Anterior thoracoscopic epiphysiodesis in the treatment of a crankshaft phenomenon

Video-Assisted Thoracoscopic Lateral Interbody Fusion for Symptomatic Pseudarthrosis in Neurofibromatosis 1-Associated Spinal Deformity

BACKGROUND

The treatment of symptomatic pseudarthrosis via posterior-only approaches in the setting of neurofibromatosis 1 (NF1) is challenging due to dural ectasias, resulting in erosion of the posterior elements. The purpose of this report is to illustrate a minimally invasive method for performing anterior thoracic fusion for pseudarthrosis in a patient with NF1-associated scoliosis and dysplastic posterior elements. To the best of our knowledge, this is the first documented case of using video-assisted thoracoscopic lateral interbody fusion to treat pseudarthrosis for NF1-associated spinal deformity.

CASE DESCRIPTION

The patient underwent video-assisted thoracoscopic anterior spinal fusion via a direct lateral interbody approach with interbody cage placement at T10-T11 and T11-T12, followed by revision of his posterior spinal fusion and instrumentation. The patient had an uneventful postoperative course. At 6 months of follow-up, the patient had complete resolution of his preoperative symptoms and had returned to full-time work with no complaints. At 3 years postoperatively, the patient reported being satisfied with the operation and had continued to work full-time without restrictions.

CONCLUSIONS

To the best of our knowledge, this is the first report of pseudarthrosis in the setting of NF1-associated scoliosis treated via minimally invasive anterior thoracic fusion facilitated by video-assisted thoracoscopic surgery. This is a powerful technique that allows for safe access for anterior thoracic fusion in the setting of dysplastic posterior anatomy and poor posterior bone stock.

The Crankshaft Phenomenon

The crankshaft phenomenon, a progressive rotational and angular spinal deformity that can occur after posterior spinal surgery, has been reported in pediatric patients with idiopathic, congenital, and neuromuscular scoliosis. In the skeletally immature patient, the crankshaft phenomenon is thought to occur secondary to continued growth of the anterior elements of the spine after solid posterior spinal fusion. The condition has also been reported in the setting of newer, so-called growth-friendly posterior distraction-based spinal instrumentation. The clinical evidence of crankshaft phenomenon is often subtle, whereas radiographic findings are usually more apparent. However, objective measurement of radiographic signs may be complicated by instrumentation and postoperative changes. Treatment options for patients with the crankshaft phenomenon are limited; in those with problematic deformity and/or risk of progression, additional surgery may be indicated.

Does thoracoscopic anterior release of rigid idiopathic scolioses associated with correction by posterior instrumentation result in better long-term frontal and sagittal balance?

INTRODUCTION

The aim of treatment of scolioses is to reduce deformities and restore balance in the spine.

HYPOTHESES

In rigid forms of scoliosis, associating anterior release could provide greater frontal and/or sagittal plane correction and improve balance in the spine.

PATIENTS AND METHODS

This study compared correction and long-term balance on two planes between two homogeneous groups of idiopathic rigid scolioses treated with and without thoracoscopic release. The study included rigid scolioses with less than 35% reducibility and a Cobb angle of more than 60°, who all underwent posterior correction using a rod rotation technique. There were 29 patients, 14 who underwent a one-step procedure (group A) and 15 a two-step procedure (group B), with the subgroups of kyphoscolioses and lordoscolioses determined in each group. Frontal balance, Cobb angle, thoracic kyphosis and the Jackson plumbline were measured on pre- and postoperative X-rays and at the final follow-up.

RESULTS

The mean long-term final follow-up was 144 months for group A and 54 months for group B. Frontal plane correction was identical in groups A and B. Frontal balance was preserved in all cases at the final follow-up. Sagittal balance was not modified with or without anterior release. The thoracoscopic release step resulted in an additional correction of 15.5° (23%) of thoracic hyperkyphosis in patients with kyphoscoliosis (P=0.003).

DISCUSSION

Thoracoscopy did not improve short term results in the Cobb angle or frontal or saggital balance. Nevertheless, enhanced correction of thoracic hyperkyphosis was obtained with this procedure. In this study, the association of thoracoscopic anterior release with posterior correction by rod rotation to treat rigid scolioses did not appear to improve results, except for the correction of thoracic hyperkyphosis.

Prone thoracoscopic release does not adversely affect pulmonary function when added to a posterior spinal fusion for severe spine deformity

STUDY DESIGN

Prospective clinical study.

OBJECTIVE

To analyze the effect of adding a thoracoscopic release and fusion performed in the prone position with double lung ventilation to a posterior spinal fusion and instrumentation (PSFI) for severe idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

A prone thoracoscopic anterior release (TAR) offers the advantages of a minimally invasive approach, without requiring repositioning for the PSFI, and has significantly less acute pulmonary complications since single lung ventilation is avoided. It is unclear whether prone thoracoscopy adversely affects pulmonary function tests (PFT) when added to a PSFI for severe deformity.

METHODS

A prospective consecutive series of patients from a single institution undergoing spinal deformity surgery were reviewed. Those patients who underwent prone TAR followed by PSFI were compared to patients who had PSFI alone. In addition, those patients who had a thoracoplasty and PSF (PSFI-T) were compared to those who had a TAR and PSFI with T. (PFTs were measured before surgery and 1, 3, 6 weeks, 3 and 6 months, and 1 year after surgery. Forced vital capacity (FVC) and FE-1 parameters were compared to baseline levels for each patient. RESULTS.: There were 13 patients in the TAR + PSFI groups and 83 in the PSFI groups. The patients in the TAR + PSFI group had larger thoracic curves (83.2 degrees vs. 59.7 degrees ), greater correction (59.4% vs. 50.1%) (P = 0.07), and greater increase in thoracic height (16.4% vs. 6.8%) following surgery. (P < 0.05) PFTs declined more rapidly for the TAR + PSFI patients in the first 3 weeks, however, improved rapidly until 1 year when they were significantly better than the PSFI group for predicted FVC % (29.7% vs. 7.5% above baseline) and forced expiratory volume (FEV) 1% (28.5% and 8.9% above baseline). (P < 0.05) When a thoracoplasty was added to the procedure, the differences in PFTs between those who had a TAR and those who did not was not significant. The TAR + PSFI-T group had FVC % predicted of 5.3% above baseline compared to 4.3% above baseline for the PSFI-T group. The percent predicted FEV 1% was 10.4% above baseline for the TAR + PSFI-T group compared to 4.5% for the PSF-T group (P > 0.05).

CONCLUSION

When performing a prone thoracoscopic release for severe thoracic deformity, excellent coronal plane correction is achieved. There does not appear to be any detrimental effect on pulmonary function when a prone thoracoscopic release using double lung ventilation is added to a PSFI. This technique can be efficacious in achieving excellent deformity correction without adversely affecting pulmonary function and is recommended when treating severe spinal deformity. Adding a thoracoplasty provided a negative effect on pulmonary function and limited the benefits of performing a thoracoscopic release to the PSFI patients.

Anterior thoracoscopic instrumentation in adolescent idiopathic scoliosis: a systematic review

STUDY DESIGN

A Systematic Review of published series of patients with adolescent idiopathic scoliosis treated with anterior thoracoscopic instrumentation.

OBJECTIVE

To conduct a systematic review of the results of thoracoscopic surgery and to compare them with those of open anterior and posterior spine instrumentation to enable surgeons judge the applicability of the method.

SUMMARY OF BACKGROUND DATA

Instrumentation through video-assisted thoracoscopic surgery is an attractive alternative for the treatment of thoracic adolescent idiopathic scoliosis. The advantages claimed by its proponent over conventional instrumentations are better cosmesis and reduced morbidity due its minimal invasive nature. However, superiority of thoracoscopic instrumentation over conventional methods has not been proven so far.

METHODS

Via Medline, Pubmed, and other literature searches, 8 articles met the inclusion criteria for our systematic review. The evaluations were made according to the parameters employed for evaluating spinal deformities. Instrumentation through video-assisted thoracoscopic surgery results were compared to those of open anterior or posterior surgeries.

RESULTS

Mean number of instrumented levels was 7. The extent of disc excision was not indicated in any of the studies. The mean operative time was found to be approximately 5.2 hours. Average blood loss was 391.7 mL (100-1300 mL). The average Cobb curve correction was 64.6%. The mean preoperative kyphosis angle was 21.3 degrees ; the postoperative kyphosis angle was 25.2 degrees . These angular corrections were found to be comparable to posterior procedures using hooks, but less than with pedicle screws. Two studies reported on patient satisfaction favoring thoracoscopic instrumentation. Instrumentation-related complications were the most predominant.

CONCLUSION

Anterior thoracoscopic instrumentation is comparable in terms of curve correction to anterior or posterior procedures. Theoretical advantages of better cosmesis and less aggressiveness seem to be offset by the increased operative and intensive care unit time, and complication rate. More prospective studies need to be conducted to determine the benefit and general applicability of this procedure.