Analysing the change of sagittal balance in patients with Lenke 5 idiopathic scoliosis

Lowest Instrumented Vertebra at L3 Versus L4 in Posterior Fusion for Moderate Lenke 5C Type Adolescent Idiopathic Scoliosis: A Case-Match Radiological Study

OBJECTIVE

To compare the radiological outcomes in Lenke 5C type patients whose lowest instrumented vertebra (LIV) was L3 or L4 in a case-match study.

METHODS

We conducted a retrospective case-match study and included 82 patients in the study. Radiological results before surgery, after surgery, and at last follow-up were recorded and analyzed in the L3 and L4 groups.

RESULTS

After matching the age, Risser's sign, sex, and main Cobb, 41 pairs of patients were enrolled in our study. The total fusion segments in the L3 group (median [interquartile range]: 5.0 [6.0-5.0]) were shorter than those in the L4 group (6.0 [6.5-6.0]). The main curve was significantly corrected after surgery in both groups, and was comparable at the last followup between groups. In addition, according to the results of Fisher precision probability test, there was no significant difference of coronal or sagittal imbalance between the 2 groups at the 2-year follow-up.

CONCLUSION

The correction in coronal and sagittal planes in L3 group and L4 group remains similar. On account of more motion segments, L3 could be an ideal choice as LIV in moderate Lenke 5C type AIS. Long-term follow-up is needed to evaluate the effect of larger compensatory lumbar-sacral curve when stopping at L3.

Compensatory Ground Reaction Forces during Scoliotic Gait in Subjects with and without Right Adolescent Idiopathic Scoliosis

Although the asymmetries of scoliotic gait in adolescent idiopathic scoliosis (AIS) groups have been extensively studied, recent studies indicated conflicting results regarding the ground reaction forces (GRFs) during gait in subjects with spinal deformity. The asymmetry during the stance phase might be clarified with three-dimensional (3D) compensations of GRFs between similar characteristics of subjects with and without AIS. The purpose of this study was to compare the normalized 3D GRF differences during the stance phase of gait while considering age, BMI, and Cobb angle between subjects with and without right AIS. There were 23 subjects with right convexity of thoracic idiopathic scoliosis and 22 age- and gender-matched control subjects. All subjects were right upper/lower limb dominant, and the outcome measures included the Cobb angles, normalized GRF, and KAI. The mediolateral (M/L) third peak force on the dominant limb decreased in the AIS group (t = 2.58, p = 0.01). Both groups demonstrated a significant interaction with the 3D indices (F = 5.41, p = 0.02). The post-hoc analysis identified that the M/L plane of asymmetry was significantly different between groups. The Cobb angles were negatively correlated with the vertical asymmetry index (r = −0.45, p = 0.03); however, there was no significant correlation with age (r = −0.10, p = 0.65) or body mass index (r = −0.28, p = 0.20). The AIS group demonstrated decreased GRF in the dominant limb M/L plane of the terminal stance phase. This compensatory motion was confirmed by a significant group difference on the M/L plane of the KAI. This KAI of vertical asymmetry correlated negatively with the Cobb angle. The asymmetric load transmission with compensatory vertical reactions was evident due to abnormal loading in the stance phase. These kinetic compensatory patterns need to be considered with asymmetry on the dominant limb when developing rehabilitation strategies for patients with AIS.

Pelvic incidence correlates to sagittal spinal morphology in lenke 5 adolescent idiopathic scoliosis and influences the proximal junctional kyphosis rate after correction surgery

PURPOSE

This study aimed to investigate the relationship between pelvic incidence and sagittal spinal morphology in Lenke 5 adolescent idiopathic scoliosis (AIS) and its impact on the proximal junctional kyphosis rate after surgery.

METHODS

The study enrolled a total of 52 cases of Lenke 5 AIS between September 2009 and December 2018. Sagittal spinal morphological parameters, pelvic incidence (PI) and the proximal junctional angle were measured on full-length spinal standing lateral x-ray films preoperatively, postoperatively and at the final follow-up. Pearson correlation analysis was performed to reveal the relationship between sagittal spinal morphology and PI. Multivariable regression analysis and receiver operating characteristic (ROC) curve analysis were performed to identify the risk factors for proximal junctional kyphosis (PJK).

RESULTS

A correlation was found between PI and sagittal spinal morphological parameters, but not between PI and lumbar lordosis. The PJK rate after surgery was 23% (12/52). PI was revealed as an independent risk factor for proximal junctional kyphosis according to multivariable regression analysis (OR = 0.902, p = 0.049). Both multivariable regression analysis and ROC curve analysis verified that restoring a rational postoperative PI-LL/PLL relationship reduced the rate of PJK, including PI-LL mismatch (OR = 0.743, p = 0.046; cutoff value = - 15.5°), the LL-PI ratio (OR = 5.756, p = 0.021; cutoff value = 1.09), and the PLL-PI ratio (OR = 2.116, p = 0.016; cutoff value = 0.40).

CONCLUSIONS

PI influences sagittal spinal morphology in Lenke 5 AIS, although it does not show an inherent relationship with lumbar lordosis. PI also correlates to the PJK rate after surgery. Restoring an ideal postoperative PI-LL relationship could decrease the PJK rate.

Surgical Treatment of Lenke Type 5 Adolescent Idiopathic Scoliosis: A Systematic Review

STUDY DESIGN

A systematic review.

OBJECTIVE

To systemically review the previous literature regarding surgical treatment of Lenke type 5 adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

The Lenke classification was published in 2001 as the classification of AIS. Since then, numerous articles have been published reporting the outcomes of surgical treatment of Lenke type 5 AIS.

METHODS

The electronic databases PubMed, EMBASE, and Web of Science were queried up to Aug 2018 for articles regarding surgical treatment of Lenke type 5 AIS. Surgical variables, radiographic assessments, and clinical outcomes of surgical treatment of Lenke type 5 AIS were summarized.

RESULTS

Fifty studies met the inclusion criteria. The average fused levels, % correction of thoracolumbar/lumbar curve at final follow-up, and % correction of thoracic curve at final follow-up for anterior and posterior procedures were reported to be 3.6-5.3 and 4.3-7.8 levels, 53-86 and 55-94% and 17-52 and 19-67%, respectively. Average coronal balance was imbalanced (≥20 mm) at preoperation in 22/43 reporting study groups and balanced (<20 mm) at final follow-up in all 37 reporting study groups. Scoliosis Research Society Version 22 scores showed no difference between anterior and posterior procedures in most of the reporting studies (5/6).

CONCLUSION

Overall, the outcomes of surgical treatment of Lenke type 5 AIS are excellent. The thoracic curve was spontaneously corrected after surgery and coronal balance after surgery was better than before surgery. Both anterior and posterior procedures demonstrated satisfactory outcomes.

LEVEL OF EVIDENCE

4.

Proximal junctional kyphosis following correction surgery in the Lenke 5 adolescent idiopathic scoliosis patient

BACKGROUND

To investigate the risk factors of proximal junctional kyphosis (PJK) in Lenke 5 AIS patients after all-pedicle instrumentation and correction, and to compare the difference of radiographic and clinical outcome between PJK and Non-PJK populations.

METHOD

Medical records of Lenke 5 AIS patients were reviewed from January 2008 to January 2013, included posteroanterior and lateral full spine X-ray films preoperatively, postoperatively (4-7 days after surgery), and at final follow-up. Demographic data and radiologic parameters were evaluated. Based on the proximal junctional angle (PJA) at final follow-up, those patients were divided into 2 groups: PJK group (n = 35, PJA≧10°), and Non-PJK group (n = 52, PJA<10°). Comparisons analyses between PJK and Non-PJK groups were carried out. Binary logistic Regression analysis was performed to detect the risk factors of PJK at follow-up.

RESULTS

The current study recruited 87 Lenke 5 AIS patients with average follow-up of 4.67 ± 1.17 years. Significant differences between PJK and Non-PJK groups were observed as follows: UIV(P = 0.010), the disruption of junctional ligaments (P < 0.001); preoperative variables [MTC (P = 0.001), TK(P < 0.001), LL (P = 0.017), SVA (P = 0.036), and PJA (P = 0.014)], postoperative variables [TLK(P = 0.004), and PJA (P < 0.001)], and follow-up [SVA (P = 0.014), C-SVA (P < 0.001), and PJA (P0.001). Binary logistic regression showed that the disruption of junctional ligaments, postoperative PJA and UIV (upper instrumented vertebra) at proximal or lower thoracic levels were the main risk factors of PJK [Odds Ratio (OR) = 5.114, 2.345, and 6.212, respectively]. However, the SRS-22 scores did not change significantly in PJK and Non-PJK groups.

CONCLUSION

Greater postoperative PJA, disruption of junctional ligaments, UIV at lower thoracic levels were the main risk factors for PJK in Lenke 5 AIS patients. Recommedation: Preserve junctional ligaments in those individuals with UIV located in the lower thoracic region.