Introduction: Confusion exists regarding the consequences of postoperative proximal junctional kyphosis (PJK). PJF, defined as failure of the structures stabilizing the upper instrumented vertebra (UIV) region, is a severe form of PJK that is a potentially catastrophic complication. No validated classification exists for PJF. Purpose: develop and validate a PJF classification and severity scale.
Methods: 14 surgeons participated in a modified Delphi approach to identify clinical and radiographic features of PJF. A classification assigning severity of 6 distinct PJF characteristics was agreed upon (Neurological Deficit, Focal Pain, Instrumentation Problem, Kyphosis/PLC Integrity, UIV/UIV+1 Fracture, and Level of UIV) and a total PJF severity score (PJFSS) created. 15 case examples were graded by 14 surgeons in 2 separate grading sessions; time between grading sessions= 7 days. Intra and inter-rater reliability of 6 PJF severity features and PJFSS was calculated. Correlation with recommended treatment (observation, cement augmentation or revision surgery) was assessed.
Results: Mean kappa intra-rater (0.74) and inter-rater (0.71) agreement for severity scores of all 6 PJF characteristics was substantial (kappa intra-rater range; UIV/UIV+1 Fracture =0.43 to Neuro status=0.89; kappa inter-rater range; UIV/UIV+1 Fracture =0.31 to Neuro status=0.89). Mean PJFSS intra-rater (kappa=0.47) and inter-rater (kappa= 0.42) agreement was moderate. All 6 PJF features significantly correlated with treatment recommendation (mean R value=0.3; p<.01). Mean R values for PJF features and recommended treatment ranged from level of UIV (0.13) to Pain (0.44). Total PJFSS score strongly correlated with recommended treatment (mean R value=0.63; p<0.01). PJFSS =7 uniformly resulted in recommendation for revision surgery.
Conclusions: PJF requires accurate diagnosis. The proposed PJFSS classification has good reliability and repeatability and correlates strongly with recommended treatment. Pain, kyphosis, neurological status, and instrumentation failure were the strongest predictors for recommendation for surgical revision. Further validation of the PJFSS classification using a prospective cohort is needed and underway.
Patient Care: This research improves patient care by describing and assessing a novel standardized classification system for proximal junctional failure following long-segment spinal fusion. This classification system can serve as the basis for improved communication among surgeons regarding this complication. It can also help to facilitate more objective classification of this complication for future research efforts.
Learning Objectives: By the conclusion of this presentation, participants should: (1) recognize that proximal junctional failure (PJF) is a potentially catastrophic complication following adult spinal deformity (ASD) surgery requiring accurate diagnosis, (2) appreciate the application and potential benefits of the newly-proposed PJF severity scoring scale (PJFSS).