Biomechanical evaluation of lateral lumbar interbody fusion with secondary augmentation.

OBJECTIVE Lateral lumbar interbody fusion (LLIF) has emerged as a popular method for lumbar fusion. In this study the authors aimed to quantify the biomechanical stability of an interbody implant inserted using the LLIF approach with and without various supplemental fixation methods, including an interspinous plate (IP). METHODS Seven human cadaveric L2-5 specimens were tested intact and in 6 instrumented conditions. The interbody implant was intended to be used with supplemental fixation. In this study, however, the interbody was also tested without supplemental fixation for a relative comparison of these conditions. The instrumented conditions were as follows: 1) interbody implant without supplemental fixation (LLIF construct); and interbody implant with supplemental fixation performed using 2) unilateral pedicle screws (UPS) and rod (LLIF + UPS construct); 3) bilateral pedicle screws (BPS) and rods (LLIF + BPS construct); 4) lateral screws and lateral plate (LP) (LLIF + LP construct); 5) interbody LP and IP (LLIF + LP + IP construct); and 6) IP (LLIF + IP construct). Nondestructive, nonconstraining torque (7.5 Nm maximum) induced flexion, extension, lateral bending, and axial rotation, whereas 3D specimen range of motion (ROM) was determined optoelectronically. RESULTS The LLIF construct reduced ROM by 67% in flexion, 52% in extension, 51% in lateral bending, and 44% in axial rotation relative to intact specimens (p < 0.001). Adding BPS to the LLIF construct caused ROM to decrease by 91% in flexion, 82% in extension and lateral bending, and 74% in axial rotation compared with intact specimens (p < 0.001), providing the greatest stability among the constructs. Adding UPS to the LLIF construct imparted approximately one-half the stability provided by LLIF + BPS constructs, demonstrating significantly smaller ROM than the LLIF construct in all directions (flexion, p = 0.037; extension, p < 0.001; lateral bending, p = 0.012) except axial rotation (p = 0.07). Compared with the LLIF construct, the LLIF + LP had a significant reduction in lateral bending (p = 0.012), a moderate reduction in axial rotation (p = 0.18), and almost no benefit to stability in flexion-extension (p = 0.86). The LLIF + LP + IP construct provided stability comparable to that of the LLIF + BPS. The LLIF + IP construct provided a significant decrease in ROM compared with that of the LLIF construct alone in flexion and extension (p = 0.002), but not in lateral bending (p = 0.80) and axial rotation (p = 0.24). No significant difference was seen in flexion, extension, or axial rotation between LLIF + BPS and LLIF + IP constructs. CONCLUSIONS The LLIF construct that was tested significantly decreased ROM in all directions of loading, which indicated a measure of inherent stability. The LP significantly improved the stability of the LLIF construct in lateral bending only. Adding an IP device to the LLIF construct significantly improves stability in sagittal plane rotation. The LLIF + LP + IP construct demonstrated stability comparable to that of the gold standard 360° fixation (LLIF + BPS).

G Protein-Coupled Estrogen Receptor Levels After Peripheral Nerve Injury in an Experimental Rat Model.

OBJECTIVE: To assess whether G protein-coupled estrogen receptor (GPER) levels were altered during crush-induced peripheral nerve injury in an experimental rat model. METHODS: Male Wistar rats (N = 80) were allocated to 1 sham and 6 study groups, and crush-type peripheral nerve injury was performed using a clamp on the sciatic nerves of study groups. In the sham group, the sciatic nerve was exposed only, and the wound was closed primarily without any surgical interventions. Peripheral nerve samples were obtained at 1 hour, 6 hours, 12 hours, 24 hours, 3 days, and 7 days. After analysis of nerve tissues by protein analysis and Western blotting, the groups were compared in terms of expression of GPER levels. RESULTS: The average levels of GPER in the sham group and study groups at 1 hour, 6 hours, 12 hours, 24 hours, 3 days, and 7 days were 15.06 ng/mL ± 2.91, 3.31 ng/mL ± 0.91, 4.06 ng/mL ± 0.87, 11.94 ng/mL ± 1.15, 10.76 ng/mL ± 1.76, 9.16 ng/mL ± 2.60, and 8.49 ng/mL ± 3.55. All study groups displayed significantly lower levels of GPER compared with the sham group. CONCLUSIONS: Our results demonstrate that a basal level of GPER expression occurs in peripheral nerve tissue. The lowest level was detected 1 hour after crush injury, and the highest levels of GPER were detected 12 hours and 24 hours after trauma. Further trials on larger series are required to elucidate the role of GPER in terms of protection and treatment after nerve injury.

Oxidative/Nitrosative Stress in Patients With Modic Changes: Preliminary Controlled Study.

STUDY DESIGN: Oxidative/nitrosative stress in vertebral endplates of patients with low back pain and Modic changes (MCs) (types I, II, and III) endplate changes on magnetic resonance imaging. OBJECTIVE: The aim of this study was to assess the levels of oxidative/nitrosative stress biomarkers in patients with MCs. SUMMARY OF BACKGROUND DATA: Degenerated discs and endplate abnormalities is postulated as a possible source of low back pain. Oxidative/nitrosative stress plays an important the role in various human diseases. However, the presence of oxidative/nitrosative stress has not been studied in patients with low back pain and endplate changes on magnetic resonance imaging. METHODS: Patients with MCI, II, and III (n = 32) and age- and sex-matched controls subjects (n = 15) were enrolled in this study. Also, 3-nitrotyrosine (3-NT) and nitric oxide levels as nitrosative stress biomarkers were measured with enzyme-linked immunosorbent assay. Also, the activities of catalase (CAT) and superoxide dismutase (SOD), and the levels of malondialdehyde (MDA) as oxidative stress biomarkers were determined on spectrophotometer. RESULTS: Oxidative/nitrosative stress was confirmed by the significant elevation in nitric oxide, 3-NT, MDA and decreased of CAT and SOD activities in MCI compared with other MCs and the control group (P < 0.05). The highest CAT and SOD activities were found in patients with MCII compared with the other MCs and the control group. However, the levels of nitric oxide, 3-NT, and MDA showed moderate increase in this group (P < 0.05). In addition, the levels of nitrosative stress biomarkers in patients with MCIII were approximated to the control values (P > 0.05). However, the levels of oxidative stress biomarkers in patients with MCIII were slightly higher than that of the control group (P < 0.05). CONCLUSION: Our findings indicated that oxidative/nitrosative stress in patients with MCI may be aggravated as a result of oxidant/antioxidant imbalance and it may cause formation of the lesion in these patients. However, the increased antioxidant activities and MDA, 3-NT levels in patients with MCII and MCIII may be an adaptative response to against oxidative/nitrosative stress. LEVEL OF EVIDENCE: 4.

Intraperitoneal Alpha-Lipoic Acid to prevent neural damage after crush injury to the rat sciatic nerve.

OBJECTIVE: Crush injury to the sciatic nerve causes oxidative stress. Alfa Lipoic acid (a-LA) is a neuroprotective metabolic antioxidant. This study was designed to investigate the antioxidant effects of pretreatment with a-LA on the crush injury of rat sciatic nerve. METHODS: Forty rats were randomized into four groups. Group I and Group II received saline (2 ml, intraperitoneally) and a-LA (100 mg/kg, 2 ml, intraperitoneally) in the groups III and IV at the 24 and 1 hour prior to the crush injury. In groups II, III and IV, the left sciatic nerve was exposed and compressed for 60 seconds with a jeweler's forceps. In Group I (n = 10), the sciatic nerve was explored but not crushed. In all groups of rats, superoxide dismutase (SOD) and catalase (CAT) activities, as well as malondialdehyde (MDA) levels were measured in samples of sciatic nerve tissue. RESULTS: Compared to Group I, Group II had significantly decreased tissue SOD and CAT activities and elevated MDA levels indicating crush injury (p < 0.05). In the a-LA treatment groups (groups III and IV), tissue CAT and SOD activities were significantly increased and MDA levels significantly decreased at the first hour (p < 0.05) and on the 3rd day (p < 0.05). There was no significant difference between a-LA treatment groups (p > 0.05). CONCLUSION: A-LA administered before crush injury of the sciatic nerve showed significant protective effects against crush injury by decreasing the oxidative stress. A-LA should be considered in the treatment of peripheral nerve injuries, but further studies are needed to explain the mechanism of its neuroprotective effects.

Combined anterior and posterior approach for sacral/retroperitoneal hydatid cyst disease: case report.

Achieving complete resolution of spinal hydatid cyst disease is quite challenging when bone is involved. Many authors reported the poor outcome of posterior decompression and laminectomy for intraosseous spinal hydatid disease. In an attempt to avoid a similar poor outcome, hydatid cysts were reached via both anterior and posterior surgical approaches in our patient. A 73-year-old man presented with complaints of low back and right leg pain. Symptoms or signs of systemic hydatid cyst disease were absent. MRI demonstrated a cystic lesion in the presacral/retroperitoneal region, involving the body of the sacrum and sacral canal. Computed tomography images showed enlargement of the sacral foraminae. The multiseptated cysts and their contents were isodense with cerebrospinal fluid. The cysts were removed via an anterior extraperitoneal approach, using a paramedian vertical incision, and then were also approached posteriorly via bilateral S1 hemilaminectomy. No neurological deficits occurred following surgery. The patient's symptoms completely disappeared after this combination of aggressive surgery and antihelminthic therapy. The application of both anterior and posterior approaches to intraosseous sacral hydatid cysts may be preferred when faced with hydatid disease in this location.