Recurrence of proximal junctional kyphosis after revision surgery for symptomatic proximal junctional kyphosis in patients with adult spinal deformity: incidence, risk factors, and outcomes

Purpose: Although proximal junctional kyphosis (PJK) is common after long spinal fusion, the outcomes of revision surgery for symptomatic PJK are unclear. Our aim was to assess the outcomes of revision surgery for symptomatic PJK in patients with adult spinal deformity and elucidate the incidence and risk factors for recurrent PJK (rePJK). Methods: We evaluated standing radiographs and health-related quality of life (HRQOL) in patients who underwent revision surgery for symptomatic PJK with at least 2-year follow-up. Patients were assigned to the non-rePJK or rePJK group according to PJK recurrence. Results: Thirty-nine consecutive patients (mean age, 63 ± 11 years; 24 women) met the inclusion criteria. RePJK occurred in 12 patients (31%). There were significant differences in the following parameters between groups (non-rePJK vs. rePJK): initial proximal junctional sagittal Cobb angle (PJA) (26.6° vs. 35.6°), thoracic kyphosis (TK) (38.6° vs. 52.8°), and sagittal vertical axis (SVA) (9.3 vs. 15.9 cm), and pre- to postoperative SVA decrease (6.1 vs. 12.2 cm). Significant risk factors for rePJK were initial PJA > 40°, preoperative TK > 60°, preoperative SVA > 10.0 cm, correction of TK > 15°, and correction of SVA > 5.0 cm. HRQOL scores improved significantly; however, postoperative SRS-22r activity scores were significantly worse in the rePJK group vs the non-rePJK group. Conclusion: The incidence of rePJK was 31%. Risk factors for rePJK were large initial PJA, high preoperative TK and SVA, and greater correction of TK and SVA. HRQOL did not differ significantly between patients with vs without rePJK, except immediate postoperative SRS-22r activity scores. Level of evidence: III.