Application of Laparoscopic Lumbar Discectomy and Artificial Disc Replacement: At Least Two Years of Follow-Up

Feasibility of anterior pedicle screw fixation in lumbosacral spine: a radiographic and cadaveric study

Background

The anterior pedicle screw (APS) technique for L5 and S1 is crucial for proper anterior lumbar interbody fusion (ALIF). This study aimed to determine the projection, screw trajectory angle, and bone screw passageway length (BSPL), as well as the screw insertion regularity and the operating area within which it is safe to perform insertion.

Methods

Forty patients with low back pain, all of whom had lumbar computed tomography scans available, was included in this retrospective analysis. Radiographic parameters were measured, including: the distances from the projection to the upper endplate, lower endplate, and midline; the transverse and sagittal screw angles; and the BSPL. In addition, 10 fresh adult cadaveric lumbosacral spine segments were selected to determine the safe anatomic area in which to operate. Finally, APSs were inserted in L5 and S1 to determine the regularity of APS insertion.

Results

We measured the anterior projection parameters, including: the distances to the upper endplate (L5: 12.5±1.3 mm; S1: 4.54±0.87 mm), lower endplate (L5: 17.3±1.6 mm), and midline (L5: 6.6±0.7 mm; S1: 6.6±0.6 mm); the screw trajectory angle, including the transverse screw angle (L5: 25.3±2.8°; S1: 25.7±2.6°), sagittal screw angle (L5: 17.1±1.7°; S1: 22.4±1.1°); and the BSPL (L5: 48.6±3.5 mm; S1: 48.0±3.5 mm). The regularity of APS insertion in L5 and S1 was determined. Upon the needle reaching a point in the lateral view, it reached the corresponding point in the anteroposterior (AP) view. The anatomic parameters of the safe operating area were as follows: the distance from the abdominal aortic bifurcation to the L5 lower edge (40.50±9.40 mm); the distance from the common iliac vein confluence to the L5 lower edge (27.80±8.60 mm); and the horizontal distance from the inner edge of the common iliac vein to the L5 lower edge (37.50±1.30 mm). We also determined the distance between S1 holes (29.30±1.30 mm), the L5/S1 intervertebral height (17.20±1.50 mm), and the safe operating area (2,058.20±84.30 mm²).

Conclusions

This study has determined the projection, screw trajectory angle, and BSPL of APSs in L5 and S1, their insertion regularity, and the area in which the operation can be safely performed.

Biomechanical properties of a novel nonfusion artificial vertebral body for anterior lumbar vertebra resection and internal fixation

The aim of the study was to evaluate the biomechanical properties of a novel nonfused artificial vertebral body in treating lumbar diseases and to compare with those of the fusion artificial vertebral body. An intact finite element model of the L1–L5 lumbar spine was constructed and validated. Then, the finite element models of the fusion group and nonfusion group were constructed by replacing the L3 vertebral body and adjacent intervertebral discs with prostheses. For all finite element models, an axial preload of 500 N and another 10 N m imposed on the superior surface of L1. The range of motion and stress peaks in the adjacent discs, endplates, and facet joints were compared among the three groups. The ranges of motion of the L1–2 and L4–5 discs in flexion, extension, left lateral bending, right lateral bending, left rotation and right rotation were greater in the fusion group than those in the intact group and nonfusion group. The fusion group induced the greatest stress peaks in the adjacent discs and adjacent facet joints compared to the intact group and nonfusion group. The nonfused artificial vertebral body could better retain mobility of the surgical site after implantation (3.6°–8.7°), avoid increased mobility and stress of the adjacent discs and facet joints.

Lumbar subtotal corpectomy non-fusion model produced using a novel prosthesis

OBJECTIVE

In this study, we aimed to design a movable artificial lumbar complex (MALC) prosthesis for non-fusion reconstruction after lumbar subtotal corpectomy and to establish an in vitro anterolateral lumbar corpectomy non-fusion model for evaluating the biomechanical stability, preservation of segment movements and influence on adjacent inter-vertebral movements of this prosthesis.

METHODS

Imaging was performed on a total of 26 fresh goat lumbar spine specimens to determine which of the specimens did not meet the requirements (free of deformity and fractures); the residual specimens were randomly divided into an intact group, a fusion group and a non-fusion group. Bone mineral density (BMD) was tested and compared among the three groups. Biomechanical testing was conducted to obtain the range of motion (ROM) in flexion-extension, lateral bending at L2-3, L3-4 and L4-5 and axial rotation at L2-5 in the three groups.

RESULTS

Two specimens were excluded due to vertebral fractures. BMD showed no statistical significance among three groups (P > 0.05). The stability of the prosthesis did not differ significantly during flexion, extension, and lateral bending at L2-3, L3-4, and L4-5 and axial torsion at L2-5 between the intact group and the non-fusion group (P > 0.05). Segment movements of the specimens in the non-fusion group revealed significantly decreased L2-3 ROM and significantly increased L3-4 and L4-5 ROM in flexion and lateral bending compared with the fusion group (P < 0.05).

CONCLUSIONS

Reconstruction with a MALC prosthesis after lumbar subtotal corpectomy not only produced instant stability but also effectively preserved segment movements, without any abnormal gain of mobility in adjacent inter-vertebral spaces. However, additional studies, including in vivo animal experiments as well as biocompatibility and biomechanical tests of human body specimens are needed.

Application of anterior debridement and reconstruction with anatomical screw-plate fixation for lumbosacral tuberculosis: A 2-year-plus follow-up

This study aimed to determine the efficacy and safety of anterior debridement and reconstruction with anatomical screw-plate fixation in patients with lumbosacral junction tuberculosis (TB).A total of 48 patients (30 males and 18 females) diagnosed with lumbosacral junction TB were included in this study. All patients underwent surgery in our institution from January 2008 to July 2014, using anterior debridement and reconstruction with anatomical screw-plate. Outcome data were evaluated before and after surgery and included lumbosacral angle, Frankel classification, bone fusion, and visual analog scale (VAS) scores.All patients were then followed up for an average of 49.4 months (range, 24-96 months). The mean lumbosacral angle improved from 8.36° ± 5.92° pre-operation to 22.38° ± 4.52° post-operation and 21.13° ± 3.73° during the final follow-up (both P < .05). Solid vertebral fusion was achieved in all patients after 7.6 months on average (range, 6-12 months). No severe complications appeared during operation and post-operation. Neurological performance and VAS scores were significantly improved compared with pre-operation (P < .05).Following standard anti-TB chemotherapy, anterior debridement and reconstruction with anatomical screw-plate fixation may be a feasible and effective therapeutical option for lumbosacral junction TB. This procedure can result in satisfactory bone fusion and deformity correction, and effectively restore lumbosacral junction stability.