Adult spinal deformity.

Pathophysiological changes in the spinal cord white and grey matter resulting from injury can be observed with MRI techniques. These techniques provide sensitive markers of macrostructural and microstructural tissue integrity, which correlate with histological findings. Spinal cord MRI findings in traumatic spinal cord injury (tSCI) and nontraumatic spinal cord injury - the most common form of which is degenerative cervical myelopathy (DCM) - have provided important insights into the pathophysiological processes taking place not just at the focal injury site but also rostral and caudal to the spinal injury. Although tSCI and DCM have different aetiologies, they show similar degrees of spinal cord pathology remote from the injury site, suggesting the involvement of similar secondary degenerative mechanisms. Advanced quantitative MRI protocols that are sensitive to spinal cord pathology have the potential to improve diagnosis and, more importantly, predict outcomes in patients with tSCI or nontraumatic spinal cord injury. This Review describes the insights into tSCI and DCM that have been revealed by neuroimaging and outlines current activities and future directions for the field.

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Traumatic and nontraumatic spinal cord injury: pathological insights from neuroimaging

How the spine differs in standing and in sitting-important considerations for correction of spinal deformity.

Adult spinal deformity (ASD) is characterized by three-dimensional abnormalities of the thoracic or thoracolumbar spine that exerts significant impacts on the health-related quality of life (HRQoL). With the important effects that deformity of the sagittal plane exerts on the HRQoL, there have been paradigm shifts in ASD evaluation and management. Loss of lumbar lordosis is recognized as a key driver of ASD followed by reducing kyphosis, pelvic retroversion, and knee flexion. The Scoliosis Research Society (SRS)- Schwab classification reflects the sagittal spinopelvic parameters that correlate pain and disability in ASD patients. Although the SRS-Schwab classification provides a realignment target framework for surgeons, a structured patient-specific systemic approach is crucial for the process of decision-making. ASD management should be focused on restoring age-specific harmonious alignment and should consider the comorbidities and risk factors of each patient to prevent catastrophic complications and enhance the HRQoL.

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Adult Spinal Deformity: Current Concepts and Decision-Making Strategies for Management

STUDY DESIGN Retrospective review of a prospective database. OBJECTIVE The aim of this study was to define the role of sagittal orientation of the construct at the upper instrumented levels in the development of proximal junctional kyphosis (PJK) in adult spinal deformity (ASD) patients. SUMMARY OF BACKGROUND DATA PJK following ASD surgery remains challenging. The final alignment of the upper instrumented vertebral segments has been proposed as a risk factor for PJK, but has not been fully investigated. METHODS ASD patients with 2-year follow-up and long posterior fusion to the pelvis were analyzed. Radiographic measurements included pelvic incidence (PI), lumbar lordosis (LL), pelvic tilt (PT), sagittal vertical axis, and two upper-most instrumented vertebra (UIV) parameters: UIV slope (UIV vs. horizontal) and inclination of the proximal-end of the construct. UIV parameters were secondarily evaluated with regard to the compensatory impact of post-PJK increased PT (PREF). A comparison between PJK and non-PJK patients was performed, according to the UIV location (upper thoracic [UT] or thoracolumbar). RESULTS A total of 252 patients (mean age, 61.5 years, 83% females) were included. PJK incidence was 56% at 2-years. PJK patients had a greater change in LL and thoracic kyphosis than non-PJK patients. In the UT group, there was no difference in UIV slope for PJK versus non-PJK. However, PJK patients had a smaller inclination of the upper instrumented segments versus vertical (P < 0.001) and the PREF (P = 0.005). Similarly, in the LT group, PJK patients had a posterior inclination versus the vertical (P < 0.001) and the PREF (P = 0.041). CONCLUSION Analysis revealed that a more posterior construct inclination was present in patients who developed PJK. These results support previous hypotheses suggesting that PJK may develop in response to excessive spinal realignment. Proper rod contouring, especially at the proximal end, may reduce the risk of PJK. LEVEL OF EVIDENCE 3.

Orientation of the Upper-most Instrumented Segment Influences Proximal Junctional Disease Following Adult Spinal Deformity Surgery.

STUDY DESIGN Retrospective cohort. OBJECTIVE To explore proximal junctional kyphosis (PJK) as a function of age-adjusted surgical correction goals. SUMMARY OF BACKGROUND DATA Recent adult spinal deformity (ASD) studies show that alignment targets are age-specific. Despite recognizing age and malalignment as PJK risk factors, no study has assessed the age-specific effects of alignment on PJK. METHODS ASD patients with fusions to the pelvis were included and stratified into three groups: young adults (YA 65 years old). Analysis of variance compared the groups with respect to 1-year postoperative alignments and 1-year offsets from age-specific alignment targets. RESULTS A total of 679 patients were enrolled (mean age = 61 years old, 77% female, body mass index = 28.1). At 1 year postoperatively, there was a significant decrease in pelvic tilt (PT; 29-23°), spinopelvic mismatch (pelvic incidence [PI]-lumbar lordosis [LL]) (28-5°), and sagittal vertical axis (SVA; 110-37 mm); overall incidence of PJK was 45.1%. Stratification by age (YA, n = 28; MA, n = 389; ED, n = 262) revealed an increase in PJK incidence with age: YA = 17.9%, MA = 43.8%, and ED = 50.2% (P < 0.001). PJK patients had smaller postoperative PI-LL mismatches (ED 0.8° vs. 9.8°, MA 3.1° vs. 7.3°) than non-PJK patients, without any significant differences in PT or SVA. Analysis of the postoperative offsets from age-specific norms revealed that PJK patients in the two older subgroups and in the study cohort as a whole were overcorrected as compared to non-PJK patients (PI-LL offset-all: -5.2° vs. 2.8°, MA: -1° vs. +4°, ED: -11° vs. -2°; SVA offset-all: -10 mm vs. 7 mm, MA: -3 mm vs. 10 mm, ED: -18 mm vs. -6 mm). The correlation coefficients between PJK angles and the offsets from age-adjusted objective were small (0.320 for PI-LL, 0.114 for PT, and 0.136 for SVA). CONCLUSION Overall, this study suggests that PJK patients were overcorrected when compared to age-adjusted alignment goals. Certainly, elderly patients are subject to independent risk factors for PJK, making the prevention of PJK complex. However, individualized optimization of surgical alignment can improve outcomes. This emphasizes the need for surgeons to incorporate age-specific alignment targets into the standard preoperative planning process. LEVEL OF EVIDENCE 3.

Age-Adjusted Alignment Goals Have the Potential to Reduce PJK.

Study Design.Reliability/external validation study.Objective.Investigate inter- and intrarater reliability of the Hart-International Spine Study Group (ISSG) Proximal Junctional Failure Severity Scale (PJFSS) and its correlation with operative revision in patients with proximal junctional failure (P

Justin K. Sheer

Papers

Age-Adjusted Alignment Goals Have the Potential to Reduce PJK.

Inter- and Intra-rater Reliability of the Hart-ISSG Proximal Junctional Failure Severity Scale.