Surgical Strategies and Choosing Levels for Spinal Deformity: How High, How Low, Front and Back

Thoraco-lumbar selective fusion in adolescent idiopathic scoliosis with Lenke C modifier curves: clinical and radiographic analysis at 10-year follow-up

PURPOSE

To examine the radiological and clinical outcomes of a single-center case series of selective thoracic fusions (STF) in adolescent idiopathic scoliosis with Lenke C modifier curves, with a long-term follow-up.

METHODS

We evaluated at 6 months and 10 years different radiological parameters on both thoracic and lumbar districts: coronal curves, sagittal curves, apical vertebral translation (AVT), and apical vertebral rotation (AVR). The clinical outcome was determined using the SRS 22 score. Data were also analyzed dividing the patients by their Risser and Lenke scores.

RESULTS

In examining 90 patients we reported a radiological benefit from STF on both thoracic and lumbar districts. The corrections in the values of both coronal curves, AVT, and AVR are relevant at 6 months and do not significantly vary at the latest follow-up. Sagittal curves are not relevantly affected at any time point. All the SRS 22 score evaluations showed significant improvement at 6 months, in particular, the self-image analysis. A further improvement was also reported at 10 years, in particular in pain and function scores. At no time point were significant differences retrieved by comparing SRS 22 results as divided by Risser or Lenke grading systems.

CONCLUSIONS

STF is an effective treatment option both in clinical and radiographical terms. The results at 10-year follow-up confirm both the stability of the correction and the improvement of the clinical outcome scores. Risser and Lenke grading systems are not relevant variables predictive of clinical efficacy.

The axial transsacral approach to interbody fusion at L5-S1

Lumbosacral interbody fusion may be indicated to treat degenerative disc disease at L5-S1, instability or spondylolisthesis at that level, and severe neural foraminal stenosis resulting from loss of disc space height. In addition, L5-S1 interbody fusion may provide anterior support to a long posterior fusion construct and help offset the stresses experienced by the distal-most screws. There are 3 well-established techniques for L5-S1 interbody fusion: anterior lumbar interbody fusion, posterior lumbar interbody fusion, and transforaminal lumbar interbody fusion. Each of these has advantages and pitfalls. A more recently described axial transsacral technique, utilizing the presacral corridor, may represent a minimally invasive approach to obtaining lumbosacral interbody arthrodesis. Biomechanical studies demonstrate that the stiffness of the axial rod is comparable to existing fixation devices, suggesting that, biomechanically, it may be a good implant for obtaining lumbosacral interbody fusion. Clinical studies have demonstrated good early results with the use of the axial transsacral approach in obtaining lumbosacral interbody fusion for degenerative disc disease, spondylolisthesis, and below long posterior fusion constructs. The technique is exacting and complications can be major, including rectal perforation and fistula, loss of correction, and pseudarthrosis.

Loss in spinal motion from inclusion of a single midlumbar level in posterior spinal fusion for adolescent idiopathic scoliosis

STUDY DESIGN

Prospective study.

OBJECTIVE

Evaluate the impact of the distal fusion level on overall spine motion in patients with adolescent idiopathic scoliosis.

SUMMARY OF BACKGROUND DATA

In the surgical treatment of adolescent idiopathic scoliosis, the impact of incorporating a single additional distal lumbar fusion level on residual spinal motion is unclear. This study uses radiographs and computerized motion capture technology to determine whether the addition of a single lumbar level in a posterior fusion construct produces a detectable alteration in spinal motion.

METHODS

Twenty-three patients with adolescent idiopathic scoliosis were evaluated with standing radiographs and computerized motion analysis preoperatively and 1 year after fusion. Patients were divided into 2 groups: L1-L2 group (distal fusion ended at L1-L2) and an L3 group (distal fusion ended at L3). Cobb angle, coronal vertical alignment, sagittal vertical alignment, thoracic kyphosis, and lumbar lordosis were measured from radiographs. Three-dimensional motion data were obtained for static standing and repeated bending or twisting motions. Statistical analysis was performed with Student t test, analysis of variance, and Fisher exact methods.

RESULTS

Both the L1-L2 and L3 groups demonstrated loss of spinal motion compared with preoperative values. The L1-L2 group showed a significant loss of rotational motion but no significant loss of motion in the sagittal and coronal planes. The L3 group demonstrated significant loss of motion in both the coronal plane and the rotational plane. When the 2 groups were compared, the L3 group showed a significant loss of coronal plane bending (18° ± 10°, P = 0.002).

CONCLUSION

Distal extension of a posterior spinal fusion construct to include L3 results in a significant decrease in spine motion in at least one plane. Preservation of a single lumbar segment may improve overall spine motion in the short term and may have implications for the long-term health of the unfused spine.

LEVEL OF EVIDENCE

3.

Selection of proximal fusion level for adult degenerative lumbar scoliosis

INTRODUCTION

There is controversy regarding the appropriate proximal fusion level for adult degenerative scoliosis. Ideally, the horizontal vertebra is chosen for the upper instrumented vertebra to create a balanced spine. Fusion to T10 is recommended to prevent junctional problems at the proximal adjacent segment. The purpose of this retrospective study was to determine the optimal proximal fusion level for adult degenerative lumbar scoliosis.

MATERIALS AND METHODS

Fifty-one patients with adult degenerative lumbar scoliosis (mean age 64.6 years) who underwent posterior instrumentation were analyzed after a minimum 2-year follow-up. The average number of levels fused was 5.9 segments (range 3-9) with distal fusion at L5 in 30 patients and S1 in 21 patients. The upper instrumented vertebra (UIV) ranged from T9 to L2. According to the relationship between UIV, horizontal vertebra (HV) and upper end vertebra (UEV), the patients were divided into three groups in the coronal plane: Group HV (UIV = HV or above); Group HV-UEV (UIV = between HV and UEV); and Group UEV (UIV = UEV or below). In the sagittal plane; the patients were divided into Group T9-10 (UIV = T9-10), Group T11-12 and Group L1-2.

RESULTS

Proximal adjacent segment disease (ASD) was identified in 13 (25 %) out of 51 patients, including junctional kyphosis (n = 5), compression fractures (n = 4), progression of disc wedging (n = 2) and spinal stenosis (n = 2). Group UEV had more ASD (9 of 16 patients) compared to Group HV (2 of 21 patients) and Group HV-UEV (2 of 14 patients). It appeared that neutral vertebra could be a criterion for the selection of UIV in the coronal plane. Among the groups divided in the sagittal plane, proximal ASD was found in 47 % of 19 patients in Group L1-2, which was notably higher than 9 % in Group T9-10 and 20 % in Group T11-12.

CONCLUSIONS

Proximal adjacent segment disease developed more commonly when the proximal fusion stopped at the UEV or below in adult degenerative lumbar scoliosis. UIV must be above UEV in the coronal plane. Fusion to T11 or T12 was acceptable when UIV was above UEV, since there was no significant difference in the rate of proximal adjacent segment between fusion to T10 and fusion to T11 or T12.

Axial lumbosacral interbody fusion appears safe as a method to obtain lumbosacral arthrodesis distal to long fusion constructs

BACKGROUND

Current methods to achieve lumbosacral interbody fusion have been complicated by approach-related morbidity, nerve root or cauda equina injury, or difficulty in implanting a large lordotic graft posteriorly. There is little information in the literature evaluating the presacral axial approach to the lumbosacral disc space.

QUESTIONS/PURPOSES

What are the short-term clinical and radiographic outcomes in patients undergoing axial lumbosacral interbody fixation and fusion at the end of long fusion constructs using the AxiaLIF implant (Trans1 Inc., Wilmington, NC, USA)? Furthermore, what complications are associated with this procedure?

PATIENTS AND METHODS

We performed a retrospective evaluation of nine patients who underwent presacral axial lumbosacral interbody fixation and fusion at the end of long fusion constructs using the AxiaLIF implant. Preoperative diagnoses included adjacent segment degeneration below a long fusion construct for adult scoliosis and progressive sagittal plane deformity.

RESULTS

There were two pseudoarthroses, one at L4-5 and one at L5-S1. No major complications occurred. There were no significant differences in coronal or sagittal plane alignment at the time periods measured. There was no significant difference in implant position between immediate postoperative and final follow-up periods. There were significant postoperative improvements in Scoliosis Research Society-22 scores, specifically in the pain, self-image, and satisfaction with management domains.

CONCLUSIONS

The axial lumbosacral interbody fusion is a minimally invasive and safe method to obtain lumbosacral fixation and arthrodesis distal to a long fusion construct. Longer follow-up of larger numbers of patients are needed prior to recommending this procedure as a routine method to fuse L4-5 or L5-S1.

Bilateral pars fractures complicating long fusion to L5 in a patient with rheumatoid arthritis

STUDY DESIGN

Case report.

OBJECTIVE

To report bilateral pars fractures at L5 complicating a long fusion for adult idiopathic scoliosis in a patient with rheumatoid arthritis.

SUMMARY OF BACKGROUND DATA

To our knowledge, there are no reports in the literature regarding bilateral pars fractures at the end instrumented vertebrae of a long fusion at the lumbosacral junction, nor reports that have evaluated long spinal deformity corrections in patients with rheumatoid arthritis. The question of ending a long fusion at L5 or S1 is controversial, and a review is presented.

METHODS

We present the patient's history, physical examination, and radiographic findings; describe the surgical treatment and long-term follow-up; and provide a literature review.

RESULTS

Bilateral pars fractures at the end instrumented vertebrae of a long construct (T4-L5) that we discovered were subsequently revised by extension of the fusion to the sacrum. Anterior structural support at L5-S1 was also provided. At the latest follow-up (46 months), the patient has had no recurrence of her symptoms. Her radiographs showed a stable construct without loss of alignment in the sagittal or coronal planes. Her rheumatoid arthritis continues to be treated with biologic, disease-modifying antirheumatic drugs.

CONCLUSION

To our knowledge, this is the first report of the treatment and long-term outcome of a patient with rheumatoid arthritis and bilateral pars fractures at the end instrumented vertebrae (L5) of a long deformity correction construct.

Selective fusion for adolescent idiopathic scoliosis: a review of current operative strategy

Selective fusion of thoracic and thoracolumbar/lumbar curves in adolescent idiopathic scoliosis is a concept critically debated in the literature. While some surgeons strongly believe that a more rigid and straighter spine provides predictably excellent outcomes, some surgeons recommend a mobile and less straight spine. This topic is a crucial part of surgical treatment of idiopathic scoliosis, particularly in young patients who will deal with the stress of the fusion mass at the proximal and distal junctions over many years. This study will review the literature on various aspects of selective fusion.