Clinical outcome and safety of cannulated pedicle screw with polymethylmethacrylate augmentation for degenerative lumbar diseases

English Keywords:PMMA  Cannulated cemented pedicle screw  Degenerative lumbar diseases  Osteoporosis

English Abstract:

  【Abstract】 Objectives: To compare the clinical outcomes between polymethylmethacrylate(PMMA) augmented cannulated pedicle screw and conventional screw plus PMMA augmentation for degenerative and osteoporotic lumbar diseases. Methods: 48 patients with degenerative lumbar diseases and osteoporosis during 2009 and 2011 were analyzed retrospectively, including 27 patients(average age 71.2, average bone density 0.60±0.16g/cm2) undergoing conventional screwand 21 patients(average 72.0, average bone density 0.57±0.24g/cm2) undergoing cannulated pedicle screw. The clinical outcomes were compared by using the Oswestry disability index scores(ODI) and Japanese Orthopaedic Association scores(JOA). The fusion status and the position of screw were observed by computed tomography(CT) and digital radiography(DR). Results: In conventional screw group, the average operation time was 158±43min, the average blood loss was 233±23ml, and the average hospital stay was 12.3±4.6d. While in cannulated pedicle screw group, the average operation time was 146±34min, average blood loss was 225±36ml, and the average hospital stay was 13.2±6.5d, which showed no statistical differences between 2 groups(P＞0.05). In conventional screw group which was followed up for 20.5 months, PMMA leakage to the spinal canal was observed in 3 patients, and PMMA broke through of the anterior wall due to anterior wall fracture in one patient, all had no neurological complications; screw loosening and bony nonunion were observed in 2 patients. In cannulated pedicle screw group which was followed up for 18.4 months, PMMA leakage to the lateral side of vertebral body and leakage into the spinal canal was observed in one patient respectively, but no neurological complications were found. In conventional screw group, JOA score before operation was 10.21±2.27 and 21.32±2.80 after operation, ODI before and after operation was 47.34±6.30 and 18.47±4.89 respectively. In cannulated pedicle screw group, JOA before operation and after operation was 10.12±2.64 and 21.83±2.43, ODI before operation and after operation was 48.07±5.06 and 17.67±3.64, which showed no statistical differences between 2 groups(P＞0.05). While there were significant differences of JOA and ODI score between pre and post operation in two groups(P＜0.05). Conclusions: There is good clinical efficacy of using PMMA augmentation of a cannulated pedicle screw as the same of PMMA augmentation of conventional screw, which also has good safety and simple operation.