Spine Deformity With Fused Ribs Treated With Proximal Rib- Versus Spine-Based Growing Constructs

Novel Use of Subcostal Polyethylene Bands to Manage Tumor-Related Scoliosis Requiring Serial Imaging: A Case Report

CASE

A 16-year-old male patient with severe kyphoscoliosis, paraplegia, and neurogenic bowel/bladder caused by a juvenile pilocytic astrocytoma was treated surgically using a hybrid fusion construct with polyethylene bands after neoplasm resection. Owing to the necessity of serial postoperative magnetic resonance imaging studies to evaluate the recurrence of pathology and known effect of metal artifact from spinal instrumentation, preservation of radiographic resolution was critical.

CONCLUSION

We describe the novel utility of polyethylene bands placed around the ribs as a safe and effective form of hybrid construct for reducing radiographic metal artifact in spinal deformity cases requiring serial imaging.

Vertical Expandable Rib-based Distraction Device for Correction of Congenital Scoliosis in Children of 3 Years of Age or Younger: A Preliminary Report

BACKGROUND

This study was designed to evaluate the treatment outcome of very young children with congenital scoliosis aged 3 years or under after surgery with a vertical expandable prosthetic titanium rib (VEPTR)-based distraction device.

METHODS

A retrospective study of 13 children undergoing implantation of a vertical expandable rib-based distraction device. From September 2007 to June 2018, 13 children (7 male and 6 female patients) with congenital scoliosis were followed after treatment with a VEPTR. The outcome parameters were complications, thoracic height, kyphosis, lordosis, and coronal major scoliosis curve. In addition, the American Society of Anaesthesiologists (ASA) score, assisted ventilation rating, and hemoglobin and body mass index were analyzed. Data were examined separately by 2 investigators.

RESULTS

The mean age at initial surgical treatment was 24.4±10.6 months, follow-up was 91.5±23.1 months. The mean number of surgical procedures per patient was 14±3.9 (total 182 operations). Apart from planned operations every 6 months, 5 unplanned operations (2.7%) were performed. The major scoliosis curve improved significantly from 55.2±21.9 degrees to 40.5±18.7 degrees, thoracic spine height T1-T12 significantly from 111±12 mm to 137±23 mm, T1-S1 height significantly from 211±13 mm to 252±36 mm and space available for the lung from 80.9%±11.3% to 84.4%±8.8% (preoperatively and at 5-y follow-up, respectively). Kyphosis increased significantly from 30±21.4 degrees to 42.6±23.5 degrees and lordosis from 32.4±20.9 degrees to 37.6±10.4 degrees. Hemoglobin levels were virtually unchanged. Weight increased from 10.6±2.8 kg to 20.2±5.0 kg at final follow-up, but body mass index decreased from 16.6±3.7 kg/m² to 15.7±2.9 kg/m².

CONCLUSIONS

The expandable rib-based distraction device is an effective method to treat severe congenital scoliosis in very young children. It can control the deformity and promotes spinal and thoracic growth.

LEVEL OF EVIDENCE

Level IV.

Proximal anchor fixation in magnetically controlled growing rods (MCGR): preliminary 2-year results of the impact of anchor location and density

STUDY DESIGN

Multicenter, retrospective cohort study.

OBJECTIVES

Analyze the impact of MCGR proximal anchor location and density on radiographic outcomes and complications. Magnetically controlled growing rods (MCGRs) reduce the need for repeat operations for lengthening when treating spinal deformity in children. The evidence behind choosing the location and density of proximal anchors comes from the traditional growing rod and rib-based distraction technique literature. Thus, there is much debate regarding the optimal quantity and location of proximal anchors.

METHODS

This study included early-onset scoliosis patients treated with MCGR with a minimum 2-year follow-up. Comparisons of 2-year correction in the coronal and sagittal planes, complication rates, and patient-reported outcomes were made based on proximal fixation type, proximal anchor density, and type of case (primary, conversion).

RESULTS

This study included 155 MCGR patients. Spinal deformity correction at 2 years was significantly higher in spine-based than rib-based constructs, in terms of both the major (23.9° vs. 17.1°, p = 0.05) and minor curves (10.0° vs. 4.5°, p = 0.03). Greater proximal anchor density, regardless of location, was also associated with better major curve correction at 2 years (25.0° vs. 18.2°, p < 0.05). There was a trend towards higher risk of device migration with rib-based fixation (13.8% vs. 4.1%, p = 0.06) and rod breakage with spine-based fixation (10.3% vs. 3.4%, p = 0.21). Having 5+ proximal anchors did not significantly decrease the risk of complication, including device migration (8.4% vs. 7.7%).

CONCLUSIONS

When using the MCGR, proximal spine anchors and greater anchor density impart superior deformity correction but do not significantly impact the risk of device complications. Although rib-based constructs afford less rigidity than spine-based constructs, there is a similar risk of rod breakage and device migration. This study suggests that having 5+ MCGR proximal anchors does not protect against proximal anchor complication.

LEVEL OF EVIDENCE

Level III-therapeutic.

Comparison of T1-S1 Spine Height of Postoperative Rib-based Implant Patients With Age-matched Peers

BACKGROUND

Severe early-onset scoliosis leads to deficient spine height, thoracic growth inhibition, and ultimately pulmonary compromise. Rib-based growing instrumentation seeks to correct thoracic deformities, in part by correcting the spinal deformity, adding height, increasing thoracic volume, and allowing for continual spinal growth until maturity. However, the amount of growth in these patients relative to their peers is unknown.

METHODS

Sixty patients who had undergone surgical intervention for the treatment of early-onset scoliosis were assessed via radiographic measurements of coronal T1-S1 height and major curve angle before implantation and again at most recent follow-up (minimum 2 years). T1-S1 measurements were then compared with age-matched peers to assess growth differences. Clinical information was examined for relevant parameters.

RESULTS

The average age of our cohort at initial surgery and most recent follow-up was 4.4±3.8 and 10.0±4.4 years old, respectively. In this patient set, there was an average increase in T1-S1 height of 13.1±11.1 mm per year, with the majority of growth occurring in the first 2 years following implantation, and improvement in a major curve from 68±8 to 53±7 degrees. Overall, 77% of patients saw improvement in the major curve at most recent follow-up. Furthermore, a statistically significant greater percent of expected growth was seen in congenital compared with neuromuscular scoliosis (P<0.001). In addition, a weak negative correlation was observed between a number of surgical lengthenings and T1-S1 growth.

CONCLUSIONS

Rib-based implant intervention has been shown to improve the major curve, but only improves growth potential to around 80% of expected growth. Scoliosis diagnosis type also influences growth rate potential, with congenital scoliosis patients being surgically treated earlier in life and having a growth rate approaching that of a healthy individual.

LEVEL OF EVIDENCE

Level III-Case control.

The Effect of Expansion Thoracostomy on Spine Growth in Patients with Spinal Deformity and Fused Ribs Treated with Rib-Based Growing Constructs

STUDY DESIGN

Retrospective review of prospective registries.

OBJECTIVES

We hypothesized that patients with congenitally fused ribs who underwent thoracostomy upon implantation of rib-based distraction devices would achieve improved spine growth compared with those who did not undergo thoracostomy.

SUMMARY OF BACKGROUND DATA

Patients with fused ribs may develop thoracic insufficiency syndrome. Treatment for severe early-onset spinal deformity with rib fusions often includes the placement of rib-based expansion devices with surgical division of the fused ribs (thoracostomy). The effect of thoracostomy on spinal growth has not been fully examined.

METHODS

Two multicenter registries of primarily prospectively collected data were searched. Patients with fused ribs and implantation of a rib-based device were identified. A total of 151 patients with rib fusions treated with rib-based constructs and minimum two-year follow-up were included. Among those, 103 patients were treated with expansion thoracostomy at the time of implantation, whereas 48 patients received device implantation alone. We evaluated change in T1-T12 and T1-S1 height, coronal Cobb angle, kyphosis, and number of surgeries. Preoperative deformity was similar between the two groups. Only 19% of patient underwent final fusion, with similar numbers fused in each group.

RESULTS

At latest follow-up, the expansion thoracostomy group had a greater total improvement in T1-S1 height (7.2 cm vs. 4.8 cm, p = .004). There was no difference between the two groups for change in spinal height at each lengthening procedure. Interestingly, thoracostomy patients also underwent more total surgeries (11.5 vs. 9.6, p = .031) and more lengthening procedures (8.3 vs. 6.6, p = .017) than the comparison group despite similar length of follow-up.

CONCLUSIONS

Patients who underwent expansion thoracostomy at the time of rib expansion device implantation achieved greater improvement in T1-S1 height than those who underwent implantation of rib expansion device alone. Further work is needed to evaluate whether expansion thoracostomy impacts pulmonary function.