ABSTRACT
Objective To study the stability of lumbar spine after transforaminal lumbar interbody fusion (TLIF) surgery combined with a novel articular process fixation system (APFS). Methods Based on the validated finite element model of L3-S1 intact segment (Model A), TLIF surgery was simulated to establish bilateral pedicle screw TLIF model (Model B), right unilateral pedicle screw TLIF model (Model C), APFS combined with right pedicle screw fixation TLIF model (Model D). The range of motion (ROM) of the lumbar spine model and stress distributions on pedicle screws, APFS and interbody fusion cages under different working conditions were observed. Results The overall ROMs of Models B, C, and D under different working conditions were comparable, which were all smaller than those of the physiological model. Compared with Models B and C, the maximum compressive stress of the right pedicle screw and the interbody fusion cage in Model D was the smallest or between Models B and C under different working conditions. Model D had the largest peak stress of APFS and right pedicle screw during anterior flexion. Conclusions APFS combined with contralateral pedicle screw fixation can be used as a novel fixation method for TLIF surgery of lumbar spine.
ABSTRACT
Objective To investigate the efficacy of posterior intervertebral autogenous bone grafting combined with long-segment fixation for type C thoracolumbar fractures.Methods A retrospective case series study was performed in 28 patients with type C thoracolumbar fractures admitted to the 903 Hospital of PLA from January 2013 through January 2016.There were 20 males and eight females,aged 25-55 years,with an average of 36.8 years.All patients had type C fractures according to the new AO classification system.The injury occurred at T11-12segment in 5 patients,T12-L1 segment in 8,L1-2 segment in 9,and L2-3 segment in 6.These patients were scored 7-9 points [(8.0 ± 1.1) points]according to the thoracolumbar injury classification and severity score (TLICS) and 7-10 points [(8.5 ±1.4) points] according to Load sharing score (LSC).There were 20 patients with grade A and eight patients with grade B based on the American Spine Injury Association (ASIA).All patients were treated with posterior intervertebral autogenous bone grafting combined with long-segment fixation.The operation time and volume of blood loss were recorded.Kyphosis Cobb angle,visual analogue scale (VAS) and Oswestry disability index (ODI) were compared between before operation and 1 week,3 months,12 months and 24 months after operation.Bone grafting union was evaluated during the follow-up period by CT scan.ASIA grade was used to evaluate the functional recovery.Results All patients were followed up for average 26 months (range,24-36 months).The operation time was (135.8 ± 30.5) minutes and the intraoperative blood loss was (350.5 ± 50.7) ml,respectively.No serious complications occurred during the operation such as blood vessel or nerve injury aggravation.No serious complications occurred after operation such as incision infection and internal fixation loosening or fracture.Cobb angles of local kyphosis at 1 week,3,12 and 24 months after operation were significantly improved compared with preoperative Cobb angle (P ＜0.01).VAS and ODI were also significantly improved at 1 week,3,12 and 24 months after operation (P ＜0.01).The last follow-up found that all the intervertebral bone grafts were fused.At the last follow-up,ASIA grading results were as follows:grade A in 20 patients,grade B in 3 and grade C in 5.Conclusion Posterior intervertebral autogenous bone grafting combined with long-segment fixation has the advantages of simple operation,short operation time,minimal trauma,good fusion effect,significant relief of the pain and improvement of neurological function,indicating a surgical option for the treatment of type C thoracolumbar fracture.