Combined Anterior-Posterior Surgery is the Most Important Risk Factor for Developing Proximal Junctional Kyphosis in Idiopathic Scoliosis

Abstract Background: There are several risk factors for proximal junctional kyphosis (PJK) in adolescent idiopathic scoliosis (AIS) surgery. Decreased rod contouring angle (RCA) has been proposed as a risk factor for PJK, but the role of difference between proximal junctional angle (PJA) and RCA (PJA-RCA) has not been fully investigated. The aim of this study was to assess the role of PJA-RCA for the development of postoperative PJK in AIS. Methods: We performed a retrospective analysis of 96 AIS patients who underwent posterior segmental spinal instrumentation and fusion between the years 2012 and 2018 (minimum 1.5-year and average 2-year follow-up) at a single institution. Each patient was measured on preoperative, postoperative and final follow-up long-cassette standing radiographs. The PJA-RCA was regarded as a new definition that reflects the match degree between proximal rod contouring and vertebra curvature, and radiographic parameters were compared between PJK and non-PJK group. Results : Among the 96 patients with a mean age of 14.00 years (± 0.82), the overall incidence of PJK was 22%. PJK group showed a significantly greater preoperative SVA (P = 0.032) and larger correction of SVA (P = 0.007) than non-PJK group. At the last follow-up, PJK patients had significantly greater LL (P = 0.046). Patients in the PJK group had significantly greater preoperative PJA-RCA than the non-PJK group (4.07±3.30 vs. 1.42±4.28, P = 0.024). However, RCA was not significantly different between two groups (3.88 ± 4.34 vs. 2.86 ± 3.36, P = 0.405). In addition, Pearson correlation coefficient showed a significant correlation between the change of SVA and the last follow-up PJA (r = -0.208, P = 0.042). Preoperative PJA-RCA and postoperative PJA-RCA demonstrated similar results which showed a strong correlation with the last follow-up PJA (r = 0.528 and r = 0.532 respectively, P < 0.000). Conclusions: As a new reflex of improper rod contouring, large PJA-RCA is a risk factor for PJK in AIS, and PJK might be a compensation mechanism rather than complication when spine is shifted and overcorrected. Keywords: adolescent idiopathic scoliosis, proximal junctional kyphosis, proximal junctional angle, rod contouring angle.

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Postoperative proximal junctional kyphosis in Lenke 5C adolescent idiopathic scoliosis following posterior surgery: extending fusion versus thoracolumbar/lumbar fusion

10.21203/rs.2.20882/v1 ◽

2020 ◽

Author(s):

Bowen Hu ◽

Linnan Wang ◽

Xin He ◽

Yueming Song ◽

Xi Yang ◽

...

Keyword(s):

Adolescent Idiopathic Scoliosis ◽

Idiopathic Scoliosis ◽

Lumbar Fusion ◽

Posterior Fusion ◽

Proximal Junctional Kyphosis ◽

Thoracic Inlet ◽

Posterior Surgery ◽

Increased Risk ◽

Junctional Kyphosis

Abstract Background: Proximal junctional kyphosis is a common complication after posterior fusion in adolescent idiopathic scoliosis patients, and was correlated with postoperative change of thoracic kyphosis. However, no previous literature has evaluated the correlation of PJK with thoracervical parameters in the AIS patients. Methods: Data from 61 patients who underwent posterior fusion for Lenke 5C AIS and had 2 years of follow-up were retrospectively reviewed. Patients were fused higher than two levels above the upper-end-vertebra in the extended fusion group (n=32), whereas they were fused below or at UEV+2 in the TL/L fusion group (n=29). Results: During an average follow-up of 32.5 months, 14/61 patients had PJK. The extended fusion group had a greater incidence of PJK than the TL/L fusion group did (11/32 vs. 3/29,P = 0.03) and a significant more decrease of TK than the TL/L group(p<0.01). Patients with PJK had a significantly larger Thoracic inlet angle(TIA) than those without PJK (P <0.01). Multivariate analysis revealed a greater preoperative TIA to be a positive predictor for PJK (p = 0.015). TIA >72° with extended fusion was a risk factor for PJK at final follow-up. The SRS-22 score did not significantly differ between the extended fusion and TL/L fusion groups. Conclusions: TIA could be a predictor of PJK. In Lenke 5C AIS patients, those with TIA >72° were more likely to develop PJK. And extended fusion in patients with Lenke 5C adolescent idiopathic scoliosis may be at an increased risk of proximal junctional kyphosis.

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