualitative independent data. The SPSS 22.0 program was used in the analyses. Statistical significance was set at P<0.05.

Results

There was a significant difference between the CC and non-CC group in the operation time and the number of the instrumented levels (195.5 ± 65.9 vs. 261.4 ± 73.5 and 8.2 ± 1.8 vs. 12.1±1.4, respectively, p<0.001) but not in the mean age of the patients and the follow-up period (Table 1). In Lenke-1 patients, there were significant differences between the CC and non-CC groups regarding postoperative 6^th month CL (5.9 ± 4.4 vs. 12.1 ± 10.9, p=0.022) and T2-T5 kyphosis (10.7 ± 3.8 vs. 14.2 ± 5.9°, p=0.023) angles. There were significant pre to post-operative changes in the T5-T12 angle in the non-CC group (23.7 ± 11.6 vs. 18.1 ± 8.5°, p<0.001), T10-L2 angle in the CC group (9.6 ± 6.6 vs. 5.5 ± 4.7°, p=0.003), and LL in the non- CC group (50.7 ± 9.7 vs. 53.6 ± 11.1°, p=0.032) (Table 2). In Lenke-5 patients, there were significant differences between CC and non-CC groups regarding post-operative 6^th month and the final follow-up TK angle (46.8 ± 8.9 vs. 37.4 ± 11.0, p<0.001 and 43.6 ± 9.2 vs. 37.9 ± 10.6, p=0.009, respectively), preoperative and the final follow-up T2- T5 angle (17.8 ± 10.6 vs. 12.3 ± 7.4, p=0.005 and 10.3 ± 5.6 vs. 14.8 ± 6.7, p=0.001, respectively), post-operative 6^th month and the final follow-up T5-T12 angle (37.4 ± 9.4 vs. 25.2 ± 8.5, p<0.001 and 34.4 ± 11.4 vs. 24.7 ± 7.6, p<0.001, respectively), preoperative T10-L2 angle (8.3 ± 5.6 vs. 13.2 ±12.8, p=0.028), and preoperative and the final follow-up PT angle (9.6 ± 4.9 vs. 12.8 ± 6.9, p=0.015, and 8.4 ± 5.1 vs. 11.3 ± 7.3, p=0.040, respectively). In addition, there were significant pre to post-operative changes in TK, LL, and SS angles in both the CC and non-CC groups (Table 3). Comparison of SF36 and SRS22 scores between the CC and non-CC groups in the preoperative and post-operative periods did not show a significant difference (p=510, p=0.555, p=0.773, p=0.981, respectively) (Table 4).

Table 1: Comparison between age/follow-up period/operation period/instrumentation quantities among groups.

Table 2: Lenke 1 patient’s sagittal plane measurements.

Table 3: Lenke 5 patient’s sagittal plane measurements.

Table 4: Comparison of SF-36 and SRS-22 scores between CC and non-CC groups in pre-op and post-op period.

Discussion

The most important finding of this study was that the choice of CC or non-CC surgery affects the parameters proximal rather than distal to the instrumentation, and the effect of the level selection on the parameters is mostly limited to the early post-operative period, and the long-term results are similar.

In our study, the CL level showed a statistically significant difference only in terms of the post-operative 6^th month measurement averages in the G1 population when CC and non-CC were compared (p=0.022). In a study by Dumpa (4) no significant difference was found between the preoperative and post-operative periods in thoracic curves, in the level of CL after selective and non-selective surgeries. These results are consistent with those of the present study. Moreover, Charles and Norheim considered in their study that LL may affect CL [15,16]. This result may be significant in terms of the reflection of the differences in LL parameters of the CC and non-CC groups on the CL level in populations with thoracic and lumbar curves. In our study, there was no significant difference between groups in terms of CL when evaluating the CC and non-CC groups in both populations. The relationship between CL level and LL and spinopelvic parameters is worth investigating. When the TK level was compared in terms of the 6^th post-operative month and after the last follow-up measurements in the G2 population, TK level was found to be significantly higher (p?0.05) in the CC group. In the CC group, the post-operative 6^th and post-operative final check levels were also significantly higher than those in the pre-operative period (p?0.05). In their study comparing selective and non-selective surgery, Carreon found that the TK level was higher in the group that underwent selective surgery in both the pre-operative and post-operative periods [17]. Our findings are consistent with the literature. In our study, while there was no difference between the groups in patients who underwent thoracic isolated fusion, the high level of CC fusion in patients who underwent lumbar isolated fusion suggested that we iatrogenically decrease the TK level of the proximal level in lumbar curves. When T2-T5 and T5- T12 levels were examined together, these levels were found to be significantly higher in the CC group both in the preoperative period and in the final check when the G2 population was examined (p?0.05). Charles suggested that LL could affect the level of TK. Wang reported that thoracolumbar fusion provides spontaneous improvement in thoracic sagittal parameters [18]. When the results were evaluated, the statistical difference between thoracic fusion and lumbar fusion was evaluated as the effect of lumbar fusion on thoracic parameters via the lumbar curve by affecting the level reached at the proximal. Our results support Lenke ’s views on the level reached at the proximal in lumbar fusion and Suk’s views regarding descending to distal stroke in thoracic fusion. When we evaluated LL levels in both populations, there was no difference between the CC and non-CC groups [19]. When the Lenke 1 population was evaluated, the variation in time was significant in the non-CC group. Accordingly, this variation was between the preoppostop times of 6^th months (p=0.019) (Table 3). In the Lenke 5 population (G2), the variation in the LL variable in the CC group was statistically significant (p<0.001). Accordingly, this variation was between the periods of preop-postop of 6^th months (p=0.001). The variation in LL by time was statistically significant in the non-CC group (p<0.001). Accordingly, this variation was between the preoppostop 6^th months (p=0.001) (Table 4). In their studies, Park did not observe any difference between CC fusion and LEV+1 (non-CC) fusion in terms of sagittal parameters. The difference between the findings may be due to the fact that Sun did not consider the proximal fusion level differences in their study, and they only applied LEV+1 fusion for curves above 60°. Although these findings suggest that the selection of CC fusion may be appropriate in the lumbar fusion group, the level selection needs to be evaluated in detail. When examining the sagittal spinopelvic parameters, no significant difference between the CC and non-CC groups in either population (p>0.05) was noted. In their study, Zachary obtained similar results in patients with Lenke 1 and 2 [20]. Pasha argued that the sagittal spinopelvic parameters in patients with Lenke 1 did not change [21]. In a study by Ilharreboerde that compared hyperselective and selective patients, they showed that the sagittal spinopelvic parameters were not affected. The results of our study are consistent with those in the literature. In our study, both populations were evaluated with the SRS-22 and SF-36 scoring systems in preoperative and post-operative final checks. Groups showed significant score increases within themselves in the 6^th post-operative month and post-operative final checks compared to the preoperative period, but there was no significant difference when the groups were compared. In a study by Lark, when comparing the selective TL/L fusion group with the non-selective fusion group, they reported that there was no significant difference in both groups when they compared the selective fusion group with the non-selective fusion group before surgery in terms of the SRS-22 score [22]. In our study, there was no significant difference between the groups, which supports the literature. No major complications were observed in the patients included in the study. Since re-operated patients and patients with revision were not included in the study, this may be considered among the reasons for not having complications in our patients.

Our study had a few limitations. Our study was retrospective, conducted in a single center, and was not evaluated separately for fusion end levels. The fact that the patients were operated in a 10-year interval and were operated by more than one surgeon made the optimization of the level selection difficult. In our study, the patients consisted of two different large populations and the level selection criteria of each population were different, which is limiting in terms of standardization of level selection. Although the number of patients is higher than that reported in the literature, we think that more patients are needed to reflect the general population.

Conclusion

The most important finding of our study is that the choice of cobbto- cobb or non cobb-to-cobb surgery affects the parameters proximal rather than distal to the instrumentation, and the effect of the level selection on the parameters is mostly limited to the early postoperative period, and the long-term results are similar. We believe that it is in the best interest of the patient to limit the instrumentation to the main curve as much as possible and to protect the mobile segments.

Funding Disclosures

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Declaration of Interest

The authors declare that there is no conflict of interest regarding the publication of this article.

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