Sublaminar polyester band fixation construct in the treatment of neuromuscular scoliosis

Instrumentation of hypoplastic pedicles with patient-specific guides

PURPOSE

Hypoplastic pedicles of the thoracolumbar spine (<5 mm diameter) are often found in syndromic deformities of the spine and pose a challenge in pedicle screw instrumentation. 3D-printed patient-specific guides might help overcome anatomical difficulties when instrumenting pedicles with screws, thereby reducing the necessity for less effective fixation methods such as hooks or sublaminar wires. In this study, the surgical feasibility and clinical outcome of patients with hypoplastic pedicles following pedicle screw instrumentation with 3D-printed patient-specific guides were assessed.

METHODS

Hypoplastic pedicles were identified on preoperative computed tomography (CT) scans in six patients undergoing posterior spinal fusion surgery between 2017 and 2020. Based on these preoperative CT scans, patient-specific guides were produced to help with screw instrumentation of these thin pedicles. Postoperatively, pedicle-screw-related complications or revisions were analyzed.

RESULTS

93/105 (88.6%) pedicle screws placed with patient-specific guides were instrumented. 62/93 (66.7%) of these instrumented pedicles were defined as hypoplastic with a mean width of 3.07 mm (SD  ±0.98 mm, 95% CI [2.82-3.32]). Overall, 6 complications in the 62 hypoplastic pedicles (9.7%) were observed and included intraoperatively managed 4 cerebrospinal fluid leaks, 1 pneumothorax and 1 delayed revision due to 2 lumbar screws (2/62, 3.3%) impinging the L3 nerve root causing a painful radiculopathy. The mean follow-up time was 26.7 (SD  ±11.7) months. Complications were only noted when the pedicle-width-to-screw-diameter ratio measured less than 0.62.

CONCLUSION

Patient-specific 3D-printed guides can aid in challenging instrumentation of hypoplastic pedicles in the thoracolumbar spine, especially if the pedicle-width-to-screw-diameter ratio is greater than 0.62.

Surgical complications in neuromuscular scoliosis surgery: systematic review and meta-analysis of the last ten years

PURPOSE

Surgical correction of neuromuscular scoliosis is often a challenging and extensive procedure. Due to this complexity and the high disease burden that these patients carry, per and post-operative complications are not uncommon. The purpose of this study was to systematically review and describe the pooled rates of postoperative complications and analyze risk factors for complications in neuromuscular scoliosis surgery described in the literature in the last ten years.

METHODS

A systematic review of the English literature across multiple databases was conducted using search criteria (neuromuscular scoliosis AND complications) and using PRISMA guidelines (Jan 2012-July 2022). Studies with less than 30 patients and follow-up of < 2 years were excluded. Data extraction and meta-analysis were performed using random mode effect. Statistical analysis was conducted using OpenMeta software. Meta-regression analysis was used to detect risk factors (surgical approach, intraoperative time, intraoperative blood loss, preoperative Cobb angle and patient diagnosis) associated with each complication group. Confidence interval (CI) was set at 95%.

RESULTS

Twenty-two studies met the inclusion criteria involving 2155 patients. The level of evidence among studies were III (9) and IV (13). The most common primary diagnosis was cerebral palsy (43%) followed by Duchenne muscle dystrophy (20%), myelomeningocele (7.4%), spinal muscle atrophy (7.1%), Rett syndrome (< 2%) and combined other pathologies (20.2%). The pooled incidence rate of wound complications was the highest, amongst all complications, at 13.3% (CI 10.838 to 16.861); closely followed by respiratory complications (11.8%;CI 5.7 to 19.7). Implant failure occurred in 7.1% cases (CI 6.418 to 11.465), gastrointestinal complications was 5.2%; CI 2.4 to 8), pseudarthrosis in (4.6%;CI 2.2 to 6.9) and neurological deficit in 2.9% (CI 1.989 to 6.086). The pooled rate of revision surgery was (9.6%; CI 6.2 to 12.9). Heterogeneity was assessed using I2 test which results were moderately heterogeneous. Meta-regression analysis revealed that the diagnosis of myelomeningocele or Duchenne muscle dystrophy or spinal muscle atrophy were strongly associated with wound and respiratory complications (p = 0.007 and p = 0.005, respectively).

CONCLUSION

Wound-related (13.3%) and respiratory complications (11.8%) remain the most common complications among studies after corrective surgery for neuromuscular scoliosis. Both are significantly associated with Duchenne muscle dystrophy, spinal muscle atrophy and myelomeningocele.

Does the addition of convex uniplanar screws in hybrid constructs improve 3D surgical correction in thoracic adolescent idiopathic scoliosis posterior fusion?

Purpose

Hybrid techniques using thoracic sublaminar bands have proved their efficacy in adolescent idiopathic scoliosis posterior fusion, but clinical axial correction sometimes remained disappointing. One solution found was "the frame technique" and the second alternative was the replacement of the convex sublaminar bands by periapical uniplanar screws. The goal of this study was to compare clinical and radiological outcomes of both techniques in a consecutive cohort of adolescent idiopathic scoliosis patients.

Methods

All patients undergoing primary posterior fusion for thoracic adolescent idiopathic scoliosis between January 2017 and March 2020 were included. Two groups were compared: Group 1 with thoracic sublaminar bands only and Group 2 with periapical uniplanar screws. All patients underwent standing stereoradiographs. The main frontal, sagittal, and axial (apical vertebra rotation) radiological parameters of interest were analyzed. Functional outcomes were assessed using the Scoliosis Research Society 30 score.

Results

A total of 147 adolescents were included (Group 1, n = 73 and Group 2, n = 74 patients). In the frontal plane, a greater reduction index was observed in Group 2 (68% versus 62%, p < 0.001) as well as a better apical axial correction (67.8% versus 46.6%, p = 0.03). The number of thoracoplasty performed was reduced (6.7% versus 20.5%, p = 0.02) in Group 2, with a significant decrease in the rate of mechanical complication. No significant loss of correction was observed during follow-up in any of the group.

Conclusion

The adjunction of convex uniplanar screws at the periapical levels improved the three-dimensional surgical correction of thoracic adolescent idiopathic scoliosis treated with hybrid constructs.

Level of evidence

level III, retrospective comparative study.

Sublaminar Band Fixation Provides Excellent Anchors for MAGEC Rod Distraction Systems

MAGEC rods (NuVasive) provide distraction growth in early-onset scoliosis. Pedicle screw use with MAGEC rods can lead to anchor failure. Sublaminar bands offer superior fixation points for the MAGEC system while preserving pedicles and facets, avoiding spinal cord injury, and eliminating the need for fluoroscopy. Sublaminar bands can be safely used up to cervical vertebra four (C4), substantially decreasing the risk of complications such as anchor pull-out, rod breakage, and proximal junctional kyphosis that typically occurs with pedicle screws and hooks. This case demonstrates the viable option of sublaminar band fixation as an anchor system for MAGEC rods. This is a retrospective case review of one patient with early-onset scoliosis who underwent multiple osteotomies, spinal cord decompression, and placement of MAGEC rods with sublaminar bands. The patient had successful distraction procedures conducted routinely throughout a 44-month period with no associated implant complications or neurologic sequelae during that period. The patient had achieved maximal distraction with the implanted rods and thereafter underwent removal of the MAGEC rods and replacement implantation with longer MAGEC rods. The purpose of this case review was to demonstrate the superior fixation results provided with sublaminar band fixation for MAGEC rod distraction systems.

Comparison of Pedicle Screws Versus Hybrid Fixation With Sublaminar Polyester Bands in the Treatment of Neuromuscular Scoliosis

BACKGROUND

The choice of implants in neuromuscular scoliosis (NMS) surgery remains controversial. Sublaminar polyester bands (SPBs) seem to be a promising alternative implant. The purpose of current study was to compare clinical and radiologic results of posterior instrumentation and fusion using hybrid constructs versus only pedicle screws for NMS treatment.

METHODS

In 24 patients, pedicle screws were used in all segments, and 18 patients underwent hybrid fixation. Cobb angle, thoracic kyphosis, lumbar lordosis angles, and pelvic obliquity were compared before and immediately after surgery, at the last follow-up radiographs. Demographic, clinical information, duration of surgery, estimated blood loss (EBL), blood transfusion, and complications were compared between groups. Additionally, patients were assessed for pain with visual analog scale (VAS) and quality of life with Short Form 36 (SF-36) and the Oswestry scale.

RESULTS

Baseline characteristics of patients were similar except for EBL (P = 0.002) and follow-up duration (P = 0.004). The mean curve correction was 58.1% in the hybrid group, and 67.6% in the screw group (P = 0.07), and loss of correction was significantly lower in hybrid group (2.72° ± 1.48° vs. 3.66° ± 1.52°, P = 0.049). Functional scores at final follow-up were equal in both groups (VAS P = 0.865, Oswestry P = 0.097, SF-36 Physical P = 0.358, SF-36 Mental P = 0.145).

CONCLUSIONS

SPBs might be a better fixation alternative at the apex of rigid spinal deformity in NMS. The deformity can be corrected with less blood loss and at a similar rate of correction, with similar rate complications compared with pedicle screws.