Effectiveness of modified sagittal age-adjusted score in predicting the occurrence of PJK/PJF after corrective surgery of spinal deformity in Chinese adults

English Keywords:Adult spinal deformity  Sagittal age-adjusted score  Proximal junctional kyphosis  Postoperative complications

English Abstract:

  【Abstract】 Objectives: To evaluate the abilities of sagittal age-adjusted score(SAAS) and modified SAAS score(M-SAAS) based on Chinese age-matched spine in predicting proximal junctional kyphosis/failure(PJK/PJF) after corrective surgery for patients with adult spinal deformity(ASD) in Chinese adults. Methods: The pelvic incidence(PI), lumbar lordosis(LL), pelvic tilt(PT), and T1-pelvic-angle(TPA) were measured in 66 subjects of age matched with spino-pelvic sequence from the imaging system of our hospital, including 28 males and 38 females, aged 54.7±6.2 years. The linear regression equations of age and PI-LL, PT and TPA were analyzed and recorded as M-SAAS formulas. The medical records of 68 ASD patients who underwent spinal correction surgery in our hospital from 2017 to 2021 were retrospectively analyzed, including 10 males and 58 females, aged 64.0±8.1 years old, and postoperative PJK/PJF occurred in 12 cases. Data such as PI, LL, PT and TPA were measured to calculate the SAAS score and the matching degree between the incidence of PJK/PJF and the score was observed. M-SAAS was calculated by substituting the postoperative imaging parameters of 68 ASD patients, and the matching degree between the incidence of PJK/PJF and the score was observed. Results: The SAAS was 1.9±2.6(range, -4 to 6). Immediately after surgery, 5 patients(7.4%) were evaluated as "Under-corrected", 25 patients(36.7%) as "Matched", and 38 patients(55.9%) as "Over-corrected". The incidence of PJK/PJF was 40.0%(2/5), 20.0%(5/25) and 13.2%(5/38), respectively. There was no significant difference in the incidence of PJK/PJF between the matched group and the other two groups. According to the normal spino-pelvic sequence, the linear regression equations of M-SAAS were as follows: ideal PI-LL=0.47×(age-55)+0.3, ideal PT=0.44×(age-55) +14 and ideal TPA=0.37×(age-55)+9. The final M-SAAS of ASD patients was 0.2±2.8(-5 to 5). Immediately after surgery, 17 patients(25.0%) were evaluated as "Under-corrected", 31 patients(45.6%) as "Matched", and 20 patients(29.4%) as "Over-corrected". The incidence of postoperative PJK/PJF was 11.8%(2/17), 6.5%(2/31) and 40.0%(8/20), respectively. The incidence of PJK/PJF in the "Over-correction" group was higher than that in the "Matched" group with statistical significance(P=0.008). Conclusions: SAAS is not suitable for the prediction of postoperative PJK/PJF in Chinese ASD patients. M-SAAS modified according to the age-matched spinal-pelvic sequence parameter relationship in middle-aged and elderly Chinese can predict the incidence of postoperative PJK/PJF in ASD patients.