Summary: This study reports the incidence, risk factors, and natural course of proximal junctional kyphosis (PJK) in a long term follow‐up of adult idiopathic scoliosis patients undergoing long instrumented spinal fusion and shows that the majority of PJK developed in the early post‐op period and can continue to progress over long term. However, few patients required revision surgery for PJK.
Introduction: PJK is a well recognized post operative phenomenon in adult and adolescent scoliosis after long instrumented fusion. Although recent reports have showed the prevalence, clinical outcomes, and the possible risk factors of PJK, few reports exist about long term follow‐up outcome of PJK.
Methods: A retrospective chart and x‐ray review of 76 consecutive adult scoliosis pts treated with long instrumented spinal fusion was performed. PJK was defined by a proximal junctional angle greater than 10° and at least 10° greater than the corresponding pre‐op measurement. Radiographic measurements included sagittal vertical axis (SVA), thoracic kyphosis (TK), lumbar lordosis (LL) and pelvic incidence (PI) on pre‐op, post‐op, and latest most recent f/u. Bone mineral density (BMD), body mass index (BMI), age, sex, instrumentation type, surgery type and fusion to sacrum were reviewed. Post‐op SRS and ODI scores were also evaluated. Means were compared with student's t test and chi‐square test. P value of <0.05 with confidence interval 95% was considered significant.
Results: The mean age was 48.3yrs (23‐75yrs) and the avg f/u was 7.3yrs (5‐14yrs). PJK occurred in 17pts (22.4%). SRS and ODI scores were not significantly different between PJK group and non PJK group. 76% of PJK occurred within 3 months after surgery, and the remaining 24% identified between 3 months to 5 yrs post‐op. 4 pts were symptomatic, and 2 pts had revision surgery. Low BMD, posterior fusion, fusion to the sacrum, inappropriate global spine alignment, and greater SVA change were significant risks for PJK (P=0.035, P=0.03, P=0015, p<0.001 and p<0001).
Conclusion: In a long term review of minimum 5 yrs, 76% of PJK occurred within 3 months after surgery. Despite the occurrence of PJK in 22% of adult scoliosis pts undergoing long fusion, no significant differences were found in SRS and ODI scores in PJK and non PJK pts. Pre‐existing low BMD, posterior fusion, fusion to the sacrum, inappropriate global spine alignment, and greater SVA change were significant risks for PJK.