Influence of the sublaminar band density in the treatment of Lenke 1 adolescent idiopathic scoliosis

Sagittal plane assessment of manual concave rod bending for posterior correction in adolescents with idiopathic thoracic scoliosis (Lenke 1 and 3)

OBJECTIVES

The objectives of this study were to evaluate the repeatability and reproducibility of a method for measuring freehand rod bending and to analyze the relationship between the rod's bend and the resulting sagittal correction.

MATERIALS AND METHODS

All the children who underwent correction by posterior translation using pedicle screws at all levels were included prospectively in 2018 and 2019. The rod's sagittal parameters were measured retrospectively by three independent surgeons on two separate occasions using the same protocol. After the rods were bent but before they were inserted, the surgeon traced the contours of the rods on a sheet of paper that was later scanned and analyzed semiautomatically. The spinal parameters were calculated based on biplanar radiographs taken preoperatively, postoperatively and at the final follow-up visit. Patients who had less than 10° thoracic kyphosis (T5-T12) made up the "Lenke N-" subgroup.

RESULTS

Thirty patients were included (14 of whom were Lenke N-) who had a Cobb angle of 59.2±11.3° preoperatively and 13.3±8.4° postoperatively (p<0.00001). The inter- and intrarater ICC for the rod measurements were>0.9 (excellent). The mean kyphosis of the concave rod was 48.4±5.7° (38.3-60.9°). The mean change in T5-T12 kyphosis was 9.7±10.8° (-14.3-30.8°) (p<0.0001) in the entire population, while it was 17.7±7.1° (5.5-30.8°) (p<0.0001) in the Lenke N- subgroup. The change in thoracic kyphosis was positively correlated with the kyphosis of the concave rod (rho=0.52; p=0.003).

CONCLUSION

This study found excellent reproducibility and repeatability of measuring freehand rod bending. The kyphosis applied to the concave rod is positively correlated to the change in the resulting kyphosis and made it possible to restore satisfactory thoracic kyphosis.

LEVEL OF EVIDENCE

III.

Feasibility, Safety and Reliability of Surgeon-Directed Transcranial Motor Evoked Potentials Monitoring in Scoliosis Surgery

(1) Background: Neuromonitoring is essential in corrective surgery for scoliosis. Our aim was to assess the feasibility, safety and reliability of "surgeon-directed" intraoperative monitoring transcranial motor evoked potentials (MEP) of patients. (2) Methods: A retrospective single-center study of a cohort of 190 scoliosis surgeries, monitored by NIM ECLIPSE (Medtronic), between 2017 and 2021. Girls (144) and boys (46) (mean age of 15 years) were included. There were 149 idiopathic and 41 secondary scoliosis. The monitoring consisted of stimulating the primary motor cortex to record the MEP with muscular recording on the thenar, vastus lateralis, tibialis anterior and adductor hallucis muscles. (3) Results: The monitoring data was usable in 180 cases (94.7%), with 178 true negatives, no false negatives and one false positive. There was one true positive case. The predictive negative value was 100%. The monitoring data was unusable in 10 cases (i.e., three idiopathic and seven secondary scoliosis). (4) Conclusions: Simplified transcranial MEP monitoring known as "surgeon-directed module" is usable, safety and reliable in surgery for moderate scoliosis. It is feasible in 95% of cases with a negative predictive value of 100%.

A retrospective cohort study of bleeding characteristics and hidden blood loss after segmental pedicle screw instrumentation in neuromuscular scoliosis as compared with adolescent idiopathic scoliosis

Background

Progressive scoliosis in neuromuscular patients often requires a long instrumented spinal fusion. Previous studies have shown larger intraoperative blood loss in these patients than those with adolescent idiopathic scoliosis (AIS), but the total blood loss composed of visible and hidden blood loss has not been described in this patient population. The aim of our study was to investigate the bleeding characteristics and hidden blood loss related to spinal fusion in neuromuscular scoliosis (NMS) as compared to AIS patients.

Methods

A retrospective cohort study with prospective data collection of NMS patients undergoing segmental pedicle screw instrumentation at a university hospital between 2009 and 2021. A comprehensive statistical analysis was performed regarding intra- and postoperative blood loss compared to patient characteristics such as age and diagnosis. Hidden blood loss was estimated and compared to the total blood loss. We standardized amount of bleeding with patient weight and fusion level for further analysis. Consecutive AIS patients served as a control population. Eighty-one consecutive patients with NMS (mean age 15.2 years, 37 females) were included and their bleeding characters were compared with 199 AIS patients (mean age 15.8 years, 143 females). The primary outcome was total blood loss including intraoperative, 24-hour drain output and hidden blood loss. Secondary outcome measures included requirement for blood transfusion.

Results

Neuromuscular patients had a significantly larger total blood loss with mean values of 1914 mL in the NMS and 1357 mL in the AIS groups, respectively (p<0.001). The hidden blood loss was also significantly larger in NMS than in AIS group (566 ± 533 mL vs. 398 ±411 mL, p=0.0332). Neuromuscular scoliosis was also associated with significantly greater weight and levels of fused adjusted intraoperative bleeding (1.79 ml/kg/fused level in NMS vs. 0.87 ml/kg/fused level in AIS vs. p< 0.0001) and hidden blood loss (1.00 ml/kg/levels fused vs. 0.65 ml/kg/fused levels, p=0.053). NMS diagnosis was also a risk factor for greater hidden blood loss in multivariable analysis (p=0.0011). 24-hour drain output was similar in the NMS and AIS groups. Male gender was a risk factor for greater hidden blood loss in the NMS group (p=0.0429). Fifty-nine (73%) NMS and 27 (14%) AIS patients received allogenic red blood cell infusions perioperatively (p<0.001).

Conclusions

Hidden blood loss constitutes one-third of total blood loss in children undergoing segmental pedicle screw instrumentation for neuromuscular scoliosis. Hidden blood loss is significantly greater in the neuromuscular as compared with idiopathic scoliosis. Hidden blood loss should be considered in the perioperative management of NMS.

Hidden blood loss in adolescent idiopathic scoliosis surgery

INTRODUCTION

Posterior spinal fusions (PSF) for adolescent idiopathic scoliosis (AIS) have higher blood loss than other pediatric orthopedic surgeries. There is a paucity of literature estimating the hidden blood loss (HBL) in patients with AIS undergoing PSF. The purpose of this study was to compare intraoperative and postoperative estimated blood loss (EBL) in patients undergoing PSF for AIS to determine HBL.

HYPOTHESIS

With contemporary blood loss prevention strategies, HBL will be higher than intraoperative EBL.

MATERIAL AND METHODS

Over a 3-year period, 67 patients with preoperative and postoperative hemoglobin (Hgb) measurements undergoing PSF for AIS were evaluated. Intraoperative EBL was estimated using a volumetric method and recorded by a perfusionist managing a cell saver machine. Total perioperative EBL was estimated using the validated formula: EBL=weight (kg)×age sex factor×(preoperative Hgb - postoperative Hgb)/preoperative Hgb. HBL was calculated as the total perioperative EBL minus the intraoperative EBL.

RESULTS

Calculated total EBL was higher than intraoperative EBL (771±256mL vs. 110±115mL, p<0.001). Mean HBL after wound closure was 660±400mL. Patients 14 years or greater (p=0.03), with a BMI≥25kg/m²(p=0.02) and with surgical times over 3.5hours (p=0.05) had increased HBL. Multivariate analysis determined BMI≥25kg/m² (OR 9.91; CI, 1.01-104.26; p=0.05) was associated with increased HBL. Allogenic blood transfusion was rare (4%) and associated with increased HBL (897±112mL vs. 540±402mL, p=0.05).

DISCUSSION

For patients undergoing PSF for AIS there is more HBL after wound closure than intraoperative blood loss. This HBL is higher in older patients who undergo longer operations and have a BMI≥25kg/m².

LEVEL OF EVIDENCE

IV; retrospective cohort study.

Comparison of four correction techniques for posterior spinal fusion in adolescent idiopathic scoliosis

INTRODUCTION

When performing posterior spinal fusion for adolescent idiopathic scoliosis (AIS), it is of major importance to address both coronal and sagittal deformities. Although several techniques have been described, few data exist comparing them. Our objective was to compare four techniques (in situ bending (ISB), rod derotation (RD), cantilever (C) and posteromedial translation (PMT)) for the correction of spinal deformity in AIS including thoracic deformity.

MATERIAL AND METHODS

We conducted a multicenter retrospective study including 562 AIS patients with thoracic deformity with at least 24-month follow-up. Radiographic analysis was performed preoperatively, postoperatively and at last follow-up. The main outcomes were main curve correction and thoracic kyphosis restoration (TK).

RESULTS

Coronal correction rate was significantly different among the four treatment groups (ISB 64% vs C 57% vs RD 55% vs PMT 67%, p < 0.001). Multivariate regression revealed that correction technique did not influence correction rate, whereas implant density, convex side compression and use of derotation connectors did. TK increase was significantly higher in the PMT group (average + 13°) than in DR (+ 3°), while ISB (-3°) and cantilever (-13°) resulted in TK decrease (p < 0.001). Multivariate analysis revealed that TK increase was only influenced by the reduction technique (p < 0.001) and preoperative TK (p < 0.001).

DISCUSSION

The four techniques had the same ability to correct spinal deformity in the coronal plane. Three factors were identified to improve correction rate: implant density, convex compression and use of derotation connectors. On the other hand, PMT was more effective in restoring TK, particularly in hypokyphotic patients.