Unilateral Pedicle Screw Research Articles

Novel Technique for Degenerative Lumbar Spine Fusion: Unilateral Pedicle Screw Fixation Combined with Contralateral Interbody Cage Fusion for Posterior Lumbar Interbody Fusion

Abstract Objective The common traditional surgical techniques for posterior lumbar interbody fusion (PLIF) and fixation are bilateral pedicle screw fixation with or without interbody cage fusion and unilateral pedicle screw fixation with ipsilateral cage fusion. However, the novel unilateral pedicle screw fixation combined with the contralateral interbody cage fusion technique may provide the benefits and avoid the hazards of those traditional techniques. This prospective randomized comparative clinical trial aims to compare pedicle screw fixation with contralateral interbody cage fusion and unilateral pedicle screw fixation with ipsilateral cage fusion in single-level PLIF and fixation. Methods This comparative prospective study was conducted on 60 patients subjected to a single-level PLIF and unilateral pedicle screw fixation during the period from January 2022 to July 2022 to compare two different surgical modalities: group A (unilateral pedicle screw fixation with contralateral interbody cage fusion) and group B (unilateral pedicle screw fixation with ipsilateral cage fusion). Results Operative time, blood loss, operative complications, and visual analog scale improvements showed insignificant differences between the two groups, while group A showed significant improvements in the Oswestry Disability Index and wider coronal disc heights contralateral to the screw, which is the side of the cages, during postoperative follow-up. Conclusion Unilateral pedicle screw fixation with contralateral cage fusion during the PLIF and pedicle screw fixation procedure is preferred to maintain bilateral coronal disc heights and thus better clinical and mechanical results without affection of the preceding disc.

Innovative 3D Navigation Module for Precise Unilateral Pedicle Screw Combined with Contralateral Translaminar Facet Screw Placement in Lumbar Spine Surgery.

The incidence of degenerative diseases of the lumbar spine has increased in recent years. Unilateral pedicle screw combined with contralateral translaminar facet screw fixation offers the advantages of less trauma, better stability, and fewer complications. However, the surgical difficulty and suboptimal pinning accuracy of translaminar facet screw placement in clinical practice limit its use. Therefore, in this study, we designed a novel suspended 3D-printed navigation module to facilitate fast and accurate intraoperative screw placement. The aim of this study is to investigate the digital design, precise implementation, and evaluation methods for placing unilateral pedicle screws in the lumbar spine combined with translaminar facet screw placement using a new suspended 3D navigation module. This retrospective study included 46 patients with single-level lumbar lesions who underwent spine surgery at the Affiliated Hospital of Putian University between June 2022 and December 2023. The suspended navigation module was designed digitally. Preoperative screw placement was simulated using 3D printed models, followed by an intraoperative accurate screw placement facilitated by the navigation module and a postoperative evaluation of the accuracy of screw placement. The absolute difference in three-dimensional coordinates of the inlet and outlet points of the preoperative design and the postoperative screw-nail channel served as the precision index. In a study involving 46 patients, surgery was successful with 92 pedicle screws and 46 translaminar facet screws placed without any penetration of the cortex. The difference in coordinates before and after screw insertion was minimal, with entry points varying between 1.21 to 1.36 mm and exit points between 1.97 to 2.46 mm. When screw accuracy met certain thresholds, there was no significant difference between preoperative design and postoperative coordinates, indicating precise replication of the surgical plan. The new suspended 3D navigation module enables the precise placement of unilateral pedicle screws in the lumbar spine combined with translaminar pedicle screws for precise surgery.

Biomechanical changes of oblique lumbar interbody fusion with different fixation techniques in degenerative spondylolisthesis lumbar spine: a finite element analysis

ObjectiveThere is a dearth of comprehensive research on the stability of the spinal biomechanical structure when combining Oblique Lumbar Interbody Fusion (OLIF) with internal fixation methods. Hence, we have devised this experiment to meticulously examine and analyze the biomechanical changes that arise from combining OLIF surgery with different internal fixation techniques in patients diagnosed with degenerative lumbar spondylolisthesis.MethodsSeven validated finite element models were reconstructed based on computed tomography scan images of the L3-L5 segment. These models included the intact model, a stand-alone (S-A) OLIF model, a lateral screw rod (LSR) OLIF model, a bilateral pedicle screw (BPS) OLIF model, an unilateral pedicle screw (UPS) OLIF model, a bilateral CBT (BCBT) OLIF model, and an unilateral CBT(UCBT) OLIF model. The range of motion (ROM), as well as stress levels in the cage, L4 lower endplate, L5 upper endplate, and fixation constructs were assessed across these different model configurations.ResultsS-A model had the highest average ROM of six motion modes, followed by LSR, UPS, UCBT, BPS and BCBT. The BCBT model had a relatively lower cage stress than the others. The maximum peak von Mises stress of the fixation constructs was found in the LSR model. The maximum peak von Mises stress of L4 lower endplate was found in the S-A model. The peak von Mises stress on the L4 lower endplate of the rest surgical models showed no significant difference. The maximum peak von Mises stress of the L5 upper endplate was found in the S-A model. The minimum peak von Mises stress of the L5 upper endplate was found in the BCBT model. No significant difference was found for the peak von Mises stress of the L5 upper endplate among LSR, BPS, UPS and UCBT models.ConclusionAmong the six different fixation techniques, BCBT exhibited superior biomechanical stability and minimal stress on the cage-endplate interface. It was followed by BPS, UCBT, UPS, and LSR in terms of effectiveness. Conversely, S-A OLIF demonstrated the least stability and resulted in increased stress on both the cage and endplates. Combining OLIF with BCBT fixation technique enhanced biomechanical stability compared to BPS and presented as a less invasive alternative treatment for patients with degenerative lumbar spondylolisthesis.

Unilateral versus bilateral pedicle screw fixation with anterior lumbar interbody fusion: a comparison of postoperative outcomes.

To determine of the impact of ALIF with minimally invasive unilateral pedicle screw fixation (UPSF) versus bilateral pedicle screw fixation (BPSF) on perioperative outcomes, radiographic outcomes, and the rates of fusion, subsidence, and adjacent segment stenosis. All adult patients who underwent one-level ALIF with UPSF or BPSF at an academic institution between 2015 and 2022 were retrospectively identified. Postoperative outcomes including length of hospital stay (LOS), wound complications, readmissions, and revisions were determined. The rates of fusion, screw loosening, adjacent segment stenosis, and subsidence were assessed on one-year postoperative CT. Lumbar alignment including lumbar lordosis, L4-S1 lordosis, regional lordosis, pelvic tilt, pelvic incidence, and sacral slope were assessed on standing x-rays at preoperative, immediate postoperative, and final postoperative follow-up. Univariate and multivariate analysis compared outcomes across posterior fixation groups. A total of 60 patients were included (27 UPSF, 33 BPSF). Patients with UPSF were significantly younger (p = 0.011). Operative time was significantly greater in the BPSF group in univariate (p < 0.001) and multivariate analysis (ß=104.1, p < 0.001). Intraoperative blood loss, LOS, lordosis, pelvic parameters, fusion rate, subsidence, screw loosening, adjacent segment stenosis, and revision rate did not differ significantly between fixation groups. Though sacral slope (p = 0.037) was significantly greater in the BPSF group, fixation type was not a significant predictor on regression. ALIF with UPSF relative to BPSF predicted decreased operative time but was not a significant predictor of postoperative outcomes. ALIF with UPSF can be considered to increase operative efficiency without compromising construct stability.

Comparative Biomechanical Analysis of Unilateral, Bilateral, and Lateral Pedicle Screw Implantation in Oblique Lumbar Interbody Fusion: A Finite Element Study.

Oblique lumbar interbody fusion (OLIF) can be combined with different screw instrumentations. The standard screw instrumentation is bilateral pedicle screw fixation (BPSF). However, the operation is time consuming because a lateral recumbent position must be adopted for OLIF during surgery before a prone position is adopted for BPSF. This study aimed to employ a finite element analysis to investigate the biomechanical effects of OLIF combined with BPSF, unilateral pedicle screw fixation (UPSF), or lateral pedicle screw fixation (LPSF). In this study, three lumbar vertebra finite element models for OLIF surgery with three different fixation methods were developed. The finite element models were assigned six loading conditions (flexion, extension, right lateral bending, left lateral bending, right axial rotation, and left axial rotation), and the total deformation and von Mises stress distribution of the finite element models were observed. The study results showed unremarkable differences in total deformation among different groups (the maximum difference range is approximately 0.6248% to 1.3227%), and that flexion has larger total deformation (5.3604 mm to 5.4011 mm). The groups exhibited different endplate stress because of different movements, but these differences were not large (the maximum difference range between each group is approximately 0.455% to 5.0102%). Using UPSF fixation may lead to higher cage stress (411.08 MPa); however, the stress produced on the endplate was comparable to that in the other two groups. Therefore, the length of surgery can be shortened when unilateral back screws are used for UPSF. In addition, the total deformation and endplate stress of UPSF did not differ much from that of BPSF. Hence, combining OLIF with UPSF can save time and enhance stability, which is comparable to a standard BPSF surgery; thus, this method can be considered by spine surgeons.

Design and Biomechanical Evaluation of a Bidirectional Expandable Cage for Oblique Lateral Interbody Fusion

Oblique lateral interbody fusion (OLIF) surgery is a minimally invasive spinal surgery technique that has become increasingly popular in recent years. The primary objective of the current study was to design a minimally invasive expandable fusion device that can reduce iatrogenic nerve damage and minimize endplate damage during OLIF surgery, while restoring intervertebral height and alignment. The second objective was to use finite element analysis to evaluate the biomechanical stability of the newly designed expandable fusion device after implantation into the intervertebral space. A new bidirectional expandable cage was designed in this study. A finite element model (FEM) of L3-L5 lumbar segment was modified to simulate decompression and fusion. The modified FEMs were constructed in the following cases: intact model, bidirectional expandable cage (alone, with unilateral pedicle screws [UPSs], and with bilateral pedicle screws [BPSs]) model, conventional OLIF cage (alone, with UPSs, and with BPSs) model. To simulate physiological loadings, the models were subjected to a follower compressive pre-load of 400 N, in addition to 8.0 Nm of flexion, extension, lateral bending, and axial rotation moments. All modified FEMs exhibited a significant reduction in motion at L3-L5 compared to the intact model. Among the fusion models, the bidirectional expandable cage (BEC) with BPS model displayed the highest stiffness and demonstrated a reduced range of motion (48.5%-75.7%). Additionally, the peak stress on the endplate in the conventional OLIF cage (Conv-OLIF) model was generally lower than that in the BEC models. The cage in the BEC ALONE model exhibited the highest stress (93.87-176.3 MPa) on the endplate in most motion modes, while the cage in the Conv-OLIF+BPS model had the lowest stress (16.67-30.58 MPa) on the endplate in most motion modes. The maximum stress on the fixation in the BEC fusion models was generally lower than that in the Conv-OLIF fusion group under the same loading conditions. The OLIF ALONE model had the lowest stress on the adjacent disc, while the stress level in the BEC ALONE model was very close to it. The BEC implanted models had higher stiffness, and more proper stress distribution on the posterior fixation was comparable to that of the Conv-OLIF models. However, the endplate stress peaks and cage stress peaks of the BEC models were slightly higher than those of the Conv-OLIF models, though still within a clinically acceptable range. Taking into account both biomechanical and clinical perspectives, BEC-assisted unilateral pedicle screw fixation meet clinical demand and may serve as a viable alternative to Conv-OLIF fusion.

Unilateral pedicle screw fixation with interbody fusion in lumbar degenerative disease

ObjectiveUnilateral transpedicular screw is widely used in lumbar spine surgery due to its primary role in enhancing arthrodesis with less tissue damage when combined with posterolateral lumbar interbody fusion (PLIF). Unilateral instrumentation can achieve similar outcomes to those of bilateral instrumentation. Its advantage is that it precludes the possibility of damaging the contralateral soft tissues and muscles. Our study assess the operative efficacy and benefits of unilateral pedicle screw (PS) fixation and decompression with interbody diagonal cage for lower lumbar degenerative diseases (LDD). Patients and MethodsA total of 60 consecutive patients who underwent either a bilateral or unilateral procedure (30 patients in each group) for treating lower LDD were included in this study. Radiological and clinical assessments were performed at 3, 6, and 12 months after surgery to assess interbody fusion rates and clinical outcomes. ResultsNo significant differences were observed between the two cohorts regarding age, gender, weight, presence of comorbidities, or baseline neurologic deficit. The unilateral cases showed statistically significant less surgical trauma in terms of fluoroscopy time, operative time, intraoperative blood transfusion, and length of incision. The clinical and radiological outcomes in both cohorts were quite similar. ConclusionBoth unilateral and bilateral PS fixations with PLIF have quite similar outcomes for LDD. However, based on its minimal invasiveness, the unilateral approach can be an attractive alternative to bilateral instrumentation. Our study recommends unilateral short-segment fixation as an appropriate choice in selected cases.

Biomechanical stability of oblique lateral interbody fusion combined with four types of internal fixations: finite element analysis.

Objective: Using finite element analysis to identify the optimal internal fixation method for oblique lateral lumbar interbody fusion (OLIF), providing guidance for clinical practice. Methods: A finite element model of the L4 - L5 segment was created. Five types of internal fixations were simulated in the generated L4-L5 finite element (FE) model. Then, six loading scenarios, i.e., flexion, extension, left-leaning, right-leaning, rotate left, and rotate right, were simulated in the FE models with different types of fixations. The biomechanical stability of the spinal segment after different fixations was investigated. Results: Regarding the range of motion (ROM) of the fused segment, OLIF + Bilateral Pedicle Screws (BPS) has a maximum ROM of 1.82° during backward bending and the smallest ROM in all directions of motion compared with other models. In terms of the von Mises stress distribution on the cage, the average stress on every motion direction of OLIF + BPS is about 17.08MPa, and of OLIF + Unilateral Vertebral Screw - Pedicle Screw (UVS-PS) is about 19.29MPa. As for the von Mises stress distribution on the internal fixation, OLIF + BPS has the maximum internal fixator stress in left rotation (31.85MPa) and OLIF + Unilateral Pedicle Screw (UPS) has the maximum internal fixator stress in posterior extension (76.59MPa). The data of these two models were smaller than those of other models. Conclusion: OLIF + BPS provides the greatest biomechanical stability, OLIF + UPS has adequate biomechanical stability, OLIF + UVS-PS is inferior to OLIF + UPS synthetically, and OLIF + Double row vertical screw (DRVS) and Individual OLIF (IO) do not present significant obvious advantages.

Minimally invasive transforaminal lumbar interbody fusion with unilateral pedicle screw fixation (UNILF): outcomes at 7years.

To assess clinical, functional and radiographical results of one-level minimally invasive transforaminal interbody fusion with unilateral pedicle screw fixation (UNILIF) in the treatment of stable lumbar degenerative diseases with a minimum of 5years of follow-up. From January 2012 to December 2016, clinical and radiological data of patients with degenerative lumbar disease managed by UNILIF were prospectively collected. Patients with a follow-up that ended before 5years were excluded. SF-12, Oswestry disability index (ODI) and visual analog scale (VAS) were collected preoperatively, at 2 years and at the last follow-up. A full-spine standing radiograph was performed at each follow-up appointment. Mean operative time was 74.7 (± 19) minutes, mean blood loss was 131.1 (± 207) ml and mean follow-up was 7.5 (± 1.7) years. All functional scores and VAS were significantly improved between the preoperative and the 2 years postoperative. Between the 2 years postoperative and the last follow-up ODI and VAS continued to significantly improved. Fusion rate was 98.6% on radiographic analysis at follow-up. UNILIF method is a safe and effective surgical strategy. It provides a durable improvement in functional score over 7years of follow-up with a stable radiological correction over time.

Interspinous-Interbody Fusion via a Strictly Lateral Surgical Approach: A Biomechanical Stabilization Comparison to Constructs Requiring Both Lateral and Posterior Approaches.

Objective Lumbar fusion performed through lateral approaches is becoming more common. The interbody devices are generally supported by supplemental posterior fixation implanted through a posterior approach, potentially requiring a second incision and intraoperative repositioning of the patient. A minimally invasive lateral interspinous fixation device may eliminate the need for intraoperative repositioning and avoid disruption of the supraspinous ligament. The objective of this in vitrobiomechanical study was to investigate segmental multidirectional stability and maintenance of foraminal distraction of a lateral interspinous fixation device compared to commonly used pedicle screw and facet screw posterior fixation constructs when combined with lumbar interbody cages. Methods Six human cadaver lumbar spine specimens were subjected to nondestructive quasistatic loading in the following states: (1) intact; (2) interspinous fixation device alone and (3) with lateral interbody cage; (4) lateral lumbar interbody cage with bilateral pedicle screws; (5) lateral lumbar interbody cage with unilateral pedicle screws; and (6) lateral lumbar interbody cage with facet screws. Multidirectional pure bending in 1.5 Nm increments to 7.5 Nm, and 7.5 Nm flexion-extension bending with a 700 N compressive follower load were performed separately with optoelectronic segmental motion measurement. Relative angular motions of L2-L3, L3-L4, and L4-L5 functional spinal units were evaluated, and the mean instantaneous axis of rotation in the sagittal plane was calculated for the index level.Foraminal height was assessed during combined flexion-extension and compression loading for each test construct. Results All implant configurations significantly restricted flexion-extension motion compared with intact (p < 0.05). No significant differences were found in flexion-extension when comparing the different posterior implants combined with lateral lumbar interbody cages. All posterior fixation devices provided comparable neuroforaminal distraction and maintained distraction during flexion and extension. Conclusions When combinedwith lateral lumbar interbody cages, the minimally invasive lateral interspinous fixation device effectively stabilized the spine and maintained neuroforaminal distraction comparable to pedicle screw constructs or facet screws. These results suggest the lateral interspinous fixation device may provide a favorable alternative to other posterior systems that require patient repositioning during surgery and involve a greater disruption of native tissues.

Far lateral lumbar interbody fusion with unilateral pedicle screw fixation and double traversing cages using a biportal endoscopic technique.

Transforaminal lumbar interbody fusion (TLIF) with a single cage and bilateral pedicle screw fixation results in decreased stability or increased risk of cage displacement Wang and Guo (Comput Methods Biomech Biomed Eng, 24(3):308-319, 6). We succeeded in inserting double traversing cages with unilateral pedicle screw fixation (UPSF) during far lateral TLIF using unilateral biportal endoscopy (UBE). We attempted far lateral UBE-TLIF through two small incisions for degenerative lumbar spondylolisthesis with unilateral stenosis. With the help of novel instruments, far lateral UBE-TLIF with double traversing cages and UPSF was performed under trachealintubationanaesthesia. We successfully performed far lateral UBE-TLIF with double traversing cages and UPSF. This procedure may be an alternative minimally invasive method for treating lumbar instability.

Biomechanical Analysis of Double-Level Oblique Lumbar Fusion with Different Types of Fixation: A Finite Element-Based Study.

One well-liked less invasive procedure is oblique lumbar interbody fusion (OLIF). The biomechanical characteristics of double-level oblique lumbar interbody fusion in conjunction with various internal fixations are poorly understood. The purpose of this study was to clarify the biomechanical characteristics of double-level oblique lumbar interbody fusion for osteoporosis spines using various internal fixation techniques. Based on CT scans of healthy male volunteers, a complete finite element model of osteoporosis in L1-S1 was established. After validation, L3-L5 was selected as the surgical segment to construct four surgical models: (a) two stand-alone cages (SA); (b) two cages with unilateral pedicle screws (UPS); (c) two cages with bilateral pedicle screws (BPS); and (d) two cages with bilateral cortical bone trajectory screws (CBT). Segmental range of motion (ROM), cage stress, and internal fixation stress were studied in all surgical models and compared with the intact osteoporosis model. The SA model had a minimal reduction in all motions. The CBT model had the most noticeable reduction in flexion and extension activities, while the reduction in the BPS model was slightly less than that in the CBT model but larger than that in the UPS model. The BPS model had the greatest limitation in left-right bending and rotation, which was greater than the UPS and CBT models. CBT had the smallest limitation in left-right rotation. The cage stress of the SA model was the highest. The cage stress in the BPS model was the lowest. Compared with the UPS model, the cage stress in the CBT model was larger in terms of flexion and LB and LR but slightly smaller in terms of RB and RR. In the extension, the cage stress in the CBT model is significantly smaller than in the UPS model. The CBT internal fixation was subjected to the highest stress of all motions. The BPS group had the lowest internal fixation stress in all motions. Supplemental internal fixation can improve segmental stability and lessen cage stress in double-level OLIF surgery. In limiting segmental mobility and lowering the stress of cage and internal fixation, BPS outperformed UPS and CBT.

Osteoid Osteomas of Spine: From Open to Minimally Invasive Excision of the Nidus – A Case series

Osteoid osteomas of spine are not uncommon and majority of which occurs in posterior elements of lumbar spine. Management of such lesions in spine ranges from open en bloc excision to percutaneous radiofrequency ablation. In this series, we have managed three cases of osteoid osteomas of spine, each managed differently from conventional open technique to minimally invasive method. All three cases underwent appropriate radiological investigations and followed by surgical excision of the lesion and histopathological analysis post-operatively. First case was managed with open excision of the lesion with conventional unilateral pedicle screw stabilisation. Second case, who underwent open excision of the lesion developed recurrence which was managed by re-excision without any further complications. Last case underwent microendoscopic quadrant tubular excision of the tumour with unilateral MISS with pedicle screws. The technique of Microendoscopic quadrant tubular excision of posterior element benign tumour had advantages of small skin incision, less bleeding, clear macroscopic visualisation of the small tumour (enables complete excision of the nidus thus decreasing the recurrence), early mobilisation and shorter hospitalization with effective and complete excision of the tumour better than open method. Further, histological evidence of tumour will be available. The complete excision of nidus using microendoscopic tubular retractors with unilateral fixation in young age gives encouraging results. This case series is followed by review of literature highlighting the role of COX-2 inhibitors in osteoid osteoma, cause for scoliosis and neurological deficit in osteoid osteoma and management of osteoid osteomas of spine. Keywords: Tumor, Osteoid osteoma, Minimally invasive, Dorsolumbar spine, Excision biopsy

Biomechanical assessment of lumbar stability: finite element analysis of TLIF with a novel combination of coflex and pedicle screws.

Purpose: Finite element analysis is frequently used for lumbar spine biomechanical analysis. The primary scope of this work is to illustrate, using finite element analysis, how the biomechanical behavior of the transforaminal lumbar interbody fusion (TLIF), along with a novel combination of the interspinous process device (IPD) and pedicle screws, improves lumbar spine stability. Methods: In this study, unilateral pedicle screw fixation (UPSF) and bilateral pedicle screw fixation (BPSF) were used. Four FE models were developed using ANSYS software, as follows: (1) Intact model; (2) TLIF with "U"-shaped Coflex-F IPD (UCF); (3) TLIF with Coflex-F and UPSF (UCF + UPSF); (4) TLIF with Coflex-F and BPSF (UCF + BPSF). The intact model was subjected to four pure moments (10 Nm), and the results were validated with previous literature data. The intact model results correlated well with the literature data, and the model was validated. Three surgical models were subjected to 7.5 Nm four pure moments, flexion (FL), extension (ET), lateral bending (LB), and axial rotation (AR) and a 280N follower load. Results: The surgical model results were compared with the intact model. The comprehensive analysis results show the UCF + BPSF surgical model gave a good advantage on range of motion, cage stress, Coflex-F stress and endplate stress compared among the two models. Conclusion: This study proposes that the UCF + BPSF system helps to reduce the stress on the implant and adjacent endplates and gives very good stability to the lumbar spine under the various static loading conditions.

Biomechanical Comparison of Unilateral and Bilateral Pedicle Screw Fixation after Multilevel Lumbar Lateral Interbody Fusion.

Human Cadaveric Biomechanical Study. Lumbar Lateral Interbody Fusion (LLIF) utilizing a wide cage has been reported as having favorable biomechanical characteristics. We examine the biomechanical stability of unilateral pedicle screw and rod fixation after multilevel LLIF utilizing 26mm wide cages compared to bilateral fixation. Eight human cadaveric specimens of L1-L5 were included. Specimens were attached to a universal testing machine (MTS 30/G). Three-dimensional specimen range of motion (ROM) was recorded using an optical motion-tracking device. Specimens were tested in 3 conditions: 1) intact, 2) L1-L5 LLIF (4 levels) with unilateral rod, 3) L1-L5 LLIF with bilateral rods. From the intact condition, LLIF with unilateral rod decreased flexion-extension by 77%, lateral bending by 53%, and axial rotation by 26%. In LLIF with bilateral rods, flexion-extension decreased by 83%, lateral bending by 64%, and axial rotation by 34%. Comparing unilateral and bilateral fixation, LLIF with bilateral rods reduced ROM by a further 23% in flexion-extension, 25% in lateral bending, and 11% in axial rotation. The difference was statistically significant in flexion-extension and lateral bending (P < .005). Considerable decreases in ROM were observed after multilevel (4-level) LLIF utilizing 26mm cages supplemented with both unilateral and bilateral pedicle screws and rods. The addition of bilateral fixation provides a 10-25% additional decrease in ROM. These results can inform surgeons of the incremental biomechanical benefit when considering unilateral or bilateral posterior fixation after multilevel LLIF.

Successful outcomes of unilateral vs bilateral pedicle screw fixation for lumbar interbody fusion: A meta-analysis with evidence grading.

Whether it's better to adopt unilateral pedicle screw (UPS) fixation or to use bilateral pedicle screw (BPS) one for lumbar degenerative diseases is still controversially undetermined. To make a comparison between UPS and BPS fixation as to how they work efficaciously and safely in patients suffering from lumbar degenerative diseases. We have searched a lot in the databases through 2020 with index terms such as "unilateral pedicle screw fixation" and "bilateral pedicle screw fixation." Only randomized controlled trials and some prospective cohort studies could be found, yielding 15 studies. The intervention was unilateral pedicle screw fixation; Primarily We've got outcomes of complications and fusion rates. Secondarily, we've achieved outcomes regarding total blood loss, operative time, as well as length of stay. Softwares were installed and utilized for subgroup analysis, analyzing forest plots, sensitivity, heterogeneity, forest plots, publication bias, and risk of bias. Fifteen previous cases of study including 992 participants have been involved in our meta-analysis. UPS had slightly lower effects on fusion rate [relative risk (RR) = 0.949, 95%CI: 0.910 to 0.990, P = 0.015], which contributed mostly to this meta-analysis, and similar complication rates (RR = 1.140, 95%CI: 0.792 to 1.640, P = 0.481), Δ visual analog scale [standard mean difference (SMD) = 0.178, 95%CI: -0.021 to 0.378, P = 0.080], and Δ Oswestry disability index (SMD = -0.254, 95%CI: -0.820 to 0.329, P = 0.402). In contrast, an obvious difference has been observed in Δ Japanese Orthopedic Association (JOA) score (SMD = 0.305, 95%CI: 0.046 to 0.563, P = 0.021), total blood loss (SMD = -1.586, 95%CI: -2.182 to -0.990, P = 0.000), operation time (SMD = -2.831, 95%CI: -3.753 to -1.909, P = 0.000), and length of hospital stay (SMD = -0.614, 95%CI: -1.050 to -0.179, P = 0.006). Bilateral fixation is more effective than unilateral fixation regarding fusion rate after lumbar interbody fusion. However, JOA, operation time, total blood loss, as well as length of stay were improved for unilateral fixation.

Unilateral biportal endoscopic extreme transforaminal lumbar interbody fusion with large cage combined with endoscopic unilateral pedicle screw fixation for lumbar degenerative diseases: a technical note and preliminary effects.

The purpose of the study was to investigate the feasibility and preliminary effects of unilateral biportal endoscopic extreme transforaminal lumbar interbody fusion(UBE-eXTLIF) with large cage combined with endoscopic unilateral pedicle screw fixation for lumbar degenerative diseases. Patients with lumbar degenerative diseases who received UBE-eXTLIF with large cage combined with endoscopic unilateral pedicle screw fixation from June 2022 to July 2022 were retrospectively analyzed, including 4 females and 1 males. The clinical symptoms and signs were consistent with the imaging changes. We recorded operation time, length of postoperative hospital stay, and complications. Visual Analogue Scale (VAS), Oswestry Disability Index (ODI), and modified Macnab scale was used to evaluate the clinical efficacy at preoperative, postoperative 1month, and the last follow-up. The operation was successfully completed in all cases. The operation time was 150-180min, with an average of 164.60 ± 12.03min. No serious complications such as dural tears and vascular and nerve injuries occurred during operation. All the patients got out of bed 1-3days after surgery and were hospitalized 4-5days after surgery, with an average of 4.20 ± 0.45days. Preoperative VAS scores of low back pain were 6.20 ± 0.84 and respectively decreased to 2.20 ± 0.45 and 1.40 ± 0.55 at postoperative 1month and at the last follow-up, and the difference was statistically significant (P < 0.05). Preoperative VAS scores of lower limb pain were 4.60 ± 2.61 and respectively decreased to 1.00 ± 0.71 and 0.60 ± 0.55 at postoperative 1month and at the last follow-up, and the difference was statistically significant (P < 0.05). Preoperative ODI scores were 62.00 ± 3.16 and respectively decreased to 38.00 ± 1.41 and 32.40 ± 3.29 at postoperative 1month and at the last follow-up, and the difference was statistically significant (P < 0.05). According to the modified Macnab criteria, the final outcome was excellent in 4 cases and good in 1 case. Five patients could return to normal activities within 3weeks. UBE-eXTLIF with large cage combined with endoscopic unilateral pedicle screw fixation can achieve excellent clinical results and may become a new minimally invasive endoscopic fusion method for lumbar degenerative diseases.

Unilateral pedicle screw fixation of lumber spine: A safe internal fixation method

BackgroundUnilateral pedicle screw fixation several advantages, including reduced trauma and low cost. However, its stability and safety have not been widely recognized. In this study, the biomechanical differences in the vertebral body and screw-rod system after unilateral and bilateral pedicle screw fixation were compared using both the finite element model and calf lumbar model. MethodWe used the verified finite element model to establish unilateral and bilateral posterior lumbar surgery models. The biomechanical data of different parts of the models were recorded under different working states. Then, three calf lumbar models were selected to simulate different working states with the help of a universal testing machine and other instruments. Finally, the biomechanical data of the screw-rod system were obtained from a static strain test and analysis system. ResultsBy analyzing and comparing biomechanical data obtained using two different methods, this study found that unilateral pedicle screw fixation does not bring excessive loads to the lumbar spine and screw-rod system. ConclusionFrom the perspective of biomechanics, unilateral pedicle screw fixation is considered a safe and reliable implantation technique.

Minimally Invasive Transforaminal Lumbar Interbody Fusion with Enhanced Recovery after Surgery (ERAS): Early Experience with Initial Consecutive Cases at a Spine Naïve Community Hospital

Objective: The objective of this study was to examine a spine naïve community hospital’s ability to perform MITLIF safely and with speedy discharge via implementation of a minimally invasive spine surgery (MISS) program utilizing ERAS. Methods: Single community hospital retrospective cohort analysis for initial consecutive MITLIF cases with unilateral pedicle screws performed by a single surgeon from October 2019 to March 2021. Minimum postoperative follow-up was one year. Narcotic use was assessed per the state prescription drug monitoring program. Surgery protocol included single paraspinal incision, non-expandable 18/22 mm tube, operating microscope, fluoroscopic guidance, EMG with SSEP monitoring and Enhanced Recovery After Surgery (ERAS) protocol. Results: 52 patients were included. Average OR time, and fluoroscopy time were 143±115 minutes, and 1.00±0.47 minutes, respectively. Patients were prescribed an average of 38±33 post-operative opioid doses for an average of 8±7 days. All patients on preoperative, chronic narcotics had no prescription changes, pre-op versus post-op, despite clinical improvement. Complications included one irrigation a(1.9%) nd debridement with retention of hardware for surgical site infection, and one revision(1.9%) for displaced hardware. Discharge data included 47 (90.4%), four (7.7%), and one patients (1.9%) discharged on POD1, POD2, and beyond POD2, respectively.Conclusion: MITLIF can be safely and successfully performed at a spine naïve community hospital with excellent intraoperative metrics, a low complication rate, and speedy discharge. MITLIF performed well in multiple perioperative and postoperative variables compared to MISS techniques. Considerations for implementation of MITLIF in the community setting include special equipment, personnel training, surgeon experience, ERAS protocols and diligent patient/indication selection.

Clinical efficacy of oblique lumbar interbody fusion combined with unilateral pedicle screw fixation via Wiltse approach in the treatment of lumbar spinal stenosis

To evaluate the efficacy of oblique lumbar interbody fusion combined with unilateral pedicle screw fixation via Wiltse approach in the treatment of lumbar spinal stenosis. From July 2017 to January 2019, 90 patients with lumbar spinal stenosis, including 38 males and 52 females, aged from 43 to 75 years old with an average of(59.9±8.8) years old, and were treated with oblique lumbar interbody fusion(OLIF) combined with Wiltse unilateral pedicle screw fixation. Surgical decompression and fixation was performed in 50 cases of single segment, 32 cases of double segments and 8 cases of three segments. The distribution of responsible segments included 8 cases of L2-L3, 12 cases of L3-L4 and 30 cases of L4-L5 on single segment, 10 cases of L2-L4 and 22 cases of L3-L5 on double segments, and 8 cases of L2-L5 on three segments. The operation time, blood loss and occurrence of complications were recorded, Visual analogue scale(VAS), Oswestry Disability Index(ODI) and SF-36 scale were used to evaluate clinical efficacy. Lumbar X-ray and MRI were taken at three days after operation, interverterbral space height, intervertebral foraminal height, interverterbral foraminal area, and spinal canal area were measured, and interbody fusion was evaluated according to CT at half a year after operation. All patients were followed up from 12 to 33 months, with an average of (20.2±6.6) months. Mean operation time was (103.3±35.9) min, and mean intraoperative blood loss was (70.4±17.8) ml. VAS of low back pain leg pain, and ODI decreased from 6.2±1.1, 6.1±0.9 and (59.9±4.2)% to 2.7±0.5, 2.5±0.5 and (31.3±8.8)%. SF-36 scale significantly increased from (37.2±3.1) to (54.9±6.1) at the six months postoperation(P<0.05). The intervertebral space height, intervertebral foraminal height, intervertebral foraminal area, and spinal canal area were significantly improved at 3 days after operation(P<0.05). Six months after operation, CT scan showed well fusion in 87 cases, but 3 cases with poor fusion, including 1 case of single segment, 2 cases of multi-segments. The total fusion rate was 96.7% (87/90), the single segment fusion rate was 98.0% (49/50), and the multi-segments fusion rate was 95.0%(38/40). The overall incidence of complications was 17.8%(16/90), including transient iliopsoas muscle weakness in 5 cases (5.6%), endplate fracture in 2 cases (2.2%), peritoneal injury in 1 case (1.1%), postoperative hematoma in 1 case (1.1%), adjacent segment disease in 1 case(1.1%), and fusion cage subsidence in 6 cases (6.7%). Three patients was followed up for recurrent nerve root pain and the symptoms were relieved after revision operation. All complications were relieved or disappeared in varying degrees during the follow-up period, and there were no complications such as cage displacement and screw fracture. OLIF combined with unilateral pedicle screw fixation via Wiltse approach is effective in treating lumbar spinal stenosis with minimally invasive advantages such as less trauma and less complications. Under the premise of strictly grasping the indications, this method could also achieve satisfactory clinical results in multi-segments oprations.