INTRODUCTION: Recently, long spinal fusions for adult spinal deformity (ASD) have been markedly increasing in the aging society. However, they have high complication rate because the patients often have severe osteoporosis and other medical problems. Therefore, revision surgery due to proximal junctional kyphosis (PJK) is a big problem in the populations. Because PJK is multifactorial, the preventive measures against PJK and consequent revision surgery have not been established. The purpose of this study was to elucidate the preventive effects of different proximal end fixation methods, hooks and polyethylene tapes, on PJK as well as revision surgeries.

METHODS: Eighty-three adult patients with spinal deformity who underwent corrective long spinal fusion with S2AI screws as distal anchors and followed up at least for 12 months were enrolled. As the proximal end of fusion constructs, hooks (group H) or polyethylene tapes (group T) were used. The PJK was defined as the progression of kyphosis over 10 degrees at the proximal end of fusion. In addition, revision surgery due to PJK was defined as proximal junctional failure (PJF). We evaluated age, gender, operation time, estimated blood loss, presence or absence of severe osteoporosis, pre- and postoperative sagittal parameters (TK, LL, SS, and PI), sagittal vertical axis (SVA), and the incidence of PJK and PJF in the two groups.

RESULTS: Twenty patients were involved in group H (age, 72.3 years) and 63 in group T (age, 74.4 years). Mean operation time was 452 minutes and 440 minutes, respectively. Mean estimated blood loss was 1151 ml and 1197 ml, respectively. There were 7 patients with severe osteoporosis in group H and 27 patients in group T. There was no significant difference in age, gender, operation time, estimated blood loss, presence or absence of severe osteoporosis, and pre- and postoperative sagittal parameters between the two groups. Group H had 11 PJK (55.0%), while group T had 15 (23.8%), indicating that PJK was significantly prevented in group T (P=0.013). Moreover, group H had 8 PJF (40.0%) and group T had 7 (11.1%), indicating that PJF was also significantly prevented in group T (P=0.007). No clinical problems related to S2AI screws were found, regardless of the presence or absence of screw loosening.

DISCUSSION: It was suggested that PJK and PJF were suppressed by using polyethylene tapes at the proximal end of fusion constructs and the S2AI screw would be a reliable distal anchor with minimal clinical problems.