P97. The risk of proximal junctional kyphosis increases with greater preoperative thoracic kyphosis in the elderly patient

Abstract

BACKGROUND CONTEXT Despite improvements in spinal deformity techniques, proximal junctional kyphosis and proximal junctional failure continue to be challenging complications after adult spinal deformity surgery, particularly in the elderly patient. To date, there are few ASD studies evaluating radiographic risk factors for PJK in the elderly patient, who may have significant higher baseline thoracic kyphosis and lower capacity for thoracic compensation. PURPOSE To identify radiographic risk factors for proximal junctional kyphosis preoperatively in elderly patients. STUDY DESIGN/SETTING Retrospective review of prospectively collected single center database. PATIENT SAMPLE There were 155 patients > 70 years of age who were followed for more than two years and underwent ASD surgery were included (Age: 75 ± 4 y; mFI: .84 ± .76; Levels fused: 9.3 ± 5.1). OUTCOME MEASURES We investigated the rate of proximal junctional kyphosis at 2 year follow-up. METHODS Patients were divided into PJK and non-PJK groups based on accepted radiographic criteria using whole spine standing radiographs. Radiographic risk factors for development of PJK were assessed using multivariate analysis. RESULTS The cohort had sagittal malalignment as demonstrated by PT 32.2 ± 10.2°, PI–LL 27.4 ± 20.0°, TPA 38.4 ± 12.3°, and SVA 127.7 ± 69.6 mm. Mean PI for the cohort was 56.3 ± 13.5°, mean TK was 33.5 ± 17.8°, mean expected TK was 35.9 ± 14.4°, and mean thoracic compensation was 2.3 ± 21.9°. The PJK and non-PJK groups comprised 82 and 73 cases, respectively. No differences were seen in the incidence of PJK with preoperative thoracic kyphosis < 20° (21%) , 20-30° (34%), or 30-40° (48%), however a significantly higher rate was seen with a preoperative TK ≥40° (63%) (p<0.05). There was no significant difference in thoracic compensation between patients who developed PJK (1.6 ± 20.1°), and those who did not (3.1 ± 20.4°). The amount of change in TK before and just after surgery was significantly associated with PJK (PJK: 20.5 ± 21.9°, no PJK: 4.4 ± 30°, p<0.0001) and was a significant risk factor for PJK by regression analysis (OR 1.064, p < 0.0001). CONCLUSIONS Elderly patients (> 70 years) have a low level of thoracic compensation and those with preoperative kyphosis > 40° are at higher risk for development of PJK. Greater change in thoracic kyphosis before and just after surgery was a significant predictor of PJK. FDA DEVICE/DRUG STATUS This abstract does not discuss or include any applicable devices or drugs. Despite improvements in spinal deformity techniques, proximal junctional kyphosis and proximal junctional failure continue to be challenging complications after adult spinal deformity surgery, particularly in the elderly patient. To date, there are few ASD studies evaluating radiographic risk factors for PJK in the elderly patient, who may have significant higher baseline thoracic kyphosis and lower capacity for thoracic compensation. To identify radiographic risk factors for proximal junctional kyphosis preoperatively in elderly patients. Retrospective review of prospectively collected single center database. There were 155 patients > 70 years of age who were followed for more than two years and underwent ASD surgery were included (Age: 75 ± 4 y; mFI: .84 ± .76; Levels fused: 9.3 ± 5.1). We investigated the rate of proximal junctional kyphosis at 2 year follow-up. Patients were divided into PJK and non-PJK groups based on accepted radiographic criteria using whole spine standing radiographs. Radiographic risk factors for development of PJK were assessed using multivariate analysis. The cohort had sagittal malalignment as demonstrated by PT 32.2 ± 10.2°, PI–LL 27.4 ± 20.0°, TPA 38.4 ± 12.3°, and SVA 127.7 ± 69.6 mm. Mean PI for the cohort was 56.3 ± 13.5°, mean TK was 33.5 ± 17.8°, mean expected TK was 35.9 ± 14.4°, and mean thoracic compensation was 2.3 ± 21.9°. The PJK and non-PJK groups comprised 82 and 73 cases, respectively. No differences were seen in the incidence of PJK with preoperative thoracic kyphosis < 20° (21%) , 20-30° (34%), or 30-40° (48%), however a significantly higher rate was seen with a preoperative TK ≥40° (63%) (p<0.05). There was no significant difference in thoracic compensation between patients who developed PJK (1.6 ± 20.1°), and those who did not (3.1 ± 20.4°). The amount of change in TK before and just after surgery was significantly associated with PJK (PJK: 20.5 ± 21.9°, no PJK: 4.4 ± 30°, p<0.0001) and was a significant risk factor for PJK by regression analysis (OR 1.064, p < 0.0001). Elderly patients (> 70 years) have a low level of thoracic compensation and those with preoperative kyphosis > 40° are at higher risk for development of PJK. Greater change in thoracic kyphosis before and just after surgery was a significant predictor of PJK.