On the pedicle subtraction osteotomy technique and its modifications during the past two decades: a complementary classification to the Schwab's spinal osteotomy classification

Lumbar pedicle subtraction osteotomy: techniques and outcomes

Pedicle subtraction osteotomy has been thoroughly described and studied over the past 2 decades, being applied mainly in the lumbar spine, followed by the thoracic spine. Our better understanding of alignment biomechanics, and the progressive refinements of the surgical technique over time made it a very efficient procedure for the management of fixed sagittal malalignment. However, a long learning curve is mandatory to mitigate the associated risks particularly neurological deficits and achieve satisfactory clinical and radiological outcomes with an acceptable rate of complications.

The "Sandwich" Extended Pedicle Subtraction Osteotomy for the Treatment of Fixed Sagittal Malalignment: Technical Description, Case Series, and Early Results With 2-Year Outcomes

BACKGROUND AND OBJECTIVES

Adult spinal deformity (ASD) with fixed sagittal malalignment (FSM) may require a pedicle subtraction osteotomy (PSO) for greater focal lordosis and restoration of global alignment. Despite growing trends in minimizing PSOs given their associated high risks, a considerable portion of patients with ASD still require a lumbar PSO most commonly because of iatrogenic flat back deformity. The purpose of this article is to describe a modified extended PSO technique with additional anterior column support coined the "sandwich" extended PSO (SE-PSO) to promote arthrodesis and report the outcomes in a consecutive case series.

METHODS

Patients with ASD treated with a lumbar SE-PSO at a single institution from 2015 to 2020 were analyzed. Complications, radiographic data, and patient-reported outcomes were compared preoperatively, at immediate postoperative follow-up, and at a 2-year postoperative follow-up (FU).

RESULTS

Fourteen patients who underwent revision operations for FSM were included. Improvements in segmental lordosis across the PSO site (14.8 ± 6.8 vs 39.9 ± 7.1, P < .0001), overall lumbar lordosis (14.6 ± 15.4 vs 44.6 ± 12.1, P < .0001), sacral slope (21.0 ± 10.5 31.1 ± 10.7, P = .0150), C7 sagittal vertical axis (140.1 ± 59.0 mm vs 35.9 ± 28.5, P < .0001), and spinopelvic mismatch (52.5 ± 21.3 vs 18.6 ± 14.1, P = .0001) were obtained in all patients. Eight patients experienced perioperative complications, with intraoperative durotomy being the most common (n = 7). Eight patients had a 2-year FU and demonstrated improvements in their segmental lordosis across the PSO site (14.3 ± 7.0 vs 41.3 ± 7.3, P = .0003), overall lumbar lordosis (8.7 ± 17.8 vs 46.1 ± 14.2, P = .0014), sacral slope (19.1 ± 12.8 vs 32.3 ± 12.5, P = .0479), C7 sagittal vertical axis (173.6 ± 54.4 mm vs 35.8 ± 30.0, P < .0001), and spinopelvic mismatch (63.0 ± 19.7 vs 21.1 ± 18.3, P < .0001), all of which were maintained at final FU (P > .05). At 2 years, a significant increase in Scoliosis Research Society-22r total score (2.5 ± 0.8 vs 3.6 ± 0.7, P = .0023 was reported. There were no reports of symptomatic pseudarthrosis or mechanical complications.

CONCLUSION

SE-PSO is an effective technique to correct FSM and is associated with low complications, improved patient-reported outcomes, and spinopelvic parameters that are maintained at 2 years.

Domino connector for thoracic pedicle subtraction osteotomy reduction: surgical technique and patient series

PURPOSE

Different techniques have been previously described to close the pedicle subtraction osteotomy (PSO) site for correction of sagittal malalignment; the use of a side-to-side domino connector as a correction tool in the thoracic spine has not been specifically studied.

METHODS

Twenty adult patients who underwent single-level thoracic PSO from T1 to T12 were included and retrospectively reviewed (two centers). Preoperative and postoperative full-body X-rays, perioperative data, clinical data and complications were recorded with a minimum 2 years of follow-up. Surgical technique and the nuances in using the domino connector were described in detail.

RESULTS

Patients had a mean age of 40y; 40% were female. Two different techniques involving the domino were applied for closure of the PSO site depending on the type of kyphosis (smooth vs. angular deformity). Both techniques provided significant correction of the local kyphosis (from 48° to 18°) with reciprocal reduction of compensatory cervical lordosis (from 37.6° to 18.6°, p < 0.01) in upper thoracic PSO or lumbar lordosis (from 74.5° to 46.6°, p < 0.01) in lower thoracic PSO. Four patients presented postoperative complications that resolved (hemothorax, GI bleeding), and two patients presented transient neurological deficit. Oswestry Disability Index score improved in the majority of the patients (from 32.7 to 22.5, p < 0.05). There were no pseudarthroses, symptomatic instrumentation breakage, or surgical site infection.

CONCLUSION

Use of a side-to-side domino connector in combination with two different rod cantilever techniques is effective for the reduction of thoracic pedicle subtraction osteotomy achieving satisfactory radiological and clinical outcome.

Trans-intervertebral osteotomy classification of posterior spinal corrective osteotomy procedures via the intervertebral space

•This is a diagnostic study for a classification for posterior spinal osteotomy procedures via the intervertebral space.•Proposed ​a novel classification ​with ​excellent reliability ​and ​validity, differ from the SRS-Schwab osteotomy classification.•Give a novel definition of "trans-intervertebral osteotomy" (TIO) for posterior spinal osteotomy procedures.•Thoroughly discussed about the histories of posterior spinal osteotomy procedures via the intervertebral space.•Systematically introduced the TIO technique with fine original schematics.

Domino connector is an efficient tool to improve lumbar lordosis correction angle after pedicle subtraction osteotomy for adult spinal deformity

PURPOSE

To compare the radiological outcomes and complications of adult spinal deformity patients who underwent a pedicle subtraction osteotomy (PSO) below L2 but categorized according to their construct where either a domino connector was applied for osteotomy correction or not.

METHODS

Retrospective review of a prospective, multicenter adult spinal deformity database (5 sites). Inclusion criteria were adult patients who underwent PSO between L3 and L5 with a minimum follow-up of 2 years. Among 1243 patients in the database, 79 met the inclusion criteria, 41 in the no-domino (ND) group and 38 in the domino (D) group. The domino technique consisted of using 2 parallel rods connected by a domino on one side of the PSO in order to achieve gradual and controlled compression at the osteotomy site. Demographic data, operative parameters, spinopelvic parameters and complications were collected.

RESULTS

Demographic data and operative parameters were globally similar between both groups, and they showed a comparable preoperative sagittal malalignment. Segmental lordosis improved by 22° and 31° (p < 0.05) and L1S1 lordosis improved by 23° and 32° (p < 0.05) in the ND and D group, respectively. The use of multiple rods was similar between the groups (58% vs. 57%). Also, mechanical complications rate was globally similar between both groups with no statistically significant difference (22% vs. 28.9%).

CONCLUSION

Domino connector is a safe, powerful and efficient tool for pedicle subtraction osteotomy site closure. It improved the lumbar lordosis correction angle with an acceptable rate of complications.

Osteotomies for the Treatment of Adult Spinal Deformities: A Critical Analysis Review

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Spinal osteotomies are powerful deformity correction techniques that may be associated with serious complications.

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The anatomical spinal osteotomy classification system proposes 6 grades of resection corresponding to different anatomic bone, disc, facet, and ligament interventions.

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Surgeons should be aware of the nuances of 3-column osteotomies with regard to spinal level selection, construct composition, and posterior column reconstruction and closure techniques.

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There is a global tendency toward avoiding 3-column osteotomies as much as possible because of the growing evidence regarding the effectiveness of posterior column osteotomies and halo-gravity traction.

Multiple-Rod Constructs Do Not Reduce Pseudarthrosis and Rod Fracture After Pedicle Subtraction Osteotomy for Adult Spinal Deformity Correction but Improve Quality of Life

Objective

To compare the radiological and functional outcomes and complications of adult spinal deformity patients who underwent a pedicle subtraction osteotomy (PSO) below L2 but categorized according to their construct where either 2-rod or multiple-rod construct is applied.

Methods

Sixty-seven patients met the inclusion criteria, and were categorized into 3 groups: 2 rods (2R), multiple rods around the PSO (MRP), multiple rods around the PSO and lumbosacral junction (MRL). Demographic data, operative parameters, spinopelvic parameters, functional outcomes, and complications were collected.

Results

Health-related quality of life scores showed a better outcome at 6 months and last follow-up visits in the MRP and MRL groups which were noted on different domains of Scoliosis Research Society-22 questionnaire, 36-item Short Form Health Surve, and Oswestry Disability Index scores (p<0.05). The 3 groups showed similar rates of rod-related complications with no significant difference (p=0.95). And inside each group, distribution of complications between pseudarthrosis with revision and rod fracture without revision was also similar (p=0.99).

Conclusion

The use of multiple rods across the PSO did not show a better outcome when compared to single rods in terms of incidence and types of mechanical complications. However, better postoperative coronal alignment and health-related quality of life scores in the multiple rods group could be seen demonstrating an improved functional outcome.

Radiographic outcomes and complications after L4 or L5 pedicle subtraction osteotomy for fixed sagittal malalignment in 102 adult spinal deformity patients with a minimum 2-year follow-up

PURPOSE

The objective of this retrospective study was to provide the radiographic outcomes and complications for pedicle subtraction osteotomy (PSO) performed at the low lumbar spine, i.e., L4 or L5 for ASD patients with fixed sagittal malalignment.

METHODS

ASD patients who underwent L4 or L5 PSO with a minimum 2-year follow-up were included. Preoperative and postoperative radiographs, and complications were collected. Radiographic analysis included lumbar lordosis (LL), pelvic incidence (PI), pelvic tilt (PT), thoracic kyphosis (TK), sagittal vertical axis (SVA), spinal lordosis (SL) ratio and global tilt (GT) on standing long-cassette radiographs.

RESULTS

A total of 102 patients from 2 spinal centers were analyzed. 66 patients underwent PSO at L4 and 36 patients at L5. From preoperatively to the final follow-up, significant improvements occurred in LL (from - 31° to - 52°), SVA (from 13 to 5 cm), and GT (from 44° to 27°) (all, p < 0.05). 12 patients had transient neurological deficits, and 8 patients had persistent neurological deficit. 23 patients underwent revision for PJK (2), pseudarthrosis (10), neurological deficit (2), epidural hematoma (1), or deep surgical site infection (8). No PJK was observed in any of the patients with L5 PSO.

CONCLUSIONS

PSO at the level of L4 or L5 remains a challenging technique but with an acceptable rate of complications and revisions. It enables correction of fixed sagittal malalignment in ASD patients with a globally satisfactory outcome. In comparison with L4 PSO, L5 PSO patients did not show PJK as a mechanical complication. Distal lumbar PSO at the level of L5 may represent one of the factors that may help preventing the proximal junctional kyphosis complication.

T12 pedicle subtraction osteotomy for post-laminectomy kyphoscoliotic deformity following resection of a thoracolumbar astrocytoma in an adolescent with a previous paraplegic context

STUDY DESIGN

Case report.

PURPOSE

To describe a rare case of iatrogenic post-laminectomy thoracolumbar kyphoscoliosis in an adolescent, and its surgical management with pedicle subtraction osteotomy (PSO).

BACKGROUND

Kyphoscoliosis secondary to multilevel laminectomies for intradural astrocytoma resection is rare and its management can be very challenging.

METHODS

We report the case of 15-year-old boy who has been complaining of a progressively increasing hump in his back during the past 6 months. Two years prior to presentation, he underwent multilevel thoracolumbar laminectomies from T10 to L2 for resection of an intradural astrocytoma that was causing progressive paraplegia predominant on the right side. Full spine anteroposterior and lateral X-rays revealed a thoracolumbar kyphosis with an angulation of 73° between T10 and L1, with a long left thoracolumbar scoliosis of 24 degrees. CT scan confirmed the multilevel laminectomies and showed T12 anterior wedging. MRI did not show any tumor recurrence.

RESULTS

The patient underwent T12 PSO with instrumentation from T4 to L3 with the use of a one-sided domino on the convex side. Thoracolumbar kyphosis was corrected to 9°, and scoliosis was corrected to 7°, with a maintained correction at 7 years of follow-up.

CONCLUSION

Literature is sparse on the management of post-laminectomy kyphoscoliotic deformity after intradural astrocytoma resection. Despite previous paraplegia context, aggressive correction technique such as PSO can be a safe option if proper management of the scar tissues and adhesions is performed, with satisfactory clinical and radiological long-term results.