OBJECTIVE Score on the proximal junctional kyphosis severity scale (PJKSS) has been validated to show good correlations with likelihood of revision surgery for proximal junctional failure (PJF) after surgical treatment of adult spinal deformity (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 likelihood 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 segments. All components of PJKSS, such as focal pain, instrumentation problem, change in kyphosis, fracture at the uppermost 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 neurologically 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° focal kyphotic deformity. Therefore, early revision surgery should be considered for these patients even in the absence of neurological deficit.

BACKGROUND: Although several studies were performed to measure stiffness-related functional disability (SRFD) after long segmental fusion for adult spinal deformity, the evaluation of SRFD was done at a single point in time. We do not know whether the disability will stay the same, worsen, or improve over time. OBJECTIVE: To evaluate the time-dependent changes of SRFD and any factors affecting these changes. METHODS: Patients who had ≥4-segment fusion with the sacrum were reviewed retrospectively. Specific Functional Disability Index (SFDI), consisting of a 12-item tool with 4 categories (sitting on the floor, sanitation activities, lower body activities, and moving activities), was used to assess the severity of SRFD. The SFDI taken at 3 months, 1 year, and 2 years postoperatively and at the last follow-up were used for evaluating the changes in SRFD. The presumed factors affecting these changes were analyzed. RESULTS: This study included 116 patients. Total SFDI scores significantly improved from 3-month to the last follow-up. Among the 4-category of SFDI, sitting on the floor showed the highest scores followed by lower body activities, sanitation activities, and moving activities at all time points. All categories except for sitting on the floor showed significant improvement from 3 months until the last follow-up. This improvement was most pronounced between 3 months and 1 year. American Society of Anaesthesiologists grade was identified as the only factor affecting time-dependent changes. CONCLUSION: SRFD was highest at 3 months, but it improved over time except for sitting on the floor. The improvement was observed greatest between 3 months and 1 year. Patients with less American Society of Anaesthesiologists grade experienced more improvement in SRFD.

BACKGROUND:In general, stiffness-related functional disability (SRFD) is expected to increase as longer fusion length, but there have been no studies on factors affecting SRFD besides fusion length.OBJECTIVE:To identify the factors affecting SRFD after long segmental fusion in patients with adult spinal deformity (ASD).METHODS:We retrospectively reviewed the patients who underwent ≥4-segment fusion including sacrum for ASD. The severity of SRFD was evaluated using the Specific Functional Disability Index (SFDI) consisting of 12 items with 4 categories as follows: sitting on the floor, sanitation activity, lower body activity, and moving activity. Each category contains 3 items which was given a maximum of 4 points. The presumed factors affecting SFDI were analyzed.RESULTS:A total of 148 patients were included in the study with their mean age of 67.3 years. The mean fusion length was 6.4 segments. The mean score of each SFDI category was highest in sitting on the floor (9.9), followed by lower body activities (7.6), sanitation activities (6.0), and moving activities (5.9). The total sum was 29.3 points. In multivariate analysis, total sum of SFDI was significantly higher in female sex, patients with higher American Society of Anesthesiology grade, and longer fusion length. However, the sagittal parameters did not show a significant correlation with SRFD, except pelvic incidence-lumbar lordosis which correlated with only one category (lower body activities).CONCLUSION:This study showed that female sex, higher American Society of Anesthesiology grades, and longer fusion length influenced SRFD after long segmental fusion for ASD. Sagittal parameters related to the degree of deformity correction did not significantly affect SRFD.