The clinical application of expandable pedicle screws in the short segment lumber fusion surgery in osteoporosis patients

English Keywords:Osteoporosis  Posterior lumbar interbody fusion  Pedicle screws

English Abstract:

  【Abstract】 Objectives: A retrospective analysis on the mid-term clinical effect of expandable pedicle screws in the short segment lumber fusion surgery in osteoporosis patients. Methods: From January 2007 to July 2013, 406 patients treated with standard posterior lumbar interbody fusion(PLIF) were reviewed retrospectively. All patients were followed up for a minimum of 3 years. Among the 406 cases, 147 were males and 259 were females with an overall mean age of 63.4±5.2 years(range, 50-79 years). The T value of pre-operative lumbar BMD was -3.3±0.6(2.5-4.6). Among these patients, 173 patients received PLIF with expandable pedicle screws(EPS group) and the other 223 patients received PLIF with conventional pedicle screws(CPS group). No significant difference was detected between the two groups on gender composition, T value of pre-operative BMD, disease composition and the time of last follow-up visit(P＞0.05). The pre-operative and post-operative(3 months, 6 months and last follow-up) visual analogue scores(VAS) and Oswestry disability index(ODI) scores were compared to evaluate the function recoverly conditions. X-ray or CT scan was taken to compare the screw loosening rate, breakage rate and fusion rate between the two groups. Results: The average follow-up period was 3.7±1.0 years(range, 3-8 years). No significant difference was detected between the two groups on pre-operative VAS and ODI scores(P＞0.05). After surgeries, VAS and ODI scores at 3 months, 6 months and last follow-up improved significantly in both groups. Compared with CPS group, post-operative VAS and ODI scores at 3 months, 6 months and last follow-up in the EPS group improved significantly(P＜0.05). In EPS group, 2 screws loosening(0.3%, 2/796) occurred in 1 patient(0.6%, 1/173), and 7 screws breakage(0.9%, 7/796) occurred in 5 patients(2.9%, 5/173). In the CPS group, 17 screws loosening(1.8%, 17/960) occurred in 13 patients(5.6%, 13/233), and 4 screws breakage(0.4%, 4/960) occurred in 2 patients(0.9%, 2/233). The screw loosening rate in EPS group was significantly lower than that in CPS group(P＜0.05). The screw breakage rate was higher than that in CPS group, but there was no significant difference(P＞0.05). The fusion rate in EPS group(99.4%, 172/173) was significantly higher than that in CPS group(93.6%, 218/233)(P＜0.05). Conclusions: In the short segment lumbar fusion surgery in osteoporosis patients, the application of expandable pedicle screws can provide lower screw loosening rate and higher fusion rate. It is a safe and reliable implant for osteoporotic spinal surgery.