Abstract:

Objective： To describe the application of polymethylmethacrylate (PMMA)  augmentation of cement-injectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis. Methods: Retrospective cohort study was used to compare cement injectable cannulated pedicle screws ( CICPs) group with PMMA augmentation and control group with traditional method in the correction surgery for Lenke-silva level Ⅲ and level Ⅳ degenerative scoliosis cases with osteoporosis. Both groups were followed up for 1 year. The clinical results were assessed by visual analog scale (VAS) of pain on lumbar and lower limbers, Oswestry disability index (ODI) score and EuroQol-5 dimensions (EQ-5D) score. The coronal major curve Cobb angel in coronal plane and thoracic kyphosis Cobb angle, lumbar lordosis Cobb angle and sagittal vertical axis (SVA) in sagittal plane were tested in whole long spine X ray. The fusion rates were evaluated by lumbar X ray and dynamic X ray. Results： In this study 34 cases were enrolled, 15 cases in CICPs group and 19 cases in control group. The general characteristics including age, gender, weight, height, BMI and BMD were without statistical difference between the two groups. There were （5.7±2.2）PMMA augmentation screws in CICPs group. The operation time, blood loss and blood transfusion were higher in CICPs group than in control group, but without statistical difference. Lumbar VAS, lower limbers VAS, ODI score and EQ-5D were all better in 1 month post-operation, 6 months postoperation and 1 year postoperation than in preoperation in both groups. lumbar VAS scores of CICPs group in 6 months postoperation(CICPs group 3.1±1.3 vs. control group 4.4±1.4， P<0.01） together with lumbar VAS scores (CICPs group 3.3±1.0 vs. control group 5.2±1.4， P<0.01），ODI scores (CICPs group 22.7±17.2 vs. control group 31.4±18.5， P<0.01） and EQ-5D in 1 year postoperation (CICPs group 2.9±2.0 vs. control group 3.5±2.5， P<0.01）were lower than those of control group. The coronal major curve Cobb angels were all lower in 1 month postoperation, 6 months postoperation and 1 year postoperation than in preoperation in both groups; thoracic kyphosis Cobb angle and lumbar lordosis Cobb angle were all higher in 1 month postoperation, 6 months postoperation and 1 year postoperation than in preoperation in both groups. The coronal major curve Cobb angel was lower in CICPs group than that in control group in 1 year postoperation (CICPs group 17.6°±6.9° vs. control group 21.2°±7.2°， P<0.01）and thoracic kyphosis Cobb angle was higher in CICPs group than that in control group in 6 months postoperation (CICPs group -33.5°±8.8 °vs. control group -28.9°±8.3°， P<0.01）and 1 year postoperation(CICPs group -33.0°±8.1° vs. control group -26.3°±7.4°， P<0.01） together with lumbar lordosis Cobb angle were higher in CICPs group than that in control group in 1 year postoperation(CICPs group 26.4°±8.1° vs. control group 22.1°±7.3°， P<0.01）. Conclusion: Polymethylmethacrylate augmentation of bone cementinjectable cannulated pedicle screws for the treatment of degenerative lumbar scoliosis with osteoporosis was effective and safe, the short-term clinical result was good.

Key words: Cannulated pedicle screws, Bone cement, Osteoporosis, Degenerative lumbar disease