Comparison of pedicle screw fixation with or without cement augmentation in osteoporotic spine combined with single-segment lumbar degenerative disease

English Keywords:Osteoporosis  Pedicle screws  Degenerative lumbar disease  PMMA

English Abstract:

  【Abstract】 Objectives: To explore the necessity of cement augmented pedicle screw fixation in osteoporotic patients combined with single-segment lumbar degenerative disease. Methods: 74 cases followed up for a minimum of 2 years with single-segment degenerative lumbar disease combined with osteoporosis spine receiving posterior lumbar fusion and routine anti-osteoporosis treatment from January 2012 to December 2014 were reviewed retrospectively. 36 cases(3 males and 33 females; 70.61±6.37 years old on average; average bone density -3.38±0.77SD; surgical segment, L4/5 32 cases and L5/S1 4 cases) were in the polymethylmethacrylate-augmented pedicle screw group(PMMA-PS) and the other 38 cases(2 males and 36 females; 69.79±5.90 years old on average; average bone density -3.32±0.57SD; surgical segment, L4/5 32 cases and L5/S1 6 cases) in the conventional pedicle screw group(CPS). Surgical data including operation time, intra-operative blood loss, hospitalization day and surgical complications were recorded, as well as the radiological parameters measured from postoperative X-rays and CT scans including the rates of fusion and screw loosening. In addition, the visual analogue scores(VAS) and Oswestry disability index(ODI) were evaluated preoperatively, at 6 months and last follow-up postoperatively. Results: In CPS group, the average operation time was 147.21±17.11min, the blood loss was 138.03±42.45ml, and the average hospital stay was 8.82±1.07d. PMMA-PS group was 185.75±18.37min, 142.64±35.08ml, 9.36±1.17d, respectively. Compared with PMMA-PS group, operation time in CPS group decreased significantly(P<0.05). While no statistical difference for the average hospital stay or blood loss was found between 2 groups(P>0.05). The VAS scores of CPS group and PMMA-PS group on pre-operation, at 6 months after operation and final follow-up were 7.16±0.82, 6.93±10.88; 1.74±0.49, 1.92±0.47; 1.76±0.43, 1.81±0.40 respectively. The ODI were (51.84±4.41)%, (52.50±4.71)%; (18.03±2.74)%, (18.89±3.61)%; (17.24±2.77)%, (16.67±2.67)%; respectively. After surgeries, VAS and ODI at 6 months and final follow-up improved significantly in two groups(P<0.05). There were no significant differences of VAS and ODI preoperatively and postoperatively between 2 groups(P>0.05). In PMMA-PS group, no screw loosening occurred, and the fusion rate was 100%. In CPS group, 2 screws loosened(1.3%, 2/152) in 1 patient(2.7%, 1/36), and the fusion rate was(97.3%, 37/38), however, no significant difference was found between 2 groups(P>0.05). Besides, 27 (18.7%, 27/144) asymptomatic trajectory PMMA leakages were detected. Conclusions: It is not recommended conventional application of PMMA augmented screw in osteoporotic spine with single-segment lumbar degenerative disease due to the similar clinical efficacy and fusion rate achieved on the basis of routine anti-osteoporosis treatment with or without augmentation, besides, less operation time needed and potential complications caused by cement leakagein CPS.