Characteristics of patients undergoing revision surgery for proximal junctional failure after adult spinal deformity surgery: revalidation of the Hart-International Spine Study Group proximal junctional kyphosis severity scale

초록

OBJECTIVE Score on the proximal junctional kyphosis severity scale (PJKSS) has been validated to show good corre-lations with likelihood of revision surgery for proximal junctional failure (PJF) after surgical treatment of adult spinal de-formity (ASD). However, if the patient has progressive neurological deterioration, revision surgery should be considered regardless of severity based on PJKSS score. This study aimed to revalidate the correlation of PJKSS score with likeli-hood of revision surgery in patients with PJF but without neurological deficit. In addition, the authors provide the cutoff score on PJKSS that indicates need for revision surgery.METHODS A retrospective study was performed. Among 360 patients who underwent fusion of more than 4 segments including the sacrum, 83 patients who developed PJF without acute neurological deficit were included. Thirty patients underwent revision surgery (R group) and 53 patients did not undergo revision surgery (NR group). All components of PJKSS and variables other than those included in PJKSS were compared between groups. The cutoff score on PJKSS that indicated need for revision surgery was calculated with receiver operating characteristic curve analysis. Multivariate analysis with logistic regression was performed to identify which variables were most predictive of revision surgery.RESULTS The mean patient age at the time of index surgery was 69.4 years, and the mean fusion length was 6.1 seg-ments. All components of PJKSS, such as focal pain, instrumentation problem, change in kyphosis, fracture at the up-permost instrumented vertebra (UIV)/UIV+1, and level of UIV, were significantly different between groups. The average total PJKSS score was significantly greater in the R group than in the NR group (6.0 vs 3.9, p < 0.001). The calculated cutoff score was 4.5, with 70% sensitivity and specificity. There were no significant between-group differences in patient, surgical, and radiographic factors (other than the PJKSS components). Three factors were significantly associated with revision surgery on multivariate analysis: instrumentation problem (OR 8.160, p = 0.004), change in kyphosis (OR 4.809, p = 0.026), and UIV/UIV+1 fracture (OR 6.462, p = 0.002).CONCLUSIONS PJKSS score positively predicted need for revision surgery in patients with PJF who were neurologi-cally intact. The calculated cutoff score on PJKSS that indicated need for revision surgery was 4.5, with 70% sensitivity and specificity. The factor most responsible for revision surgery was bony failure with > 20 degrees focal kyphotic deformity. Therefore, early revision surgery should be considered for these patients even in the absence of neurological deficit.

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