Risk factors for the development of DJK in AIS patients undergoing posterior spinal instrumentation and fusion

Costs of revision operations for distal junctional kyphosis following thoracic posterior spinal fusion for adolescent idiopathic scoliosis

PURPOSE

To assess direct costs and risks associated with revision operations for distal junctional kyphosis/failure (DJK) following thoracic posterior spinal instrumented fusions (TPSF) for adolescent idiopathic scoliosis (AIS).

METHODS

Children who underwent TPSF for AIS by a single surgeon (2014-2020) were reviewed. Inclusion criteria were minimum follow-up of 2 years, thoracolumbar posterior instrumented fusion with a lower instrumented vertebra (LIV) cranial to L2. Patients who developed DJK requiring revision operations were identified and compared with those who did not develop DJK.

RESULTS

Seventy-nine children were included for analysis. Of these, 6.3% developed DJK. Average time to revision was 20.8 ± 16.2 months. Comparing index operations, children who developed DJK had significantly greater BMIs, significantly lower thoracic kyphosis postoperatively, greater post-operative lumbar Cobb angles, and significantly more LIVs cranial to the sagittal stable vertebrae (SSV), despite having statistically similar pre-operative coronal and sagittal alignment parameters and operative details compared with non-DJK patients. Revision operations for DJK, when compared with index operations, involved significantly fewer levels, longer operative times, greater blood loss, and longer hospital lengths of stay. These factors resulted in significantly greater direct costs for revision operations for DJK ($76,883 v. $46,595; p < 0.01).

CONCLUSIONS

In this single-center experience, risk factors for development of DJK were greater BMI, lower post-operative thoracic kyphosis, and LIV cranial to SSV. As revision operations for DJK were significantly more costly than index operations, all efforts should be aimed at strategies to prevent DJK in the AIS population.

Risk factors for distal junctional kyphosis after posterior spinal surgery in adolescent idiopathic scoliosis: a meta-analysis

Introduction

Distal junctional kyphosis (DJK) is a serious complication after posterior spinal surgery in managing adolescent idiopathic scoliosis (AIS). Our study aims to investigate the predictors of DJK in AIS patients.

Methods

We searched the English databases of PubMed, Embase, and the Cochrane Library for clinical research studies on AIS. To identify the risk factors for DJK, we collected demographic data, such as age, gender, and body mass index (BMI), and sagittal parameters, including preoperative pelvic tilt (PT), sagittal vertical axis (SVA), lumbar lordosis (LL), thoracic kyphosis (TK), thoracolumbar kyphosis (TLK), distal junctional angle (DJA), lowest instrumented vertebrae (LIV) relative to sagittal stable vertebrae (SSV), and postoperative DJA. Data were analyzed by RevMan (5.3 version) and STATA (12.0 version).

Results

Finally, six included articles (1,240 patients) showed 9% (98 of 1,240 patients) of patients suffering from DJK. Our findings indicated that preoperative TK [p = 0.007, OR = 0.35, 95% CI (0.10, 0.61)], TLK [p < 0.0001, OR = 5.99, 95% CI (3.33, 8.65)], and postoperative DJA [p = 0.002, OR = 0.56, 95% CI (0.21, 0.91)] in the DJK group were markedly higher than those in the non-DJK group. Moreover, patients with LIV above SSV [p < 0.0001, OR = 7.95, 95% CI (4.16, 15.22)] were more likely to develop DJK. No discernible difference was found in age, sex, BMI, preoperative PT, SVA, LL, or DJA between the two groups.

Conclusions

Regarding the AIS patients, factors such as higher preoperative TK and TLK, higher postoperative DJA, and LIV above the SSV were related to an increased rate of DJK.

Strategies to Avoid Distal Junctional Pathology

Distal junctional pathology remains an unsolved issue in spine surgery. Distal junctional pathology can occur on a spectrum from asymptomatic radiographic finding to catastrophic distal construct failure. It is significant to address as postoperative sagittal balance has been shown to be correlated with patient-reported outcomes. Current literature and clinical experience suggest there are techniques that can be implemented regardless of setting to avoid distal junctional pathology. Much of the avoidant strategy relies on understanding the deformity pathology, selection of the lowest instrumented vertebra (LIV), health of the segments caudal to the LIV, and methods of fixation.

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.

Thoracic posterior spinal instrumented fusion vs. thoracic anterior spinal tethering for adolescent idiopathic scoliosis with a minimum of 2-year follow-up: a cost comparison of index and revision operations

PURPOSE

To compare direct costs of index and revision operations of thoracic posterior spinal instrumented fusion (TPSIF) and thoracic anterior spinal tethering (TAST) for adolescent idiopathic thoracic scoliosis in children.

METHODS

Children (ages 11-18 years) who underwent TPSIF and TAST (2/2013-9/2019) were reviewed. Follow-up < 2 years and cervical instrumentation and/or instrumentation of a lumbar level at L3 or below were exclusion criteria. Patient demographics, radiographic curve magnitude, index operations and postoperative data, as well as indications for revisions/readmissions were collected. Direct costs were identified and compared for index and revision operations during follow-up.

RESULTS

One hundred and four patients were included (TPSIF: 78; TAST: 25). TAST procedures were performed in children significantly younger and for smaller curve magnitudes. They had significantly fewer levels instrumented, shorter operating room (OR) times, and less estimated blood loss (EBL). After operation, a significantly higher percentage of TAST were admitted to ICU. Hospital length of stay (LOS) was similar between groups. Index operations' average direct costs were significantly higher for TAST than TPSIF ($52,947 v. $46,641; p = 0.02). Major cost drivers for both groups were implants, OR services, post-anesthesia care unit (PACU), and room/board. Revisions following TAST were more frequent than for TPSIF (36 v. 11.5%). Majority of TPSIF revisions were for junctional deformity. Curve progression and overcorrection were most common reason for TAST revisions. Average direct costs for revisions/readmissions were similar between groups (TPSIF: $28,485 v. TAST: $27,590; p = 0.46).

CONCLUSIONS

Index operations' average direct costs were statistically similar between TPSIF and TAST for adolescent idiopathic scoliosis. Major cost drivers were implants, OR services, PACU, and room/board. TAST index operations' direct costs and associated direct costs for implants and room/board were significantly higher, while their anesthesia and OR services were significantly lower than TPSIF. TAST revisions were for overcorrection and curve progression, while TPSIF revisions were most commonly for junctional deformity. Overall average direct costs for revisions were similar despite revision rates being higher for TAST.

LEVEL OF EVIDENCE

III.

The Sagittal Plane in Spinal Fusion for Adolescent Idiopathic Scoliosis

Sagittal balance is widely recognized as the primary determinant of optimal outcomes in adult spinal deformity. In adolescent idiopathic scoliosis (AIS), coronal correction risks being obtained at the expense of sagittal malalignment after posterior spinal fusion. Apical lordosis, often underestimated on two-dimensional imaging, is the primary deforming factor in AIS. Failure to restore thoracic kyphosis and lumbar lordosis during posterior spinal fusion contributes to problematic early surgical complications, including proximal or distal junctional kyphosis and failure. Although adolescent patients often compensate for sagittal imbalance in the short-term and mid-term, late sequelae of iatrogenic sagittal imbalance include flatback syndrome, disk degeneration, cervical kyphosis, and late decompensation. Objective criteria using spinopelvic parameters and preoperative three-dimensional planning can guide sagittal plane correction during PSF for AIS. Technical caveats can help avoid sagittal plane complications, including instrumentation level selection, anchor type, and anatomic protection of adjacent levels. Other surgical techniques to optimize restoration of thoracic kyphosis include higher implant density, stiffer rod material, Ponte osteotomies, and deformity correction technique.

Blood loss estimation during posterior spinal fusion for adolescent idiopathic scoliosis

PURPOSE

Blood loss (BL) during posterior spinal fusion for adolescent idiopathic scoliosis (AIS) may be estimated using a variety of unproven techniques. Patient care and research on BL are likely impacted by a lack of standardization. A novel FDA-approved blood volume (BV) analysis system (BVA-100 Blood Volume Analyzer) allows rapid processing with > 97% accuracy. The purpose of this study was to investigate common methods for BL estimation.

METHODS

BV assessment was performed with the BVA-100. After obtaining a baseline sample of 5 mL of blood, 1 mL of I-131-labeled albumin was injected intravenously over 1 min. Five milliliter blood samples were then collected at 12, 18, 24, 30, and 36 min post-injection. Intravenous fluid was minimized to maintain euvolemia. Salvaged blood was not administered during surgery. BL was estimated using several common techniques and compared to the BV measurements provided by the BVA-100 (BVABL).

RESULTS

Thirty AIS patients were prospectively enrolled with major curves of 54° and underwent fusions of 10 levels. BL based on the BVA-100 (BVABL) was 519.2 [IQR 322.9, 886.2] mL. Previously published formulas all failed to approximate BVABL. Multiplying the cell saver volume return by 3 (CS3) approximates BVABL well with a Spearman correlation coefficient and ICC of 0.80 and 0.72, respectively. An extrapolated cell salvage-based estimator also showed high intraclass correlation coefficient (ICC) and Spearman coefficients with less bias than CS3.

CONCLUSION

Published formulaic approaches do not approximate true blood loss. Multiplying the cell saver volume by 3 or using the cell salvage-based estimator had the highest correlation coefficient and ICC.

LEVEL OF EVIDENCE

Prospective cohort Level 2.