Effect of Position on Regional Kyphosis Angle in Patients with Kyphosis Secondary to Symptomatic Old Osteoporotic Thoracolumbar Fracture.

OBJECTIVE:The purpose of this study was to evaluate the effect of position on regional kyphosis angle (RKA) in patients with kyphosis secondary to symptomatic old osteoporotic thoracolumbar fracture (so-OTLF). METHODS:The authors evaluated the radiographic data of patients with kyphosis secondary to so-OTLF who underwent posterior corrective fusion surgery in our hospital. The spine sagittal parameters were evaluated in the standing position preoperatively. RKA was measured under standing radiograph, full-length spine computed tomography image in prone position and intraoperative prone X-ray radiograph, respectively. Changes in RKA were compared between groups. RESULTS:Thirty-three patients were included. The average RKAs in the standing position, preoperative prone position, and intraoperative prone position were 46.2°, 31.1°, and 30.5° respectively. RKA decreased significantly from standing to preoperative prone position or intraoperative prone position (P < 0.001). In 93.9% (31/33) of the patients, the difference between preoperative prone RKA and intraoperative prone RKA was within 5°. The changes in RKA from standing to intraoperative prone position in the moderate to severe kyphosis group were significantly greater than those in the mild kyphosis group (P < 0.001). CONCLUSIONS:The reductive effect of the intraoperative prone position was greater in patients with moderate to severe kyphosis deformities. RKA in the preoperative prone position was almost the same as the RKA in the intraoperative prone position. Therefore, assessing preoperative full-length spine computed tomography in the prone position helped formulate the plan for corrective surgery in patients with kyphosis secondary to so-OTLF.