Risk factors for PJK and DJF in operatively corrected adult patients with congenital hemivertebra.

INTRODUCTION: Congenital hemivertebra (HV) is a morphological defect that occurs during embryonic development. This study investigates the risk factors for developing proximal junctional kyphosis (PJK) and distal junctional failure (DJF) after surgery for adults.

METHODS: A retrospective analysis was conducted on 72 consecutive HV patients undergoing surgical treatment at a single center with a minimum 2-year follow-up. Patients' baseline data, clinical features, surgical details, and radiographic parameters were retrospectively analysed. Univariate and multivariate analyses were conducted to explore risk factors affecting the occurrence of PJK and DJF postoperatively.

RESULTS: A study of 72 patients found that at final follow-up, 14 (19.4%) developed PJK and 12 (16.7%) developed DJF. PJK patients showed significant differences in multiple hemivertebrae (MHV) and postoperative sagittal parameters (Sacral slope (SS): 34.1 vs 25.6; lumbar lordosis (LL): 42.9 vs 33.7) compared to non-PJK patients. DJF patients differed significantly in BMI, intraoperative transfusions, lumbar disc herniation (LDH) prevalence, and pre/postoperative parameters (preop Pelvic Tilt (PT): 15.7 vs 23.3; postop LL: 34.9 vs 50.5). Patients with PJK (p = 0.008) and DJF (p = 0.041) demonstrated greater preoperative kyphosis. The DJF group had a significantly higher rate of LDH at the distal or adjacent junctional area (83.3% vs 26.7%, p<0.001) and of significant disc degeneration at lower instrumented vertebra+1 (LIV+1) (83.3% vs 38.3%, p = 0.004). While preoperative quality of life scores were similar, the DJF group had worse final Health Related Quality of Life (HRQoL) (p≤0.016). Logistic regression analysis showed that multiple hemivertebrae and smaller postoperative SS (the cut-off value was 32.4°) were risk factors for PJK at the last follow-up. A larger postoperative LL (with a cut-off value of 36.9°) and the presence of lumbar disc herniation were identified as risk factors for DJF.

CONCLUSION: Multiple hemivertebrae and postoperative SS <32.4° are risk factors for PJK, while postoperative LL > 36.9° and LDH are risk factors for DJF.