Bone graft in posterior spine fusion for adolescent idiopathic scoliosis: a meta-analysis

Can hydroxyapatite charged collagen sponge help reduce perioperative blood loss in adolescent idiopathic scoliosis surgery? Preliminary results in 68 patients

PURPOSE

Patient blood management has been recently emphasized to avoid perioperative blood transfusion in AIS surgery. Hydroxyapatite charged collagen sponge (HCS) is a bone substitute material made of collagen and ceramized hydroxyapatite, with associated haemostatic properties. The goal of this study was to assess the impact of HCS in the perioperative blood loss in AIS surgery.

METHODS

After IRB approval, all AIS patients undergoing primary correction were prospectively included over a 15-month period. Patients receiving HCS at the end of the procedure were compared to a control group (matched for age, gender, and fusion levels) without any haemostatic agent or bone substitute. The same perioperative blood saving strategies were used in both groups. Two subfascial drains were used for 48 h in all patients. Perioperative blood loss and transfusion rates were analysed.

RESULTS

A total of 34 patients were included in each group. No difference in drainage volume was observed at day 1, but the reduction was statistically different at day 3 (1135 mL [800-1640] versus 930 [480-1510], p = 0.028, 0.63 ml/Kg/h [0.4-0.92] versus 0.46 [0.29-0.7], p = 0.042). Multivariate analysis found that the use of HCS was associated with a decrease in the postoperative blood loss (OR = 1.17 [1.10-1.25]). The transfusion rate was lower in the HCS group [0 (0% vs. 3(8.8%), p = 0.076)]. No infection occurred, and no complication was reported.

CONCLUSION

With 27% reduction in drain volume, hydroxyapatite charged collagen sponge can be considered as a blood salving strategy in AIS surgery. The role of the biomaterial in fusion rate still needs to be further assessed.

Safety and Efficacy of Stand-Alone Bioactive Glass Injectable Putty or Granules in Posterior Vertebral Fusion for Adolescent Idiopathic and Non-Idiopathic Scoliosis

Posterior spinal fusion (PSF) is the standard procedure for the treatment of severe scoliosis. PSF is a standard procedure that combines posterior instrumentation with bone grafting and/or bone substitutes to enhance fusion. The aim of this retrospective study was to evaluate and compare the post-operative safety and efficiency of stand-alone bioactive glass putty and granules in posterior spine fusion for scoliosis in a paediatric cohort. A total of 43 children and adolescents were included retrospectively. Each patient's last follow-up was performed at 24 months and included clinical and radiological evaluations. Pseudarthrosis was defined as a loss of correction measuring >10° of Cobb angle between the pre-operative and last follow-up measurements. There was no significant loss of correction between the immediate post-operative timepoint and the 24-month follow-up. There was no sign of non-union, implant displacement or rod breakage. Bioactive glass in the form of putty or granules is an easily handled biomaterial but still a newcomer on the market. This study shows that the massive use of bioactive glass in posterior fusion, when combined with proper surgical planning, hardware placement and correction, is effective in providing good clinical and radiological outcomes.

Perioperative complications after posterior spinal fusion versus minimally invasive fusionless surgery in neuromuscular scoliosis: a comparative study

INTRODUCTION

Early-onset scoliosis is a common deformity in neuromuscular disease. When conservative treatment becomes ineffective, several surgical options can be proposed. The most common technique is posterior spinal fusion (PSF) consisting of performing a multiple segmental instrumentation with pedicular screws on the full spine associated with decortication and bone graft. Minimally invasive fusionless surgery (MIFS) is an alternative to correct and fix definitively the spine without graft. The objective of this study was to compare early surgical inpatient period between PSF and MIFS in neuromuscular scoliosis.

MATERIAL AND METHODS

140 NMS operated by PSF or MIFS between 2012 and 2017 was retrospectively reviewed. The following data were compared between groups: general characteristics (age, sex, etiology), preoperative preparation (halo traction, noninvasive ventilation or tracheostomy), Cobb angle and pelvic obliquity correction, use of drugs (vasopressor and/or inotropes, expansion fluids, transfusion and volumes), postoperative complications, and need of noninvasive ventilation.

RESULTS

75 patients were managed by PSF with a mean age of 14.3 ± 2.3y and 65 by MIFS with a mean age of 11.8 ± 3y. Average pelvic obliquity and major curve correction were similar postoperatively. Intraoperative blood transfusion was significantly more common in PSF group (OR, 14; 95% CI [6.3-33.0]). Vasopressors were used non-significantly more often in the PSF group and expansion fluids similar in the two groups. PSF group had more overall complications (OR, 4.6; 95% CI [2.3-9.8]), more infections (OR, 3.6; 95% CI [1.5-9.3]) and more hemodynamic complications (OR, 4.1; 95% CI [1.4-15.1]). Average intubation duration was 5 days in the PSF and 4 days in MIFS (p = 0.05).

CONCLUSION

In this series of neuromuscular patients, the complication rate was reduced in MIFS comparatively to PSF, with lower blood transfusion and less infections.

Paediatric Spinal Deformity Surgery: Complications and Their Management

Surgical correction of paediatric spinal deformity is associated with risks, adverse events, and complications that must be preoperatively discussed with patients and their families to inform treatment decisions, expectations, and long-term outcomes. The incidence of complications varies in relation to the underlying aetiology of spinal deformity and surgical procedure. Intraoperative complications include bleeding, neurological injury, and those related to positioning. Postoperative complications include persistent pain, surgical site infection, venous thromboembolism, pulmonary complications, superior mesenteric artery syndrome, and also pseudarthrosis and implant failure, proximal junctional kyphosis, crankshaft phenomenon, and adding-on deformity, which may necessitate revision surgery. Interventions included in enhanced recovery after surgery protocols may reduce the incidence of complications. Complications must be diagnosed, investigated and managed expeditiously to prevent further deterioration and to ensure optimal outcomes. This review summarises the complications associated with paediatric spinal deformity surgery and their management.

Bovine-derived xenograft is a viable bone graft substitute in multilevel, instrumented, spinal fusion

Objective

To evaluate radiological outcomes following the use of xenogeneic bone graft substitute (BGS) in patients undergoing multisegmental spinal fusion.

Summery of Background Data

Data exists for single level and short segment fusions, there presently is a paucity of data on fusion rate after bone augmentation with BGS in multisegmental posterior spinal fusion (PSF). The leading concern is pseudarthrosis, which often leads to a loss of correction after PSF. Therefore, the bone graft is an essential aspect of PSF.

Methods

We retrospectively analysed the radiological data of a consecutive cohort of patients who had been treated for adolescent idiopathic scoliosis (AIS) via multisegmental spinal fusion, in whom a bovine derived BGS had been used and had a complete dataset of 24 months follow-up. The Cobb angle of the main curve was measured pre-operatively and then at 6, 12 and 24 months post-operatively. Loosening of the screws was recorded at the same post-operative time points.

Results

After applying inclusion and exclusion criteria, 28 patients were included. We found no significant change of the cobb angle from the main curve as well as the cobb angle from the thoracic kyphosis during the 24 months of follow up. No patient showed a lack of bony fusion. There was 1 revision surgery, which was due to trauma.

Conclusion

In this cohort, all patients showed successful bone fusion during a 24-month follow-up. Additionally, there was no change in the Cobb angle during the 2-year post-operative period. Our data indicates that the use of bovine-derived BGS supports bone fusion after multisegmental posterior instrumented fusion of the spine.

Local Bone Grafting Is Sufficient for Instrumented Adolescent Idiopathic Scoliosis Surgery: A Preliminary Study

BACKGROUND

Several options for grafting exist; iliac crest bone grafting, allografts, and bone substitutes. Local bone graft (LBG) offers high-quality bone graft and no commercial cost. The aim of this study was to assess the clinical and radiologic results of adolescent idiopathic scoliosis (AIS) surgery with posterior instrumentation and fusion (PIF) in patients using only LBG and to measure the quantities harvested.

METHODS

A total of 218 AIS patients who underwent pedicle screw PIF surgery using only LBG with a minimum 1-year follow-up were reviewed. Bone was harvested during surgery from the excised facet joints, spinous processes (not from the end instrumented vertebrae) and decortication of laminae and transverse processes in the operative field. The harvested bone graft weight of 127 patients was recorded prospectively and then computed to graft weight per kilogram body weight (GWPK) and graft weight per motion segment (GWPMS).

RESULTS

The median follow-up time was 24.7 months (12.1 to 133 mo) with 128 of the 218 patients having over 2 years follow-up. A total of 280 curves were fused. One hundred fifty-six of the patients had single curve instrumentation and 62 had double curve surgery. The median preoperative primary Cobb angle was 57.0 (31 to 100) degrees and postoperatively was 20.0 (0 to 66) degrees, indicating a median correction of 65.3% (17.5% to 100%). The median graft weight was 30 g (14 to 62 g), GWPK was 0.54 g/kg (0.24 to 1.29 g/kg) and GWPMS was 3.3 g/motion segments (2.3 to 10.0 g/kg). Twelve of 218 patients (5.5%) required subsequent surgery. Only 2 patients developed pseudarthrosis (0.91%), noting that modern segmental instrumentation warrants longer follow-up for increased confidence of complete fusion.

CONCLUSIONS

LBG achieved successful fusion in over 99% of patients undergoing PIF for AIS. The described terms GWPK and GWPMS can be insightful for future studies. LBG offers a safe and low-cost solution for bone grafting in AIS surgery.

LEVEL OF EVIDENCE

Level IV.

Surgical Site Infection Following Primary Definitive Fusion for Pediatric Spinal Deformity: A Multicenter Study of Rates, Risk Factors, and Pathogens

STUDY DESIGN

A retrospective multicenter study.

OBJECTIVE

To determine the surgical site infection (SSI) rate, associated risk factors, and causative pathogens in pediatric patients with spinal deformity.

SUMMARY OF BACKGROUND DATA

There have been no extensive investigations of the risk factors for SSI in Japan.

METHODS

Demographic data, radiographic findings, and the incidence of SSI were retrospectively analyzed in 1449 pediatric patients who underwent primary definitive fusion surgery for spinal deformity at any of 15 institutions from 2015 to 2017. SSI was defined according to the US Centers for Disease Control and Prevention guideline.

RESULTS

The incidence of all SSIs was 1.4% and that of deep SSIs was 0.76%. The most common pathogenic microbes were methicillin-resistant staphylococci (n = 5) followed by gram-negative rods (n = 4), methicillin-sensitive staphylococci (n = 1), and others (n = 10). In univariate analysis, younger age, male sex, a diagnosis of kyphosis, type of scoliosis, American Society of Anesthesiologists (ASA) class ≥3, mental retardation urinary incontinence, combined anterior-posterior fusion, greater magnitude of kyphosis, three-column osteotomy, use of blood transfusion, and number of antibiotic administration were associated with the likelihood of SSI (all P < 0.05). Multivariate logistic regression analysis identified the following independent risk factors for SSI: syndromic scoliosis etiology (vs. idiopathic scoliosis; adjusted odds ratio [OR] 16.106; 95% confidence interval [CI] 2.225-116.602), neuromuscular scoliosis etiology (vs. idiopathic scoliosis; adjusted OR 11.814; 95% CI 1.109-125.805), ASA class 3 (vs. class 2; adjusted OR 15.231; 95% CI 1.201-193.178), and administration of antibiotic therapy twice daily (vs. three times daily; adjusted OR 6.121; 95% CI 1.261-29.718).

CONCLUSION

The overall infection rate was low. The most common causative bacteria were methicillin-resistant followed by gram-negative rods. Independent risk factors for SSI in pediatric patients undergoing spinal deformity surgery were scoliosis etiology, ASA class 3, and administration of antibiotic therapy twice daily.Level of Evidence: 3.

Comparing the efficacy of syngeneic iliac and femoral allografts with iliac crest autograft in a rat model of lumbar spinal fusion

BACKGROUND

Despite widespread use of femoral-sourced allografts in clinical spinal fusion procedures and the increasing interest in using femoral reamer-irrigator-aspirator (RIA) autograft in clinical bone grafting, few studies have examined the efficacy of femoral grafts compared to iliac crest grafts in spinal fusion. The objective of this study was to directly compare the use of autologous iliac crest with syngeneic femoral and iliac allograft bone in the rat model of lumbar spinal fusion.

METHODS

Single-level bilateral posterolateral intertransverse process lumbar spinal fusion surgery was performed on Lewis rats divided into three experimental groups: iliac crest autograft, syngeneic iliac crest allograft, and syngeneic femoral allograft bone. Eight weeks postoperatively, fusion was evaluated via microCT analysis, manual palpation, and histology. In vitro analysis of the colony-forming and osteogenic capacity of bone marrow cells derived from rat femurs and hips was also performed to determine whether there was a correlation with the fusion efficacy of these graft sources.

RESULTS

Although no differences were observed between groups in CT fusion mass volumes, iliac allografts displayed an increased number of radiographically fused fusion masses and a higher rate of bilateral fusion via manual palpation. Histologically, hip-derived grafts showed better integration with host bone than femur derived ones, likely associated with the higher concentration of osteogenic progenitor cells observed in hip-derived bone marrow.

CONCLUSIONS

This study demonstrates the feasibility of using syngeneic allograft bone in place of autograft bone within inbred rat fusion models and highlights the need for further study of femoral-derived grafts in fusion.

Proximal junctional kyphosis and rates of fusion following posterior instrumentation and spinal fusion for adolescent idiopathic scoliosis

BACKGROUND

Proximal junctional kyphosis (PJK) can cause significant functional impairment and neural compression. Varying rates of PJK and pseudoarthrosis following posterior instrumentation and fusion for adolescent idiopathic scoliosis (AIS) are described with multiple biologic and biomechanical correlations attributed. This retrospective study aims to determine our rate of pseudoarthrosis and PJK in posterior spinal fusion for AIS, along with analysing the influence of autograft and allograft bone volume.

METHODS

Immediate and 12-month post-operative radiographs of 78 patients treated for AIS were analysed along with late complications to a minimum of 2 years. Proximal kyphosis was determined by measuring and comparing the angle between the upper instrumented vertebra and upper instrumented vertebra + 2 for both immediate and 12-month post-operative radiographs. Spinal fusion was determined using an accepted grading scale on the 12-month radiograph. These findings were correlated with known surgical variables in bone grafting technique.

RESULTS

There was one case of PJK and no cases of pseudoarthrosis. Three patients showed a defect in the fusion mass but were still suggestive of fusion. The rates of fusion and PJK were not significantly different when using different allograft volumes or incorporating autograft.

CONCLUSION

Relatively low rates of PJK following AIS correction were observed compared to the literature. Rates were not increased with the use of proximal autograft. The amount of allograft used did not affect fusion rates either.