Thoracolumbar Junction Orientation: A Novel Guide for Sagittal Correction and Proximal Junctional Kyphosis Prediction in Adult Spinal Deformity Patients

Hong Joo Moon; Keith H Bridwell; Alekos A Theologis; Micheal P Kelly; Thamrong Lertudomphonwanit; Lawrence G Lenke; Munish C Gupta

doi:10.1093/neuros/nyaa311

Thoracolumbar Junction Orientation: A Novel Guide for Sagittal Correction and Proximal Junctional Kyphosis Prediction in Adult Spinal Deformity Patients

Neurosurgery. 2020 Dec 15;88(1):55-62. doi: 10.1093/neuros/nyaa311.

Authors

Hong Joo Moon^{1

2}, Keith H Bridwell², Alekos A Theologis^{2

3}, Micheal P Kelly², Thamrong Lertudomphonwanit⁴, Lawrence G Lenke⁵, Munish C Gupta²

Affiliations

¹ Department of Neurosurgery, Korea University College of Medicine, Seoul, South Korea.
² Department of Orthopaedic Surgery, Washington University in St. Louis, St. Louis, Missouri.
³ Department of Orthopaedic Surgery, University of California - San Francisco (UCSF), San Francisco, California.
⁴ Department of Orthopaedic Surgery, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand.
⁵ Department of Orthopaedic Surgery, Columbia University Medical Center, The Spine Hospital at New York Presbyterian, New York, New York.

PMID: 32761200
DOI: 10.1093/neuros/nyaa311

Abstract

Background: Novel radiographic sagittal parameters of the thoracolumbar junction orientation (TLJO, thoracolumbar slope [TLS] and thoracolumbar tilt [TLT]) have been introduced and correlated with lumbopelvic parameters and thoracic kyphosis.

Objective: To determine a predictive model for reciprocal thoracic kyphosis and proximal junctional kyphosis (PJK) based on the TLJO.

Methods: A total of 127 patients who had fusion from sacrum to T10-L2 from 2004 to 2014 were reviewed. TK (T5-T12), PI, SS, PT, LL, and proximal junctional angle (PJA) were measured preoperatively, 6 wk postoperatively, and at final follow-up. TLJO was measured by TLS and TLT. Changes between time points were determined (preop-6 wk = ΔParameterPre6wk and preop-final follow/up = ΔParameterPreFinal). Scoliosis Research Society (SRS) and Oswestry Disability Index (ODI) questionnaires were evaluated at final follow-up. Patients were divided into 2 groups based on the presence of PJK (ΔPJAPreFinal >15°). Independent t-tests and receiver operating characteristic (ROC) curves were used to investigate the significance of differences and cut-off values. Pearson correlations and linear regressions were used to analyze the entire cohort to determine the relationship between the changes in parameters.

Results: Compared to patients without PJK (n = 100), those with PJK (n = 27) had significantly lower SRS scores and significantly greater ΔTKPreFinal, ΔLLPre6wk, and ΔTLSPre6wk. To maintain in the nonPJK group, ROC curves demonstrated a cut-off value of -9.4° for ΔTLSPre6wk. PJK was significantly correlated with ΔTKPreFinal and ΔTLSPre6wk. The linear correlation revealed that ΔTLSPre6wk < -25.3° is the risk factor of PJK > 15°.

Conclusion: As change of TLS reflects lumbopelvic realignment and influences reciprocal TK, reducing the change of TLS may be a sagittal realignment guideline to reduce the risk of PJK.

Keywords: Lumbar degenerative kyphosis; Proximal junctional kyphosis; Reciprocal change; Sagittal alignment; Thoracolumbar slope; Thracolumbar junction orientation.

MeSH terms

Adult
Aged
Cohort Studies
Female
Humans
Kyphosis / etiology*
Lumbar Vertebrae / diagnostic imaging
Middle Aged
Postoperative Complications / diagnostic imaging*
Postoperative Complications / etiology
Retrospective Studies
Risk Factors
Scoliosis / diagnostic imaging*
Scoliosis / surgery*
Spinal Fusion / adverse effects*
Thoracic Vertebrae / diagnostic imaging