Abstract

Background
Proximal junctional kyphosis (PJK) following long instrumented fusion is a well-recognized complication that does not negatively affect the clinical outcomes. However, there were few studies with regard to the long-term consequences of PJK. Objective: To investigate the long-term clinical and radiographic consequences of proximal junctional kyphosis (PJK) following the long instrumented fusion for elderly patients with sagittal imbalance.
Methods
Patients older than 60 years who underwent ≥4 fusion including the sacrum for sagittal imbalance were followed up longer than five years. PJK was defined as proximal junctional angle (PJA) >10° without any bony compromise or myelopathy. The radiographic and clinical outcomes were compared between PJK and non-PJK groups. Clinical outcome measures included visual analog scale (VAS) for back and leg, Oswestry disability index (ODI), and Scoliosis Research Society (SRS)-22 scores.
Results
A mean age was 69.2 years. An average follow-up duration was 92.4 months. There were 30 patients in PJK group and 43 in non-PJK group. At the final follow-up, pelvic incidence-lumbar lordosis mismatch, pelvic tilt, and sacral vertical axis were not different between the two groups. In PJK group, PJA significantly increased from 6.5° postoperatively to 21.2° at the final follow-up. At the final follow-up, clinical outcomes were worse in PJK group than in non-PJK group with regard to VAS for back, ODI, and SRS-22 scores except satisfaction domain. Three (10%) of 30 patients underwent a revision surgery for PJK progression.
Conclusions
PJK progressed with time and negatively affect the clinical outcomes in a long-term follow-up after ASD surgery.

• Keywords: Proximal junctional kyphosis, Clinical; Radiographic, Consequences, Long instrumented fusion, Elderly patients, Sagittal imbalance