Distal adding-on phenomenon in adolescent idiopathic scoliosis patients with thoracolumbar vertebra fusion: A case-control study

Radiographic and clinical outcomes after definitive spine fusion for skeletally immature patients with idiopathic scoliosis

PURPOSE

To assess the intermediate-term radiographic and clinical outcomes of skeletally immature idiopathic scoliosis (IS) patients that underwent definitive fusion (DF).

METHODS

A retrospective review of patients with IS who were Risser 0 with open tri-radiate cartilages at the time of DF with minimum 5-year follow-up. Outcomes included Scoliosis Research Society (SRS)-30 scores, major Cobb angle, pulmonary function tests (PFTs), and unplanned returns to the operating room (UPROR). Adding-on was defined as progression of the major Cobb angle > 5° or tilt of the lowest instrumented vertebra > 5°.

RESULTS

Thirty-two patients (78% female, mean age 12.2 ± 1.3 years old, mean preoperative major Cobb 64.8° ± 15.9) were included. Of these patients, 20 (62.5%) experienced adding-on and 6 (18.8%) required a revision surgery to correct their progressive spinal deformity. Adding-on was associated with lower 5-year postoperative SRS scores for appearance (3.7 ± 0.7 vs 4.4 ± 0.3, p = 0.0126), mental health (4.2 ± 0.6 vs 4.6 ± 0.3, p = 0.0464), satisfaction with treatment (4.0 ± 0.8 vs 4.7 ± 0.4, p = 0.0140), and total score (4.0 ± 0.4 vs 4.4 ± 0.2, p = 0.0035). The results of the PFTs did not differ between groups. Patients experienced an average of 0.53 UPROR/patient.

CONCLUSION

DF in skeletally immature patients results in a high rate of adding-on, which adversely affects Health-Related Quality of Life. However, reoperation rates, both planned and unplanned, remain lower when compared to patients undergoing growth-friendly treatment.

Optimal lowest instrumented vertebra selection with consideration of coronal and sagittal planes to prevent distal junctional complications in patients with Lenke type 1A and 2A adolescent idiopathic scoliosis

PURPOSE

Postoperative distal adding-on and distal junctional kyphosis are major distal junctional complications after selective thoracic fusion in patients with adolescent idiopathic scoliosis (AIS). This study aimed to investigate the incidence of distal adding-on and distal junctional kyphosis and evaluate the validity of our selection criteria for the lowest instrumented vertebra (LIV) in patients with Lenke type 1A and 2A AIS.

METHODS

We retrospectively analyzed the data of patients with Lenke type 1A and 2A AIS, who underwent posterior fusion surgery. LIV selection included the followings: (1) stable vertebra on traction film, (2) disc space neutralization below the LIV on the side-bending film, and (3) lordotic disc below the LIV on the lateral film. Radiographic parameters and the revised 22-item Scoliosis Research Society Questionnaire (SRS-22r) were evaluated. The incidence of postoperative distal adding-on and distal junctional kyphosis was also investigated.

RESULTS

Ninety patients (83 women and 7 men; 64 with type 1A and 26 with type 2A) were included. After the operation, each curve and the SRS-22r of self-image, mental health, and subtotal domains were significantly improved. Distal adding-on occurred in three patients (3.3%, one in type 1A and two in type 2A) at 2 years postoperatively. No patients exhibited distal junctional kyphosis.

CONCLUSIONS

Our LIV selection criteria could reduce the incidence of postoperative distal adding-on and distal junctional kyphosis in patients with Lenke type 1A and 2A AIS.

LEVEL OF EVIDENCE

Level IV.

Preoperative "Cervical Axis" Deviation Increases the Risk of Distal Adding-On Following Surgery in Lenke 1 and 2 Adolescent Idiopathic Scoliosis Patients

STUDY DESIGN

Retrospective.

PURPOSE

To evaluate the relationship between shoulder/ neck imbalance with distal adding-on phenomenon and to identify other risk factors in Lenke 1 and 2 (non-AR curves) adolescent idiopathic scoliosis (AIS) patients.

METHODS

100 Lenke 1 and 2 AIS patients with lowest instrumented vertebra (LIV) cephalad to or at L1 were recruited. Medial shoulder/ neck balance was represented by T1-tilt and cervical axis (CA). Lateral shoulder balance was represented by clavicle angle (Cla-A) and radiographic shoulder height (RSH). Distal adding-on phenomenon was diagnosed when there was disc wedging below LIV of >5^o at final follow-up. Predictive factors and odds ratio were derived using univariate and multivariate logistic regression analysis.

RESULTS

Mean age of this cohort was 15.9 ± 4.4 years. Mean follow-up duration was 30.9 ± 9.6 months. Distal adding-on phenomenon occurred in 19 patients (19.0%). Only Risser grade, preoperative CA and final follow-up lumbar Cobb angle were the independent factors. A positive preoperative CA deviation increased the odds of distal adding-on by 5.4 times (95% CI 1.34-21.51, P = 0.018). The mean immediate postoperative T1-tilt, CA, RSH and Cla-A were comparable between the group with distal adding-on and the group without.

CONCLUSION

Distal adding-on phenomenon occurred in 19.0% of patients. Preoperative "Cervical Axis" was an important factor and it increased the risk of distal adding-on by 5.4 times. Other significant predictive factors were Risser grade and lumbar Cobb angle at final follow-up. Immediate postoperative shoulder or neck imbalance was not a significant factor for postoperative distal adding-on phenomenon.

Is it Safe to Save Levels and Choose the Lowest Instrumented Vertebra as Touched Vertebra While Selectively Fusing Lenke 1/2 Curves? A Proportional Meta-Analysis of Existing Evidence

STUDY DESIGN

Meta-analysis.

OBJECTIVE

To compare the clinical and radiological outcomes in patients with Adolescent Idiopathic scoliosis (AIS) treated by selective thoracic fusion (STF) with lowest instrumented vertebra (LIV) at touched vertebra (TV) vs stable vertebra (SV).

METHODS

The databases PubMed, Embase and Google Scholar were searched until November 2020.Studies which had Lenke type 1 curves and Lenke type 2 curves in adolescent population treated by STF and which reported pre- and post-operative curve characteristics including correction percentage and complications were included. Studies which did not report the LIV selection, curve correction percentages and whose full text could not be acquired were excluded.

RESULTS

Eight studies were included for analysis of which seven were found to be retrospective studies (level III evidence) and one was prospective study (level II evidence) each. Overall proportional meta-analysis found no significant difference in correction rate, total srs-22 scores, and complication rates.

CONCLUSION

The evaluation of SV group and TV group as LIV for selective thoracic fusions in AIS reveals a comparable outcome in terms of curve correction, patient satisfaction scores and complication rates. The TV can be chosen safely as the LIV especially in type A and B Lenke 1&2 curves, as it saves more motion segments when compared to SV.

Defining risk factors for adding-on in Lenke 1 and 2 AR curves

PURPOSE

To identify curve/correction characteristics associated with adding-on at 2 years after posterior spinal fusion (PSF) in Lenke 1/2 AR curves.

METHODS

A prospective multicenter registry was queried to identify patients with adolescent idiopathic scoliosis (AIS), Lenke 1/2 AR curves, who underwent PSF with a minimum of 2-year follow-up. Patient characteristics as well as pre- and post- operative radiographic variables were evaluated using Classification and Regression Tree (CART) analysis to determine which factors contribute to adding-on.

RESULTS

253 patients treated with PSF were assessed for adding-on, of which 50 met our adding-on criteria. Univariate analysis revealed adding-on was associated several factors including: post-operative thoracic and lumbar curve magnitude (p > 0.001), first erect (FE) end instrumented vertebra (EIV) angulation (p = 0.009) and EIV translation (p = 0.001), younger age (p = 0.027), Risser stage (p = 0.024), and a more proximal lowest instrumented vertebra (LIV) (p < 0.001). Multivariate CART analysis showed the chance of adding-on was more than 2 times greater (42 vs 16%) when the chosen LIV was translated more than 2.7 cm from the CSVL. When the LIV was within 2.7 cm, the post-op risk of adding-on was increased when the LIV was not perfectly leveled (> 0.5°).

CONCLUSION

In Lenke 1 and 2 AR curves, pre-operative LIV translation appears to be an independent risk factor for adding-on; and in those with < 2.7 cm of LIV translation, FE LIV angulation also seems to increase the risk of adding-on. These factors are relevant in determining appropriate LIV selection and aid in identifying patients at risk for developing adding-on.

Postoperative T1 tilt is a risk factor for postoperative distal adding-on in Lenke type 1 adolescent idiopathic scoliosis: A preliminary report

Retrospective comparable study.Postoperative loss of correction, which is referred to as the distal adding-on phenomenon, sometimes occurs during the postoperative course in Lenke type 1 adolescent idiopathic scoliosis (AIS). Selection of the lowest instrumented vertebra (LIV) has been reported to be one of the significant factors for preventing distal adding-on. However, proximal parameters, such as the Cobb angle of the proximal thoracic (PT) curve, radiographic shoulder height, and T1 tilt, were rarely described in previous reports. This study aimed to identify the risk factors for postoperative distal adding-on, including proximal radiographic parameters, in Lenke type 1 AIS.Preoperative and postoperative radiographs of 34 consecutive patients with Lenke type 1 curve who underwent selective thoracic fusion were analyzed. The patients were divided into an adding-on group and a no-adding-on group according to the presence of adding-on at a 2-year follow-up. The 2 groups were compared with regard to age at surgery, Lenke lumbar modifier, Risser grade, instrumentation type, and radiographic parameters.Distal adding-on was noted in 10 patients (29%). The adding-on group had significant variables including preoperative larger PT Cobb angle (P = .002), larger main thoracic (MT) flexibility (P = .006), smaller thoracolumbar (TL) Cobb angle (P = .012), larger LIV shift (P < .001), larger T1 tilt (P = .001), postoperative larger PT Cobb angle (P = .012), smaller MT Cobb angle (P = .016), smaller TL Cobb angle (P < .001), larger PT-MT mismatch (P < .001), larger LIV shift (P = .026), and larger T1 tilt (P = .006) when compared with the findings in the no-adding-on group. Postoperative T1 tilt was significantly correlated with PT-MT mismatch.Our findings suggest that not only the LIV but also proximal parameters, including T1 tilt and PT-MT mismatch, are associated with postoperative distal adding-on in Lenke type 1 AIS. Strategies to reduce postoperative T1 tilt and PT-MT mismatch are required to prevent distal adding-on.

Does Symmetric Thoracic Fusion Make a Difference in Lenke 1 A/B AIS Patients?

STUDY DESIGN

A retrospective study.

OBJECTIVE

The aim of this study was to compare the long-term outcomes of correction surgery for Lenke 1 A/B scoliosis among those with symmetric fusion (SF), upper-dominant fusion (UF), and lower-dominant fusion (LF) in adolescent idiopathic scoliosis (AIS).

SUMMARY OF BACKGROUND DATA

Symmetric fusion, defined as equal number of vertebral levels included in instrumented fusion above and below the apical vertebra or disc of the primary curve, was a new concept raised in AIS selective fusion. Previous study showed that similar correction the effect on clinical outcomes of this fusion style.

METHODS

Preoperative, postoperative, and last follow-up radiographs of 117 consecutive patients with Lenke type 1A/B curves who underwent posterior selective thoracic instrumentation surgery were analyzed. Patients were divided into two groups (SF and nonsymmetric fusion [NSF]). Patients in NSF was further divided into two groups UF (more vertebrate was fused above the apex) and LF (more vertebrate was fused below the apex). Clinical outcomes and coronal decompensation including adding-on and trunk shift were analyzed and compared among three groups.

RESULTS

There was no significant difference between SF and NSF in magnitude of preoperative main thoracic curve (P = 0.69) and correction rate (P = 0.50). Distal adding-on was observed in 21 patients (17.9%), and coronal decompensation was observed in eight patients (6.8%) in all at final follow up. No significant differences were found between the two groups regarding adding-on phenomenon (P = 0.64) and coronal imbalance (P = 0.72). Significantly higher rates of adding-on were found in UF compared with SF and LF (P < 0.001). In a subgroup analysis between UF and LF in NSF patients, significant differences were found between two subgroups in the rate of trunk shift (P = 0.038). No significant differences in SRS-22 scores were observed among the three groups.

CONCLUSION

In Lenke 1A/B AIS with posterior selective fusion, SF provides no significant differences from NSF. However, in NSF, UF was found to be high risky of adding-on phenomenon.

LEVEL OF EVIDENCE

3.

The radiographic parameter risk factors of rapid curve progression in Lenke 5 and 6 adolescent idiopathic scoliosis: A retrospective study

Various parameters related to growth and maturity have been shown to be risk factors for scoliosis curve progression. We previously identified correlations between curve progression and radiographic parameters in clinical practice, but there is a lack of research.The aim of this study was to investigate and identify the radiographic parameters that are risk factors for rapid curve progression in Lenke 5 or 6 adolescent idiopathic scoliosis (AIS).A retrospective review of patients who were prospectively enrolled at the initiation of brace wear and followed through completion of bracing or surgery was performed. The inclusion criteria were as follows: a Lenke type 5 or 6 classification, Risser sign grade 0 or 1 at the initial outpatient examination, a follow-up period of 6 months including a minimum of 4 follow-ups, At each visit, the whole spine x-ray was completed, the following data were measured and collected: angle of the lumbar curve (LC), rotation of the apical vertebra (RAV) in the LC, deviation of the apical vertebra (DAV) in the lumbar curve, clavicle angle, L5 tilt angle (TA), body mass index, flexibility of the LC (FLC), and peak angle velocity (PAV). A binary logistic regression analysis was used to assess the contribution of each variable to PAV onset. The touch types for the determination of the lowest instrumented vertebra (LIV) were compared at both the PAV and final follow-up.Thirty-six AIS patients were recruited. The binary logistic regression model indicated that the following variable values significantly contributed to a high risk of PAV occurrence: LC ≥30° (OR = 6.153, 95%CI = 1.683-22.488, P = .006), RAV ≥III (OR = 15.484, 95%CI = 4.535-52.865, P <.001), DAV ≥40 mm (OR = 8.599, 95%CI = 2.483-29.784, P <.001), and TA ≥10° (OR = 2.223, 95%CI = 3.094-27.563, P <.001). The touch types for LIV determination changed in 12 of 36 patients, with at least 1 segment added as the LIV between the PAV and the final visit.LC ≥30°, RAV ≥III, DAV ≥40 mm, and L5 TA≥10° were radiographic parameters associated with an increased risk of curve progression in Lenke 5 and 6 AIS. The orthopedic surgery performed at the PAV is the ideal timing, and it will preserve 1 active segment than later surgery.Level of evidence was 4.