Ligament augmentation for prevention of proximal junctional kyphosis and proximal junctional failure in adult spinal deformity

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Proximal junctional kyphosis (PJK) is a well-recognized, yet incompletely defined, complication of adult spinal deformity surgery. There is no standardized definition for PJK, but most studies describe PJK as an increase in the proximal junctional angle (PJA) of greater than 10°–20°. Ligament augmentation is a novel strategy for PJK reduction that provides strength to the upper instrumented vertebra (UIV) and adjacent segments while also reducing junctional stress at those levels.


In this study, ligament augmentation was used in a consecutive series of adult spinal deformity patients at a single institution. Patient demographics, including age; sex; indication for surgery; revision surgery; surgical approach; and use of 3-column osteotomies, vertebroplasty, or hook fixation at the UIV, were collected. The PJA was measured preoperatively and at last follow-up using 36-inch radiographs. Data on change in PJA and need for revision surgery were collected. Univariate and multivariate analyses were performed to identify factors associated with change in PJA and proximal junctional failure (PJF), defined as PJK requiring surgical correction.


A total of 200 consecutive patients were included: 100 patients before implementation of ligament augmentation and 100 patients after implementation of this technique. The mean age of the ligament augmentation cohort was 66 years, and 67% of patients were women. Over half of these cases (51%) were revision surgeries, with 38% involving a combined anterior or lateral and posterior approach. The mean change in PJA was 6° in the ligament augmentation group compared with 14° in the control group (p < 0.001). Eighty-four patients had a change in PJA of less than 10°. In a multivariate linear regression model, age (p = 0.016), use of hook fixation at the UIV (p = 0.045), and use of ligament augmentation (p < 0.001) were associated with a change in PJA. In a separate model, only ligament augmentation (OR 0.193, p = 0.012) showed a significant association with PJF.


Ligament augmentation represents a novel technique for the prevention of PJK and PJF. Compared with a well-matched historical cohort, ligament augmentation is associated with a significant decrease in PJK and PJF. These data support the implementation of ligament augmentation in surgery for adult spinal deformity, particularly in patients with a high risk of developing PJK and PJF.

ABBREVIATIONS PJA = proximal junctional angle; PJF = proximal junctional failure; PJK = proximal junctional kyphosis; UIV = upper instrumented vertebra.

Article Information

Correspondence Michael Safaee: University of California, San Francisco, CA.

INCLUDE WHEN CITING Published online February 23, 2018; DOI: 10.3171/2017.9.SPINE1710.

M.M.S. and V.D. contributed equally to this work.

Disclosures Dr. Deviren: consultant for NuVasive, Guidepoint, Medicrea, Seaspine, and Biomet. Dr. Ames: employee of UCSF; consultant for DePuy Synthes, Medtronic, Stryker, and Medicrea; and royalties from K2M, Stryker, Biomet Spine, DePuy Synthes, and NuVasive.

© AANS, except where prohibited by US copyright law.



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    Ligament augmentation. Using a matchstick burr, holes are drilled through the spinous processes of the UIV (U) and the levels immediately above (+1) and below (–1). A sublaminar cable is passed through each level in a stepwise fashion (A) and is then pulled to 1 side (B). The process is repeated with a second cable on the opposite side (C). This cable is then pulled down to obtain the desired amount of tension (D). The cables are locked onto the rods on each side using supplied connectors (E). Copyright University of California, San Francisco, courtesy of Kenneth Xavier Probst. Figure is available in color online only.


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