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BACKGROUND: Endoscopic transforaminal lumbar interbody fusion is a breakthrough technique for effective treatment of lumbar degenerative diseases. It has the advantages of less trauma, fast recovery, less bleeding, clear vision of water medium, decompression of nerve roots under direct vision, and treatment of the endplate under direct vision to increase the fusion rate. At present, there are few researches on the internal fixation based on endoscopic transforaminal lumbar interbody fusion. OBJECTIVE: To observe the effect of unilateral pedicle screw combined with contralateral translaminar facet screw fixation, unilateral pedicle screw fixation, and bilateral pedicle screw fixation on the biomechanics of lumbar vertebra after endoscopic transforaminal lumbar interbody fusion and to verify the reliability and effectiveness of unilateral pedicle screw combined with contralateral translaminar facet screw fixation. METHODS: By establishing an element model of endoscopic transforaminal lumbar interbody fusion, the effects of unilateral pedicle screw combined with contralateral translaminar facet screw fixation, unilateral pedicle screw fixation, and bilateral pedicle screw fixation on the overall displacement of the model, stress of intervertebral fusion cage and pedicle screw, and stress-strain of adjacent discs were analyzed. RESULTS AND CONCLUSION: (1) Compared with unilateral pedicle screw combined with contralateral translaminar facet screw fixation, overall displacement, screw and rod system stress, and intervertebral cage stress were significantly increased in models with unilateral pedicle screw fixation. (2) Overall displacement, screw and rod system stress, and intervertebral cage stress were basically the same under six operating conditions between the bilateral pedicle screw fixation and unilateral pedicle screw combined with contralateral translaminar facet screw fixation. (3) There was no significant difference in the stress of the adjacent intervertebral disc under the three fixation methods, and the change trend was basically the same. (4) It is confirmed that unilateral pedicle screw combined with contralateral translaminar facet screw fixation have good biomechanical properties. [ABSTRACT FROM AUTHOR]

It is technically demanding and requires rich experience to insert the translaminar facet screw(TFS) via the paramedian mini-incision approach. It seems that it is easy to place the TFS using computer-assisted design and rapid prototyping(RP) techniques. However, the accuracy and safety of these techniques is still unknown. The aim of this study is to assess the accuracy and safety of translaminar facet screw placement in multilevel unilateral transforaminal lumbar interbody fusion using a rapid prototyping drill guide template system. A patient-matched rapid prototyping translaminar facet screw guide was examined in fourteen cadaveric lumbar spine specimens. A three-dimensional (3D) preoperative screw trajectory was constructed using spinal computed tomography scans, from which individualized guides were developed for the placement of translaminar facet screws. Following bone tunnel establishment, the 3D positioning of the entry point and trajectory of the screws was compared to the preoperative plan as found in the Mimics software.Among 60 trajectories eligible for assessment, no cases of clinically significant laminar perforation were found. The mean deviation between the planned and the actual starting points on spinous process was 1.22 mm. The mean tail and submergence angle deviation was found to be 0.68°and 1.46°, respectively. Among all the deviations, none were found to have any statistical significance. These results indicate that translaminar facet screw placement using the guide system is both accurate and safe.

Little is known about the biomechanical performance of various fixation constructs after oblique lumbar interbody fusion (OLIF). This study aimed to explore the stability of various fixation options for OLIF by using finite element analysis based on three-dimensional scanning models. Six validated finite element models of the L3-L5 segment were reconstructed via computed tomography images, including (1) intact model, (2) stand-alone model with no instrument, (3) lateral rod-screw model, (4) lateral rod-screw plus contralateral translaminar facet screw (LRS-CTLFS) model, (5) unilateral pedicle screw model, and (6) bilateral pedicle screw (BPS) model. Models of the OLIF cage and pedicle screw were created with three-dimensional scanning to improve the accuracy of finite element analysis. Range of motion, stress of the cage, and stress of fixation were evaluated in the different models. Range of motion increased from least to greatest as follows: BPS, LRS-CTLFS, unilateral pedicle screw, lateral rod-screw, stand-alone. Differences in range of motion between BPS and LRS-CTLFS were not significant for all loading cases. Compared with the other 3 models, the stress of the cage was found to be lower in BPS and LRS-CTLFS under all loading conditions, especially in BPS. Stress exerted on the fixation was the greatest in LRS-CTLFS, and the stress experienced by the translaminar facet screw was concentrated in part of the facet joint. The BPS model provided the best biomechanical stability for OLIF; the stand-alone model could not provide sufficient stability. The LRS-CTLFS procedure increases the approximate stability and reduces stress at the cage-endplate interface; however, it causes an increase in screw stress. [ABSTRACT FROM AUTHOR]

Background: There are various posterior fixations utilized with transforaminal lumbar interbody fusion (TLIF). Previous studies have focused on the comparison of two fixation techniques. Materials and Methods: Sixty five patients with single-level lumbar disease were included in this retrospective study. Group A was treated by TLIF with bilateral pedicle screw (BPS), Group B treated by TLIF with unilateral pedicle screw (UPS), and Group C treated by TLIF with UPS plus contralateral translaminar facet screw (UPSFS). The operative time, blood loss, Oswestry disability index (ODI), Japanese Orthopaedic Association Scores (JOA), and visual analog scores (VAS) were recorded. Radiographic examination was used to assess fusion rates and incidence of screw failure. Results: The blood loss and operative times were 188.69 ± 37.69 ml and 132.96.5 ± 8.69 min in BPS group, 117.27 ± 27.11 ml and 99.32 ± 12.94 min in UPS group, and 121.50 ± 22.54 ml and 112.55 ± 9.42 min in UPSFS group; UPS and UPSFS were better than BPS (P < 0.05). The mean followup time was 38.2 months. Fusion rates were – BPS group: 95.6%, UPS group: 90%, UPSFS: 95% (P > 0.05). Screw and/or rod failures were found in three groups (BPS group: 1, UPS group: 2 and UPSFS: 1, P > 0.05). The average postoperative VAS, ODI, and JOA scores of BPS, UPS, and UPSFS were improved significantly in each group compared to preoperative scores (P < 0.05); there were no significant differences between any two groups at each followup time point (P > 0.05). Conclusion: UPSFS with TLIF is a viable treatment option that provides satisfactory clinical results; the clinical outcome and the complication rate were comparable to BPS. In addition, the invasive of UPSFS cases was comparable to UPS and better than BPS cases. For UPS, it could be used in suitable patients. [ABSTRACT FROM AUTHOR]

It is technically demanding and requires rich experience to insert the translaminar facet screw(TFS) via the paramedian mini-incision approach. It seems that it is easy to place the TFS using computer-assisted design and rapid prototyping(RP) techniques. However, the accuracy and safety of these techniques is still unknown. The aim of this study is to assess the accuracy and safety of translaminar facet screw placement in multilevel unilateral transforaminal lumbar interbody fusion using a rapid prototyping drill guide template system. A patient-matched rapid prototyping translaminar facet screw guide was examined in fourteen cadaveric lumbar spine specimens. A three-dimensional (3D) preoperative screw trajectory was constructed using spinal computed tomography scans, from which individualized guides were developed for the placement of translaminar facet screws. Following bone tunnel establishment, the 3D positioning of the entry point and trajectory of the screws was compared to the preoperative plan as found in the Mimics software.Among 60 trajectories eligible for assessment, no cases of clinically significant laminar perforation were found. The mean deviation between the planned and the actual starting points on spinous process was 1.22 mm. The mean tail and submergence angle deviation was found to be 0.68°and 1.46°, respectively. Among all the deviations, none were found to have any statistical significance. These results indicate that translaminar facet screw placement using the guide system is both accurate and safe. [ABSTRACT FROM AUTHOR]

Background: Transforaminal lumbar interbody fusion (TLIF) has been used in lumbar degenerative diseases. Some researchers have applied unilateral fixation in TLIF to reduce operational trauma without compromising the clinical outcome, but it is always suspected biomechanically unstable. The supplementary contralateral translaminar facet screw (cTLFS) seemed to be able to overcome the inherent drawbacks of unilateral pedicle screw (uPS) fixation theoretically. This study evaluates the safety, feasibility and efficacy of TLIF using uPS with cTLFS fixation in the treatment of lumbar degenerative diseases (LDD). Materials and Methods: 50 patients (29 male) underwent the aforementioned surgical technique for their LDD between December 2009 and April 2012. The results were evaluated based on visual analogue scale (VAS) of the leg and back, Japanese Orthopedic Association (JOA) score and Oswestry Disability Index (ODI) were recorded. The radiographic examinations in form of X‑ray, computed tomography (CT) or magnetic resonance imaging was done preoperatively and 1 week, 3 months, 6 months, 12 months and 24 months postoperatively. The student t‑test was used for comparison between the preoperative values and postoperative counterparts. P < 0.05 was considered to be statistically significant. Results: Among 50 patients, 22 received one level fusion and 28 two level’s, with corresponding operation time and estimated blood loss being approximately 90 min, 150 ml and 120 min, 200 ml, respectively. No severe complications happened perioperatively. The mean VAS (back, leg) scores dropped from (7.6, 7.5) preoperatively to (2.1, 0.6) at 12 months’ followup, ODI from 49.1 preoperatively to 5.6 and JOA score raised from 10.6 preoperatively to 28.5, all P < 0.001, suggesting of good clinical outcome. From the three‑dimensional reconstructed CT, 62 out of 70 segments displayed solid fusion with fusion rate of 88.6% at 12 months postoperatively. Conclusions: TLIF using uPS fixation plus cTLFS fixation is a safe, feasible and effective technique in the treatment of one or two level lumbar degenerative diseases short termly. [ABSTRACT FROM AUTHOR]

Translaminar facet screw fixation (TLFS) achieves stabilization of the vertebral motion segment by screws inserted at the base of the spinous process, through the opposite lamina, traversing the facet joint, and ending in the base of the transverse process. It is simple, does not require any specialized equipment, and has the advantages of being a procedure of lesser magnitude, lesser operative time, less cost and few complication rate. Recently there is growing interest in this technique to augment the anterior lumbar fusions to achieve global fusion less invasively. In this review article, we discuss the clinical and biomechanical considerations, surgical technique, indications, contraindications and recent developments of TLFS fixation in lumbar spine fusion. [ABSTRACT FROM AUTHOR]

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