Comparison of the Unilateral and the Bilateral Pedicle Screw Fixation without Using an Interbody Cage: Randomized Clinical Trial

BACKGROUND: Lumbar spine instability is one of the main causes of low back pain and has become more prevalent in recent years. Bilateral pedicle screw fixation is used to perform posterior lumbar stabilization, which is complemented by the installation of an interbody cage. AIM: The aim of the study was evaluating of the results of unilateral and bilateral pedicle screw fixation without using of an interbody cage. METHODS: A prospective randomized study of 96 patients was carried out. Forty-seven patients were assigned to the group of the unilateral pedicle screw fixation versus 49 patients were moved to the group of the bilateral pedicle screw fixation of the lumbar spine. Of the 96 patients, 80 patients eventually were included in the study. However, seven patients in the first group and nine patients were lost to follow-up. Surgery timing, blood loss volume, clinical outcomes (scores on the Oswestry disability index [ODI], EQ-5D and visual analogue scale [VAS]) were evaluated in 6–12 months after surgical treatment. All the patients included in this study underwent functional and control computed tomography in 12 months after surgery. RESULTS: Both groups showed a significant improvement in VAS, EQ-5D, and ODI in 1 year after surgical treatment. The two groups significantly differed in the surgery timing (unilateral – 90.2 min; and bilateral – 129.4 min) and blood loss volume (unilateral – 152.7 ml; and bilateral – 230.1 ml), p < 0.05. CONCLUSIONS: Unilateral and bilateral pedicle screw fixation showed similar clinical results, while results in both types of fixation differed in slight manner. However, the duration of surgical treatment and intraoperative blood loss volume proved to be lower for the unilateral fixation group, which indicates that the use of the unilateral fixation can be the choice of performing posterior stabilization at a single-level instability of the spine without using an interbody cage.

Cadaveric biomechanical analysis of multilevel lateral lumbar interbody fusion with and without supplemental instrumentation

Background This study was to evaluate and compare the biomechanical features of multilevel lateral lumbar interbody fusion (LLIF) with or without supplemental instrumentations. Methods Six human lumbar specimens were tested under multidirectional nondestructive moments (7.5 N·m), with a 6 degree-of-freedom spine simulator. The overall and intervertebral range of motion (ROM) were measured optoelectronically. Each specimen was tested under the following conditions at L2–5 levels: intact; stand-alone; cage supplemented with lateral plate (LP); cage supplemented with unilateral or bilateral pedicle screw/rod (UPS or BPS). Results Compared with intact condition, the overall and intersegmental ROM were significantly reduced after multilevel stand-alone LLIF. The ROM was further reduced after using LP instrumentation. In flexion-extension (FE) and axial rotation (AR), pedicle screw/rod demonstrated greater overall ROM reduction compared to LP (P < 0.01), and bilateral greater than unilateral (P < 0.01). In lateral bending (LB), BPS demonstrated greater overall ROM reduction compared to UPS and LP (P < 0.01), however, UPS and LP showed similar reduction (P = 0.245). Intervertebral ROM reductions showed similar trend as the overall ones after using different types of instrumentation. However, at L2/3 (P = 0.57) and L3/4 (P = 0.097) levels, the intervertebral ROM reductions in AR were similar between UPS and LP. Conclusions The overall and intervertebral stability increased significantly after multilevel LLIF with or without supplemental instrumentation. BPS provided the greatest stability, followed by UPS and LP. However, in clinical practice, less invasive adjunctive fixation methods including UPS and LP may provide sufficient biomechanical stability for multilevel LLIF.

Biomechanical effect of cage position combined with bilateral pedicle screw fixation in the osteoporotic lumbar spine of oblique lumbar interbody fusion: a finite element analysis

Background: The influence of cage position on postoperative cage subsidence has been paid increasing attention. The best cage position in oblique lumbar interbody fusion (OLIF) is still unclear. This study aimed to evaluate the biomechanical effects of different cage positions with stand-alone (SA) methods and bilateral pedicle screw fixation (BPSF) in the osteoporotic lumbar spine after OLIF.Methods: A finite element (FE) model of an intact L3-L5 lumbar spine was constructed. After validation, an osteoporosis model (OP) was constructed by assigning osteoporotic material properties. SA models (SA1, SA2, SA3) and BPSF models (BPSF1, BPSF2, BPSF3) in which a cage was placed in the anterior, middle and posterior third of the L5 superior endplate (SEP) were constructed at the L4-L5 segment of the OP. The L4-L5 range of motion (ROM), the stress of the L5 SEP, the stress of the cage and the stress of fixation were compared among the different models.Results: According to the degree of ROM of L4-L5, the stress of the L5 SEP and the stress of the cage for most physiological motions, the SA and BPSF models were ranked as follows: SA2＜SA1＜SA3, BPSF2＜BPSF1＜BPSF3. In BPSF2, the stress of fixation was minimal in most motions. At the same cage position, the ROM of L4-L5, the stress of the L5 SEP and the stress of the cage in the BPSF models were significantly reduced compared with those in SA models; compared with SA2, BPSF2 had a maximum reduction of 83.24%, 70.71% and 73.52% in these parameters, respectively.Conclusions: Placing the cage in the middle third of the L5 SEP for OLIF could reduce the maximum stresses of the L5 SEP, the cage and the fixation, which may reduce the risk of postoperative cage subsidence, endplate collapse and fixation fracture in the osteoporotic lumbar spine. Compared with SA OLIF, BPSF could provide sufficient stability for the surgical segment and may reduce the incidence of the aforementioned complications.

Unilateral versus bilateral pedicle screw fixation with oblique lateral interbody fusion in the treatment of multi-level degenerative lumbar disease: a prospective study

Background: The purpose of this study was to compare the clinical and radiological outcomes of oblique lateral interbody fusion (OLIF) combined with unilateral (UPSF) and bilateral pedicle screw fixation (BPSF) in the treatment of multi-level degenerative lumbar disease (LDD).Methods: We conducted a prospective study from May 2016 to June 2018. A total of 81 LDD patients were randomized into groups. The first group involving 39 patients received OLIF combined with USPF (UPS group), and the second group of 41 patients received OLIF combined with BPSF (BPS group). The perioperative conditions included intraoperative bleeding, operating time, average hospital stay, and hospitalization expenses. The clinical outcomes included Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and complications. Moreover, the radiological outcomes included disc height, fusion rate, and cage subsidence rate. These perioperative conditions, clinical outcomes, and radiological conditions of the two study groups were evaluated and compared. All the patients were followed up for 24 to 28 months, with an average follow-up time of 26 months.Results: The intraoperative bleeding, operating time, and hospitalization expenses of the UPS group were significantly less compared with those of the BPS group. Compared with preoperatively, the VAS and ODI scores of the two groups were improved significantly after the operation. At 6 months after operation, the VAS score for back pain and ODI of the UPS group were better than in the BPS group (P < 0.05). Both groups were able to maintain the intervertebral space height of the fusion segment, and there was no significant difference in the fusion rate at the 24 months. There were no significant differences in complications. At the 24 months, there was no significant difference in the cage subsidence of the fusion segment between the two groups. Finally, there was no loose screw and screw fracture in both groups.Conclusions: OLIF combined with UPSF is an effective and reliable surgical method for the treatment of multilevel LDD.

Unilateral Versus Bilateral Pedicle Screw Fixation With Oblique Lateral Interbody Fusion in the Treatment of Multi-level Degenerative Lumbar Disease: a Prospective Study

Background: The purpose of this study was to compare the clinical and radiological outcomes of oblique lateral interbody fusion (OLIF) combined with unilateral (UPSF) and bilateral pedicle screw fixation (BPSF) in the treatment of multi-level degenerative lumbar disease (LDD).Methods: We conducted a prospective study from May 2016 to June 2018. A total of 81 LDD patients were randomized into groups. The first group involving 39 patients received OLIF combined with USPF (UPS group), and the second group of 41 patients received OLIF combined with BPSF (BPS group). The perioperative conditions included intraoperative bleeding, operating time, average hospital stay, and hospitalization expenses. The clinical outcomes included Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and complications. Moreover, the radiological outcomes included disc height, fusion rate, and cage subsidence rate. These perioperative conditions, clinical outcomes, and radiological conditions of the two study groups were evaluated and compared. All the patients were followed up for 24 to 28 months, with an average follow-up time of 26 months.Results: The intraoperative bleeding, operating time, and hospitalization expenses of the UPS group were significantly less compared with those of the BPS group. Compared with preoperatively, the VAS and ODI scores of the two groups were improved significantly after the operation. At 6 months after operation, the VAS score for back pain and ODI of the UPS group were better than in the BPS group (P < 0.05). Both groups were able to maintain the intervertebral space height of the fusion segment, and there was no significant difference in the fusion rate at the 24 months. There were no significant differences in complications. At the 24 months, there was no significant difference in the cage subsidence of the fusion segment between the two groups. Finally, there was no loose screw and screw fracture in both groups.Conclusions: OLIF combined with UPSF is an effective and reliable surgical method for the treatment of multilevel LDD.