[A novel rabbit disc degeneration model induced by fibronectin fragment].

OBJECTIVE: To establish a novel and useful rabbit model of lumbar disc degeneration using microinjection of fibronectin fragment (Fn-f). METHODS: Thirty-two New Zealand white rabbits underwent injection of N-terminal 30 kDa Fn-f (experimental group) or phosphate buffered saline (PBS) (control group) into the central region of L1-2, L2-3, L3-4, L4-5 discs using a 32-gauge microsyringe. Two rabbits (blank group) with no treatments were sacrificed to examine the proteoglycan synthesis of neucleus pulposus (NP) using (35)S-sulfate incorporation assay. At the 4-, 8-, 12-, and 16-week time points, the discs were examined histologically, radiographically, and with proteoglycan synthesis. RESULTS: Histology demonstrated a progressive loss of the cell numbers in NP and architecture destruction in NP and anulus fibrosus (AF) in Fn-f-injected discs over the 16-week study period. The NP regions in Fn-f-injected discs shrinked distinctly after the 4-week time point, and were not discernible with the inner AF by the 16-week time point. Protoglycan synthesis in Fn-f-injected discs decreased progressively (F = 263.241, P = 0.000). At each time point, the Fn-f-injected discs showed significantly decreased proteoglycan synthesis compared with controls (t = -27.010 - -2.833, P < 0.05). The DHI% of the Fn-f-injected discs at the 4-, 8-, 12-, and 16-week time points were 96.5% ± 1.7%, 85.6% ± 3.8%, 77.2% ± 3.5% and 65.5% ± 5.6%, respectively. Comparing with the DHI% of PBS-injected discs (97.4% ± 1.2%), the Fn-f-injected discs exihibited no significant differences in disc heights at the 4-week time point (P > 0.05), but significant decreases in disc heights at the 8-, 12-, and 16-week time points (t = -21.225 - -10.795, P < 0.01). Apparent anterior osteophytes formed at the 12-week time point and enlarged remarkablely by the 16-week time point in the experimental spines. CONCLUSIONS: Fn-f can induce a progressively degenerative process in rabbit discs which is ethical, cost-effective, reproducible, and consistent with the spontaneous degeneration in human. And it seem to be a novel and useful model for the study of disc degeneration at the molecular level.

Does the Position of Cage Affect the Clinical Outcome of Lateral Interbody Fusion in Lumbar Spinal Stenosis?

STUDY DESIGN: A retrospective study. OBJECTIVE: This study aims to identify the ideal cage position in lateral lumbar interbody fusion (LLIF) and to investigate if the posterior instrumentation would affect the indirect decompression. METHODS: Patients underwent 2-stage surgeries: stage I was LLIF and stage II was percutaneous pedicle screws fixation after 1 week. Anterior disc height (ADH), posterior disc height (PDH), left and right foraminal height (FH), and segmental angle (SA) were measured on lateral computed tomography reconstructions. The cross-sectional area of the thecal sac (CSA) was determined by the outlined area of the thecal sac on a T2-weighted axial magnetic resonance imaging. The patients were subgroups according to the cage position: the anterior (cage located at the anterior 1/3 of disc space) and posterior groups (cage located at the posterior 2/3 of disc space). P values <.05 were considered significant. RESULTS: This study included 46 patients and 71 surgical levels. After stage I LLIF, significant increase in ADH, PDH, bilateral FH was found in both 2 subgroups, as well as the CSA (all Ps < .01). SA increased 2.84° ± 3.2° in the anterior group after stage I LLIF and increased 0.81° ± 3.1° in the posterior group (P = .013). After stage II surgery, SA was similar between the anterior and posterior groups (P = .20). CONCLUSION: The anteriorly placed cage may provide better improvement of anterior disc height and segmental angle after stand-alone LLIF surgery. After the second stage posterior instrumentation, the cage position would not affect the segmental angle or foraminal height.

Revision for Endoscopic Diskectomy: Is Lateral Lumbar Interbody Fusion an Option?

OBJECTIVE: This study aims to report the clinical outcome of stand-alone lateral lumbar interbody fusion (LLIF) on recurrent disk herniation and to compare the outcome of stand-alone LLIF to that of conventional transforaminal lumbar interbody fusion (TLIF). METHODS: A retrospective study of 47 patients with recurrent disk herniation was included from January 2008 to October 2016. The inclusion criteria were 1) with recurrent disk herniation that needs revision surgery, 2) with only 1 previous percutaneous endoscopic lumbar diskectomy surgery, 3) underwent 1-level stand-alone LLIF or 1-level TLIF surgery, and 4) with follow-up more than 1 year. Patients were asked to complete the following questionnaires for outcome evaluation: visual analog scales (VAS) for both low back pain and leg pain, the Oswestry Disability Index (ODI), and the 12-item Short-Form Health Survey. RESULTS: Eighteen patients underwent stand-alone LLIF, and 29 patients underwent TLIF surgery. Radiographic analysis revealed a similar baseline and postoperative lumbar lordosis in both the LLIF and TLIF groups. Two weeks after surgery, the ODI and VAS scores showed a significant decrease in both groups. The TLIF group showed significantly larger postoperative VAS back pain after surgery (P = 0.03). For both VAS leg pain and ODI score during follow-up, no significance difference was found between the LLIF and TLIF groups. CONCLUSIONS: Stand-alone LLIF is a safe and effective approach with low morbidity and acceptable complication rates for patients with recurrent disk herniation after a previous percutaneous endoscopic lumbar diskectomy surgery. Compared with the TLIF procedure, LLIF could achieve a similar improvement of patient-reported outcome with a better VAS back pain score.

Effect of rAAV2-hTGFß1 Gene Transfer on Matrix Synthesis in an In Vivo Rabbit Disk Degeneration Model.

STUDY DESIGN: In vivo gene transfer for disk regeneration. OBJECTIVE: To evaluate the efficiency and effect of human transforming growth factor ß1 (hTGFß1) gene transfer mediated by adeno-associated virus (AAV) in a rabbit disk degeneration model induced by fibronectin fragment (Fn-f). SUMMARY OF BACKGROUND DATA: Gene therapy for disk degeneration has been reported to be effective. Nevertheless, few investigations have targeted the degenerative nucleus pulposus (NP) cells in vivo. Fn-f-induced degeneration has been previously verified to be a useful model for the study of disk degeneration at the molecular level. AAV vector is well suited for gene transfer in the disk for its lower immunogenicity and higher safety. MATERIALS AND METHODS: The early dedifferentiated NP cells were transfected with rAAV2-mediated enhanced green fluorescent protein (EGFP) gene in vitro. Fluorescence expression was observed 48 hours later. The rabbit disk degeneration model was established with a microinjection of Fn-f. Ninety-six degenerative disks of 24 rabbits were injected with rAAV2-hTGFß1 (group A), rAAV2-EGFP (group B), or PBS (group C). Immunohistochemical staining for hTGFß1 and fluorescence observation were performed at the 1- and 12-week time points, respectively. 35S-sulfate incorporation assay and Western blot analysis were used to measure the synthesis of proteoglycan and collagen type II at 4-, 8-, and 12-week time points. RESULTS: The dedifferentiated NP cells exhibited intensive fluorescence expression in vitro, with a transfection rate of 90%. In vivo, disks in group A showed enhanced positive hTGFß1 immunostaining at the 1-week time point. At the 4-, 8-, and 12-week time points, disks in group A exhibited significantly increased proteoglycan and collagen type II synthesis compared with the other 2 groups (P<0.01). Abundant green fluorescence was observed in the disks in group B at the 12-week time point. CONCLUSIONS: Early degenerative NP cells are susceptible to AAV-mediated gene transfer in vitro and in vivo. The rapid and prolonged target protein expressions and increased matrix synthesis indicated that AAV-mediated therapeutic gene transfer can be a promising form of treatment for disk regeneration in vivo.

A novel rabbit disc degeneration model induced by fibronectin fragment.

OBJECTIVE: To establish a novel and useful rabbit model of lumbar disc degeneration using microinjection of a fibronectin fragment. METHODS: Thirty-two rabbits underwent injection of N-terminal 30 kDa fibronectin fragment (Fn-f) (Group A, n=12; Group B, n=4) or phosphate buffered saline (PBS) (Group C, n=12; Group D, n=4) into the lumbar discs using a 32-gauge microsyringe. Two rabbits (Group E) with no treatment were sacrificed to examine the proteoglycan synthesis of neucleus pulposus (NP) using (35)S-sulfate incorporation assay. At the 4-, 8-, 12-, and 16-week time points, the discs were examined histologically, radiographically and with proteoglycan synthesis. RESULTS: (1) Histology demonstrated a progressive loss of cell numbers in NP and architecture disorganization in NP and annulus fibrosus (AF) over the study period. (2) Radiology: comparing with the PBS-injected discs, the Fn-f-injected discs exhibited no significant differences in disc heights at the 4-week time point, but significant decreases in disc heights at the 8-, 12-, and 16-week time points (P<0.01). Apparent anterior osteophytes formed at the 12-week time point and enlarged remarkably by the 16-week time point in the Fn-f-injected spines. (3) Protoglycan synthesis in the Fn-f-injected discs decreased progressively (P<0.01). At each time point, the Fn-f-injected discs showed significantly decreased proteoglycan synthesis compared with controls (P<0.05 or P<0.01). CONCLUSIONS: Fn-f induced a progressively degenerative process in rabbit discs, which was consistent with the spontaneous degeneration in human. Fn-f induced degeneration seemed to be a novel and useful model for the study of disc degeneration at the molecular level.

Platelet-rich plasma gel in combination with Schwann cells for repair of sciatic nerve injury.

Bone marrow mesenchymal stem cells were isolated from New Zealand white rabbits, culture-expanded and differentiated into Schwann cell-like cells. Autologous platelet-rich plasma and Schwann cell-like cells were mixed in suspension at a density of 1 × 10(6) cells/mL, prior to introduction into a poly (lactic-co-glycolic acid) conduit. Fabricated tissue-engineered nerves were implanted into rabbits to bridge 10 mm sciatic nerve defects (platelet-rich plasma group). Controls were established using fibrin as the seeding matrix for Schwann cell-like cells at identical density to construct tissue-engineered nerves (fibrin group). Twelve weeks after implantation, toluidine blue staining and scanning electron microscopy were used to demonstrate an increase in the number of regenerating nerve fibers and thickness of the myelin sheath in the platelet-rich plasma group compared with the fibrin group. Fluoro-gold retrograde labeling revealed that the number of Fluoro-gold-positive neurons in the dorsal root ganglion and the spinal cord anterior horn was greater in the platelet-rich plasma group than in the fibrin group. Electrophysiological examination confirmed that compound muscle action potential and nerve conduction velocity were superior in the platelet-rich plasma group compared with the fibrin group. These results indicate that autologous platelet-rich plasma gel can effectively serve as a seeding matrix for Schwann cell-like cells to construct tissue-engineered nerves to promote peripheral nerve regeneration.

Computer-assisted virtual surgical procedure for acetabular fractures based on real CT data.

OBJECTIVE: To develop and evaluate a computer-assisted virtual surgical procedure for preoperative planning that simulates the reduction and plate fixation for acetabular fractures based on real computed tomography (CT) data using computer softwares on personal computers. METHODS: Virtual preoperative planning for reduction and plate fixation for seven acetabular fractures was performed. Three-dimensional (3D) models of acetabular fractures based on real CT data in Dicom format were built to perform reduction first. Then fixation was undertaken after plate contouring. Virtual planning was compared with real surgery with respect to operative approach, plate length and screw count. Furthermore, the time required for virtual surgery was recorded. RESULTS: Virtual surgery was successfully achieved and identical to the real operation in all cases. The mean time required was 79 min. CONCLUSION: The virtual surgical procedure for acetabular fractures is feasible and useful clinically for surgeons to determine surgical planning. It may be a valuable tool for surgeons in learning about the nature of the fracture and in formulating an appropriate surgical plan.

Three-dimensional computed tomography imaging increases the reliability of classification systems for tibial plateau fractures.

OBJECTIVE: The purpose of this study was to determine whether three-dimensional reconstructed computed tomography (CT) images can improve intra-observer and inter-observer reliability for classification systems of tibial plateau fractures compared to plain radiographs and two-dimensional CT images. METHODS: Twenty-one tibial plateau fractures were classified independently by four attending orthopaedic trauma surgeons using the AO/ASIF and Schatzker classification systems. First, a combination of plain radiographs and two-dimensional (2D) CT images were evaluated. Second, 4 weeks later, plain radiographs and three-dimensional (3D) CT images were assessed. Then, 4 weeks later, these two rounds of evaluation were repeated. The intra-observer and inter-observer reliability were assessed using kappa statistics. RESULTS: Three-dimensional CT images can improve the inter-observer and intra-observer reliability regarding both AO/ASIF and Schatzker classification systems of tibial plateau fractures compared to 2D CT images. The degree of agreement of the inter-observer and intra-observer reliability among four surgeons increased from 'substantial' to 'almost perfect'. CONCLUSION: Three-dimensional CT is a more reliable radiographic modality than 2D CT in evaluation of fracture patterns in tibial plateau fractures. This finding seems to show that more sophisticated imaging techniques can improve the reliability of fracture classification systems.