Can Proximal Junctional Kyphosis After Surgery for Adult Spinal Deformity Be Predicted by Preoperative Dynamic Sagittal Alignment Change With 3D Gait Analysis? A Case–control Study

Abstract PurposeTo investigate whether preoperative dynamic spinal alignment that worsened during gait as detected by three-dimensional (3D) gait analysis can be a predictive factor for proximal junctional kyphosis (PJK) after corrective surgery for adult spinal deformity (ASD) with a minimum 1-year follow-up.MethodWe included 27 patients with ASD who underwent 3D gait analysis before corrective surgery and had >1-year follow-up. Dynamic spinal alignment parameters were obtained using a Nexus motion capture system (Vicon, Oxford, UK) with reflective markers. Spinal alignment was assessed in each region and pelvic alignment was assessed with surface markers. Patients were asked to walk for as long as possible around an oval walkway. We obtained the averaged dynamic parameters in the final lap and compared them between patients with PJK(+) and those with PJK(–).ResultsPJK occurred in 7 patients (26%). Preoperative angle between the thoracic spine and the pelvis was larger in patients with PJK(+) than in those with PJK(–) (32.3 ± 8.1 vs 18.7 ± 13.5, P = 0.020) with sufficient sample size. Multiple logistic regression analysis identified the angle between the thoracic spine and pelvis as an independent risk for PJK.ConclusionPreoperative thoracic kyphosis exacerbated by gait as determined in 3D gait analysis is a preoperative independent risk factor of PJK in patients undergoing ASD corrective surgery.

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Risk Factor Analysis for Proximal Junctional Kyphosis After Adult Spinal Deformity Surgery: A New Simple Scoring System to Identify High-Risk Patients

Global Spine Journal ◽

10.1177/2192568219882350 ◽

2019 ◽

Vol 10 (7) ◽

pp. 863-870

Author(s):

Renaud Lafage ◽

George Beyer ◽

Frank Schwab ◽

Eric Klineberg ◽

Douglas Burton ◽

...

Keyword(s):

Risk Factor ◽

Thoracic Spine ◽

Spinal Deformity ◽

Scoring System ◽

Adult Spinal Deformity ◽

Proximal Junctional Kyphosis ◽

Point Score ◽

Spinal Deformity Surgery ◽

Upper Thoracic ◽

Junctional Kyphosis

Study Design: Retrospective cohort study. Objective: Develop a simple scoring system to estimate proximal junctional kyphosis (PJK) risk. Methods: A total of 417 adult spinal deformity (ASD) patients (80% females, 57.8 years) with 2-year follow-up were included. PJK was defined as a >10° kyphotic angle between the upper-most instrumented vertebra (UIV) and the vertebrae 2 levels above the UIV (UIV+2). Based on a previous literature review, the following point score was attributed to parameters likely to impact PJK development: age >55 years (1 point), fusion to S1/ilium (1 point), UIV in the upper thoracic spine (UIV-UT: 1 point), UIV in the lower thoracic region (UIV-LT: 2 points), flattening of the thoracic kyphosis (TK) relative to the lumbar lordosis (LL; ie, ▵LL − ▵TK) greater than 10° (1 point). Results: At 2 years, the overall PJK rate was 43%. The odds ratios for each risk factor were the following: age >55 years (2.52), fusion to S1/ilium (5.17), UIV-UT (6.63), UIV-LT (8.24), and ▵LL − ▵TK >10° (1.59). Analysis by risk factor revealed a significant impact on PJK (no PJK vs PJK): age >55 years (28% vs 51%, P < .001), LIV S1/ilium (16.3% vs 51.4%, P < .001), UIV in lower thoracic spine (12.0% vs 38.7% vs 52.9%, P < .001), and a >10° surgical reduction in TK relative to LL increase (40.0% vs 51.5%, P < .001). The PJK rate by point score was as follows: 1 = 17%, 2 = 29%, 3 = 40%, 4 = 53%, and 5 = 69%. Conclusion: A pragmatic scoring system was developed that is tied to the increasing risk of PJK. These findings are helpful for surgical planning and preoperative counseling.

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Posterior Displacement of L1 May be a Risk Factor for Proximal Junctional Kyphosis After Adult Spinal Deformity Correction

Global Spine Journal ◽

10.1177/21925682211015651 ◽

2021 ◽

pp. 219256822110156

Author(s):

Zhuo Xi ◽

Ping-Guo Duan ◽

Praveen V. Mummaneni ◽

Jinping Liu ◽

Jeremy M.V. Guinn ◽

...

Keyword(s):

Thoracic Spine ◽

Spinal Deformity ◽

Adult Spinal Deformity ◽

Deformity Correction ◽

Vertical Axis ◽

Proximal Junctional Kyphosis ◽

Sagittal Vertical Axis ◽

Posterior Displacement ◽

Increased Risk ◽

Junctional Kyphosis

Study Design: Retrospective cohort study. Objective: Overcorrection in adult spinal deformity (ASD) surgery may lead to proximal junctional kyphosis (PJK) because of posterior spinal displacement. The aim of this paper is to determine if the L1 position relative to the gravity line (GL) is associated with PJK. Methods: ASD patients fused from the lower thoracic spine to sacrum by 4 spine surgeons at our hospital were retrospectively studied. Lumbar-only and upper thoracic spine fusions were excluded. Spinopelvic parameters, the L1 plumb line (L1PL), L1 distance to the GL (L1-GL), and Roussouly type were measured. Results: One hundred fourteen patients met inclusion criteria (63 patients with PJK, 51 without). Mean age and follow up was 65.51 and 3.39 years, respectively. There was no difference between the PJK and the non-PJK groups in baseline demographics, pre-operative and immediate post-operative pelvic incidence-lumbar lordosis mismatch, sagittal vertical axis, or coronal Cobb. The immediate postoperative L1-GL was -7.24 cm in PJK and -3.45 cm in non-PJK ( P < 0.001), L1PL was 1.71 cm in PJK and 3.07 cm in non-PJK ( P = 0.004), and PT (23.76° vs 18.90°, P = 0.026) and TK (40.56° vs 31.39°, P < 0.001) were larger in PJK than in non-PJK. After univariate and multivariate analyses, immediate postoperative TK and immediate postoperative L1-GL were independent risk factors for PJK without collinearity. Conclusions: A dorsally displaced L1 relative to the GL was associated with an increased risk of PJK after ASD surgery. The postoperative L1-GL distance may be a factor to consider during ASD surgery.

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