J Korean Neurosurg Soc.  2018 Mar;61(2):167-179. 10.3340/jkns.2017.0404.013.

Restoration of Sagittal Balance in Spinal Deformity Surgery

• Makhni MC
• Shillingford JN
• Laratta JL
• Hyun SJ
• Kim YJ

• KMID: 2408017
• DOI: http://doi.org/10.3340/jkns.2017.0404.013

Abstract

The prevalence of patients with adult spinal deformity (ASD) has been reported as high as 68%. ASD often leads to significant pain and disability. Recent emphasis has been placed on sagittal plane balance and restoring normal sagittal alignment with regards to the three dimensional deformity of ASD. Optimal sagittal alignment has been known to increase spinal biomechanical efficiency, reduce energy expenditure by maintaining a stable posture with improved load absorption, influence better bony union, and help to decelerate adjacent segment deterioration. Increasingly positive sagittal imbalance has been shown to correlate with poor functional outcome and poor self-image along with poor psychological function. Compensatory mechanisms attempt to maintain sagittal balance through pelvic rotation, alterations in lumbar lordosis as well as knee and ankle flexion at the cost of increased energy expenditure. Restoring normal spinopelvic alignment is paramount to the treatment of complex spinal deformity with sagittal imbalance. Posterior osteotomies including posterior column osteotomies, pedicle subtraction osteotomies, and posterior vertebral column resection, as well anterior column support are well known to improve sagittal alignment. Understanding of whole spinal alignment and dynamics of spinopelvic alignment is essential to restore sagittal balance while minimizing the risk of developing sagittal decompensation after surgical intervention.

Keyword

Sagittal plane; Spinal deformity; Alignment; Osteotomy

MeSH Terms

Absorption
Adult
Animals
Ankle
Congenital Abnormalities*
Energy Metabolism
Humans
Knee
Lordosis
Osteotomy
Posture
Prevalence
Spine

Figure

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  Fig. 1 Type 1 and 2 sagittal imbalance : examples of type 1 (compensated) and type 2 (decompensated) imbalance.

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  Fig. 2 A 72-year-old female with back pain and poor posture. Scoliosis AP radiographs (A) and lateral radiographs (B) reveal with poor balance and native PI of 36°. Target lumbar lordosis was 54°±7° (47° to 61°). Mismatch between target LL and current LL was 34°±7° (27° to 41°). Operative plan was a single PSO to obtain 35° versus six posterior column osteotomies (PCOs) to obtain 30°–42°. The decision was made to proceed with PSSIF T10–S1–Pelvis with PLIF at L5–S1 and PCOs at T10–11, T11–12, T12–L1, L1–2, L2–3, and L5–S1. Scoliosis lateral at 8 weeks (C) shows TK of 45° and LL of 46°. Perfect sagittal balance was achieved. Scoliosis AP (D) and lateral (E) in 2 years. Perfect sagittal balance was maintained. TK : thoracic kyphosis, TLK : thoracolumbar kyphosis, LL : lumbar lordosis, SS : sacral slope, PI : pelvic incidence, AP : anterior posterior, PSO : pedicle subtraction osteotomy, PSSIF : posterior spinal segmental instrumentation and fusion, PLIF : posterior lumbar interbody fusion.

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  Fig. 3 A 60-year-old female with back pain and poor posture. Scoliosis AP radiographs (A) and lateral radiographs (B) reveal with poor balance and native PI of 56°. Target lumbar lordosis was 45°±8° (37° to 53°). Mismatch between target LL and current LL was 61°±8° (53° to 69°). Operative plan was a single pedicle subtraction osteotomy (PSO) (35°), multilevel posterior column osteotomies (PCOs) with or without anterior spinal fusion (ASF) (18° to 34°), and ASF at L2 to S1 (20°). The decision was made to proceed with PSSIF T12–S1–Pelvis with L4 PSO and PCO at L1–2, L4–5, and L5–S1. Scoliosis lateral at 8 weeks (C) shows TK of 29° and LL of 56°. Perfect sagittal balance was achieved. Scoliosis AP (D) and lateral (E) at 4 years. Perfect sagittal balance was maintained. PT : pelvic tilt, PI : pelvic incidence, AP : anterior posterior, LL : lumbar lordosis, PSSIF : posterior spinal segmental instrumentation and fusion, TK : thoracic kyphosis.

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  Fig. 4 A 73-year-old female with back pain and poor posture. Scoliosis AP radiographs (A) and lateral radiographs (B) reveal with massive fixed kyphoscoliosis of 103° scoliosis and 115° kyphosis. Operative plan was PSSIF T9–S1–Pelvis with L1 PVCR and PLIF at L4–5 and L5–S1 with multilevel PCOs. Scoliosis AP (C) and lateral (D) at 8 weeks show correction of scoliosis to 47° and correction of kyphosis to 114°. Scoliosis AP (E) and lateral (F) at 4 years. Perfect sagittal balance was maintained. AP : anterior posterior, PSSIF : posterior spinal segmental instrumentation and fusion, PVCR : posterior vertebral column resections, PLIF : posterior lumbar interbody fusion, PCOs : posterior column osteotomies.

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  Fig. 5 A 61-year-old male who has severe sagittal imbalance of 27 cm and fixed hip contracture of 20 degree despite prior spinal instrumentation and fusion surgeries. Revision PSSIF at T9–Pelvis with 2 PLIFs at L3–4/L4–5 and PSO at L3 showed good restoration of lumbar lordosis from 0.70 to 49.20. His preoperative PI was 42 degree. However, his SVA in 2 months is 12.2 cm. Increase in thoracic kyphosis of 130 and sacral slope of 140 took out the advantage of good restoration of lumbar lordosis of 480. Better sagittal vertical axis is expected in the future if flexion contracture of the hip is relieved with physical therapy. SVA : sagittal vertical axis, PI : pelvic incidence, SS : sacral slope, LL : lumbar lordosis, TK : thoracic kyphosis, PO : postoperative, PSSIF : posterior spinal segmental instrumentation and fusion, PLIF : posterior lumbar interbody fusion, PSO : pedicle subtraction osteotomy.

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  Fig. 6 A 52-year-old male who has severe sagittal imbalance of 21 cm and fixed hip contracture of 20 degree despite prior spinal instrumentation and fusion surgeries. Revision PSSIF at T9–Pelvis with 2nd PSO at L4 showed good restoration of lumbar lordosis from 42.80 to 59.00. His preoperative PI was 69.50. However, his SVA in 3 months is 12.0 cm. Increase in thoracic kyphosis of 90 and flexion contracture took out the advantage of restoration of lumbar lordosis. Significant improvement in sagittal vertical axis in 3 years to 7.1 cm came after relief of hip flexion contracture with physical therapy. SVA : sagittal vertical axis, PI : pelvic incidence, SS : sacral slope, LL : lumbar lordosis, TK : thoracic kyphosis, PO : postoperative, PSSIF : posterior spinal segmental instrumentation and fusion, PSO : pedicle subtraction osteotomy, PLIF : posterior lumbar interbody fusion.

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  Fig. 7 Steps of sagittal re-balancing. PI : pelvic incidence, UIV : upmost instrumeted vertebra, UT : upper thoracic, TL : thoracolumbar, SVA : sagittal vertical axis, LIV : lower instrumeted vertebra, P : posterior, PA : posterior anterior, PAP : posterior anterior and posterior, PCO : posterior column osteotomie, PSO : pedicle subtraction osteotomy, PVCR : posterior vertebral column resections.

Reference

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