Effect of overcorrection on proximal junctional kyphosis in adult spinal deformity: analysis by age-adjusted ideal sagittal alignment

Related Experiment Video

Updated: Oct 14, 2025

Minimally Invasive Treatment for Thoracolumbar Burst Fracture Using Sagittal Alignment Screws and A Trauma Reduction Device

Minimally Invasive Treatment for Thoracolumbar Burst Fracture Using Sagittal Alignment Screws and A Trauma Reduction Device

Published on: November 8, 2024

Chan Woong Byun¹, Jae Hwan Cho¹, Choon Sung Lee¹

¹Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

The Spine Journal : Official Journal of the North American Spine Society

|November 6, 2021

Abstract

Background Context:

The effect of the degree of lumbar lordosis (LL) correction on proximal junctional kyphosis (PJK) has not been analyzed in context of the age-adjusted sagittal alignment goal.

Purpose:

To determine the effect of sagittal correction on the incidence of PJK after an age-adjusted analysis in patients with adult spinal deformity (ASD).

Study Design/Setting:

Retrospective comparative study.

Patient Sample:

Seventy-eight ASD patients who underwent deformity correction.

Outcome Measures:

Visual analog scale (VAS), Oswestry Disability Index (ODI), and imaging.

Methods:

This study included 78 ASD patients who underwent deformity correction and were followed-up more than 2 years. Patients were grouped according to the degree of LL correction relative to pelvic incidence (PI) by adjusting for age using the following formula: (age-adjusted ideal PI - LL) - (postoperative PI - LL). These were group U (undercorrection; <-10˚, N=15), group I (ideal correction; -10˚-10˚, N=34), and group O (over correction, >10˚, N=29). Various clinical and radiological parameters were compared among groups. The risk factors for PJK were also evaluated.

Results:

The overall incidence of PJK was 32.1% (25/78), with significantly higher PJK rate in group O (48.3%) compared with groups U (13.3%) and I (26.5%) (p=.041). The degree of postoperative LL correction relative to the PI by adjusting for age was a risk factor for the development of PJK (11.4° for PJK vs. 0.2° for non-PJK, p=.033). In addition, 2-year postoperative VAS (7.0 vs. 3.4, p<.001) and ODI (28.9 vs. 24.8, p=.040) scores were significantly higher in the PJK group than in the non-PJK group. A small PI (PI < 45°) was associated with a tendency of overcorrection (73.3%, P < 0.001) and thereby with the high incidence of PJK (53.3%, p=.005).

Conclusions:

Overcorrection of LL relative to PI considering age-adjusted ideal sagittal alignment tends to increase the incidence of PJK. The incidence of PJK is expected to be high in patients with low PI (<45°) because of the tendency of overcorrection. To reduce the risk of PJK, surgeons should take age-adjusted parameters into account and exercise caution not to overcorrect patients with low PI, since this can result in suboptimal clinical outcomes.

Keywords:

Adult spinal deformity Age Proximal junctional kyphosis Sagittal alignment

More Related Videos

Modified Posterior Vertebral Column Resection for Patients with Thoracolumbar Kyphotic Deformity

Modified Posterior Vertebral Column Resection for Patients with Thoracolumbar Kyphotic Deformity

Published on: September 16, 2022

Evaluation of Patients' Posture and Gait Profile After Lumbar Fusion Surgery by Video Rasterstereography and Treadmill Gait Analysis

Published on: March 23, 2019

Related Concept Videos

Vertebral Column: Regions and Curvature

Vertebral Column: Regions and Curvature

The vertebral column or spine is a flexible column that supports the head, neck, and body and allows for their movements. It also protects the spinal cord.
Regions of the Vertebral Column
In an adult, the spine is subdivided into five regions: the cervical, the thoracic, the lumbar, the sacral, and the coccygeal region. The spine initially develops as a series of 33 vertebrae; after 20 years of age, the nine bones in the sacral region, five sacral, and four coccygeal bones fuse to form...

Changes in the Appendicular Skeleton with Age

Changes in the Appendicular Skeleton with Age

The upper and lower limb initially develops as a small bulge called a limb bud, which appears on the lateral side of the early embryo. The upper limb bud appears near the end of the fourth week of development, with the lower limb bud appearing shortly after.
Initially, the limb buds consist of a core of mesenchyme covered by a layer of ectoderm. The ectoderm at the end of the limb bud thickens to form a narrow crest called the apical ectodermal ridge. This ridge stimulates the underlying...

General Case of Eccentric Axial Loading

General Case of Eccentric Axial Loading

Unsymmetrical bending occurs when the bending moment applied to a structural member does not align with its principal axis. This misalignment leads to complex stress distributions and deflection patterns that differ from symmetrical bending, which are essential for designing structures to withstand different loading conditions.
Consider a member subjected to equal and opposite forces that are applied along a line that does not coincide with the member's neutral axis. In unsymmetrical...

Eccentric Axial Loading in a Plane of Symmetry

Eccentric Axial Loading in a Plane of Symmetry

Eccentric axial loading occurs when an axial load is applied away from the centroidal axis of a structural member. This scenario is common in engineering, where structural elements may not be directly aligned due to various design or functional requirements.

Normal Strain under Axial Loading

Normal Strain under Axial Loading

Normal strain under axial loading is an important concept in the field of mechanics of materials. Axial loading implies the application of a force along the axis of a material, like a column or bar. This force can either compress or stretch the material. In the context of axial loading, normal strain is the deformation experienced by the material in the direction of the loading force. It's calculated as the change in length divided by the original length of the material. This unitless ratio...

Deformation of Member under Multiple Loadings

Deformation of Member under Multiple Loadings

When a rod is made of different materials or has various cross-sections, it must be divided into parts that meet the necessary conditions for determining the deformation. These parts are each characterized by their internal force, cross-sectional area, length, and modulus of elasticity. These parameters are then used to compute the deformation of the entire rod.
In the case of a member with a variable cross-section, the strain is not constant but depends on the position. The deformation of an...

Articles linked to this work by shared authors, journal, and citation graph.

Association Between the Bone-cutting Width-to-facet Distance Ratio and Neurological Recovery After Cervical Laminoplasty.

The spine journal : official journal of the North American Spine Society·2026

Prediction of Postoperative Ambulatory Function Using Nomogram in Patients with Metastatic Epidural Spinal Cord Compression.

Journal of clinical medicine·2026

Multifaceted infection prevention protocol is associated with reduced surgical site infection after spinal fusion: a before-and-after study.

The spine journal : official journal of the North American Spine Society·2026

Radiologic and Clinical Importance of Lamina Hinge Fractures After Open-Door Cervical Laminoplasty: A Propensity Score-Matched Study.

Clinical spine surgery·2026

Sacral Slanting in Adolescent Idiopathic Scoliosis: Definition, Pathomechanism, and Surgical Implications: A Narrative Review.

Neurospine·2026

Development and validation of the Korean version of the Modified Japanese Orthopedic Association Score: a prospective questionnaire study.

Asian spine journal·2026

See all related articles