Posterior Correction Techniques for Adolescent Idiopathic Scoliosis

Daniel J. Miller, MD; Patrick J. Cahill, MD; Michael G. Vitale, MD, MPH; Suken A. Shah, MD

Disclosures

J Am Acad Orthop Surg. 2020;28(9):e363-e373. 

In This Article

Abstract and Introduction

Abstract

Adolescent idiopathic scoliosis represents a complex, three-dimensional deformity of the spine. Posterior spinal fusion is commonly performed in severe cases to avoid the long-term adverse sequelae associated with progressive spinal deformity. The goals of spinal fusion include halting the progression of deformity, optimizing spinal balance, and minimizing complications. Recent advances in short-segment spinal fixation have allowed for improved three-dimensional deformity correction. Preoperative planning and assessment of spinal flexibility is essential for successful deformity correction and optimization of long-term outcomes. Judicious use of releases and/or spinal osteotomies may allow for increased mobility of the spine but are associated with increased surgical time, blood loss, and risk of complications. Appreciation of implant design and material properties is critical for safe application of correction techniques. Although multiple reduction techniques have been described, no single technique is optimal for every patient.

Introduction

Adolescent idiopathic scoliosis (AIS) is defined as a coronal plane deformity of unknown etiology >10° in patients aged 10 to 18 at diagnosis. Although AIS is defined based on a coronal plane parameter, deformities are typically associated with vertebral rotation in the axial plane and loss of thoracic kyphosis in the sagittal plane. The magnitude of coronal deformity in AIS is strongly correlated with these sagittal and axial plane abnormalities.[1]

Severe AIS has the potential for long-term adverse sequelae including adverse cosmesis, back pain, and impaired pulmonary function.[2] Because of this, posterior spinal instrumentation and fusion (PSIF) is frequently performed for deformities >50° in magnitude. Goals of PSIF include halting curve progression, optimizing spinal balance, improving cosmesis, preserving motion segments, and minimizing complications.

Despite recent advances in spinal instrumentation, many of the principles and techniques of spinal deformity correction remain unchanged since their initial conception. Although modern pedicle screws facilitate three-dimensional deformity correction (Figure 1),[3,4] no single correction technique will be applicable and/or successful in all cases. As such, a thorough understanding of various spinal deformity correction techniques and the factors that influence the success of these techniques is critical to achieving safe and reliable outcomes in AIS.

Figure 1.

Illustrations showing (A) three-dimensional rendering of the spine in a patient with severe AIS before PSIF. Note the lateral deviation in the coronal plane, the twisting in the axial plane, and the loss of thoracic kyphosis in the sagittal plane, and (B) postoperative three-dimensional rendering of the spine after PSIF with pedicle screws demonstrating notable correction in all three planes. PSIF = posterior spinal instrumentation and fusion

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