An analysis on the optimal match between thoracolumbar kyphosis and lower lumbar lordosis in adult spinal deformity after long-fusion surgery / 中华骨科杂志

ABSTRACT

Objective:To explore the optimal match degree between thoracolumbar kyphosis (TLK) and lower lumbar lordosis (LLL) in adult spinal deformity (ASD) after correction surgery.Methods:Data of 119 ASD patients (male 28, female 91), belonging to the Affiliated Hospital of Jining Medical University (19 cases), the Affiliated Hospital of Shandong University of Traditional Chinese Medicine (11 cases), and the First Medical Center of Chinese PLA General Hospital (89 cases) were reviewed and documented from March 2019 to March 2020. All patients (age, 64.48±8.88 years; range, 45-79 years) underwent the surgical procedure of thoracolumbar fusion with instrumentations were followed up over 24 months (51.68±15.60 months; range, 24-87 months) after surgery. Postoperative proximal interface failure, Oswestry disability index (ODI) score and Scoliosis Research Society-22 (SRS-22) score were recorded for all patients. The immediate match of TLK to LLL postoperatively was calculated as follows TLM=TLK/LLL. The data of those individuals with excellent improvements in the ODI (>50%) at the final follow-up were recorded and analyzed. Then the mean value and the 95% CI of TLM in those individuals were calculated. All participants were subdivided into three groups according to the 95% CI value of TLM. After the receiver operating characteristic curve (ROC) analyzing, the area under the ROC curve (AUC) was the best cutoff value of TLM. The association of proximal junctional failure (PJF) developing with the abnormal TLM postoperatively was analyzed with logistic regression, and the odds ratio (OR) was calculated. Results:62 patients had significant improvements in ODI (>50%) at the final follow-up, and the mean TLM in those individuals was 0.41 [95% CI (0.2, 0.5)]. All patients were divided into three groups TLM<0.2 (35 cases), 0.2≤TLM≤0.5 (48 cases) and TLM>0.5 (36 cases). The preoperative TLK (13.87°±16.61°) and T 1 pelvic angle (19.69°±10.55°) in the those patients with TLM<0.2 were the smallest, and those were the largest in those with TLM>0.5 (30.59°±16.68°, 28.30°±14.46°). The individuals with TLM<0.2 still had the smallest TLK (2.89°±1.78°), however, those with TLM>0.5 had the largest TLK (17.13°±12.13°) and the smallest LLL (-26.16°±11.02°) accordingly. Additionally, the ODI and SRS-22 for those with 0.2≤TLM≤0.5 at the final follow-up were the best ( P<0.05). ROC curve analysis results showed that the best cutoff value of TLM was 0.4 (sensitivity=78.9%, specificity=76.2%; AUC=0.802, 95% CI (0.708, 0.896) , P<0.001). During the follow-up after orthopedic surgery, there were 19 patients with postoperative proximal junction failure, including 16 patients in the mismatched group (6 patients in the TLM<0.2 group, 10 patients in the TLM>0.5 group) and 3 patients in the matched group (0.2≤TLM≤0.5 group), with the incidence of 23% (16/71) and 6% (3/48), respectively. The difference was statistically significant (χ 2=5.66, P=0.017). Thoracolumbar mismatch was significantly associated with proximal borderline failure after orthosis [ OR=4.35, 95% CI (1.196, 15.924)]. Conclusion:The abnormal correction in thoracolumbar kyphosis and lower lumbar lordosis may result in mismatch between thoracolumbar segments, which would undermine the quality of life, and increase the incidence of proximal junctional failure developing in those ASD patients underwent long-fusion surgeries. The match between TLK and LLL should be 0.2 to 0.5.