Risk Factor Analysis of Proximal Junctional Kyphosis after Surgical Treatment with OLIF for Adult Spinal Deformity.

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1 Risk Factor Analysis of Proximal Junctional Kyphosis after Surgical Treatment with OLIF for Adult Spinal Deformity. Yoshinao Koike, Yoshihisa Kotani, Hidemasa Terao, Yoshiaki Hosokawa, Hideyuki Kobayashi, Yusuke Kameda, Hideaki Fukaya STEEL MEMORIAL MURORAN HOSPITAL, MURORAN-SHI HOKKAIDO, Japan

2 Proximal Junctional Kyphosis (PJK) l Approximately 20% to 40% of patients who undergo longsegment instrumentation for deformity develop PJK l Many risk factors ü Older age ü High body mass index (BMI) ü Greater curvature correction ü Low bone marrow density (BMD) ü Use of pedicle screws ü Anterior-posterior spinal fusion ü Fusion to sacrum Lau et al. Spine 2015 Lee et al. Asian Spine J 2016 l Few studies have evaluated the prevalence and risk factors of PJK after surgical treatment with oblique lateral interbody fusion (OLIF) in patients with adult spinal deformity (ASD) l Objective Lau et al. Spine 2016 ü To investigate the prevalence of PJK and its risk factors after surgical treatment of ASD applying OLIF

3 Definition l Proximal junctional angle (PJA) l PJK ü The angle between caudal endplate of the upper instrumented vertebrae (UIV) to the cephalad endplate two vertebrae proximal (UIV-2) ü PJA over 10 and PJA at least 10 greater than the preoperative measurement l Proximal junctional failure (PJF) ü Any type of symptomatic PJK which requiring surgery PJK PJA

4 Methods l The database was retrospectively reviewed l Patients ü 73 patients who underwent the primary surgical treatment of ASD 5 or more levels instrumented ü 9 males and 64 females ü Mean follow-up: 41.1months (17-69) l Examination items ü Age ü Gender ü BMI ü Past medical history (PH) ü No. of fused segments ü No. of interbody fusion ü No. of OLIF ü No. of osteotomy (posterior column osteotomy: PCO) ü Level of UIV ü Level of lowest instrumented vertebrae ü erative and postoperative radiographic parameters

5 Results PJK + PJF PJK n=12 (16.5%) N=5 (6.8%) No PJK n=56 (76.7%)

6 Results PJK (n=17) No-PJK (n=56) P value Age 72.2± ± Sex male female BMI 23.9± ± PH of neurodegenerative disease PH of collagen disease PH of vertebral compression fracture PH of proximal femoral fracture Not a number

7 Results PJK (n=17) No-PJK (n=56) P value No. of fused segments 8.2± ± No. of interbody fusion 4.8± ± No. of OLIF 4.1± ± No. of corpectomy 0.12± ± No. of osteotomy (PCO) 0.12± ± UIV -T5 T6-T11 T LIV Lumber Pelvis

8 Results PJK (n=17) No-PJK (n=56) P value SVA 104.3± ± ± ± ± ± CVA 24.2± ± ± ± ± ± PI 53.5± ± PT 34.1± ± ± ± ± ± LL 19.5± ± ± ± ± ± Cobb angle 26.0± ± ± ± ± ± TK(T5-12) 30.0± ± ± ± ± ± PJA Postop 9.9± ± ± ± ± ± ± ± <0.001 <0.001

9 Multi-variate analysis l Multivariate logistic regression analysis ü Objective variable: The presence of PJK ü Independent variable Items whose P-value <0.2 in univariate analyses PJK Odds Ratio 95%CI P value (n=17) 2 群の比較にて P<0.2の因子 PH of collagen disease PH of vertebral compression fracture Fusion to pelvis No. of interbody fusion 4.8±

10 Discussion l The prevalence of PJK in previous studies ü Limit the study in which PJK was defined PJA over 10 and PJA at least 10 greater than the preoperative measurement No. of cases Mean age mean follow-up prevalence of PJK Yagi et al 1) yr 22.5% Maruo et al 2) yr 41.1% Kim et al 3) yr 38.5% Nicholls et al 4) yr 36.1% l The present study ü Prevalence of PJK = 23.3% Nearly equivalent to that of previous studies 1)Yagi et al. Spine )Maruo et al. Spine )Kim et al. Spine )Nicholls et al. Spine 2017

11 Discussion l BMD l LIV ü Pre-existing low BMD was identified as significant risk factors for PJK ü The present study The PJK group demonstrated a significantly higher number of patients who had history of vertebral compression fracture Low BMD is one of the significant risk factors for PJK ü Fusion to sacrum was risk factor of PJK The same result was obtained in the present study Yagi et al. Spine 2012 ü The fusion to pelvis is often necessary to achieve an appropriate lumber lordosis and sagittal balance ü Countermeasure Applying the OLIF up to UIV as long as possible for better anterior support and fusion capacity

12 Conclusion l The prevalence of PJK during study period following surgical treatment of ASD applying OLIF was nearly equivalent to that of previous studies l The present study demonstrated that the history of VCF and fusion to pelvis were important risk factors for the development of PJK