New method for correction of lumbo-sacral kyphosis deformity in patient with high pelvic incidence

Sacral Pedicle Subtraction Osteotomy for Treatment of High-Grade Spondylolisthesis: A Technical Note and Review of the Literature

BACKGROUND

Lumbosacral deformities are caused by high-grade spondylolisthesis, fractures, iatrogenic flat back, and other etiologies. The S1 pedicle subtraction osteotomy (PSO) can facilitate reduction of spondylolisthesis and lower the pelvic incidence. There are limited reports on the indications and outcomes of this technique.

OBJECTIVE

To present a technical description and literature review of the S1 PSO with video summary.

METHODS

This was a retrospective review of a single case to highlight the use of S1 PSO for the treatment of high-grade spondylolisthesis. A literature review was performed in accordance with STROBE guidelines.

RESULTS

A 47-year-old woman presented with back and right leg pain related to grade 4 spondylolisthesis at L5-S1 with sagittal imbalance and lumbosacral kyphosis. She was taken for an L2-pelvis instrumented fusion with S1 PSO. Three days later, she was taken for an L4-5 and L5-S1 anterior lumbar interbody fusion with the L5-S1 segmental plate. Her postoperative course was notable for right foot drop that resolved in 6 weeks. Postoperative x-rays showed successful reduction of spondylolisthesis with normal alignment and sagittal balance. Based on 6 studies involving 22 true sacral PSOs in the literature, the procedure carries a 27% risk of neurological deficit, typically in the form of L5 palsy.

CONCLUSION

The S1 PSO is a technically challenging operation that has a unique role in the treatment of high-grade spondylolisthesis. It carries a significant risk of L5 palsy and should be reserved for surgeons with experience performing complex 3-column osteotomies.

Lumbosacral osteotomy to correct PI-LL mismatch in the presence of abnormally high pelvic incidence

STUDY DESIGN

A case report. It is important to achieve optimal sagittal balance in spinal deformity surgery by matching LL to PI. A Lumbar osteotomy to increase lordosis is often the method used to achieve this in adult patients. However, in patients with high PI with compensatory lumbar hyperlordosis, providing further lordosis does not address the root cause. The paper will describe a technique of lumbosacral osteotomy to address sagittal malalignment with associated coronal imbalance and pelvic incidence (PI)-lumbar lordosis (LL) mismatch.

METHODS

A 16-year-old female patient presented with low back pain and right leg pain. Standing anteroposterior X-ray showed scoliosis with a Cobb angle of 34º and 5.7 cm of coronal imbalance. Lateral X-ray showed a sacralized L5 with a PI of 85º and LL of 47º. Pedicle subtraction osteotomy through the sacralized L5 addressed the malalignment secondary to a high PI-LL mismatch of 38º.

RESULTS

Following alar resection, an osteotomy was performed below the L5 pedicles. The cranial parts including the superior endplate and intervertebral disc were removed. Osteotomy closure was achieved using the central rod technique. L5 incidence was reduced from 59º to 33º with reduced coronal malalignment. Back pain was significantly improved and PI-LL mismatch was improved to 10º two years post-operatively with no local loss of sagittal correction.

CONCLUSIONS

A lumbosacral osteotomy at the lumbosacral junction is useful to improve high PI - LL mismatch in patients with abnormally high PI with compensatory lumbar hyperlordosis.

Clinical results and functional outcomes after three-column osteotomy at L5 or the sacrum in adult spinal deformity

PURPOSE

Three-column osteotomies at L5 or the sacrum (LS3COs) are technically challenging, yet they may be needed to treat lumbosacral kyphotic deformities. We investigated radiographic and clinical outcomes after LS3CO.

METHODS

We analyzed 25 consecutive patients (mean age 56 years) who underwent LS3CO with minimum 2-year follow-up. Standing radiographs and health-related quality-of-life scores were evaluated. A new radiographic parameter ["lumbosacral angle" (LSA)] was introduced to evaluate sagittal alignment distal to the S1 segment.

RESULTS

From preoperatively to the final follow-up, significant improvements occurred in lumbar lordosis (from - 34° to - 49°), LSA (from 0.5° to 22°), and sagittal vertical axis (SVA) (from 18 to 7.3 cm) (all, p < .01). Mean Scoliosis Research Society (SRS)-22r scores in activity, pain, self-image, and satisfaction (p < .05), and Oswestry Disability Index scores (p < .01) also improved significantly. Patients with SVA ≥ 5 cm at the final follow-up experienced less improvement in SRS-22r satisfaction scores than those with SVA < 5 cm. Patients with LSA < 20° at the final follow-up had significantly lower SRS-22r activity scores than those with LSA ≥ 20° (p = .014). Two patients had transient neurologic deficits, and 11 patients underwent revision for proximal junctional kyphosis (5), pseudarthrosis (3), junctional stenosis (2), or neurologic deficit (1).

CONCLUSIONS

LS3CO produced radiographic and clinical improvements. However, patients who remained sagittally imbalanced had less improvement in SRS-22r satisfaction score than those whose sagittal imbalance was corrected, and patients who maintained kyphotic deformity in the lumbosacral spine had lower SRS-22r activity scores than those whose lumbosacral kyphosis was corrected. These slides can be retrieved under Electronic Supplementary Material.

Anatomical considerations of safe drilling corridor upper sacral segment screw insertion

The upper segment of sacrum is an important for screw insertions of unstable lumbosacral spine. Measurements of the S1-S2 as sacral wings, pedicles, sacral foraminas and sacral canal were taken from 87 sacrums. The mean depths of S1 pedicle and sacral wing were estimated as 25.8 ± 2.3 mm and 50.1 ± 1.7 mm, respectively. Angles screw trajectory of sacral pedicle anteromedial and sacral wing were measured as 29.6 ± 0.9° and 29.7 ± 2.1°, respectively. To avoid injury to the vascular structures anteriorly and nerve roots medially, depth and angle of screw trajectory is important for the entrance off pedicular screw placement to the S1.

The Use of Sacral Osteotomy in the Correction of Spinal Deformity: Technical Report and Systematic Review of the Literature

BACKGROUND

Flat back deformity is a disabling adverse outcome following instrumented lumbar fusion. As patients are often fused in this non-physiologic alignment, correction is complex and has conventionally required fracture of the preexisting fusion mass. Sacral osteotomy may be one effective means of correcting the positive sagittal balance in these patients. Here we report a case of flat back deformity corrected using a 3-column sacral osteotomy, and systematically review the available literature on the effectiveness of 3-column sacral osteotomy for correcting flat back deformity.

METHODS

A systematic review was performed using the results of a search of the PubMed, EMBASE, Web of Science, and Cochrane databases according to PRISMA guidelines. We also include our patient as an example of the technique.

RESULTS

Eight studies-all case reports or small case series-were identified describing 37 patients, including our case example. The variety of techniques was too heterogeneous for meta-analysis, but all studies reported good correction of sagittal deformity. Transient L5 palsy was the most common side effect of this technique, being reported in 21 patients (56.8%) across all studies.

CONCLUSIONS

Sacral osteotomy is potentially an effective means of correcting positive sagittal balance in patients with flat back deformity secondary to high pelvic incidence.

Dual iliac screws in spinopelvic fixation: a systematic review

PURPOSE

The classical spinopelvic fixation includes 1 iliac screw on each side. The purpose of this study is to specify the indications of the "dual iliac screw" (DIS) construct, i.e., when to put 2 iliac screws on each side, to describe its biomechanical advantages, and to define its related technical aspects.

METHODS

A primary search on Medline through PubMed distribution was performed, with the use of the terms "pelvic fixation" or "spinopelvic" or "lumbo-iliac" and the terms "dual iliac screw" or "double iliac screw." English papers corresponding to the inclusion criteria were analyzed regarding the specific indications of the DIS construct and its surgical technique and advantages.

RESULTS

Eleven papers were identified according to the research criteria and included in this review. Three main indications were identified for the DIS technique according to three types of pathologies: in adult deformities when a long construct is needed in an osteoporotic patient or when correction requires three-column osteotomy of the sacrum; in trauma when a U-shaped fracture-dislocation of the sacrum is involved; in sacral tumors when a sacrectomy is performed or when destructive metastatic lesions of the sacrum require palliative surgical treatment. Biomechanically, the DIS technique proved to have higher construct stiffness in terms of compression and torsion.

CONCLUSION

In specific cases, affecting different areas of spinal diseases, the DIS technique is more advantageous, when compared to the "single iliac screw" version, as it would provide a stronger and safer fixation at the base of the spinopelvic construct. These slides can be retrieved under Electronic Supplementary Material.

Predicting the Effect of Bilateral Pelvic Osteotomy on Sagittal Alignment Correction and Surrounding Muscles: A Mathematical Model

Study Design. Mathematical Model. Objectives. To investigate the relationship between pelvic osteotomy opening angle (OA) and its effect on spinopelvic sagittal parameters as well as the resting length of surrounding muscles. Methods. Predictive equations correlating OA with spinopelvic parameters were derived using geometric relationships. A geometric model calculated spinopelvic parameters (SVA, pelvic incidence [PI], PT, and T1 pelvic angle [TPA]) produced by progressively increasing the OA. These values were compared to optimal balance criteria in the literature. Four muscles crossing the osteotomy site were evaluated: Gluteus Medius (GMED), Gluteus Maximus (GMAX), Piriformis (P), and Tensor Fascia Lata (TFL). Insertion points were obtained from an OpenSim software model. GMAX and GMED were subdivided into 3 (anterior, middle, and posterior). Results. OA correlated negatively with PI, TPA, and SVA and positively with PT. From baseline SVA of 22 cm, OA 21° reduced SVA to 5cm. OA 23° reduced TPA to 14°. OA 30° increased PT to 20°. OA 26° decreased PI-LL to 10°. OA range of 26°-30° resulted in optimal sagittal deformity correction. OA correlated with SR positively for TFL and anterior GMED and negatively for the rest of muscles. For this OA, the SR approximately decreased 6%, 5%, 6%, 8%, and 5% for posterior GMED, anterior GMAX, middle GMAX, posterior GMAX, and P, respectively. It increased 8% and 4% for anterior GMED and TFL, respectively. Conclusion. Predictive relationships between osteotomy OA and spinopelvic parameters were shown, providing proof of concept that sagittal balance may be achieved via pelvic osteotomy.